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The Cosmos in a Heartbeat 1: A Love Affair with the Cosmos

by Shane L. Larson

The night sky over the Pando Forest in central Utah. Pando is an 80,000 year old aspen grove — it has seen almost 30 million nights like this one, far more than any single human will ever live through. [Image: Shane L. Larson]

The Cosmos is vast in ways that are difficult for humans to wrap their brains around. That doesn’t stop us from talking about it, of course, but it is vast, none-the-less. What do I mean by “vast?

The Universe is 13.8 BILLION years old, 100 million times older than the oldest human. When you and I go out at night there are almost 10,000 individual stars we can see with the naked eye, but the Milky Way has some 400 BILLION individual stars, and there are some 500 BILLION individual galaxies in all the Cosmos. If you and I could somehow take a road trip, from one side of the Milky Way to the other, travelling at the fastest speed possible (the speed of light) it would take us 100,000 years to go from one side to the other —1000 times longer than any human has ever lived. And the entire Cosmos itself is far vaster.

These sorts of factoids are fun to know and think about. They melt your brain, and they can impress your friends and family at a dinner party. But what is always remarkable to me is even though you and I occupy only one small part of the Cosmos in space and time, we have still managed to piece together a story about the history of the Universe — its overall size and content, when it was born, how it has lived its long life to date, and what its ultimate future might be.  As a species, we have only been cognizant of the science we call astronomy for a few centuries, though we have been looking outward into the Cosmos for far longer. But in those few centuries, in just a handful of human lifetimes, we have managed to piece the story together. Even though a human only lives through the merest flash of a moment in Cosmic time, less than a single heartbeat in the life of the Cosmos.  This is a story about how we learn what we learn about the Universe around us and our place within it.

Me in elementary school. I’m not sure what I’m doing in this picture, but I’m pretty sure I’m not getting into trouble [Image: Pat Larson]

I am a professional astronomer, but like most of us, my love-affair with the Cosmos began when I was young. I would spend long hours out in the backyard, laying on the ground trying to learn my constellations with an old beat-up paper star wheel. We didn’t have a telescope (they were expensive), but my mom is an avid birder and she had an old spotting scope. She used to let me take it out in the backyard and put it on an old card table, and I discovered there was far more to the Cosmos than my naked eye could see. I looked at the Moon and discovered craters, and mountains and sinuous canyons. I looked at the brightest points of light I could see, and found out they were Mars, and Jupiter, and Saturn — other worlds, tantalizingly close, but so very far away. There were other things to discover as well.

My Mom’s spotting scope (she still has it!). This is the first telescope I ever looked at the sky with.

In the corner of the sky we call Andromeda, there is a smudge of light that looks like a wisp of cloud. It is the most distant object you can see with your naked eye, and we call it the Andromeda Galaxy. It is 2.1 million light years away, which means if you step outside tonight and look at the Andromeda Galaxy, the light that falls in your eye and makes its impression on your mind is ancient light. It left the Andromeda Galaxy 2 million years ago, at a time when the most advanced hominids on Earth were Australopithecus, and the world was dominated by mega-fauna like sabre-toothed cats (smilodons) and mastodons. This is one of the fundamental truths in astronomy: looking out is looking back in time, and the farther we can look, the more about the long history of the Cosmos we can discern. As astronomers we are always on an epic quest to build better tools to help us probe farther out into the Cosmos. 

My first astronomical telescope, an 8-inch reflector I built called Albireo, based on Richard Berry’s excellent book “Build your own telescope” .[Image: Shane L. Larson]

Let’s look back to the time when I decided to become a professional astronomer, sometime during my early years in college. Thirty years ago, in 1988, I was already improving my backyard astronomy. I’d left my mom’s spotting scope at home, and after not too long had built my own telescope. It was bigger than my mom’s spotting scope, and could see much more of the Universe. At the same time, the largest telescope used by professional astronomers was the 5-meter (200-inch) Hale Telescope on Mount Palomar. At that time, it was the largest telescope in the world, a title it had held for 40 years since it was built in 1948. Astronomers are still using it today.

The 5-meter Hale Telescope on Mount Palomar was the largest telescope in the world for 40+ years. This image was taken in the dome on a night in 2009 when one of our observing runs was clouded out. Astronomers still use this telescope today. [Image: Shane L. Larson]

So what do astronomers do with these great machines? On any given night, whether you are looking through a backyard telescope, or looking through a telescope like the Hale, the sky looks much like it did the night before. The stars are still where you remember them, living out their lives slowly, changing little. We find new and interesting things, of course, but what we are often most interested in are the unexpected events — energetic and dramatic events that appear in the sky and then are gone. Astronomers call such things “transients.” Consider a “supernova.” One of the things we have learned over the past century is that stars, like people, are born, they live long lives, and they ultimately perish. When the most massive stars reach the ends of their lives, they die in a titanic explosion that, for a few brief days or weeks, sheds enough light to be visible in the night sky. The last time an explosion like this was seen in the Milky Way was in 1604, before the first telescope was ever used to study the sky!  Four hundred years ago, we didn’t know what supernovae were, but the events were momentous enough to note down.

An astrolabe from the Adler Planetarium collection, showing the Supernova of 1604. [Image: Adler Planetarium, notations from Pedro Raposo]

You can find written notations of the 1604 supernova in paper star atlases of the day, but one of my favorites is shown in the astrolabe above, which is part of the Adler Planetarium’s historical collection. An astrolabe is a mechanical device used to visually measure the positions of stars in the sky by eye. They are elaborate and intricate machines, but also stunning and artistic in their elegance and form.You’ll see on the upper right ring of this astrolabe that Supernova 1604 is marked, preserved forever in the solid copper record of the day. You’ll notice there are other transients on this astrolabe, including the previous supernova observed in the Milky Way (Supernova 1572), as well as the great comet of 1618.  My colleague Pedro Raposo, an astronomy historian at the Adler Planetarium, points out that depicting supernova and comets on an astrolabe is an indicator of how our understanding of the Universe was evolving. At that time, we didn’t know what supernovae and comets were. Their nature was widely debated, with many believing they were atmospheric phenomena. The fact that they were recorded on a mechanical starmap is an indicator that we were slowly coming to the understanding that these events were in the deep, cosmic sky. Our views about the Cosmos were changing.

Supernova 1987a, imaged by the Hubble Space Telescope in 1995, eight years after the explosion. [Image: STScI/NASA/ESA]

Now spool ahead to the 1980s. In 1988 we understood much more about supernovae than we did when that astrolabe was built, but we had never been given the opportunity to study one up close. In the entire 400 year history of telescopic astronomy, there has not been a supernova here in our own galaxy, close enough for us to see all the fine details and study how stars reach the end of their lives. But on 23 February 1987, there was a supernova not too far away, in a small galaxy next door to the Milky Way, called the Large Magellanic Cloud. We called it Supernova 1987A, and it was visible to the eye for several months. Astronomers could see it in their telescopes, and still today the most powerful telescopes can detect the faint echoes of light coming from the explosion.

But SN1987A was special for another reason. When a star dies in a supernova, it not only sheds light, it also releases a cosmic rain of particles called neutrinos. When this supernova exploded, 1057 neutrinos were released (that’s 100,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000 neutrinos!), bursting out in every direction in the Universe. Neutrinos are notoriously hard to detect because they tend to go blasting right through matter as if it isn’t even there. When the neutrino burst from SN 1987A reached Earth, 30 trillion of them went through me and you and every other person on planet Earth, and we didn’t even know it! But astronomers had been thinking about this for a long time, and had constructed a special observatory — a neutrino telescope.

The Kamioka Observatory “KamiokaNDE” experiment, one of the neutrino observatories that captured a few of the neutrinos from SN1987a. [Image: ICRR/University of Tokyo]

A neutrino telescope is not like an ordinary telescope, because neutrinos are very difficult to capture. Instead neutrino telescopes watch for neutrinos interacting with other things. In 1987, the worlds largest neutrino telescopes were enormous tanks of very pure water underground. Sometimes when a neutrino goes through these tanks, their interaction with the atoms in the water generates bursts of light that can be detected with very sensitive cameras lining the inside walls of the tank. In the hours right before telescopes detected the light from the supernova, 25 neutrinos were seen in detectors around the world. Only 25 neutrinos from all the 1057 that were released in the supernova, but it was enough to convince astronomers they had seen neutrinos from the supernova. This was the first time in history that astronomers had detected an astrophysical event with light AND particles; this was the beginning of what we now call “multi-messenger astronomy.” It was a watershed moment in our quest to probe the Cosmos — we had, for the first time, used two machines to probe the Cosmos using different pieces of information together to make one story. It was the beginning of a new way of thinking and learning about the Universe, and it is a story that is still going on today.

This was the frontier of astronomy 30 years ago. In our next post, we’ll fast-forward to today and ponder how we plumb the deep sky with all our modern technology and combine it with the meager knowledge that we’ve gained over the past few decades.

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This post is the first of three based on a talk I have given many times over the last few years, updating it each time to reflect the latest coolest things. The next two posts in the series are:

The Cosmos in a Heartbeat 2:

The Cosmos in a Heartbeat 3: 

This post was enabled by a new version of the talk done as a Kavli Fulldome Lecture at the Adler Planetarium in Chicago. I would like to thank all my colleagues at Adler who worked so hard to translate what was in my brain into a story told in the immersive cradle of the Grangier Sky Theater. The talk was given on 9 Nov and 10 Nov 2018, and captured in 3D. You can watch it on YouTube using GoogleCardboard. When I have the link, I’ll post it here.

I also put this post up today to celebrate the occasion of Carl Sagan’s birthday. I, like many around me, was inspired at the right moment by exposure to Sagan’s “Cosmos: A Personal Voyage”. Friday (9 Nov 2018) would have been Carl’s 84th birthday. He left us more than 20  years ago now, but I still hear his voice when I think about and ponder the deep mysteries of the Cosmos around us. Happy birthday, Carl.

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The Aquarius Project 2: Into the Deep Void

by Shane L. Larson

When you stand on the shores of Lake Michigan, you cannot see the far shore. Many days of the year, the surf is a gentle lapping over stones or against breakwaters, but there are definitely days when weather whips the water into a frenzy, tossing up waves worthy of ocean waves. You can’t help but notice it is big water. 

Lake Michigan is the second largest of the Great Lakes, covering an area of 58,000 square kilometers and harboring 4918 cubic kilometers of water. In the early morning hours of 6 Feb 2017, a hunk of debris from outer space hurtled into Earth’s atmosphere, somewhere in the skies slightly to the west of Kewaskum, Wisconsin. Leaving a glittering trail of burning dust and shining brightly enough to cast shadows across the dark winter landscape of the Midwest, this space rock broke up and the fragments rained down about 10 miles off-shore in Lake Michigan, near Sheboygan, Wisconsin. Despite happening at roughly 1:30am, 511 people across the midwest reported seeing it. All those reports, together with a few others we had heard, let us make a good guess where it might have fallen in the Lake.

Here “we” are myself and colleagues from the Adler Planetarium, the Field Museum, and the Shedd Aquarium. “We” are a few professional scientists and (sorta) grown-ups, and a remarkable group of young people from the Adler, called “The Adler Teens.”  In the grandest tradition of scientific adventures, we decided it might be fun to go look for fragments of this space rock. On the bottom of Lake Michigan.

Our expedition would be aboard the Neeskay, a research vessel belonging to the University of Wisconsin-Milwaukee.

Scouring the bottom of Lake Michigan for a fallen space rock sounds like fun, but why would we do such a thing?  The answer begins far above our heads, in the inky dark between the planets. The solar system formed from a vast cloud of stuff that eventually accumulated into the planets and other bodies in the solar system. Just like when you clean your house, you don’t get every little fleck of detritus there is — there is always a little bit left over. The solar system is no different — there are bits of stuff floating around everywhere. You may remember from your ponderings of the night sky that there is a lot of such material between the orbits of Mars and Jupiter, called the asteroid belt. There is an additional vast swarm of stuff surrounding the solar system called the Oort Cloud that is the origin of most of the comets we see.

But randomly drifting around there is also other stuff; when space rocks are in space they are called meteoroids. They are interesting because they hold a set of stories, about the early history of the solar system if they are left-overs, and about the historical nature of the other planets and moons if they are fragments blasted off of their surfaces in collisions.  If by chance, one of them should tumble into the Earth’s atmosphere, the tremendous speeds generate tremendous heat and the meteoroid becomes a meteor, a glowing coal of stuff that briefly illuminates the night sky. You and I call these things “shooting stars,” and if they are spectacularly bright, we call them “fireballs.” Finally, if one of these meteors should make it to the surface of the Earth, where it can be picked up and handled and oogled and tested, we call it a meteorite. Meteorites harbour the same stories they did when they were meteoroids, they are just much easier to get your hands on. IF you can find them.

Our sled, on the desk of the Neeskay, waiting to be launched.

So we made a plan to survey the bottom of the Lake looking for this meteorite. While the original concept had been to simply dive down with an amateur ROV (“remotely operated vehicle”), like one from OpenROV, or designing our own, the team rapidly came to the realization that we wanted to keep anything we found and bring it to the surface. A cool idea, but a challenging one at the same time.

As is often the case in science, having a cool idea means you also have multiple competing problems that must be solved. For the Aquarius team, the competing problems were this: how do you cover a vast, VAST area of the lake bottom, find everything that looks interesting, and get it all to the surface. Working your way through such a list of problems is exactly what science is, and it is an iterative process. You imagine a solution, you tinker with it, you build prototypes, and you test them. When the prototypes don’t quite work, or fail dramatically, or succeed in unexpected ways, you take what you have learned and modify or build a new version, and start the testing all over again. Eventually, your efforts stabilize and coalesce around a final product — a plan, an experiment, a workable design. For Team Aquarius that design was a sled we call RV Starfall.

The sled is a scientific device in the grandest tradition. If you just walked up to the sled not knowing what was, then the most apt description of it you might come up with is contraption. A contraption it is. Overall, it is about 1.4 meters long, about 1.2 meters wide, and about 25 centimeters tall. Its made of plastics and metal, with bolts and cables holding it together.  The superstructure of the sled is laid out by four vertical slats that define the shape. The slats are held together by cross-members that provide strength and rigidity. There are two sled-rails on the bottom, bent upward at the front, to help the sled glide over the underwater landscape, no matter what it might encounter (just like the rails on a winter sled or snowmobile). 

A computer model of the sled, viewed from the rear. Note the clear sample capture bins near the front, the curved edge of the sled runner on the bottom, the three magnet wheels across the middle, and the wire capture cages on the back. The red “bricks” on the slats are also magnets. [Model by Annelise Goldman]

Attached at various points on the sled are different devices that were designed to find and recover samples and interesting objects (“possible meteorite candidates”) from the bottom of the lake. The strategy that guided the sled design was passive collection without inspection — pick up everything that is potentially interesting, and bring it back to the surface for later classification and analysis. Look at the back of the sled. There you’ll see three mesh footballs — if they hit something like a small rock (or meteorite!) as they get dragged across the lake bottom, the tines of the mesh spread open and the forward motion of the sled pushes the rock inside, then the mess closes behind it effectively trapping it. A brilliant mousetrap for a meteorite!  There are also magnets all over the sled, strategically positioned to attract metallic fragments and hold onto them until the sled reaches the surface again.

The most active group of magnets are on the three wheels in between the vertical slats. As the sled gets dragged across the lake bottom, the wheels rotate and attach to any metallic fragments they encounter. As a wheel rotates up and over, it encounters a “scraper” that pries off any large bits and drops them into three catch pods (clear acrylic) between the slats. The idea here is that something large might attach itself to a magnet, but if you don’t pry it off and save it, something might later knock if off and you’ll never know you had it. On the bottom of the sled, there are some V-shaped brushes that guide material toward the magnet wheels, as well as a variety of other magnets attached on open surfaces to catch any “just in case” bits the sled might encounter. 

Last but not least, there is an attachment bracket on the front of the sled, where we could mount a video camera to send live pictures of the bottom of the lake back to the surface. The sled is attached to a cable, which is lowered by a crane into the water to the lake bottom. A video cable attached to the camera is clipped to the cable as it is extended, delivering live movie data back to the team in the control room (“Mission Operations Center”) on the Neeskay.

A maritime navigation map of Lake Michigan, east of Manitowoc, with Chris Bresky indicating where we are heading for the sled drops.

We had a boat, we had a meteorite recovery sled, but where do we go? Despite the immense size of the lake, we had a good idea where the meteorite fell from all the reported sightings and the signature on weather radar the morning of the event. Several of the meteorite experts on our team had used codes that they had written as part of their professional research to model the breakup of the asteroid, predict the sizes of fragments, and then simulate how those fragments would fly through the atmosphere and into the water. Those analyses produced a map of the most likely areas to find meteorite fragments of different sizes. One of our meteorite colleagues on the expedition with us, Dr. Philip Willink, took those maps and predictions and estimated the average separation between meteorite fragments on the lake bottom. He estimated that in the areas dominated by 1 to 5 gram pieces (about the size of a marble) we would have to drag the sled about 1.5 kilometers across the lake bottom to encounter 2 fragments. The lake is big, and those aren’t very good odds. But it’s also not impossible!

Phil’s roughed out calculation of how far we’d have to drag the sled to find a piece of the meteorite.

I tried on the survival gear during the safety briefing!

Using Phil’s prediction, we decided to do several mile long drags of the sled (“transects” across the fall field). With that in mind, there was nothing left to do except go out and start searching. The anticipation was palpable — this was literally what we had been waiting more than a year for, planning and imagining.

Scouring the lake depths for fallen space rocks is an all day affair. We arrived bright and early to our expeditionary vessel, the Neeskay. We had a safety briefing from our captain, tried on some of the survival gear, and we set sail. Our destination was off-shore about 16 kilometers, in about 70 meters of water. The Great Lakes are temperamental — soggy days and blustery weather can whip the Lake into a frenzy. But on this day we were lucky — the skies were clear, the winds were gentle, and the Lake was calm.

We loaded all our gear on board, we stowed the sled on the rear launch deck, and before we knew it, Neeskay turned in the harbor, and pointed her bow to the southeast. We were off. The moment we left the harbor was striking to me. Being a kid from a land-locked state, the view off the bow was one of completely open water, with not a speck of land in sight. If I didn’t turn around and look back the way we had come, it could have just been the endless blue expanse of the open sea.

[LEFT] Our expedition leader, Chris Bresky, lays out our plan for the day. [RIGHT] A map of our target area, showing the predicted density of meteorite fragments of a given size on the lake bottom, worked out using a computer model. The blue dashed line near the bottom of the oval shows our first drag, and the purple dashed line shows our second drag.

It was about an hour to our first drop point. On the journey out, we had a briefing about the target area and the drag plan. We would do two mile-ish long transects, one NE to SW, and one N to S. After the first transect, we’d pull the sled up, clean it off and store recovered samples, then drop it for the second run.

[LEFT] The sled is lowered into the water using a hefty steel cable being spooled off of a crane. ][RIGHT] As we let out cable and the sled descends to the lake floor, we clip the cable to our video feed that is bringing live images back to the surface.

When we arrived on site, we attached the sled to a tow harness, we bolted our video camera onto the nose, and we hoisted it up until it hung vertically over the deck. Pivoting it out over the edge of the boat, it hung poised over the water, just waiting for a moment, then cable began to unreel, it slipped beneath the waves, and was gone. The video feed was carried along its own cable. We didn’t want it to get tangled up on something, so every couple of meters we paused and  clipped it to the main tow cable to keep them together.

Pretty much the entire time the sled was in the water, the team huddled around a couple of computer monitors, watching the live video feed, and discussing what we might be seeing, noting down interesting time markers to go back and watch more closely. These were the moments we had been waiting for — having our experiment work successfully, and showing us something that had never been observed before.

In the operations center, the team could watch the video feed as the sled descended into the depths. At first, the image was a brilliant cerulean green, but as the sled descended, less and less sunlight from the surface was making it to the depths, and the images got darker and darker. The meager light from the camera lights revealed only a monochrome murkiness, and the faint shadow of our cable stretching out into the darkness above, where the team waited aboard the Neeskay.  And then….

Live video touchdown image from the bottom of Lake Michigan, 70 meters beneath the Neeskay.

Touchdown! The sled settled onto the bottom of the Lake, churning up a cloud of silt and dirt when it landed, not unlike the landers on the Moon. We had arrived!

As is often the case in science, we discovered something new and interesting immediately. Based on previous surveys of the Lake from two to three decades ago, the depths we were at had very little in the way of a visible macroscopic biosystem — a few lake creatures and fish, but by and large the temperature and light at these depths meant the lake bottom was a bare, open, abyssal plain. But that was not what we were greeted with on the monitors. In every direction, as far as our cameras could see, the lake bottom was covered in colonies of quagga mussels.

The lakescape we could see, as far as we could see in every direction, was dominated by quagga mussels. A few bare spots existed, but they were few and far between.

Quagga mussels, like their cousins the zebra mussels, are an invasive species in the Great Lakes, having been transplanted in the ballast water of ships that plied both the Great Lakes and other waters in the world. Over the past few decades they have been spreading through the Lakes, starting in large colonies in shallow waters, but clearly now also extending into the deeper waters. There are lots of interesting questions that immediately spring to mind. For instance: As we moved across the lake bottom, there are small patches here and there where the mussels hadn’t settled — what were those? Are the mussels not there yet, were they cleared away somehow, or is there something different about those patches? How far into the depths do the colonies extend? Are the depths they are reaching simply growing with time, or correlated with other environmental aspects of the lake (like temperature, lake currents, water chemistry, or other suspensions in the water)? Those are questions for another day, and a future expedition and a future team. As dutiful observers of Nature, we record our findings and the conditions under which we made them, together with thoughts we have, and report them to our scientific colleagues for further consideration.

Once we were on the bottom, we started our run. The captain revved up the Neeskay and we started trundling along our planned transect at about 1 knot (1 nautical mile per hour, which is about 1.15 mph = 1.85 km per hour). But as you might guess, it’s not that easy! We wanted the sled to glide over the bottom in contact with the surface. If we were going too fast, the sled started to “fly” from the hydrodynamic forces of the water lifting it like it was an airplane. We knew when we were on the bottom because we would see occasional puffs of silt and dirt, like the cloud we saw when we landed. If we were going too fast and flying, then we never saw any puffs and the mussels were really flying past fast. 🙂  The video below shows about 2 minutes of what flying over the area was like, extracted from the Aquarius video feed.

So for about an hour, all we could do was watch the video screen, occasionally talking with the captain about speeding up or slowing down by a smidgen. The mussels sailed by — endless lakescapes of mussels. Surprisingly, there were often apparent detritus from our civilization that we could see — bars of metal protruding from the lake bottom or other bits of shattered something. In many ways it was surprising, because you have this sense that the lake is vast and there is no possible way that humans could have somehow made their imprint on so much of it that a random trip across the bottom would turn up some artifacts from our civilization. But we have. It is a testament to how much time humans spend on the lake, and how far reaching our influence likely is.

Two examples of interestings “things” that passed with the field of view of the Aquarius sled camera. Possibly natural (wood?) and possibly anthropogenic (metal?). The team noted where they were, in case we ever want to go back and look at them too.

Eventually, we decided to haul the sled up, clean it off, and preserve any samples we found. The ascent was a little slower than the descent because as we hauled it up, we had to separate the video cable and the tow cable. Separating the two was not nearly as straightforward as clipping them together — while the sled is in the water and the cable is under tension, the two cables wind around each other, so as they come out of the water and are separated, all of the twists remain in place! The result is a giant spaghetti ball of cable that you have to manage as the sled ascends. It’s only 70 to 100 meters of spaghetti cable, but it’s a plenty big mess! If you’re watching on the monitor, eventually the sled video can see us up through the water as it ascends, a distorted fun house view of the team, peering eagerly into the water to see what secrets had been pulled up from the depths.

[TOP ROW] As we raise the sled, we have to cut the video cable free from the tow line, but it turns into a big spaghetti mess that must be managed as the sled returns home. When it is near the surface, it can see the mess above it! [LOWER ROW] When the sled is clear of the water, it drops all kinds of mud that it has been dragged through. We have to grab the sled, and pivot it back onto the deck so we can begin cleaning it.

As the sled emerges from the water, there is a flood of mud that is released as water sheets off of it, but we move it aboard and finally it is laid down on the deck. What happens next is a burst of activity: every member of the team moving to do something to get us ready for the next transect. The captain turns the boat and heads to our next drop point. A group grabs the spaghetti ball and takes over an entire side of the Neeskay to untangle it and lay it out, untangled, for the next drop. A cadre of people with cameras and smartphones are taking pictures of everything, documenting what is going on. And the sled itself is surrounded by a pack of the Aquarius team, shoulder to shoulder, digging in to clean the sled and preserve the recovered samples.

[LEFT] The moment the sled was on the deck, the Aquarius Team was swarming all over it. No known force in the Universe could have kept them away. [RIGHT] Getting the mud off was a chore; spraying it off worked well, but then the mud had to be gathered off the deck and sifted through.

The philosophy of the sled clean-off stage is simple: keep everything for later. Set aside interesting stuff for careful consideration later.

There is a lot of mud. Some of it we spray off, carefully sifting through it for anything that was surrounded by the gooey stuff. The cleaning teams grabs great gobs of the stuff and mashes their hands through every little bit of it, looking for anything small and solid. We find rocks, we find clear bits of metallic somethings. We keep it all, and toss it in big 5 gallon buckets. The buckets are marked with the day of the expedition, and the transect that we made, so when we get back to the lab we’ll know where the samples came from. We find stuff stuck to the magnets — all the magnets — so we pull it off, and stick it in the buckets. Every now and then we find a mussel; what do you do with that? You see if it sticks to a magnet! If it sticks, you keep it — it probably has eaten something metallic (possibly a meteorite fragment) and we want to know what it is! If it doesn’t stick, we toss it back into the Lake. If something looks particularly interesting, we show it to one of our meteorite experts, who decide to toss it in the general buckets, or keep it in a special “oooo interesting” container. 

[TOP ROW] The magnets collected plenty of material. Notice the fine grain black stuff — this is “magnetic mud,” the kind of stuff you can pick up in a sandbox with a magnet, comprised largely of metallic rich grains. [LOWER ROW] We mash through ever little bit of mud with our hands, looking for fragments and interesting bits. With the mud cleared away, there are a variety of different things we find, almost all of which we keep.

The entire clean-up takes 30 to 60 minutes, and by the time we’re done, the spaghetti cable is untangled, and we’re ready to make a second drop. We hook RV Starfall back onto its cable, pivot out over the water, and drop it in for a new run. Wash, rinse, repeat!

Really interesting looking samples are set aside, to make sure we look at them more closely later, and to insure that we don’t lose them in all the detritus.

But all too soon,  you discover the day has wiled itself away. The Sun is heading toward the horizon, you have buckets of samples, thousands of pictures, hard drives full of video, and notes, thoughts, and observations from everyone on the team that need to be collected, collated, read over, pondered, and speculated with. 

With the happy melancholia that accompanies the end of any adventure, the team looks to shore as the captain turns the bow of the Neeskay to the west, and we begin to steam toward home.

Now, the samples are back in the lab, and the next long bit of hard work is happening — consulting with scientific colleagues who are experts in meteorite identification, and figuring out what all this stuff is!

Now, our samples are in the lab. Fall is winding away and winter will be here soon. This is the time for careful lab work and analysis of all the samples we’ve found. There are, perhaps, fragments of our meteorite in the collection. If there are, we will be beyond excited. But if there are not, the samples still represent a treasure trove of knowledge about one small part of Lake Michigan. Contained in those carefully preserved samples is a story, yet to be understood, about the geology and history of human influence in that part of the Lake. We’re going to find out what we can learn from that hard earned haul — truly a treasure, valued in the sweat and joy and mystery of its recovery.

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This post is the second of two describing my adventures with the Adler Planetarium’s AQUARIUS team. The first post was here: https://wp.me/p19G0g-LB

You may also enjoy listening to the Adler Planetarium’s podcast series about Aquarius, it is excellent. You can hear them online here:  https://www.adlerplanetarium.org/education/far-horizons/aquarius-project-podcast/ 

The Aquarius Project 1: The Cosmos Beneath the Waves

by Shane L. Larson

The wind is brisker, the nights cooler and crisper, and something about the slanting misted light of morning says autumn is here. Over your morning nibbles, with your family prattling around you in the kitchen and the hum of a weekend just getting underway, you look back through your memories on social media, and it’s like “Wow! I had some awesome adventures this summer!”

During the daily grind, when the morning commute is doing its best to wear down the gears of your soul, and the daily maintenance of jobs and life stretches well beyond the length of a reasonable ToDo list, I sometimes despair that there are no great adventures to be had. But those are just little demons whispering, preying on weariness. In reality, I think there are always new adventures launching without you even knowing it. Some of them lead to great friendships and growth for your community around you. Some of them bring great good to the world, even if it is just a small group of people around you. A few indelibly ink a memory in your heart and soul that you will carry around with you to the end of your days in this Cosmos. This is an adventure story with all of these. Like most adventures, it arrived unexpectedly, and grew from humble beginnings. It started one winter night in the northwest suburbs of Chicago.

I’m a bit of a short sleeper, so I’m always up late at night, long after the rest of my family and friends are slumbering. It’s always quiet, just me and the cats. When it’s nice, I can do a bit of backyard astronomy, but if the weather is inclement, I can wheedle away hours in the workshop or at the Lego table.  More often than not, I have papers from my students to read, or lectures to write, or homework to grade. The latter was the case in the early morning hours of 6 February 2017. My study is on the second floor of our house, and I have my writing desk situated to look out over the wetlands north of our home. 

I don’t recall exactly what I was doing, but I was up and at my desk. At 1:25am I just happened to be looking north and witnessed one of the awesome transient events you can see in the sky, a fireball. I’m an active amateur astronomer (I’m also a professional astronomer, but that’s a discussion for another day), so I’ve literally spent thousands of hours out under the night sky. I’ve seen fireballs before, but they are not common enough to simply shrug your shoulders when one graces the skies overhead. They are all of them dramatic, bright, beautiful, colorful, and awesome to behold. This one was no different. It had a brilliant teal colored head and a streaky tail that was long and “sparky” with a yellowish color. It was BRIGHT. So bright that it lit up the walls inside the house and cast shadows, like a long duration flash bulb had gone off.

I’m one of those amateur astronomers who has a strong habit of writing everything down when it happens; if you have a birder friend who keeps a lifelist of all the birds they’ve seen, I’m of the group of amateur astronomers who do the same thing only with objects in the night sky.  I try and immediately write down everything interesting I see happening in the sky. I note everything I can — the time, how “big” it looked in the sky, how long it lasted, and anything I noticed like its color or shape or behaviour. All those details are important to write down in the moment before your brain thinks about it and embellishes it. Colors are completely subjective, but for an event like this, they are the best description you can usually give. The size is also not precise, but you can use old astronomer tricks to estimate the size of an object, either by referencing other things you can see in the sky (like the positions of stars) or using your hands. In this case, the fireball was perfectly framed in my window, so I used my hands to estimate angles. I also like to simply write down my responses — from my journal entry above, you can see I was pretty excited.

When you need to quickly estimate angles in the night sky, use your outstretched hands. The width of your fist is about 10 degrees, and your spread hand is about 20 degrees fingertip to thumbtip. [Image: S. Larson]

It is all well and good to keep your own notes about what you see, your personal dialogue of your relationship with the sky, but if no one ever hears about what you saw in the sky we can’t use your experiences to learn more about the Universe and our place in it. There is something special in the sharing of communal experiences with the Cosmos, and sometimes we can learn something new at the same time. When that fireball lit up the night that winter morning, I did two things. The first was to ping all of my local friends on email and social media, on the off chance someone had also seen it. The second was to report the event to the American Meteor Society, which collects observations and collates them together. 

My initial query to my friends to see if any of them saw the event.

In the end, hundreds of people all over Illinois, Wisconsin, Michigan and Indiana reported the event, and collating all of our reports generated a good guess about what the fireball did, pointing to something I had speculated: it probably came down in Lake Michigan. You can see the report at the AMS online here.

The American Meteor Society map showing people in northern Illinois and southern Wisconsin who saw the fireball. Reports came in from a much larger area than this, but in this view you can see the estimate of the meteorite’s trajectory (between the green and red pins). [Image: American Meteor Society]

My email to my friends and colleagues at the Adler Planetarium ended up being the seed for this particular adventure story. One of my hobbies is constructing underwater robots (ROVs — remotely operated vehicles), which is also another story for another day. But in my email, I speculated on whether or not we could use such a “hobby” to perhaps dive down to the floor of Lake Michigan and take a look around on the off chance that we might find something.

The early email, speculating that maybe an ROV could be used to look for any possible fragments from the meteorite.

Now why would we do that? Material from outer space rains down on the Earth all the time. On any given night, if you spend enough time looking up, you’ll see numerous quick streaks of light slashing across the sky — the “shooting stars” you learned about when you were young. Most of these are small, no bigger than a grain of sand, and burn up in the atmosphere high above you, leaving only the flash of light and your memory of its existence. Throughout the year, we have regular “meteor showers” when the Earth sails through the trail of dust and debris left behind by comets as they blaze their journey toward the Sun, dropping fragments of ice and dust that we see as their tails. Such events are not unique to Earth — they also happen on other worlds (one of my first scientific papers was about using comet orbits to predict when you might see meteor showers if you lived on other planets in the solar system). Larger fragments of stuff also hit the Earth, though less frequently, with fewer and fewer instances as the size gets larger and larger. Things the size of baseballs and laundry baskets will light up the night sky and while they can cause damage, aren’t devastating. Most events of this size are over the ocean and out of sight of stargazing humans because 71% of the Earth is covered by water!

A typical shooting star (this one is a meteor during the Perseid Meteor Shower). [Image: S. Larson]

NASA estimates that around 100 tons of material hits the Earth every single day. But most of that is small flecks that vanish in a sparkling flash of light, sometimes seen by someone like you looking up from their backyard. But a few pieces — a precious few — make it all the way down. Something about the size of your fist has a good chance of making it to the ground. Meteorites are not as common as everyday rocks, but not so rare that ordinary people like you and I can own small fragments purchased in museum gift shops or from reputable dealers.  Never-the-less, they are rare enough to still be of intense scientific interest. After tracking this random fireball through the skies of the Midwest it seemed, perhaps, we knew where one had come down in Lake Michigan, and maybe a little adventure was in order.

Me and the indomitable Chris Bresky, off on an adventure.

The adventure started innocently enough, because my Adler colleague, Chris Bresky, thought pitching ROVs into Lake Michigan to look for sunken space rocks not only sounded cool, but would be a great way to engage area teens in some science investigation. It has all the hallmarks of what science is all about. It begins with a phase of Big Thinking, where there are no boundaries. You put a group of interested people together in a room or on an email thread, and you just talk. The rules are simple: no idea is too whacky, no question is too silly, everything should be put out there for discussion. During the Big Thinking phase there are no limits or considerations of limits, there is no quarter given to practicality or logic, there is no worry about regulations or costs or anything. That is all for later. In the beginning, you want to let your imagination run wild, and let your curiosity and excitement drive what you are thinking and talking about. Why? Because good ideas come from unfettered imaginative thinking. There are many ideas and hypotheses that are untenable or wrong. There’s nothing wrong with exploring those ideas — that is the pathway to finding out what is possible and what is true. When we are first embarking on a journey of scientific investigation, we do not know where fundamental insights will come from, or what will spark them. 

It’s not that all the squirrel-brained ideas that come out of the Big Thinking phase are workable or even reasonable. That’s not the point of Big Thinking. The point of Big Thinking is to have conversations about the ideas that form around all the squirrel-brained ideas. For this project, we started with simply the idea of an ROV to photograph whether there was a piece of this space rock on the bottom of Lake Michigan. That simple question opened up a remarkable spectrum of questions that would ultimately be an important part of our adventure.

Big Thinking started early, even in email. Chris’ imagination was captured early on.

What was the bottom of Lake Michigan like? Probably rock and dirt, as the depths in the target zone are too deep for sunlight to penetrate and support plant life.  Is it mud or hard packed surface? If it’s mud, will we see little divots from meteorites or will they sink in the mud? If it is hard packed will the meteorite sitting on the surface just look like another rock? What is the Lake really like in the area where the fall happened? No one really knows, because 99% of the Lake hasn’t been seen, only surveyed by sonar and most of that at low resolution. Do we just want to take pictures? What if there is a big rock we want to recover? Can we make a robot arm to pick it up? Will we need to dig on the bottom of the Lake? Can an ROV even lift a giant space rock?

And so on. Over time, we coalesce together into a team, and we develop some common language and ideas, and a plan begins to emerge. In this case:

  • we didn’t even know where there was a space rock, only a huge area that it could be in. If we were going to search, we had to be able to search vast areas.
  • we absolutely wanted to recover some space rocks if they were on the bottom of the lake. Anything was probably small, so we’d have to recover material and separate it on the surface
  • like outer space, the bottom of the lake is not amenable to humans hanging out, so we’d have to do this space-exploration style — with uncrewed, mechanical entities
  • we’ve never done ANY of this before; few if any people have looked for space rocks in deep water before. So we’re going to have to figure out how to do it, teach ourselves, learn from our mistakes, and then execute our search on the true frontier — the unexplored depths of Lake Michigan.

After that, it’s time to start rolling. You get your hands dirty and your feet wet and you make your brain tired, for months. Not exhausted tired; happy tired. So tired you can’t fall asleep at night because you’re still turning a problem over in your head tired. The core team in this endeavour are a group of kids from Chicago we call “the Adler Teens” (follow them on Twitter, and Instagram). Like all teens, they are extraordinary. They’re excited, they’re passionate, they’re full of boundless energy, and they want to learn how to solve cool problems. There are also a few of us grown-ups around too, but we try to stand back and let the team push the project forward. The beauty of science is there are as many ways to solve a problem as there are people trying to solve them. Some solutions work better than others, but no solution is right and no solution is wrong. I’ve been a science educator my entire career, and while I could go and figure out a way to find and recover space rocks on the bottom of Lake Michigan, I long ago learned that some of the most inventive solutions to problems come from students who are learning to flex their scientific skills.

Doing science requires talented minds with all kinds of skills. The AQUARIUS Project, like all great exploration missions, has a patch and logo, developed by our talented graphics designers at the Adler Planetarium [Images: Orilla Fetro]

Our project became known as “AQUARIUS” (suitably nautical and astronomical at the same time — you can follow their progress on OpenExplorer), and over the course of the next year it grew into an extraordinary voyage of discovery. The first part of the journey involved the team figuring out clever ways they could recover meteorite fragments from the bottom of the Lake. The team settled on the idea of a towed sled with scoops and magnets that could be pulled behind a boat in long transects across the fall field on the bottom of the Lake. They made simulated meteorites in the lab, threw them in shallow water and tested their sled repeatedly. When their design didn’t work quite as expected, or it ran into an unexpected problem, they rolled their sleeves up again and went back into “Big Think” mode, and thought of a way to fix the problem. They deployed and retested. 

After more than a year of work, the team was ready to take their equipment and hit the open water, searching the depths of Lake Michigan for fragments of a space rock that had fallen more than a year before, waiting quietly and patiently to be found in the dark depths of the Lake. I had the great honor of accompanying them on a sunny day in July 2018.

Our port of call was Manitowoc, Wisconsin. Our ship was the SS Neeskay, a research vessel owned and operated by the University of Wisconsin-Milwaukee. Built in 1953, the vessel had served many roles during its time at sea, but was converted into an expeditionary scientific ship in 1970. This summer, it carried a group of us on a hunt for space rocks on the bottom of Lake Michigan…

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This post is the first of two describing my adventures with the Adler Planetarium’s AQUARIUS team. The rest of the story is in the next post:  Into the Deep Void (https://wp.me/p19G0g-Md).

Global Climate Change: A Brickstory

by Shane L. Larson

Global climate change is one of the most serious problems facing our civilization, and doing something about it is hampered dramatically (particularly in the United States) by our deteriorating ability to talk about issues, and the politicization of science and evidence-based reasoning.

This presentation is rendition of an Ignite talk I gave for IgniteChicago. Ignite is a unique talk format designed to present ideas and seed conversations — it consists of 20 slides that auto-advance every 15 seconds (whether you are ready for them to or not!), so the entire talk only lasts 5 minutes! Climate change is a big enough issue that it definitely cannot be covered or discussed completely in 5 minutes, but the beginnings of a conversation can be laid down.

If you would like to learn more about global climate change, then one of the best books I know is “Dire Predicitions: Understanding Climate Change” by Michael Mann and Lee Kump. It is easy to read, has lots of explanatory material about the underlying science and the social and economic impacts to our civilization, and discussion of the major arguments you hear regarding this topic. It is an excellent book.

I built all the Lego models here; the bird on Slide 11 is the bird from Lego Set 21301 (Lego Ideas: Birds, now retired). Lego spheres of the sort I use here are a common design used by the amateur Lego community; the particular “Earth” pattern I use is the one designed by Jason Alleman in his Lego Orrery. The images are the images from my slides; the text is what I said during the talk (it was not on the original slides). Click on any of the images to make it a bit larger to read.

Thanks to the folks at Ignite Chicago and the Catalyst Ranch in Chicago for hosting this talk and providing a space to have a big conversation.























 

Ineffable Images of the Space Age

by Shane L. Larson

The arrival of each new year always engenders a brief moment of reflection on how we all would like to improve and change our lives, and very often with a recounting of how transitory life actually is.  I was reminded of this yesterday when I was reflecting on the sad fact that on December 21, astronaut Bruce McCandless II passed away at the age of 80. He was a Naval Academy graduate who joined NASA in April 1966 as part of Astronaut Group 5.

McCandless joined NASA during the Apollo era, but never flew until the Space Shuttle era, logging 312 hours on two flights: STS-41-B aboard Challenger in 1984, and STS-31 aboard Discovery in 1990. It was on his first flight that he gained notoriety: he made the first untethered spacewalk in history, flying the MMU (Manned Maneuvering Unit) some 300 feet away from the Challenger. The image of McCandless, flying free over the Earth, has become one of the most iconic images of the Space Age.

Bruce McCandless, flying the MMU about 300 feet from the space shuttle Challenger during STS-41B in 1984. It was the first untethered spacewalk in history. [Image: NASA]

There is something timeless and awe-inspiring about this image. What is it? Is it the ever-blue curve of the Earth behind him? Is the loneliness of a single human, flying in the void far from any others? Is it the thrill of the the adventure or a surge of voyeuristic fear, the “fun thrill” letting your mind roll around how you would feel in that same situation? I think it is a little bit of all of those. Just show the image to some friends at your next dinner party and ask, “Would you do that?” or “Can you imagine?” and listen to the direction of the conversation!

When McCandless made his historic untethered spacewalk, I was in high school and dreamed of being an astronaut. I didn’t become an astronaut, and likely will never travel to space, but the dream lingers in my mind and surges forward every time I see images like this one.  This isn’t the only image from the Space Age that has such an effect on me. Some photographs, some moments suspended in time on celluloid or pixels, somehow capture ephemeral emotions that are indescribable by any other means.

Many such photographs come from the astronauts themselves. Astronauts have had a singular, unique experience that is transformative to their consciousness. Nothing molds a person’s worldview more dramatically than first hand experiences, there are no first hand experiences quite like those of the astronauts. They have seen the Cosmos, seen the world, from a perspective that the rest of us can only catch elusive glances of in stunning photographs delivered from the shoals of space.

Take a look at this photo. Almost exactly 49 years before Bruce McCandless passed away, the crew of Apollo 8 made the first voyage from the Earth to the Moon. They completed ten orbits around the Moon, and on their fourth orbit were the first humans ever to see the Earth emerging from behind the Moon — the first Earthrise ever witnessed by the human species.

“Earthrise” shot by Apollo 8 astronaut Bill Anders on 24 December 1968. A recreation of the moment, with mission audio has been created by Goddard Spaceflight Center [Image: NASA]

The world first saw the image in the 10 January 1969 issue of Time Magazine, burning it indelibly into our collective consciousness.

Like so many moments captured on film and revisited with reverence and awe, the Earthrise photo was taken by chance; Apollo 8 just happened to be rolling at the moment, and the image just happened to be visible through the tiny windows on the front of the capsule. In retrospect, the moment could have been predicted, but every story told of that moment when Apollo 8 rounded the limb of the Moon describes the first sight of the Earth as an unexpected and ineffable moment — the first time in human history that we had ever seen our world in Cosmic context, behaving in relation to the rest of the Universe in ways that our minds had only previously considered for other worlds.

One of the most famous pictures returned from the Apollo missions was of Buzz Aldrin’s bootprint in the lunar soil, made and imaged by Aldrin to record the properties of the lunar soil. [Image: NASA]

Just seven months later, Apollo 11 made the first crewed landing on the surface of the Moon, leaving humanity’s first footsteps on another world. Buzz Aldrin famously took a photograph of his bootprint on the Moon to illustrate the behaviour of the lunar surface soil; it is an image that is universally recognized as being from our first journey to another world. Most of us have made footprints, in snow or mud or soft dirt. Often alongside many other footprints, a cacophony of shapes and patterns, each one a remnant of a journey from somewhere to elsewhere. The next time we cross that particular trail or particular riverbank, the prints have changed and tell new tales of new journeys. But the footprints on the Moon are different — so far, there are only 12 sets of prints, laid down five decades ago by the few humans who crossed the gulf. And they will persist for millions of years, untold aeons beyond my life and your life and the times in which we live. If some future traveller should happen upon them, perhaps laying down their own prints alongside, what will they know of the journey that first left the prints there? Will they know of Aldrin’s famous footprint, and cast about debating which one was The Print? Or will they have utterly forgotten us and these days, the remains of Apollo on the Moon just curious forgotten relics of a civilization wiped away by time? What will they remember and know of us?

After 21 hours and 36 minutes on the surface of the Moon, Armstrong and Aldrin lifted off to rejoin Michael Collins, who had remained in lunar orbit. On their approach to dock with Collins, he snapped this picture of the lunar module over the surface of the Moon, with the Earth in the background sky. Collins famously remarked that this photograph was a picture of every person in the human race, except him. What a stunning observation, a perspective that reflects how small and alone we all can be in the face of the immensity of the Cosmos.

Apollo 11 image of the Earth and Moon behind Lunar Module Eagle, carrying Armstrong and Aldrin back from the lunar surface to command module Columbia. Michael Collins, aboard Columbia, noted that this was a picture of every human being except him. [Image: NASA]

Such images are not confined to cameras held by humans. Over the past six decades, we have hurled many robots into space, mechanical emissaries designed to carry our senses to places we cannot easily visit ourselves. Among that mechanical flotilla are eight explorers sent into the outer reaches of the solar system, to visit the giant, gaseous planets and even tiny Pluto. Among them is an 800 kilogram spider of wires, foil, antennae and cameras called Voyager 1. Today it is still faithfully travelling outward, gently probing the space around it to map out the invisible bubble that defines here, the neighborhood of the Sun, from there, the wildlands of interstellar space.  On 14 February 1990, a little more than nine years after its encounter with the planet Saturn, Voyager 1 was commanded to make one last photographic survey of the neighborhood it came from — a Family Portrait of all the worlds of the Sun.  Turning inward one last time, it snapped off sixty frames. Laid side by side, one over the next, the last pictures from Voyager built a unique and humbling portrait of our homeworlds.

Voyager 1’s family portrait of all the planets of the solar system. [Image: NASA]

Buried on one of these frames is a pale point of light, small and blue, easy to miss in the flared light of the Sun bursting though Voyager’s lens. That’s the Earth, our home in the vastness of the void. That small meager point of light inspired Carl Sagan to write one of the most poignant and eloquent  assessments of human nature ever penned. The “Pale Blue Dot” soliloquy can be found in the book of the same name, but in one of the great magics of the modern age, a recording of Sagan reading it has been found and preserved; it is as moving to listen to as it is to stare at the delicate fleck of light captured by a simple robot from 6 billion kilometers away.

The Pale Blue Dot; an image of Earth from Voyager 1’s “Family Portrait” sequence, and arguably one of the most famous pictures ever taken of Earth, noted for showing the smallness of the Earth in the immensity of the Cosmos. [Image: NASA]

When leafing through stacks of images from the Space Age, I’m struck by one very clear fact: there are no boundaries to the grandeur and ineffable wonder that can be captured on film. Each frame, each snapshot, each pixel, is a gift to future generations, a record of what we attempted, a record of what we aspired to, a record of what we risked during this time in history. On most days achievements like this stand in stark contrast with the lows our civilization has sunk to, and it is difficult to understand how both can be the legacy of the same species.

Some people look at images like these, and are nonplused. For them I weep. I hope they find wonder and awe in some other visions of the world, because the emotions and exhultations that these images evoke hearken to something deep in the soul, something I think we have lost in the modern morass of social media, reality TV, consumerism, and soundbites that claim to capture the quintessence of life. There is something deep and abidingly important in being able to see and experience amazing things and tremendous accomplishments, even in the face of serious and possibly overwhelming challenges to our way of life and our future on this planet. It provides a focal point for our aspirations to be better. It provides a poignant bludgeon of hope for the better selves that we aspire to be.

Other people look at these images, and all they see are dollars spent on endeavours they regard as frivolous. I can’t help but feel agony at such narrow visions of the world. In no small way, today’s world was made by these images. Not the images themselves, of course, but the thousands and thousands and thousands of hours of problem solving, prototyping, invention, innovation, creativity, and imagination required to make every one of these possible. We didn’t strap a gazillion dollars onto the side of Voyager and catapult it into space. We paid an army of engineers and as a result fed their families and sent their kids to school. We created entire new technologies, birthed companies that today make the backbone of the trillion dollar aerospace industry. We inspired a generation of children who wanted to be astronauts, but became enamoured with science and went on to become computer scientists, cancer specialists and brain surgeons, molecular biologists, ecological physicists, and aerospace engineers. I bet if you talk to many of today’s technical professionals, there is a time in their past where they swooned over pictures of the Moon.

The point is pictures are just one small return on each of the investments that were made to send people to the Moon, or to send a robot into the depthless void of space. Maybe you don’t think they’re interesting or the cost was worth it, but consider this: these are pictures we unfailingly recognize and know of — that simple recognizability is an indicator of the intrinsic and often unspoken value we as a society put on these ephemeral moments, captured forever as a frozen memento of places we once visited and knew and experienced.

Journey to a Northern Ocean

by Shane L. Larson

Polar bear on the shores of Hudson Bay, near Churchill, Manitoba. [Image: S. L. Larson]

I’m an active professional scientist and also a university professor. One of the things about my job that I enjoy the most and take quite seriously is the opportunity to talk with everyone about science. We talk about why science is an important human endeavour, how science impacts our daily lives, and how science helps us to improve our lives. We also talk about how science helps us understand the world around us, and what our purpose in the world is. At the end of October, I had the great opportunity to join a trip to the shores of Hudson Bay to observe the annual congregation of polar bears waiting for the return of the sea ice. Ostensibly I was there to give a science talk about the aurora borealis, but I was also representing my university with the group of travellers who were largely our alumni. Our destination was Churchill, Manitoba.

Churchill has a thriving tourist industry that in the early winter focuses on polar bears, and in summer focuses on beluga whales that congregate in the Churchill River; many businesses exist to help people experience these aspects of the natural world (we were hosted by the Lazy Bear Lodge). While people come for the wildlife, there is a lot to see in the area.

I was there late in the fall, on the verge of winter; walks on the shores of Hudson Bay were fun, but the weather was bleak and the landscape was windswept and cold. The surfline was beginning to freeze, leaving long gelatinous burms of frozen seafoam as the tides receded, a harbinger of the coming ice.

The shores of Hudson Bay, at the onset of winter. The foam from the surf is freezing at the high tide line. [Images: S. L. Larson]

Outside town there is a crashed Curtis C46 Commando, known to the locals as “Miss Piggy.” It went down in 1979 trying to return to the Churchill airport after its port engine went out on take-off. Miraculously, everyone walked away from the crash, but the plane is still there on a hillside outside of town.

Miss Piggy is the wreck of a Curtis C46 Commando, left where it crashed in 1979, on the outskirts of Churchill, just north of the airport. [Images: S. L. Larson]

 To the east of town, near the mouth of Bird Cove are the hulking remains of a derelict ship known as the Ithaca. It ran aground in 1969 during a storm, after 47 years at sea; the crew walked ashore at low-tide, and the ship was left to rust away into oblivion.

The wreck of the Ithaca, grounded at the mouth of Bird Cove since 1969. [Image: S. L. Larson]

All of this and more exist in the region, but we were there to see polar bears. The scientific name for polar bears is Ursus maritimus, Latin for “sea bear,” because the bears spend much of their lives on the arctic sea ice, largely in the areas where it interfaces with the land that fronts the Arctic Ocean. The area around Churchill is the home of one of the 19 recognized sub-populations of polar bears, numbering around 1000 individual bears. The story of why there is a population of bears in this area is a magnificent tale of biology, the planet, and the changes of the season.

The boundaries of the 19 recognized individual polar bear populations. [Image: C. Brackley, Canadian Geographic]

Polar bears are generally classified as carnivores, but they are perhaps more properly called lipidivores — their main sustenance is fat, primarily the fat of seals. Seals are primarily sea-going, occasionally crawling out onto rocks during the warm season and frequenting the surface of the ice in the cold seasons. The bears have the easiest time of hunting during the cold season, when they can stalk seals on the ice.

Polar bears are well adapted to life on the ice and in the sea. These bears were at Assiniboine Park Zoo and Leatherdale Polar Bear Conservation Center in Winnipeg. [Images: S. L. Larson]

Polar bears are well adapted to a life on the sea ice, with insulative fur and wide paws suited to walking on snow and ice. Their feet sport large claws and stippled pads for traction on frozen surfaces. They have insulative layers of fat that keep them warm when they are swimming in cold arctic waters. Compared to their cousins, the grizzly bears or brown bears, polar bears have long conical heads and necks, well adapted to lunging through breathing holes on the ice and hauling out a seal.

During the northern hemisphere winter, Hudson Bay is frozen over. The sea ice extends down from the arctic cap to the north and merges with shorefast ice that forms all along the coastline. During this time of year, the polar bears live on the ice, hunting seals. It is estimated that during this time, polar bears consume about 75% of their yearly intake of food, processing and storing it away as fat reserves for the ice-free season.

The average seasonal ice coverage on Hudson Bay. Red is the thickest ice, blue is open water. [A] June 18; with the onset of summer ice begins to recede across Hudson Bay. [B] July 30; by midsummer the last shorefast ice is gone, and the bears have come ashore in southern Hudson Bay. [C] September 17; around this time, arctic sea ice has reached its minimum extent. [D] November 5; by the start of November, shorefast ice begins to form in the Churchill region [E] November 26; the ice season has begun, and the polar bears migrate out onto the sea ice. [F] January 1; deep winter and the whole of Hudson Bay is frozen. (Images: Environment Canada)

What happens in the ice-free season? The ice recedes from the center of Hudson Bay, with the shorefast ice in the vicinity of Churchill being the last to disappear. The slow, seasonal recession of the ice drives the Churchill polar bears off the sea and onto the land, where they roam the boreal forests and tundra during the Arctic spring and summer. During this time of year, their primary food source — the seals — remain at sea and are more or less inaccessible, so the polar bears embark on a seasonally enforced fast while they are landbound. They will eat some vegetation, and possibly feed on carcasses if they happen upon them, but they consume little in the landbound months because their biology is largely optimized for the consumption of fat.

While they are landbound, waiting for the return of the sea ice, the bears wander around, and can sometimes be seen! [Image: S. L. Larson]

The Churchill population of polar bears comes off the sea-ice across the shores of Hudson Bay in northern Manitoba, but as summer wears on toward fall they migrate to the area around the Churchill River estuary. More than a mile across at the mouth, the Churchill River drains a large area of Alberta, Saskatchewan, and Manitoba into Hudson Bay, about 1.2 million liters (around 317,000 gallons) of freshwater on average each second. Fresh water freezes at higher temperatures than salt-water, so the large flow of freshwater into Hudson Bay from the Churchill River insures the sea-ice appears around the river outlet first, in late October and early November. The polar bears have learned this, and their seasonal circulation brings them to the area around Churchill when the first ice appears, so they can head out onto the bay and start their seasonal feeding again.

When the polar bears are landbound, they do not expend tremendous amounts of energy. This bear was started by humans who were trying to scare it away from their home. [Image: S. L. Larson]

This seasonal pattern of feeding and fasting has influenced other aspects of polar bear biology, particularly with regard to young bears. Polar bears mate in the spring (mostly in April and May), while the bears are still on the sea ice. The females experience a delayed impregnation — after mating, they harbor fertilized eggs that do not implant or begin developing. In late September, around the time the sea-ice is reappearing, a female polar bear’s body makes an assessment of how much fat reserves she has; if it is enough, the fertilized eggs implant, and the embryos begin to develop. The gestation period is very short — only about three months. During this time, the female bear begins to look for an area to den. In the Churchill area, she typically excavates a large, protected hollow in the peat that covers the northern shores of Manitoba above the permafrost layer. Sometime around December or January, cubs are born. Generally two cubs are born, but singles or triplets are not unheard of. The cubs are feeble and small when they are born, usually around half a kilogram, covered in short fur but blind and toothless.

A mock-up by Parks Canada of a mother bear, denning in the peat with her cubs. [Image: S. L. Larson]

The mother bear remains in her den with her new cubs for several months, continuing the enforced fast that began when she came ashore with the vanishing of the sea-ice the previous spring. The cubs nurse, growing rapidly on a diet of milk that is typically about 31% fat. Within a few months, the cubs have grown to about 10-15 kilograms, have developed thicker fur coats, and are able to move around. With the arrival of spring, the mother leads them out onto the sea-ice. This is usually around the time the seals have delivered their own pups. Seal-pups are born on the ice, and spend about eight weeks of their early days in dens in the ice and snow, near breathing holes their parents use to access the sea. The pups, despite being covered in snow dens, are not quiet and make easy prey for the polar bears. Uncovering the poorly protected pups in large quantities provides an easy, exploitable source of food for a mother bear to rapidly grow her cubs before they are forced off the sea-ice in the summer months. For the seals, vast numbers of pups insure they survive this season of hunting by bears.

Schematic of a seal pupping den. The adult seals access the den from a breathing hole; the pups live out of the water, but under a crust of snow that polar bears can break through.

All told, in our two days on the tundra, we saw five bears. The last bear we saw had been tranquilized and was being airlifted to the Churchill Polar Bear Holding Facility, where it will be held for a week or more and then released far from town (ideally so it can move onto the sea ice, once it forms). Managing the interface between people and bears is part of life in Churchill. For the most part, the bears are not habituated to the humans, but they are sometimes captured and moved away from town to protect both people and the bears themselves. The bear we saw being airlifted was near town on the afternoon of Halloween — we suspect the action was taken to prevent a bear from thinking that a trick-or-treater was a delectable substitute for a seal pup.

[left] A red fox we saw; sadly, we saw no arctic foxes. [right] The best ptarmigan picture I could get! (Images: S. L. Larson)

The tundra is replete with other life as well. In addition to the bears we saw several red fox, as well as plethora of birds (including ptarmigans). My favorite other animal we saw were lemmings frolicking in a snow bank, but they are frickin’ fast and difficult to photograph. 🙂

The remoteness of this area is not to be underestimated. The town of Churchill has a population of about 1000 people. Historically, the area has been populated by indigenous people, notably the Cree and the Dene. Europeans came to the area in the 1600s, when the Hudson Bay Company built the Prince of Wales Fort at the mouth of the Churchill River, across the estuary from the location of the modern town. The port of Churchill affords access via sea during the short ice-free months. Rail service has traditionally existed, running through the forests and tundra of northern Manitoba from Churchill to Winnipeg. During the spring of 2017, many sections of the rail line have been washed out, and it is uncertain if they are going to be repaired or if the rail line will be abandoned in place. In light of this, the only reliable access to the town is via air.

Aerial view of Churchill, with the Lazy Bear Lodge in the foreground. (Image: Wikimedia Commons)

For those of us who grew up in small towns, or in remote parts of North America, Churchill feels like a typical small town — people know almost everyone in town; there is only a small business district; lots of cars and trucks that are decades old instead of a year or two old; there are only a couple of roads and few multi-lane highways. The wilderness is within walking distance of anywhere in town.

To the southeast of Churchill, hugging the shores of Hudson Bay, is the Wapusk National Park (“Wapusk” is a Cree word for polar bear), but it is not a park like Yellowstone or Banff, criss-crossed with roads and full of amenities for people who seldom emerge from urban areas. Wapusk National Park has no roads leading into it, and encloses the largest protected polar bear denning area in the world. It is 11,475 square kilometers of boreal forest and tundra with more polar bears than people who frequent it.

Maps showing Manitoba, Churchill, and Wapusk National Park. (Maps: Parks Canada)

Nestled as it is on the shores of the northern ocean, the area around Churchill and Wapusk National Park are an ideal region to study and understand the changes our planet is experiencing, particularly as anthropogenic activities drive the global climate to warmer temperatures. Already the seasonal cycles of ice growth and recession are noticeable in the Churchill area, with sea-ice forming later in the fall and melting earlier in the spring by measurable lengths of time. This expansion of the ice-free season is part of the larger pattern of global arctic sea-ice decline.

Graph showing the projected decline in arctic sea ice as Earth’s climate warms. The grey and black show model predictions, and the red line shows current observations. [Graph from National Snow and Ice Data Center]

These kinds of environmental changes ripple through the ecosystem of the area, particularly the polar bears — a shortening of the sea-ice season is a shortening of the season where they do most of their feeding and building of fat reserves, complemented by a longer fasting season. Worldwide, there are growing numbers of bears who are starving or in declining health. Currently the Churchill polar bear population appears to be stable, though other bear populations in the arctic are declining. Whether or not the global polar bear population is stable or not is highly uncertain, since a significant portion of it inhabits the shores of Siberia, and the Russians are not forth-coming with environmental data about their area of the world.

If you are a scientist who would like to study ecology, or climate, or wildlife in the tundra and boreal forests of the region, Churchill is also home to the Churchill Northern Studies Centre. The Centre is a scientific and educational institution dedicated to a deeper understanding of life in the north — the physical environment, the ecology of the flora and fauna, and the interface with humans and human cultures. The Centre resides on the grounds of the Churchill Rocket Range, which used to launch sub-orbital sounding rockets to study atmosphere and aurorae, housed in a modern LEED certified building, with lab and workspace for scientists, and residential space that allows you to come and stay for weeks at a time while working at the center.

I was in Churchill for only 3 days, and barely scratched the surface of what there is to see and experience in this remote part of the world. Beyond the ecology of the polar bears, the summer months bring vast migrations of beluga whales who birth their young in the Churchill River. The area is part of the wide territories of the indigenous people of the Arctic that have inhabited these lands for thousands of years. Sitting on the boundaries of the Arctic, the area is showing and will continue to experience the early and rapid onset changes brought on by the changing climate, and represents an area where a person can learn and focus attention on this pressing problem.

I’ve been home for a month now, but I still think every day of those windswept days I spent on the shores of the Northern Ocean. I’m going to have to go back, sometime soon.

Songs from the Stellar Graveyard (GW170817)

by Shane L. Larson

Bernie Capax meets Death in Brief Lives, by Neil Gaiman.

In Neil Gaiman’s transcendent literary comics series The Sandman,  the Endless are echoes of the patterns of force and existence that define the Universe. Among them is Death, who at the end of our lives, collects us and escorts us from this Universe. As she says to Bernie Capax, who had walked the world for some 15,000 years, “You lived what anybody gets… you got a lifetime.”  (issue 43, contained in the collection “Brief Lives“).

If there is any truth in astronomy that we have learned over the last few centuries, it is that the Universe itself evolves. The stars are born, they live their long lives, and ultimately they perish and decay away. Death waits for them too. The galaxy is littered with the remains of stars that once were. From our vantage point here on Earth, we peer out into the Cosmos and glean what we can with the meager view we have in our telescopes. We have mapped billions of stars, and millions of galaxies. But in the stellar graveyard, we have only seen a handful of objects — we know precious little about the skeletons of the stars, because they simply don’t emit much light.

On 17 August 2017, at 7:41:04 am CDT, a faint whisper from the stellar graveyard washed across the shores of Earth. It showed up first in the LIGO-Virgo gravitational wave network, which was deep in our second observing run (what we call “O2”). At that particular moment, we were all wound up and celebrating because just three days before, we had made our first joint detection with LIGO and Virgo together (a pair of black holes called GW170814). When signals register in our network, the automated software (we call them “pipelines“) generates initial numbers about what the source might be, and that morning we knew we had something special. Our group lead at Northwestern was spinning us all up to start doing computer simulations, and in an early email to us she said what we all knew: this is life changing.

On the first day, we were sending emails that had the inkling already of how important this discovery was.

Why? Because the mass of the objects in the new signal were smaller than anything we had seen in gravitational waves before — all together less than about 3 times the mass of the Sun. Our predisposition from all our years of experience in astronomy said that could mean only one thing: the LIGO-Virgo network had just detected the first binary neutron star merger in history. Today, we call this event GW170817.

Spectrograms show how the frequency of the signal (vertical axis) changes in time (horizontal axis) in each of the three detectors. The long swoop up and to the right is called a chirp. [Image: LIGO-Virgo]

But the story gets better. 1.7 seconds after the gravitational wave signature, the Fermi Gamma-ray Burst Monitor (GBM), in orbit high over the Earth, registered an event — a short gamma-ray burst, now called GRB170817A. This was hugely significant, because we have often speculated about what causes gamma-ray bursts. For short gamma-ray bursts we’ve long thought it must be colliding neutron stars.

The discovery of GRB170817A by Fermi-GBM. [Image: NASA/Fermi]

What are these neutron stars? They are the dead skeletons of stars, one possible outcome of a colossal stellar explosion known as a supernova. They are extreme objects. They have about one and a half times the mass of the Sun packed inside a sphere about 20 kilometers across (about the size of a city). That means they are extraordinarily dense — a tablespoon of neutron star matter would weigh 10 billion tonnesabout 30 times the mass of all the humans on planet Earth. Gravity on the surface is outrageously strong — about 190 billion times the strength of gravity on the surface of the Earth; if you had the misfortune of falling off a 1 millimeter high cliff, you would be travelling almost 220,000 kilometers per hour when you hit bottom (136,000 mph).

A neutron star (diameter 20 km) scaled to the Chicago skyline. [Image: LIGO-Virgo/Daniel Schwen/Northwestern]

One thing we know about the lives of the stars is that many of them live together with a partner, orbiting one another in a fashion similar to the Earth orbiting the Sun. Like human life partners, one star inevitably reaches the end of its life first, and expires in a supernova. Some such stars become neutron stars. Eventually, the second star in the pair also dies, and if it supernovas, then one end state is two neutron stars, left in an orbital dance with the skeleton of their partner. One might think that is the end of the story for such stars, but there is still one final chapter in this tale from the stellar graveyard. The orbit of the two neutron stars can and will shrink over time through emission of gravitational waves. Of course, we’ve detected gravitational waves before (GW150914, GW151226, GW170104, GW170814), but this time it’s different. Why? We’re talking about neutron stars instead of black holes, which means there can be light, and indeed there was.

The collision of the neutron stars smashes all the matter together, and under such energetic circumstances, matter generates light. The gamma-ray burst was only the beginning. The collision sheds matter into a volume around the merging pair. This matter, suddenly free of the strong nuclear forces involved in the dense matter of the neutron star, recombines and makes heavy elements (physicists call this “r-process nucleosynthesis“). This recombination also creates light, and is called a kilonova. Following the gamma-ray burst there is also a long term afterglow, from the energetic jet of the gamma-ray burst blasting through the surrounding interstellar medium.

Different phases of emission of electromagnetic radiation from the binary neutron star merger. (L) The initial gamma ray burst. (C) The kilonova from nucleosynthesis. (R) Long term afterglow from energized material around the event. [Images: NASA-GSFC SVS]

The LIGO error ellipses plotted on a skymap of the Hydra-Virgo region. The galaxy NGC 4993 is visible in amateur telescopes. [Image: S. Larson]

Together, the LIGO and Virgo detectors can determine where on the sky a source comes from, though not perfectly. They can point to a region called the gravitational-wave error ellipse. For Gw170817, the ellipse on the sky was narrowed down to just about 30 square degrees — an area about the size and shape of a small banana held out at arms length. The error ellipse spans the boundary between the constellations Hydra and Virgo, with a little tail that stretches into Corvus. This was a difficult position in the sky because at the time of the discovery in mid-August, it sets very shortly after sunset. Never-the-less, telescopes around the world began an intensive imaging search, and just 10.9 hours after the detection of GW170817 and GRB170817A, an optical signal was discovered by the Swope telescope in Chile — a pinpoint of light on the outer fringes of the galaxy NGC 4993 that was not there before. Over the course of the next 10 days, the kilonova faded away; in the end more than 70 observatories worldwide imaged and measured the kilonova.  It has been a historic discovery and observing campaign. This is the beginning of multi-messenger astronomy with gravitational waves.

An image of the kilonova associated with GW170817; the fuzzy blog is NGC 4993. [Image: TOROS Collaboration, M. Diaz]

So what can you do with gravity and light together? As it turns out, an awesome amount of science! Today there is a virtual raft of papers being published (the first wave of many, I expect) outlining what we have learned so far. There are too many to explain them all here, but let me just outline a few that stand out to me.

Probably the most important outcome is the confirmation of the connection between short gamma-ray bursts and binary neutron star mergers. Gamma-ray bursts have been a mystery for more than 40 years. First discovered in the 1960s by the military using satellites meant to monitor nuclear weapon tests, the discovery that they were of cosmic origin was revealed to the scientific community in the 1970s. Since then many ideas and models to explain their origin and intense energy have been explored, but none have been confirmed because the engines — the astrophysical systems that drive them — are far too tiny to resolve in telescopes. The LIGO-Virgo detection of gravitational waves confirms that neutron star binaries are the progenitor of short gamma-ray bursts.

The result that I’m most excited about is we used GW170817 to measure the expansion of the Universe. The expansion of the Universe was first noted by Hubble in 1929, by measuring the distances to other galaxies. This was being done just 5 years after the discovery that there were other galaxies! Fast forward 88 years to 2017 — we’ve measured the expansion of the Universe independently using the distance to a galaxy with gravitational waves and light from telescopic observations together. This measurement comes just two years after the discovery of gravitational waves!  It gives me no small amount of pleasure to echo that historic discovery so close to the beginning of this new era of astronomy. 🙂

Top shows Hubble’s original 1929 diagram (from PNAS, 168, 73[1929]); bottom shows the location on this diagram of the GW170817 measurements, at the + mark. [Image: W. Farr/LIGO-Virgo]

We try and write public accessible versions of our papers in the LIGO-Virgo Collaboration. If you’d like to explore some of the science we’ve been doing, try out some of our science summaries.

There are of course many things we still don’t know about the discovery. Foremost among them is this: what is the thing that formed after the merger of the two neutron stars? Some of us in the astrophysics community think it might be some kind of exotic super-neutron-star, larger than any neutron star ever detected. Some of us in the astrophysics community think it  might be some kind of exotic light-black-hole, smaller than any black hole ever detected. Whatever it is, it lies within a very fuzzy range of masses that we call the mass gap — a range of masses where we have never seen any stellar remnant. What is the lightest black hole Nature can create in the Universe?  What is the heaviest neutron star Nature allows? These are questions we would very much like to know the answer to. At least for the moment, it seems we may not learn the answer from GW170817, but with future detections of binary neutron star mergers we may.

The masses of known stellar remnants discovered by both electromagnetic and gravitational wave observations. Between the black holes and the neutron stars is the “mass gap.” [Image: LIGO-Virgo/Frank Elavsky/Northwestern]

So here we are. We are all simultaneously exhilarated, relieved, joyous, and eager for more discoveries to be made. We’re very tired from late nights analyzing data, arguing about results, writing papers, and furiously preparing ways to tell our story to the world.

We could all use a nap. And a pizza.

Because this is only the beginning, the culmination of decades of hard work, difficult hardships, and anticipation. And the best is yet to come. I’m so happy that I’ve seen these days. Being tired doesn’t bother me, all the struggles getting to this point don’t bother me either, because I got to watch it unfold. As Death said, we get what anyone gets; we get a lifetime. These are the moments, the discoveries, that are filling that lifetime up.  Onward to the next one.

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This post is the latest in a long series that I’ve written about all the LIGO detections up to now.  You can read those previous posts here:

The Harmonies of Spacetime – GW150914

My Brain is Melting – GW150914 (part 2)

The Cosmic Classroom on Boxing Day (GW151226)

New Astronomy at the New Year (GW170104)

Focusing our Gravitational Wave Attention (GW170814)

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I have many LIGO and Virgo colleagues who also blog about these kinds of things. You may enjoy some of their posts too!