The Red Sands of Mars

by Shane L. Larson

My grandfather and me, when I was in middle school.

I had the good fortune of knowing all my grandparents. My maternal grandfather, Robert Steele Kelher, Sr., was a chemist. I have vivid memories of spending time with him when I was young, but I don’t recall much of what we talked about. Now that I’m all grown up and a physicist, I often wish I could chat science with him. But one conversation I do remember vividly, was about Ford Thunderbirds. My grandfather once told me he had always dreamed of owning a Thunderbird. But in those later days of his life, when we would walk around the backyard together just chatting, he said he was glad he never got one; he was sure it would never have been as great as he imagined. He preferred the simple joy of savoring the idea of owning a Thunderbird.

I stumble across this memory now and then, and think about my own longings. This week, I am reminded that I often dream of Mars. I imagine an alternate reality where I get up in the morning and don a spacesuit instead of Levi’s, and walk the cold red deserts looking for clues to where we came from, clues to how Mars has changed over the aeons, and clues to what its future fate may be. But interspersed with those idle scientific longings and ponderings of an “other career” are daydreams about living and playing on Mars. What I wouldn’t give to spend a week, camping on Mars near the abandoned hulk of Spirit, once our faithful emissary on the Red Planet. Spirit was one of two Mars Exploration Rovers that landed on Mars in 2004, the ’57 Thunderbirds of their time. It spent a more than 2000 days roving across Mars, covering a total of 7.7 kilometers. Sprit has a twin, called Opportunity that is still roving, and this week we celebrated its 12th birthday on Mars.

I often dream of camping on Mars, maybe next to the Spirit rover.

I’m not yet as old as my grandfather was when we talked about Thunderbirds, but as I get older, I’m beginning to think that my future will forever be confined to the surface of the Earth. My wonderful daughter fears that she is preventing me from becoming an astronaut (an idea she is firmly against, especially after seeing “The Martian”). She has repeatedly seen us throw space probes and rovers at Mars, but she doesn’t have the perspective to know that while sending humans into space is possible, it is not easy.

Despite my fear that I was born a bit too early to be part of the generations that live and work in space, I feel fortunate that I have lived through the first age of Mars exploration. I’ve been witness to the years when our species obtained its first up close views of the red sands of Mars, and found the landscapes to be not as alien as we might have expected. Pick up any picture, any panorama from Mars and take a good look. Looking across the rubble strewn plains, across the shifting dunes of sand toward soaring mountains rising in the distance, you could easily believe you are looking at a picture of the American Southwest.

The “Rocknest Panorama” taken by the Curiosity rover in 2012. It does not look unlike places you might find on Earth. [Image: NASA, PIA16453]

But this is not Earth. This world is Mars. It does look like Earth, in many ways, and that is part of the reason it captures our imagination. Like people, every world is unique — they have their own individual characters, their own long histories, their own destinies to fulfill in the Cosmos.  But also like people, they are similar as well — the laws of Nature that govern the Earth govern Mars. We can take what we know about Earth, and what we don’t know, and use it to learn about Mars.  Mars has its own remarkable moons, atmosphere, climate, and orbit; it has a long history of physical processes that shaped the evolution of its surface. Understanding the similarities and differences between Mars and Earth is one part of the long quest to understand our own planetary home.  Understanding the similarities and differences is one of the principle reasons we send our robotic emissaries to other worlds.

The Hubble Space Telescope view of Mars, centered on the dark plain known as Syrtis Major [Image: Hubble Space Telescope]

Why does Mars fascinate us so? More than any other world (except perhaps the Moon), Mars has captured the imagination of humans.  It is the only planet whose surface can be studied telescopically, and even from Earth there are tantalizing views of a dynamic and changing world.  The polar ice caps grow and receed with the seasons, visible even in a small backyard telescope. The vast dark plain of Syrtis Major darkens and fades with the Martian seasons. The planet clearly rotates when viewed from afar, and every so often, globe girdling dust storms blanket the planet, a doleful display that other worlds have dramatic weather patterns of their own. We can see much, and what we can see itches our curiosity and engenders questions.

The Martian atmosphere is thin (only about 1% as thick as Earth’s), but it is still strong enough to toss dust around the planet in globe-girdling dust storms that envelop the world for months on end. Our spacecraft have watched (and encountered!) swirling dust devils meandering across the plains, and rimes of frost condense out of the cold winter air. Once, long ago, we think the atmosphere was thicker, thick enough to move liquid water around the planet in a vast hydrological cycle like ours on Earth.  What happened to Mars’ atmosphere? Why and how did it change, and what does that mean about our long term future? The Martian poles are studded by brilliant white ice caps that grow and shrink with the Martian seasons. As the poles grow and shrink, does the ice entomb a layered record of Mars’ storied past, like the Earth’s ice does?

We see familiar atmospheric and hydrological phenomena on Mars, similar but not identical, to what we see on Earth. L to R: Dust devils (seen by Mars Reconnaissance Orbiter), frost (at the Viking 2 site in Utopia Planitia), south polar ice cap (seen by Mars Global Surveyor).

One side of Mars is bulged out in a geologic area known as the Tharsis Bulge. It is a vast volcanic plateau dominated by four massive shield volcanoes, the largest of which is three times higher than Mount Everest as as wide as the state of Washington — it is the largest mountain in the solar system.  We call it Olympus Mons.  How did this massive volcanic landscape form? Why is it higher than the rest of Mars?  Was it created in some astronomical cataclysmic event, or is there something about Mars’ geologic past that made it prone to massive mountain building?

Topographic map of Mars. Hellas (dark blue, right center) is lowest point on Mars; Olympus Mons (white peak, farthest left center) is highest point on Mars.

Since the 1960’s we’ve been sending spacecraft to Mars, and they’ve been dutifully sending back pictures and discoveries that lead to more questions. Mars, more than any other world, is the objet du désir. So as the Space Age unfolded, it was the target of many “firsts.”

Mars was the first planet to ever be visited by interplanetary spacecraft. On 15 July 1965, Mariner 4 flew past Mars, returning the first up close pictures of that distant shore. The very first picture was returned to Earth, but with some anomalous housekeeping data that suggested something might be wrong with the spacecraft’s tape recorder. While the issues were being sorted out and the computer was processing the data, the flight team had enough time to hand draw the first image directly from the data, pixel-by-pixel in true paint-by-number style. The first picture we saw was hand drawn (the computer later caught up and confirmed it could draw just as well as the Mariner 4 flight team). In all, Mariner 4 returned only 22 pictures, but those pictures showed us a barren, rocky world pock marked by craters, not (we thought) unlike the Moon.

The hand drawn image of the first Mariner 4 image (left) and the final computer generated image (right). [Images: NASA]

In November 1971, the Mariner 9 spacecraft successfully inserted itself into Martian orbit, becoming the first spacecraft to orbit another planet. Orbiting mars for 349 days, it returned more than 7000 pictures. Hidden among that treasure trove of images were amazing discoveries, including enormous volcanoes larger than any we have ever seen on Earth, and a vast chasm that girdled the planet, now called Valles Marineris — the Valley of the Mariner Spacecraft.

Mariner 9 showed us the first close up images of the caldera atop Olympus Mons (left) and the Valles Marineris (right). We have far better pictures of both today, but these were the first time humans had ever seen either. [Images: NASA]

Mars was the first planet to ever be landed on. On 20 July 1976, Viking 1 settled down in a rock-strewn red desert called Chryse Planitia — Greek for the “Plains of Gold.” Viking 2 landed just 45 days later, 6475 kilometers away in an equally stunning Martian plain called Utopia Planitia. Together, the Viking landers worked on the surface for 3621 days, returning images, monitoring the atmosphere, and sifting the sands of Mars for indications of life.

Landscapes of Mars. Chryse Planitia seen by Viking 1 (L) and Utopia Planitia seen by Viking 2 (R). [Images: NASA]

The Curiosity rover was lowered onto Mars by a flying robotic sky crane. [Image: NASA]

Mars is, to date, the only planet ever visited by rovers. The first was Sojourner, a micro-rover the size of a toaster oven that travelled a grand total of 100 meters in 1997. It was followed in 2004 by two larger Mars Exploration Rovers called Spirit and Opportunity. Today we celebrate Opportunity‘s 12th birthday on Mars; Spirit roved for six years before it fell silent in 2010. And in 2012, and even larger rover named Curiosity was lowered to the red sands of Mars using an ambitious and daring landing technology called a sky crane. All told, the rovers have covered nearly 60 kilometers among them, and the total is still climbing as Opportunity and Curiosity continue to roll.

All these “firsts” are fun and amazing to be sure. They inspire a kind of astonishment and awe that goes hand in hand with the uncontrollable urge to blurt out, “I can’t believe they just did that!” But in the end, the things that speak to me the most about Mars, the tantalizing bits that draw the mind and the soul into pondering the shifting red sands, are the pictures. The pictures inspire an unrequited longing to walk where none have walked before.

My grandfather, R. S. Kelher, Sr.

As I myself have grown older, I’ve learned to appreciate my grandfather’s thinking about his dream Thunderbird, especially in a society that seems increasingly commercialized. But when I think about Mars, when I imagine even just a few moments of being able to shuffle around in the light gravity, to turn over a stone scoured by a billion years of Martian weather, to let the red, red sands sift through my outstretched fingers, the longing for that experience is almost overwhelming. Given the chance, I think I’d trade the daydream for the opportunity. But Grandpa? You should know I remembered what you said, and I thought hard about it first.

Cosmos 5: Blues for a Red Planet

by Shane L. Larson

More than any other world in the solar system, Mars has captured the imagination of the human race (except maybe for Pluto, but it’s not a planet, right?). Mars has dominated our imaginings of other worlds for more than a century, beginning with H.G. Wells’ masterpiece of invasion, The War of the Worlds.  Since The War of the Worlds was first written, many other tales of adventure, danger and horror have been penned or filmed concerning Mars — Kim Stanley Robinson’s epic Mars Trilogy, the classic 1964 film Robinson Crusoe on Mars, Elton John’s sonorous musings that Mars is no place to raise a family in “Rocketman,” and many many more.

Mars in fiction. (L) The frontpage of the first edition of The War of the Worlds. (C) The poster for Robinson Crusoe on Mars. (R) The three volumes of Kim Stanley Robinson’s Mars Trilogy.

Ray Bradbury [Wikimedia Commons.]

I was first exposed to Mars in elementary school, through the reading of Ray Bradbury’s The Martian Chronicles, followed closely by viewing the 1979 screen adaptation of those Chronicles starring Rock Hudson. Bradbury’s Mars was a distant frontier, populated by indigenies resisting the influx of pioneers from Earth. Those pioneers were attempting to create a human civilization on Mars, ignorant of the fading race of natives who lived on the red sands before them. Having grown up in the American West, descended from a long line of ranchers who had homesteaded on the front range in Colorado, it was a familiar tale to me cast on a fantastical tapestry of rocket ships and alien landscapes. Bradbury’s tales of Mars are stories humans have always told about the frontier — tales of discovery, of finding out who we are by looking through the lens of our interaction with (and ignorance of) other lifeforms we have discovered.  In this case, the other lifeforms are the Martians.

The word “Martians” has come to mean more than just beings of Mars; the name has become synonymous with any alien species, vaguely if not outright humanoid.  Tales of Martians are often an allegorical mirror of the best ideals and worst fears we have about our own species.  Sometimes Martians are wise and benevolent; some, like the ghosts in The Martian Chronicles are noble and introspective in the face of extinction. Sometimes Martians are implacable and malevolent conquerers bent on owning the Earth, like the invaders in The War of the Worlds.

It was only natural that Mars become a focal point for our musings about other intelligent species.  Since the invention of the telescope, Mars has sung a siren song to the human race. It is the only planet whose surface can be seen through a telescope, giving us tantalizing glimpses of icy polar caps, vast dark plains that change with the Martian seasons, and long sinuous markings that look for all the world like river channels. It is easy to tempt our imaginations with the idea that Mars could be much like the Earth.

Mars, as seen by the Hubble Space Telescope. (L) The Tharsis Bulge, showing the large shield volcanoes of Mars, and the Valles Marineris in the lower right. (R) The large, dark plain of Syrtis Major, as well as polar ice caps and fleeting clouds. [Images by NASA]

By the 1970s we discovered that Mars was indeed much like the Earth — volcanoes and canyons, ice caps and river valleys. Our landers sent pictures of rocky red deserts, studded with boulders and rolling landscapes that terminate at the foot of mountains on the distant horizon.  But Mars is simultaneously unlike its neighbor, the Earth. The volcanoes are the largest known in the solar system; the largest canyon is a rift valley that is large enough to stretch from New York to Los Angeles; craters stud the surface, worn by the ages but not completely disappeared; and there is not an open body of water to be found anywhere on the planet.  Perhaps most importantly, we have failed to find any sign of life anywhere on the planet.  Unlike our home the Earth, Mars may very well be a dead world, if indeed it was ever alive at all.

Panoramas from the surface of Mars, shot by our rovers. From top to bottom: (1) Ares Vallis from Mars Pathfinder. (2) Lookout Panorama from Spirit, looking up the slope of Husband Hill. (3) Everest Panorama from Spirit, from the summit of Husband Hill, looking out over Gusev Crater. (4) Opportunity’s view of Endurance Crater.

Thus, I was electrified on a summer’s day in 1996 when a stunning announcement was made. Tiny, mineralized structures had been found using high resolution images of a Martian meteorite known as ALH84001 (name decode, from right to left: 001 = first meteorite found, 84 = in 1984, ALH = in the Allan Hills region of Antarctica).  The structures looked very much like microbes one might encounter on Earth, leading to the very real possibility that the mineralized structures may be fossilized infusoria from the planet Mars.

(L) ALH84001 is a chunk of Mars that drifted through space and landed in Antarctica, where it was discovered in 1984. (R) Micrograph images of structures found in ALH84001, highly suggestive shapes like bacteria.

Like all monumental discoveries in science, the announcement generated tremendous debate. The evidence is not completely unambiguous, and there is still much skepticism about what ALH84001 is telling us.  But it opened up the very real possibility that microbial life could have arisen on Mars, suddenly forcing all of our idle speculations and daydreams about Martians into a definite shape and form.  The human brain is fickle, particularly with regard to the kinds of daydreams it finds compelling — a Universe where all the life in the Cosmos consists of Earthlings and a few microbes on Mars just isn’t that exciting!  Microbes, shmicrobes! So it comes as no surprise to me that I have noticed a subtle uptick in the number of adventure stories told not about Mars, but about other worlds in the solar system: Europa near Jupiter, or Saturn’s enigmatic moons, cloud-swathed Titan and cryovolcanic Enceladus.

New worlds where we might search for life. Left to right, (L) Jupiter’s moon Europa, (C) Saturn’s moon Titan, and (R) Saturn’s moon Enceladus.

Why is that?  Why are we, at least sub-conciously, singing blues for the Red Planet? I suspect it is because we have landed on Mars and mapped the planet in exquisite detail from orbit.  Mars is by no means a fully explored world; we have roved only over 49 km of  Mars, but the planet has a total surface area roughly equal to the land area of Earth.  There is no way our 4 little rovers (Sojourner, Spirit, Opportunity, and Curiosity), and a handful of landers have seen every nook and cranny of the vast Martian frontier.

Our robotic explorers on Mars: (L) Sojourner micro-rover, (C) Mars Exploration Rovers, Spirit and Opportunity are identical, (R) Curiosity.

Never-the-less, we have yet to see indications of any large lifeforms.  Our cameras have sent back no pictures of Martian tapirs, no pictures of many-legged thoats, no pictures of giant sandworms. The net result: we have given up on the idea of there being substantial lifeforms. We’ve seen enough to convince ourselves that if there is life on Mars, it will be microbial.

Don’t get me wrong — without a doubt, the discovery of a single Martian micro-organism will transform biology forever, but it is not what we’re really looking for! Microbes are not what we long to discover — we long to find companions in the Cosmos. The discovery of a single large organism, whether it is the Martian equivalent of a squirrel, or stag beetle, or snail, would tremendously boost our hopes of one day finding life we can communicate with. 

A Europa cryobot submarine mission concept from NASA.

And so, our imaginations have moved on to new unexplored worlds that could still hide the greatest discovery we have ever imagined.  Foremost among these, is Jupiter’s icy moon Europa.  Europa is sheeted in ice, a solid blanket covering a sub-surface ocean.  What lies beneath the ice?  With so much water, could it perhaps harbor life? There must be heat sources to keep the sub-surface ocean liquid. Perhaps the constant squeezing by Jupiter’s gravity has produced volcanic thermal vents that provide the heat to keep the ocean liquid. On Earth, deep ocean thermal vents were discovered by  explorers in 1977 aboard the Alvin manned submersible. Much to everyone’s surprise, the area around the vent was thriving with life, despite the intense heat and high acidity of the water.

Examples of extremophile life. (L) The Sully Vent in the Pacific; extremophile bacteria glean energy from the extreme heat and acidic water [NOAA image]. (R) The Grand Prismatic Spring in Yellowstone; different colored algae are tolerant of different water temperatures, giving the spring its banded appearance [National Park Service image].

The discovery of life around the hydrothermal vents startled us, but scientists soon realized they were seeing an example of extremophiles — lifeforms that have evolved to uniquely survive in an environment that would normally be too extreme for fragile beings such as us to survive in.  This epiphany opened our eyes, and we see extremophiles everywhere on Earth. A famous and prominent example are the microbial algae mats around the thermal features in Yellowstone National Park — the colored bands surrounding a feature like the Grand Prismatic Spring are simply different species of algae, each tolerant of different water temperatures. In most extreme environments, the extremophiles are microbes, so even a planet like Mars could harbor life, despite the cold, despite the aridness, and despite the ultraviolet radiation.

Tubeworms around a hydrothermal vent survive because the bacteria break down the acids, providing a way for the worms to chemically synthesize energy [NOAA image].

The discovery of microbial extremophiles has amplified our confidence in the odds that there is life elsewhere in the Cosmos, but it has done little to dampen our enthusiasm for large lifeforms.  In reality, microbial extremophiles should boost our chances of finding more complex organisms, if the conditions are right.  The deep ocean thermal vents are particularly interesting examples when considering life on Europa, not just because there may be similar vents heating the Europan oceans, but because of the ecosystems we see growing around the vents on Earth.  The microbes that thrive in the immediate vicinity of the vents themselves are the base for a very localized ecosystem and food chain. Other, larger, more complex organisms, such as giant tubeworms, also glom onto the thermal vent, feeding farther down the food chain from the microbes who have learned to exploit the extreme environment.  If we could sink a cryogenic robot beneath the Europan ice, maybe we could find a similar, complex ecosystem.

We have yet to explore beneath the ice of Europa. But in the minds eye of our fiction writers the adventure is on, and already we are by-passing microbes in favor of speculation about there being big Europans, complex lifeforms against which we can compare ourselves.  I was first exposed to adventures on Europa by Arthur C. Clarke’s novel, 2010 (and the associated 1984 film starring Roy Scheider), where the Monolith (already a  manifestation of an alien intelligence beyond our own) fosters the growth of big lifeforms on Europa after collapsing Jupiter into a small star.  More recently, we have all been charmed by “Europa Report” which follows an expedition to Europa to discover not only microbial life, but something more.

The depiction of the unambiguous discovery of microbial life is very tell-tale of our desperate desire to not be alone in the Cosmos.  The first discovery of life beyond the Earth will be a monumental event, but the depiction of discovering extraterrestrial microbes in the movies is similar in excitement to the construction of a new frozen yogurt shop down the street.  Discovering alien life should be an Earth shattering event for our culture: we will know for the first time that we are not alone in the Cosmos!  But perhaps our fictional heroes, like us, have become immune to wonder at the discovery of microbes.  They want to discover something more, something bigger.  Microbes, shmicrobes.  Why is Europa a destination in stories now?  Because Mars, at best, will be the home of microbes, so we are searching for new arenas upon which to cast our dreams, fears, and hopes.

I dream of camping on Mars, whether there be Martians or not. [Illustration by S. Larson]

But despite our civilization’s fleeting wonder about life on Mars, I still often dream about adventures on the Red Planet and what might be found there.  It is still a world full of mysteries, and as worthy of exploration as any corner of the Earth, or any other world in the solar system. What a grand adventure it would be to go hiking across Mars with my daughter, camping near the now dead Spirit rover, to toss rocks over the edge of the Valles Marineris,  and take iPhone panoramas of the vast rocky deserts of the Red Planet.  I would love to spend an afternoon chipping open rocks on the shoulders of the Tharsis volcanoes, looking for some sign of ancient microbial life as we watch dust devils spin lazily on the plains below.

It may yet be true that Mars harbors no indigenous life, but we’ll never know until we ourselves go, and turn over every rock we can find. It will be the work of a lifetime, indeed of uncountable lifetimes if the exploration of the Earth is any kind of indicator.  In the end, there will be Martians, but as Carl Sagan so aptly noted (and Rock Hudson discovered at the end of The Martian Chronicles), the Martians will be us.

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This post is part of an ongoing series, celebrating the forthcoming science series, Cosmos: A Spacetime Odyssey by revisiting the themes of Carl Sagan’s classic series, Cosmos: A Personal Voyage.  The introductory post of the series, with links to all other posts may be found here:  http://wp.me/p19G0g-dE

The Far Side of the Sky

by Shane L. Larson

I grew up in the Rocky Mountains and the American West, from Colorado to Oregon to Montana. Since the earliest days of my youth, I’ve been an explorer of sorts. When I was growing up, my parents had carefully delineated boundaries for our adventures that kept us close to home. I don’t think they needed to worry much, because fronting the northern edge of our domain, there was a creekland paradise of bushes, fallen logs, and crumbling cliffsides that sloped down to shoals, rushing rapids, and gentle fords where we could wander back and forth across the water course. This was the frontier — full of adventure, mystery, and discovery.

A map from memory of the creek adventureland near the house where I grew up.

Nowadays, my explorations are less filled with the wanderings of boyhood, and more focused on the world around me. I’ve walked through the deep pine forests of the Rockies, reveled in the roaring spray of mountain waterfalls, peered over the precipice of vast canyons carved from the stone of the Earth, and stood in darkened mountain meadows soaking up starlight billions of years old. All of these experiences sit well with me, but this last one truly moves me.

All my life, I have always carried one over-riding dream with me — I want to see the far side of the sky. I would love to climb into a ship, “accustomed to the breezes of heaven” (as Kepler once wrote), and set sail across the great dark between the planets and off into the vast deepness of the galaxy. To travel beyond the confines of the Earth is the ultimate dream.

I’ve often wondered where this dream came from. How did I become so enamoured with exploring the vastness of the Cosmos? I asked my Mom about this once, and she responded, “You’ve kind of always known about this stuff, ever since you were a little feller.” But I know it is all her fault, because if I ask a slightly different question, like “When did I start watching Star Trek?” she replies, “Oh, I started you on that when you were about three.” 🙂

But in all seriousness, I think my parents are largely responsible for me being an explorer. They were my first science teachers. My dad is a plant ecologist. He was born and raised in the ranch country of Colorado, he was a fist generation college student, and received his PhD from the Colorado State University. My mom is a forester. She was one of the first women in the country to enter forestry school at Stephen F. Austin University in Texas. One of the earliest stories I remember my parents telling is a story about science. After my mom and dad were married, they went on their honeymoon to Canada, driving my dad’s pickup truck (a brown Ford F150 that we had through my high school days; we called her “Bertha”) and camping along the way. The way my mom tells the story is they were driving down a lonely stretch of highway in northern Montana, and she was sitting there thinking to herself “Damn he drives slow; what’s he think he’s doing? It’s the long skinny one on the right, Larry!” She was getting ready to say something, when my dad turns to her and says, “See that duck over there? He’s flying at 45 miles per hour!”

A male Mallard Duck.

That is an awesome story! It is very typical of what I expect from both of my parents growing up. They were always cognizant of the world around them, and masters of not just figuring things out, but of noting and measuring the world around them for the sheer joy of it. There was no grand reason why my dad had to know that mallard duck was flying at 45 miles per hour, other than his own pure, curiosity about the matter. They always encouraged this kind of curiosity among me and my brothers when we were growing up.

Somewhere around the 4th grade, I distinctly remember sitting outside at our picnic table, staring at the Moon with my mom’s Bushnell spotting scope she used for bird watching. It was, as far as I can remember, the first time I had ever looked through a telescope of any sort. I don’t know how or why I came to be out on that patio with that spotting scope; perhaps my mom suggested it, or maybe I got the idea from a picture of Galileo in my favorite book, National Geographic’s “Our Universe” by Roy Gallant.

[L] “Our Universe” by Roy Gallant (still one of my favorite books!) [R] Galileo observing the Moon, from Gallant’s book.

Somehow, I ended up on the patio with my mom’s spotting scope, staring at the Moon. I was transfixed. I had seen pictures of the Moon, but I had never seen it up close, and personal. I wasn’t looking at some picture some astronaut had taken. I was seeing the Moon with my own eyes; light from every crater and mountaintop that night was funneled into my eye and burned into my brain.

My Mom’s spotting scope. This is the first telescope I ever looked at the sky with.

What is so alluring about the sky? Galileo was not the first person to be fascinated with the sky, but he was the first person to see it up close. His first telescopes were poor ancestors of my mom’s spotting scope, but they let him see further than any human had ever seen. He too turned his telescope to the Moon, and on a summer’s night in 1609 beheld what I would see almost 400 years later. Not a smooth vista of alternating bright and dark shades, what you can see with your naked eye, but rather a wonderland of illuminated plains and soaring mountains dotted with a mind-boggling array of craters of various sizes, overlapping everything else. What he saw astonished him; the telescope challenged the conventional wisdom of the day, and presented Galileo with new mysteries and new ideas that had never occurred to him (or anyone else in the human race!). He found that Venus went through phases, just like the Moon. He discovered four brilliant points of light orbiting Jupiter — the Jovian Moons, Io, Europa, Ganymede and Callisto; they were the first worlds to be discovered in the collective memory of our species. He discovered that Saturn had a ring, though his telescopic view was poor enough he did not understand it as such; “Saturn has ears,” he wrote. When he turned his telescope to the darkened sky, he found that it revealed stars that could not be seen with the naked eye, and that the Milky Way was not a diffuse band of light, but was comprised of an uncounted multitude of stars, each casting a little bit of light toward the Earth.  Galileo published his astonishing discoveries in the spring of 1610, in a book called Sidereus Nuncius (“The Starry Messenger”; you can view a digital copy of the book here).

Those views were the beginning of a journey, for Galileo and for millions of others who came after him, gazing skyward through telescopes and dreaming about what lay beyond the cerulean boundary of the sky. Astronomy with your eyeballs is awe-inspiring, astonishing, mind-boggling, and soul nourishing all at once. But for some of us, myself included, there is still a dimly lit corner of my heart that longs to go to the places I can see — to touch the sands of Mars, bound down mountainsides on the Moon, and gaze skyward to see our home the Earth suspended against the velvet of night. I would dearly love to touch the Cosmos, up close and personal. As it turns out, I can, at least in small part.

In the Sky Pavilion of the Adler Planetarium, they have a vast display about our homeworlds — giant planets hanging overhead, large displays with all the wondrous facts our telescopes and robotic emissaries have revealed, a full size model of the Curiosity rover (about the size of a Mini Cooper!). It’s an awesome place to lose yourself.

The Solar System Gallery, in the Sky Pavilion of the Adler Planetarium.

Off to one side, they have a large, metallic meteorite — a 1000 pound chunk of nickel and iron, a fragment of the 150 foot wide meteorite that impacted in Arizona 50,000 years ago and created the Barringer Meteor Crater. Now I’ve seen plenty of meteors in my museum wanderings, but I still like to touch them, to feel them under the palm of my hands and knowing that this thing came from outer space! But the other day, while I was caressing the fragment from the Barringer meteor, I noticed a trio of other displays that hadn’t captured my attention before.

A fragment of the nickel-iron meteorite that struck in Arizona, creating the Barringer Meteor Crater.

The first held two fragments of asteroids. Fragments I could touch. One came from Vesta, the third largest asteroid in the asteroid belt. The other came from Ceres, the first minor body discovered in the solar system between the orbit of Mars and Jupiter. Once considered an “asteroid”, astronomers now call Ceres a “dwarf planet”, in the same league as our much maligned favorite child of the Sun, Pluto. There has been much talk recently of a human mission to an asteroid, and many have dreamed of mining the asteroids for the untapped riches they may hold (see John Lewis’ excellent book, “Mining the Sky”). It seems unlikely that I will be selected for one of those missions, if they ever occur. But there I stood, in downtown Chicago, touching an asteroid none the less.

Four pieces of rock from the far side of the sky, which you can touch at the Adler Planetarium. [Upper L] A piece of Vesta. [Upper R] A piece of Ceres. [Lower L] A piece of the Moon. [Lower R] A piece of Mars.

A bit farther on, there is a fragment from the Moon. A fragment I could touch. Humans have not been to the Moon for 41 years; only 382 kg of lunar material was brought back from the Moon. But there I stood, in downtown Chicago, touching a rock from the surface of the Moon.

A little farther on from that, there is a fragment from Mars. A fragment I could touch. Humans have never visited Mars, though as you are reading this, our emissaries Opportunity and Curiosity are roving the surface of Mars, sampling the air and testing the rocks, rolling ever onward toward their distant horizons. Our robots have carried sophisticated laboratories with them, and have taught us much about the rusty rocks and soil of Mars by doing experiments in situ, on Mars. But there I stood, in downtown Chicago, touching a rock from the surface of Mars.

Four fragments of rock from the far side of the sky, from the four closest worlds to Earth that I could imagine humans visiting in my lifetime. Four close worlds that I could reasonably (though perhaps improbably) be able to visit before I drink my last Slurpee at the ripe old age of 107. Touching rocks from the far side of the sky really speaks to the explorer buried deep inside me.

One of my friends from graduate school once used as his signature file the words of an ancient Hawaiian chant:

E `a`a `ia makou e ho`okele hou. `A`ohe halawai ma`o oa aku.
(We are challenged to sail once again. No horizon is too distant.)

The vast blue frontier of the Pacific Ocean.

Hearing the chant roll through the back corners of my mind, I imagine the unbridled joy of the ancient Polynesians, setting out into the trackless blue waters of the Pacific, not knowing where they may make landfall, but only knowing that if they pressed on far enough, they would.

Were there new lands to discover and settle? Perhaps. Would there be fertile landscapes to provide sustenance and security to a family or a village? Perhaps. Would there be other denizens of the Earth, willing to trade the products of their livelihood for the products of yours in a mutually beneficial economy? Perhaps. But I don’t like to think that’s why they sailed the seas.

The far side of the sky, like the wide blue ocean, promises something much more than distant, undiscovered lands — something valuable beyond measure. Grandeur. There is something to be said for the discovery and exploration of beautiful places. It’s good for the spirit.

Time to go exploring again. 🙂

—

NOTE: I confess to quoting the line about grandeur from the HBO miniseries, “From the Earth to the Moon”, Episode 10: “Galileo Was Right.” It is my most favorite episode of that entire series. Go watch it now.

The Size of the Cosmos

by Shane L. Larson

As many of you know, I ascribe much of my aspirations in life as a scientist to being exposed to Cosmos at a very early age.  Within the first five minutes of the first episode, Carl said a very big thought: “The size and scale of the Cosmos are beyond ordinary human comprehension.”

As I have grown into my career in science, I have lost sight of this simple fact. I’ve learned to write big numbers. I’ve learned to convert between meters and kilometers and lightyears when needed. I’ve even learned to use “crazy relativist units” and measure distance, time, energy and mass all in meters (something that confounds my students, my parents, and many of my astronomer friends!). I’ve done this enough now that when I calculate numbers, I know if they sound right.  Two million lightyears to a galaxy in the Local Group? Sure that sounds fine.  750 Megaparsecs to a quasar? Sure, I’m down with that.  1.3 billion kilometers to Saturn?  Word.

Developing a sense for big (and small!) numbers and whether they “sound right” is an essential skill for scientists, and we spend inordinate amounts of time training ourselves and our students to be facile with them.  But that completely bypasses Carl’s point — these numbers are HUGE.  They encode how utterly small we are on the grand scale of the Cosmos!

One of my hobbies is walking Solar System Walks when I encounter them (here is a long list at Wikipedia; another list at Air & Space).  These scale models lay out the Solar System, marking the location of planets at the appropriate spatial scale to give you a sense of how large the Solar System is (forget the Universe itself).  My favorite is one in Anchorage, Alaska, known as the “Lightspeed Planet Walk”  — if you walk at normal speed, the time it takes you to reach each planet is the same time it would take light to make the journey you made.  That is awesome.  Start at Earth, and shine a laser pointer at Neptune the moment you start walking; you’ll reach Neptune at the same time your feeble green laser beam reaches the real planet Neptune!

The center of the Lightspeed Planet Walk in Anchorage, Alaska, with a scale model of the Sun.

Despite the large physical scale of these walking models, I still often feel like they don’t capture the immensity in a way that really shocks my brain. I’ve thought about this fact a lot, and suspect it is because when I’m walking the model, it feels quite ordinary.  As I’m meandering from Mars to Jupiter, I’m not really thinking about how far I’m walking. I’m distracted by my daughter prattling about why Pluto should still be a planet, and watching ducks eat algae, and avoiding speeding mountain bikers.

But a couple of weeks ago, one of my astronomy friends showed me something that blew my socks off.  It’s a very simple demonstration you can do right at home that captures how messed up my mental picture (and I’ll bet yours!) of the solar system is!  I think my mental pictures are messed up because we often show the family of the Sun all together, to better show the relative size of the planets, like the image below.

A typical representation of the Solar System, often used in books, online references, and mass media.

What this image fails to show, is the spacing between the worlds.  We’ve known the relative spacing of the planets for some time, the distances having been worked out using basic geometry together with clever observations (many of which can easily be done in your own backyard), and through application of the laws of physics (notably Kepler’s Laws of Motion, and Newton’s Universal Law of Gravitation).

Folding pattern to make a reasonably spaced representation of the planetary orbits in the Solar System on a long strip of paper.

Let me teach you the trick my friend showed me.  Get a long strip of paper (adding machine paper, or other strip paper works well), about 1 meter long.  On one end, write the word SUN and on the other end write PLUTO.  Now fold the strip in half, and unfold it again.  What object in the solar system lies halfway between the Sun and Pluto?  It is the planet Uranus; write this on the fold.  Now fold the end marked Pluto down to Uranus.  Label this as the location of the orbit of Neptune.  What does this show us?  There isn’t  much in the way of planets in the outer half of the solar system!

Now fold the end marked Sun down to Uranus.  On  this new fold write Saturn.  Fold the Sun down to  Saturn and label the new fold Jupiter.  Fold the  Sun to Jupiter and label the new fold  Asteroids.  At this point, about 93% of your strip is  between the asteroids and Pluto.  This is the part of the solar  system that is euphemistically called “The Outer Solar  System.”  Fully half of the known planets in the solar  system are still to be squeezed between the Asteroids and  the Sun!  Let’s do that next.

Fold the Sun to Asteroids, and label this fold  Mars.  The last part is two folds before labeling: fold the Sun to Mars, then fold the end over to Mars again.  The result is three folds.  Starting at the  Sun, label them Mercury, Venus and Earth.  The entire procedure creates a map with amazingly accurate spacing between the worlds (yes! I calculated the errors; I was curious!).

The results of all your folding endeavours!

Now stare at your model for a moment.  The solar system is a lot of empty space!  The places that are easiest to get to are close to Earth, but are still very far away.  The distance to the Moon is about the width of a pencil line, and it took Apollo astronauts 4 days to cross that gulf.  Mars is six to eight months away by rocket.  Look how close it is to Earth!  It took the Cassini spacecraft almost seven years to get to Saturn.   When the New Horizons spacecraft flies by Pluto in 2015, it  will be have been outbound for almost nine-and-a-half years!  The  solar system is a big place. And the Cosmos is far vaster.

I think what amazes me the most about this model is that places I normally think of as very far away are much closer to Earth than my brain normally thinks of them.  Consider Jupiter; it is in the Outer Solar System.  But on the map, it is only 1/8th the distance between the Sun and Pluto!  Wow.

“The size and scale of the Cosmos are beyond ordinary human comprehension.”  Perhaps; certainly outside the realm of our everyday experiences. But our ingenuity gives us ways to push our brains to try to understand, and clever demonstrations like this one give you ways to ponder and think.  So get out your scissors, and start folding.

(L) The full length of the Solar System model. (R) My own version of this model, shown next to a typical Earthling.