Visions, Ventures, Escape Velocities: A Collection of Space Futures

by Ed Finn

  But what is the point of all of this Mars exploration? The easiest answer is the search for past or present life. As a geologist, I could be perfectly happy just learning about the history of that distant planet independent of the search for life. But the most profound discovery in all of space exploration will come when we find life beyond Earth. We have only one data point in the entire universe regarding life, only one planetary body known to harbor it. Never mind that Earth represents an absurdly rich and fecund harbor; it’s still the only data point we’ve got. So even the discovery of fossil microbes on Mars would double the number of planets that we know to host life. And to borrow a concept from Isaac Asimov, it’s unlikely that, having found a second example of life in the universe, there are indeed only two.

  In this context, robotic explorers offer a major advantage over humans in the search for Martian life: they lower the possibility of contaminating the surface of Mars with human-borne microbes. It’s relatively straightforward to reduce the “bioload” on hardware; not so for humans. The search for microbes on Mars is more likely to yield unambiguous results if the searchers are not carrying colonies of terrestrial microbes.

  It still may take human explorers on the surface of Mars to prove once and for all whether life was or is present there. But I don’t think we’ve reached that point yet. We’ve never even brought back samples to search for traces of microbial Martians (rather than little green men). Yes, we’ve got several dozen rock samples from Mars thanks to natural impact events launching them into space to ultimately fall as meteorites on Earth. But these Martian meteorites are nearly all igneous rocks, the ones most able to survive the violent expulsion from their home world and least likely to host evidence of Martian microbes. We need to collect samples of rocks known to have formed in habitable environments on Mars from a time and place that offers the greatest likelihood of having hosted inhabitants.

  This is precisely the intent of the next NASA Mars rover mission in 2020. For the first time in the history of Mars exploration, we’ll have a rover capable of collecting cored rock samples and caching them for possible future return to Earth. It’s going to require some really interesting rock samples to compel the launch of a follow-up mission to pick them up and deliver them Earthside. But our robotic reconnaissance has already delivered a compelling view of Mars as a planet with an early history that really may have had habitable environments capable of supporting life—life which would be captured and preserved in the rock record.

  After decades of preparation, we’re finally poised to collect rock samples most likely to answer the question of life on Mars. Though complicated, collecting samples robotically and sending them back to Earth for analysis offers benefits beyond minimizing the potential for organic contamination. The full capabilities of instruments and techniques in labs on Earth can be deployed in the search for microbes in the returned samples. It’s simply not possible to equip rovers for such complex analyses. Yet the biggest benefit of sample collection via robot comes from the substantially lower costs, in part because it’s so much easier to equip rovers to deal with the incredibly inhospitable conditions of the Martian environment.

  The surface of Mars today is lethal to life as we know it, which may be why we haven’t found any yet. Even the least clement places on Earth are far more tolerable than the most hospitable places on Mars, starting with the most precious resource for human life: oxygen. The atmospheric pressure of Mars is less than 1% that of Earth, and 95% of that thin atmosphere is the stuff we breathe out, carbon dioxide. The life-giving oxygen molecules that we breathe in are considered a “trace” gas on Mars at less than 1%. Heavy tanks of oxygen would be essential gear for human explorers, as well as pressurized suits to keep one’s fluids from boiling away.

  Then there’s the cold. Despite the presence of a known greenhouse gas in the atmosphere, there’s just not enough of it to provide the warmth that humans need to survive. Although you could walk barefoot comfortably on a summer day near the equator thanks to the heat-absorbing soil and rocks, you’d need a jacket and hat for warmth against the freezing air temperatures. At night, you’d need a lot more than warm clothes to survive the plummeting temperatures that bottom out near minus 100°F. In the wintertime, at latitudes beyond about 40° from the equator, it gets cold enough on Mars that carbon dioxide in the atmosphere condenses out as a layer of dry ice at nearly 200°F below zero. So far, even rovers haven’t ventured more than 15° from the relative warmth of the equator, and even there they still require electric heaters on the motors that drive wheels and other moving components.

  Rovers are relatively immune to other nasty features of the Martian environment like global dust storms, ionizing radiation, and toxic salts in the soil that will challenge human explorers, not to mention potential future colonists. Some view colonization of Mars as a hedge against a calamitous end to human life on Earth. But for thousands of years, no war, disease, or famine has ever come close to wiping out our prolific and tenacious species. More importantly, over Earth’s history, even the greatest natural calamities produced from within the Earth and from without have never made our planet less habitable than Mars. The same goes for Earth’s most extreme climate changes. And even the dreaded scenario of all-out nuclear war would not strip Earth of its life-giving oxygen or rainfall. Humanity would be forced to mitigate the effects of ionizing radiation, but that’s already the case on Mars today. Billions of years ago its internal dynamo died, taking with it the protective bubble of a magnetic field that shielded it from cosmic and intense solar radiation. Earth’s dynamo still churns out a magnetic bubble, with no realistic scenario for its demise in sight.

  Some view Mars as a new frontier to be settled, like the American West, or as a place to create a new and better human society. But the Western pioneers didn’t have to worry about how they were going to breathe, or keep out radiation, or farm land devoid of organic matter and covered in toxic salts. Such conditions would challenge even the most committed founders of a new Mars society. It would be much easier to establish a colony in the Atacama Desert or any other of the most barren and uninhabited places on Earth.

  Regardless of the incredible challenges of sending humans to Mars, I can’t wait to see it happen. There’s no shortage of volunteers ready for a chance to go, and I fantasize about being among them. Despite my fantasy, I suspect that the first boots on Mars will arrive long after mine are packed away. As a child in the Apollo era, I watched the Moon landings and expected to see flags and footprints on Mars by my early adulthood. But that trajectory was unsustainable, driven not by science and the quest for knowledge, but instead by a Cold War imperative. In my advancing middle age, I don’t see a comparable driver for sending human explorers to Mars, or a compelling rationale for the even greater challenges of sending human colonists. But with perhaps-naïve optimism, I do imagine a scenario in which robotic missions return Martian rock samples that reveal tantalizing hints of long-dead biota, creating a new imperative for sending humans to find the answer. In doing so, there will indeed be life on Mars.

  Acknowledgments: Exploration of Mars would not be possible without the efforts of countless engineers, scientists, administrators, and staff at NASA and its academic and industrial partners. Together we are privileged to do so thanks to the commitment of the public and its representatives.

  [1] Carl Sagan, Cosmos (New York: Ballantine Books, 2013): 137. First published in 1980. [back]

  Section III: Asteroids

  Back in the socket, on the other side of the cable, upbound elevator cars were being loaded with refined metals, platinum, gold, uranium, and silver. Then the cars swung in and locked onto the piste, and up they rose again, accelerating slowly to their full speed of 300 kilometers an hour. Five days later they arrived at the top of the cable, and decelerated into locks inside the ballast asteroid Clarke, now a much-tunneled chunk of carbonaceous chondrite, so filigreed with exterior buildings and interior chambers that it seemed more a spaceship or a ci
ty than Mars’s third moon. It was a busy place; there was a continuous procession of incoming and outgoing ships, and crews perpetually in transit, as well as a large force of local traffic controllers, using some of the most powerful AIs in existence. Though most of the operations involving the cable were computer controlled and robotically accomplished, entire human professions were springing up to direct and oversee all these efforts.

  —Kim Stanley Robinson, Red Mars

  The Use of Things

  by Ramez Naam

  Useless. The word kept running through Ryan’s head. It was Beth Wu’s voice he heard, though she hadn’t said it.

  He had.

  Oh god, he wished he’d listened to her.

  “Emergency!” he yelled again. “Emergency!” The stars spun around him as he tumbled, out of control. His suit screamed alerts at him, both visual and audible:

  SUIT INTEGRITY COMPROMISED LOW AIR PRESSURE

  ANCHOR LOST MANEUVERING OFFLINE

  The asteroid swam back into view as he spun, his landing ship on it, both of them further now, tens of meters, receding away from him. Momentum from the accident that had ripped him free of his tether and free of the rock propelled him outward, away from everything. He was going to die in this ripped space suit, die thinking of Beth Wu, a hundred million miles away, and how right she’d been.

  “Fuuuuuck!” he yelled. “Emergency! Houston, this is Ryan Abrams. Torn loose from the rock, tether detached, tumbling, suit leaking. S.O.S.!”

  Shit.

  Hours Earlier

  Ryan Abrams pulled himself, hand over gloved hand, along the last few metal rungs that led to the Asteroid Landing Module. In microgravity, walking was impossible. There was no up or down. The only way to stay attached to the asteroid was to tether yourself or to physically hold on. He was doing both now, prone, his body facing the asteroid, his security harness clipped to the long metal cable bolted into the asteroid surface.

  He reached his left hand “up,” grasped the next rung, pulled his right to follow. Ahead was the Asteroid Landing Module, just a few pulls away now. Repeat. Repeat. A sample bag was clipped at his waist, full of asteroid material he’d drilled at predetermined sites. It floated free in the near-absence of gravity, tugged along each time he moved forward, then carried by its momentum to gently thump against his side each time he stopped.

  His hand left the last of the rungs the robots had drilled into the surface. He reached up, grasping a rung on the side of the ALM itself, pulling himself up until he faced it, rather than the asteroid’s surface. With one hand he moved his harness clips onto the craft. Then he palmed the airlock button. Through the metal he felt the vibration of the airlock cycling. One wall of the lander opened, and he unclipped and propelled himself and his sample bag into it.

  At the back wall he clipped in again, then turned, swiveling his head inside the helmet of his Asteroid Surface Excursion Suit. His eyes swept over the surface of this small rock, barely a hundred meters across, its skin pitted and scarred by billions of years of collisions with micro-meteorites. The edges of those impact craters were still raw and jagged. They’d stay that way for millennia, with neither wind nor water to smooth them.

  Now that surface crawled with CALTROPs, hundreds of them, like so many sea urchins, rolling slowly over the rock, thousands of carbon limbs adhering and releasing, probing, sampling.

  Doing everything he could do.

  A few hundred grams. That’s what a CALTROP massed. Hundreds of times less than he did. Almost all that mass was in the core, the fist-size package of logic and power in the heart of the spikes. The limbs themselves, half a meter long, massed little, but packed in an impressive array of capabilities. Adherence pads covered the tips of half of them: arrays of microscopic, Velcro-like carbon tendrils, inspired by the sticky finger pads of a gecko, which allowed them to adhere to nearly any surface, or release it. The other half of the limbs were tipped with an assortment of microscopic drills, sensors, material sampling instruments, tiny manipulators.

  The first time Abrams had read the specs of the CALTROPs, he’d found them impressive. When he actually saw them in action, all of them moving, perfectly coordinated, in silence, covering the surface of the rock with an ease he’d never achieve … well, he’d found them a bit unnerving.

  Now, weeks later, he just found them depressing.

  They didn’t need him here. The mission didn’t require him. These things could do the job, under Beth Wu’s command from Houston, without any human on-site, or all the expensive infrastructure required to move that human, keep him or her fed and watered and oxygenated.

  He’d heard a glib comment once, from his roommate back at MIT. The data center of the future would have just one man in it, Jimmy said, and one dog.

  The man’s job was to feed the dog.

  The dog’s job was to make sure the man didn’t touch anything.

  They should have sent me a dog, Ryan thought to himself.

  He palmed the control to close the outer airlock door.

  He and Beth had quarreled before his departure.

  “You know we shouldn’t be sending you on this,” she said. “A human’s a liability up there, not an asset.”

  Trust Beth to be so blunt.

  It was late on a Tuesday night, and the bar, a homey little place outside Johnson Space Center, was almost empty.

  He’d spread his hands wide, placatingly, one palm open, the other casually holding onto his beer.

  “Look, Beth. I know this was originally going to be an uncrewed mission. But I can do things your bots can’t.”

  She looked back at him, no placation at all.

  “They’re NASA’s bots. Not mine. They’re taxpayer bots. And sending you there costs the taxpayers as much as sending thousands of them.”

  He started to interject. She cut him off.

  “Ryan, getting you there in one piece, all your food, your water, your air, your triple-redundant safety systems, it’s twenty thousand kilos! Think about all the instruments we could pack in that payload instead! And it’s billions of dollars. Just for you!” She started gesticulating then, waving her arms about, agitated. “Yeah, you can do a few things no robot can. But thousands of them can do a whole heck of a lot more useful work than you. And with the money spent on your trip, we could close whatever capability gap there is.”

  He grimaced, breaking eye contact. “You’re saying I’m useless.”

  “No,” Beth said the word slowly, like she was explaining calculus to a child. “You have your uses. But the price is way too high. A heck of a lot higher than your value. You’re a net liability to the mission.”

  “Worse, then. Worse than useless.” He looked back up, met her eyes, dared her to agree.

  She sighed in exasperation. “Stop pouting, Ryan. This isn’t about you. It’s about the mission.”

  He grew impatient with her, let it show. “Dammit, Beth. We’re out there figuring out how to build habitats! We’re out there building a road. We’re out there figuring out how to get men and women living off-planet! Crewed missions have to be part of it!”

  She stared at him for a moment, studying him, her eyes roving over his face. “You’re half-right. We do need to get our species off this planet, out of our one little basket. Space is for humans …”

  “So why …” he tried to interject.

  She slapped a hand onto the table. “Because the fastest way to build that road into space for our species is not to send you on this mission!”

  Liftoff was by far the most demanding part of the journey out. He’d launched before, half a dozen times, on trips to LEO and an orbit of the Moon. Still, being on top of a 38-story-tall rocket, pushing 8 million pounds of thrust out of its engines, never became routine. It never got easy. The g-force slammed him back into his padded seat with the weight of four gravities, crushing the breath out of him for those first two minutes, the whole rocket shaking and shuddering and roaring around him, as the sky turned from blue to bl
ack.

  Then the boosters separated, the acceleration slowed, faded, then dribbled to nothing. His body floated in its harness.

  Orbit.

  The world sped by below him: a storm over the Atlantic in stark white; a clear stretch of ocean in stunning blue, dotted with white clouds and their darker blue shadows; the yellow and green of Western Africa, glittering with the reflected light of the giant Moroccan solar fields that powered Europe.

  Ryan exhaled, the tension leaving him. He blinked, his eyes wet. Suddenly, the whole world, the whole basket humanity’s eggs were in, spread out below him.

  Then NERFS came into view, the Near Earth Re-Fueling Station, in an orbit just below his. Its solar panels stretched out wide, framing its tubular modules stuffed full of water ferried up from the Moon. Its docking ports were crowded with droneships, tiny things massing just hundreds of kilos at most, and some much smaller, filling up with water their reactors would ionize and their efficient ion engines would thrust back out, one ion at a time, propelling themselves up and out. Many of them heading to his own final destination, on a slower, more efficient route.

  Ryan frowned. Beth’s words came back to him.

  We’re bootstrapping a whole new way to do space, she’d said. The first lift of water ice from the Moon was ungodly expensive. It used chemical rockets like the ones that’ll get you going. But then we had a little bit of fuel. The second trip just needed enough fuel to get to LEO. Then it could refuel with lunar water, use that fuel thousands of times more efficiently as propellant in its ion engines to get out to the Moon. And then we could lift twice as much fuel. Then four times. Then eight times. And soon 16 times as much fuel per cycle as that first mission. That’s where we’re going, Ryan. The robots can grow that infrastructure exponentially. They can operate 24/7. We’re going to mass produce them, make them cheap, launch them into LEO on old cheap rockets, and let them build us a home in space without any of us having to risk our lives there until it’s done.