by Steven Ruff
I consider myself a Martian, at least virtually. I’m actually a Mars geologist, a scientist who applies knowledge of Earth geology to explore Mars geology. But for three months in 2004, I and a few hundred other Earthbound explorers at the Jet Propulsion Laboratory got as close to being Martians as humanly possible at this point in history. Many of us from across the U.S. and abroad took up residence in Pasadena and surroundings so that we could ride shotgun with the Spirit and Opportunity rovers. Our apartments were equipped with blackout window shades to help adjust our wake and sleep cycle to the rising and setting sun in the Martian sky. We needed to be on Mars time, just like the rovers. Just like Wekesa Ballo.
Although we Terrans share the same Sun with the real Martians (if they exist), their planet turns just a bit more slowly on its axis than ours, such that the Martian day is 39 minutes and 35 seconds longer. This Martian “sol” is quite a cosmic coincidence. Our other next-door neighbor, Venus, rotates the slowest of any planet. So a “day” there would stretch for more than 243 Earth days, precluding any hope of living on Venus time.
Mars time, however, I could get used to. My night-owl ways had unexpectedly prepared me for a mission with about 40 minutes of bonus time each night, followed by the luxury of sleeping 40 minutes later each morning. Apparently my circadian metronome beats with a Martian rhythm. I was among the lucky few. My housemate lasted only a week before his decidedly terrestrial metronome forced him back to the rhythm of Earth time.
[…] Fortunately, the jet lag of our team of JPL Martians ended after a mere 90 sols, the prespecified length of the rovers’ primary mission. The rovers, of course, are immune to jet lag and free from human frailties. They have been loyal mechanical surrogates following the commands of their Earthbound masters each day since their landing, one of them for more than 13 years now.
For decades we’ve been sending our robotic surrogates to Mars. The first spaceships had just minutes of close encounters with the alien planet before sailing past. Subsequent missions graduated to extended visits in orbit, bolstered by ever-improving capabilities to sense the landscape a few hundred miles below and to probe the meager atmosphere in between.
40 years of Mars exploration
Our first touch of Martian soil came in 1976 from one-armed robotic landers, an incredible feat of engineering and science prowess. But the lack of mobility of the Viking landers was so frustrating that Carl Sagan wrote in “Cosmos”, how he found himself “unconsciously urging the spacecraft at least to stand on its tiptoes, as if this laboratory, designed for immobility, were perversely refusing to manage even a little hop.” The rover mission he so passionately championed would not come until after his untimely death. That 1996 Pathfinder mission was wildly successful, but its modestly equipped little rover never ventured out of sight of its aptly named home base, the Carl Sagan Memorial Station.
Nearly 10 years would pass before the next rovers visited Mars. Spirit and Opportunity arrived in 2004 with significant advances in mobility and scientific instrumentation, but their capacity to explore is still very limited. They undertake reconnaissance by committee, following orders from humans tens of millions of miles away who have an incomplete picture of the landscape through which the rovers move at the pace of a Galápagos tortoise. Even the newer, larger, and more sophisticated Curiosity rover still suffers from the same exploration-at-a-distance realities of its precursors. This is not an efficient way to investigate the vast reaches of an unknown planet. I often wonder what pieces of the scientific puzzle we’re missing that a geologist on the surface would’ve zeroed in on with ease.
[…] We’ll need significant improvements in satellite and receiver infrastructure to increase the amount of data sent between the planets. The fastest data rate from Mars to Earth today is two megabits per second. That’s about five times slower than the slowest “Starter Package” offered by my home internet service provider. We’re going to need at least the “Premier Package” to make high-definition 3D telepresence viable.
[…] We’ve already started to teach old rovers new tricks. For example, in the search for Martian dust devils using rover cameras, the otherwise data-intensive effort is minimized via software that only returns images in which a change is detected. And interesting rocks can now be targeted for imaging and other non-contact measurements using onboard software that is smart enough to recognize them without a human in the loop. Ultimately however, true in-depth exploration of the Red Planet will require highly mobile and dexterous robots that can explore and interact with the Martian environment using artificial intelligence. Just as test pilot astronauts during the Apollo era learned the fundamental skills of a geologist, so too could robotic surrogates on Mars. But unlike the rudimentary capabilities of the Apollo geologists, future Mars robotic geologists will be equipped with sensor systems unimaginable in the 1970s. These tools will identify rocks and minerals with a precision and accuracy that even skilled field geologists on Earth would envy. The discoveries of these robotic explorers would be the starting point for human explorers to make sorties from their orbiting base camp, and ultimately, from their surface exploration zones.
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 -70°C. 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 -130°C. 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.
About the author
Steven Ruff is an associate research professor in the School of Earth and Space Exploration at Arizona State University. He has been roving Mars since 2004 with Spirit and Opportunity and exploring from the perspective of orbiting spacecraft since 1988.
The Martian Chronicles by Ray Bradbury
Mars: Our Future on the Red Planet by Leonard David and Ron Howard
Mission to Mars: My Vision for Space Exploration by Buzz Aldrin, Leonard David, Andrew Aldrin