Where the rover leads, humans will follow—sooner than any of us think.
Landing on Mars should be boring by now.
NASA has been doing it since the 1970s. Last week, the agency did it again, achieving its sixth consecutive soft landing on the red planet, and its eighth total out of nine attempts. As records go, NASA never managed six consecutive controlled landings on the Moon, and either way, mere months after Neil Armstrong’s one small step for a man, the public had collectively tuned out the Apollo program. Robotic landing No. 6 on dusty old rock No. 4, then, should have been a news blip at lunch and forgotten by dinner. Yet on February 18, 2021, the world in unison watched spellbound as the rover Perseverance alighted gently on the planet Mars. Seconds after telemetry signaled the rover’s survival, people took to social media to express elation, and moments after the first objectively uninteresting image began to circulate (a chiaroscuro world as seen through a porthole), everyone seemed stupefied by this alien landscape.
It was as though we had never been there before.
They were right to feel this way, of course, and yet it is surprising that they did. Of the public response that day, the thing that struck me most was the “first footage” released, alleging to show Perseverance’s camera panning across the Martian horizon, its umber soil and apricot skies, and a gentle breeze caught by its microphone. The video was shared thousands of times with thousands of comments… and had nothing at all to do with Perseverance. The video was two years old: a 1.8-billion-pixel composite of stitched-together images captured by Curiosity, 2,300 miles away. (The breeze was fake.) Though NASA’s press office did all it could to explain that, no, this is not Perseverance, the footage continues to eclipse all else on my Facebook feed: our “first look at Mars.” People just cannot get enough of it.
I wonder, perhaps, whether our worldwide, year-long COVID-caused confinement has given our species a new perspective. Do Walt Whitman’s words not hint at some longing that Perseverance salves?
O to sail in a ship,
To leave this steady unendurable land,
To leave the tiresome sameness of the streets,
the sidewalks and the houses,
To leave you, O you solid motionless land, and
entering a ship,
To sail and sail and sail!
Certainly, something has happened in the last ten years. The euphoria in 2012 following Curiosity’s landing suggested it, or perhaps even inaugurated it. Attitudes toward space have changed, intensified. Today, public opinion polls suggest a crushing majority of Americans support NASA. A plurality favors landing astronauts on Mars over returning them to the moon. There seems to be more interest in, and support for, Mars exploration than ever. Indeed, that world — if polls and Perseverance enthusiasm is to be believed — appears to be at the heart of it.
For me, it comes back to that first image. That “first footage.” And the first legitimate video released today of the rover’s entry, descent, and landing. Perseverance carries nineteen cameras. Its lander carried four. There was a time when cameras were considered superfluous on spacecraft. Juno, the orbiter that revealed Jupiter’s stunning blue poles and forever changed our understanding of what that world looks like, nearly flew without an imager. JunoCam isn’t even a critical science instrument — it was paid for with the mission’s education and public outreach budget. My entire life, Jupiter was robed in bands of white, tan, brown, and red. My daughter will never know a day when Jupiter wasn’t a ball of boiling turquoise. It is not a one-to-one comparison, obviously, rover and satellite, but in both cases, there is an inexhaustible thirst for what it all looks like, these places, these Not Earths.
Only one of those worlds, however, will one-day welcome humans.
What more can be said about the “seven minutes of terror,” that harrowing deceleration of Perseverance from 12,000 miles per hour to zero, Mach 16 to perfect placidity, the rover set on the Martian surface with the tenderness of a teacup placed on a saucer.
For a moment, though, really think about it. The big things. Ten minutes before Perseverance entered the Martian atmosphere, the cruise stage — the spacecraft’s thrusters, propellant, and solar power — detached from the landing system. Then the rover, encapsulated in a back shell and heatshield — the whole thing looking exactly like a flying saucer — bore down into the atmosphere of Mars for four minutes, slowing itself to a thousand miles per hour.
Remember, though: It wasn’t just about slowing down. Perseverance traveled 300 million miles and had to land on another planet at a precise target the length of the Vegas strip.
Three minutes before touchdown and nine miles from the landing site, a supersonic parachute deployed, slowing the flying saucer by two-thirds. Twenty seconds later, it jettisoned its heat shield, exposing directly for the first time the rover to its Martian environs. The spacecraft thus began scanning the surface of Mars to get a lock on where it was, exactly, and where it needed to be. The parachute had slowed it to 200 miles per hour now, the contraption two and a half miles from the surface, and the same distance from its target. Within seven seconds, the computer had worked out where it was and where it was going. One minute from touchdown, the back shell and parachute were jettisoned, and a final descent stage, a kind of crown of retrorockets atop a contracted rover, started blasting like hell. The whole thing was by then 70 feet from the ground and slowed to four miles per hour. The descent stage — a sky crane now — began to lower the rover on a twenty-foot tether, and in sixteen seconds, the landing speed at precisely zero, the rover’s wheels pressed into sienna soil.
Remember, the goal wasn’t just to land. It was to land without kicking up too much dust. Which is so absurd a requirement that it verges on comical: like an artificial constraint to make things interesting for the smartest kids in the class. (It was necessary, however, to prevent damage to the rover’s delicate scientific payload.)
But the landing wasn’t over yet! Perseverance was still tethered to the sky crane, which could crush or drag the rover and that would be that. The moment the rover sensed its wheels had touched the ground, however, it cut its tether, and the descent stage blasted off and away, angled forty-five degrees so as not to go straight up, and crash straight down, flattening Perseverance, cartoon piano style.
Seven minutes after entering the atmosphere, it was all over. Perseverance survived.
All of this is offensively oversimplified. The stitching of the parachute’s seams alone could fill a textbook, and result only from an engineer’s lifetime of experience. The spacecraft “scanning the surface of Mars” — it is so easy to write those words, but there are no GPS satellites circling the red planet, and during that final minute before landing, contradancing subsystems were swinging each other round and round to identify and avoid hazards.
Imagine the complexity of the hazard-recognition code. After settling on a precise landing spot given the fuel remaining in the descent stage, it still had to get those thrusters pointing in the right direction, and to maintain an appropriate altitude, and to remain upright, and all the while, it had to run algorithms to double-and triple-check everyone’s work, because if some subroutine crashed because Mars threw something left-field at the lander — or if a sensor malfunctioned and returned an unexpected value — or if a memory register flipped to a zero when it should have been a one — or if the altimeter suddenly said we are thirty miles over the surface rather than thirty feet — then there’s no rebooting the system, no asking Earth for help. With seconds to go, the lander would have to recover gracefully given sub-optimal conditions and somehow set down a one-ton rover without creating a new, four-billion-dollar hole in Jezero Crater on Mars.
Now: pick any single noun or verb in the preceding paragraph, and recognize the decade of development, the years of testing that went into it. And every noun and verb have to work together, and each time you add another to the equation, complexity doesn’t increase linearly, but exponentially, and there is a dictionary’s worth of nouns and verbs that aren’t even listed here, but that engineers at Jet Propulsion Laboratory, which built the thing, had to identify and develop and test and integrate and test again. And the first time it was actually switched on, it had to work perfectly, because it was a hundred million miles from Earth with a three billion dollar rover attached.
I think a lot about the heat shield. Just over a minute after entering the Martian atmosphere, one side of the shield reached 2,370 degrees Fahrenheit. But the heat shield is only a few inches thick. On the other side, the rover remained at room temperature. That alone is indistinguishable from magic, but it’s the details that get me: tiny sensors were embedded in the shield, each a couple of millimeters deep, some measuring the atmospheric pressure, others measuring the heat shield’s performance, all feeding data to Perseverance’s avionics. None of that would save the spacecraft had things gone south. They were there for the next mission, just as sensors on Curiosity’s shield were there for this one. This is how you build institutional knowledge. This is how you build the most extraordinary exploration program in NASA’s history.
This is how you get astronauts on Mars.
After the landing, reading the celebratory Perseverance posts on social media and the texts from friends who don’t know asteroids from black holes, it’s like there was a collective realization of the feasibility of all this. That it wasn’t adventurism, and that NASA doesn’t just throw spacecraft at problems until something works. It took decades to get to this societal moment, but the templates of our collective culture seem somehow to have shifted. Something is happening here, and the world has taken notice.
We are witnessing the nations of the Earth converging on Mars. This month alone, United Arab Emirates entered orbit around Mars (that country’s first), followed a day later by China, which will soon set down a small rover of its own (another first). Waiting for them were orbiters by the United States, India, Russia, and the European Union. Japan will join them next year. There is no place else on Earth where such countries would meet so conspicuously outside of a United Nations summit or some terrible warzone.
If this were a race, though — and it feels impossible to separate that metaphor from space exploration — NASA would be at the half-marathon mark as the rest of the world just crossed the starting line. The agency has cultivated a perishable, astounding ability that no other country possesses, but if the United States doesn’t use it, doesn’t floor it, doesn’t go all in — it’s going to lose that lead. That already happened at the moon, where NASA hasn’t landed a single atom in a half-century, and has no ability to do so now, while China has built a robust and inventive exploration program, with taikonauts soon to follow.
As a society, I assert, we are ready, culturally, for Mars in a way that we were not during the Apollo program. NASA has spent twenty years — April 2001 to today — building a skillset and proving its prowess. Each rover and orbiter is a demonstration of its commitment to doing a crewed mission to Mars correctly, each robot — no: each human precursor mission — amasses a library of knowledge on everything from windspeeds to the probable effects of dust storms on human health.
For human missions to Mars, there are challenges yet to solve, among them radiation, but these are engineering problems. They are surmountable. Randii Wessen, lead study architect of the A-Team, the group at Jet Propulsion Laboratory that matures experimental spacecraft concepts, once taught me the definition of impossible: “It is that which violates a natural law,” he said over coffee. “Can you make a spacecraft go faster than the speed of light? No, that’s impossible. Can I have a human body live to four hundred years old? If I can’t point to the law that it violates, it just means we don’t know how to do it.”
Materials engineers and space physicists at the Advanced Materials and Processing Branch at NASA Langley Research Center; Jet Propulsion Laboratory; the Applied Physics Laboratory at Johns Hopkins University; and dozens of research centers across the country and around the world are hard at work on the problem, developing materials, models, and measurements to understand and diminish the effects of solar and galactic radiation. Cosmic Rays aren’t showstoppers. Given a mandate, they barely qualify as speedbumps.
We talk a lot about the private sector’s role in space exploration, but this sort of fundamental research is the domain of the government. Perseverance — like Curiosity and spacecraft going all the way back to the Viking landers — is a science-making machine. Its instrument payload is responsive to key questions on the evolution of the solar system and the aqueous history of Mars and past evidence of prebiotic and biotic processes there, among other things.
As Bruce Jakowski, chair of the Mars Architecture Strategy Working Group and leader of NASA’s MAVEN spacecraft, explains, Mars is central to understanding many pressing issues that vex the planetary science community. As a terrestrial planet, he says, each elapsing spacecraft and the nature of Mars itself has helped unlock the entire 4.4-billion-year history of terrestrial planets: the relationship between a planet’s interior and its surface and atmosphere and upper atmosphere and the solar wind, and so on. “The insights we get really address all the components of the evolution of a planet. I think that Mars, with its potential for life and being so close to us that we can actually do multiple missions: I think those are the things that set it apart. In addition, Mars has been the long-term stated goal for human exploration.”
The rover seems designed to prep the field, so to speak, for future human exploration. It carries an experiment designed to produce oxygen from the Martian carbon dioxide-rich atmosphere. A ground-penetrating radar will search for subsurface waters and ice. Perhaps most notable is the rover’s ability to drill core samples in the Martian soil and bottle them in small jars, which will be deposited for a future rover to collect and launch into space. Though Curiosity and Perseverance are powerful rolling laboratories, their analytical capabilities pale next to what could be achieved in state-of-the-art laboratories. For more than forty years, planetary scientists have sought pristine samples of Mars for analysis on Earth. At long last, the sample return sequence has begun.
The road to landing astronauts on Mars has always run through sample return. The idea is to develop a fine understanding of the chemistry of Martian material and search for signs of past or extant life. The chemistry helps you know what resources await astronauts, and what can be utilized; biosignatures could meanwhile galvanize public support for a human expedition there. The inestimable value to planetary science and astrobiology is self-evident, with persuasive cases published in the late 1980s. The goals today are more or less the same.
Likewise, NASA advisory committees have for forty years endorsed sample return as a centerpiece science objective to enable future human exploration of Mars. As the National Commission on Space recommended in 1986: “It is conceivable that Mars samples would include fossil evidence showing that life once existed on the planet; one can hardly imagine a more exciting discovery. In addition to their great scientific value, these samples can provide the basis for our initial steps in the development of Martian resources.”
A formal study led by legendary astronaut and physicist Sally Ride made the same recommendation the following year: “This bold initiative is committed to the human exploration, and eventual habitation, of Mars. Robotic exploration of the planet would be the first phase and would include the return of samples of Martian rocks and soil. Early in the 21st Century, Americans would land on the surface of Mars; within a decade of these first piloted landings, this initiative would advance human presence to an outpost on Mars.”
NASA has never deviated from these goals, though they have taken longer than anyone hoped. Ultimately, the robotic exploration of Mars has always been about more than proximity and more than science. (Venus, for example, is closer and is basically Earth gone wrong: a scientific bonanza for comparative planetology.) No, for NASA, robots on Mars have always been about the humans that will one day walk there.
To that end, commercial space is an enabler in ways that few could have predicted, and that the Apollo program lacked. With NASA demonstrating a serious commitment to tackling the fundamental research necessary to enable human exploration of Mars, there is every reason to believe that Elon Musk, CEO of SpaceX, will press the issue of landing humans there in our lifetimes. He has certainly made no secret of his desire to make humans multi-planetary. Initial human reconnaissance of Mars would require super heavy-lift rockets and expertise in power generation and storage. A medium-term outpost-type settlement would necessitate the ability to dig stable, subsurface habitats. In the long term, transportation infrastructure and robust communications infrastructure are essential. As Earth-based industries go, Musk would seem to hold the most bizarre and disjointed portfolio in corporate history. For Mars-based ventures, however, his companies solve each of the above requirements. The Boring Company thus isn’t about traffic, Tesla isn’t about cars, and Hyperloop would work better on Mars than on Earth — you wouldn’t even need the pressurized tubes at Martian atmospheric pressures.
If NASA rovers and orbiters are buying down risk for landing astronauts on Mars, SpaceX and its associated enterprises are removing obstacles for what crews do once they get there. With public engagement with NASA and Mars at a zenith, we might be witnessing a rare alignment of circumstances that could enable at last the dreams of Golden Age science fiction authors. The home stretch that ends with boot prints begins with Perseverance and sample return. As evidenced by the flotilla of international spacecraft on and around Mars, when NASA makes its next move, it will not be alone. The agency’s tentative plans call for a 2026 launch to collect Perseverance’s cached samples and rocket them to space. NASA plans to partner with the European space agency to cut costs and accelerate development of the mission.
For 50 years, NASA has been 20 years away from sending astronauts to Mars. For the first time, it feels like we’re a decade away. As Whitman asked:
Have we not darken'd and dazed ourselves with books long enough?
Sail forth—steer for the deep waters only,
Reckless O soul, exploring, I with thee, and thou with me,
For we are bound where mariner has not yet dared to go,
And we will risk the ship, ourselves and all.
David W. Brown is the author of THE MISSION, or: How a Disciple of Carl Sagan, an Ex-Motocross Racer, a Texas Tea Party Congressman, the World's Worst Typewriter Saleswoman, California Mountain People, and an Anonymous NASA Functionary Went to War with Mars, Survived an Insurgency at Saturn, Traded Blows with Washington, and Stole a Ride on an Alabama Moon Rocket to Send a Space Robot to Jupiter in Search of the Second Garden of Eden at the Bottom of an Alien Ocean Inside of an Ice World Called Europa (A True Story). It is available now.