A little perspective: the Moon, right next door in astronomical terms (or perhaps better, “just upstairs”), is still 240,000 odd miles away, which only sounds like a short hop until you realize that it would take something going as fast as a rifle bullet five whole days to get there. Still, as these things are measured, it is just a little way to go. The Earth and Moon are themselves much, much farther away from the Sun, fully 93 million miles, far enough that it starts making sense to speak in terms of the speed of light, not miles; the Sun is about eight and a third light minutes distant, which means that it takes sunlight, travelling at 186,000 miles per second, over eight minutes to reach us. The distance from here to Mars, our close planetary neighbour, is similarly vast but varies greatly. The planets aren’t laid out in a static line stretching out from the Sun like a string of pearls, though it looks that way in the books you read as a kid; they’re all moving in concentric orbits, like horses running on an expanding set of circular racetracks, so sometimes they find themselves on opposite sides of the Sun, and sometimes they’re very close together (relatively), as they move at their own speeds and one periodically laps another. Mars travels in an orbit that’s about 1.5 times farther from the Sun than ours is, which means it can be as far as 250 million miles away from Earth, or as close as 34 million, give or take. It’s thus vital to pick the optimal moment if you want to throw an object from here to Mars, and even at that it’ll take the fastest thing we can launch about seven months to run down its moving target. That’s how long it took the latest NASA Mars rover, dubbed Perseverance, to make the trip, after chasing Mars around the track over a distance of roughly 300 million miles:
…and when it touched down yesterday it was over eleven light minutes distant.
Radio signals travel at the speed of light. That’s what makes landing something as delicate and complex as a Mars rover so frighteningly difficult. Once it’s that far away, it’s on its own. There isn’t time, as it hurtles towards the alien planetary surface at an initial velocity of 12,100 miles per hour, to phone home for instructions, which would take more than 22 minutes to arrive. The whole thing has to be pre-programmed, and the nervous folks at the Jet Propulsion Laboratory in Pasadena can do nothing except watch the clock, and receive reports of the progress of the lander through the seven agonizing minutes of the process, knowing that everything they’re seeing already happened eleven minutes ago, and for all they know their baby has already thundered in like a multi-billion dollar meteor to form just another sad little crater on the Martian surface. With this mission such a grim fate was almost as likely as not, since the landing sequence for a heavy, car-sized machine like Perseverance is extremely complicated, and goes like this:
I suppose the video makes obvious what a feat of technology and engineering it is to stick the landing of such a large and sophisticated vehicle, but it’s perhaps an even bigger deal than it seems, given how difficult it is just to get a spacecraft to intercept the Red Planet and insert itself into a stable orbit, let alone attempt anything crazy like dropping a virtual Toyota down to the planet below. Only about 40% of all the missions launched by all the world’s space agencies since the beginning of the 1960s, most of them mere orbital probes, have succeeded, and only America has managed to land a functioning machine, a feat accomplished multiple times in a remarkable string of successes that began with the two Viking landers of the late 1970s. Those were immobile, but took soil samples, conducted various experiments, and snapped amazing colour photographs of the surrounding landscape that made Mars look almost as hospitable as, say, The Mojave Desert:
Then came the little Sojourner rover in 1997, the first wheeled vehicle to ever roam another planet, which weighed just 25 pounds, and travelled only a hundred yards over about three months before becoming inoperative. This set the stage for the much more capable pair of rovers named Spirit and Opportunity, which landed in 2004. Designed to last only 90 days, the plucky little machines instead worked doggedly for years, and wandered for miles across the Martian surface. Spirit went first, in 2010, while Opportunity soldiered on, mile after mile, until finally sending its last message in June of 2018, by which time the immensely more ambitious Curiosity, upon which Perseverance is based, had been on the surface with it for six years, having landed in 2012. Curiosity is still going strong, though it’s now a little bit beat up, suffering wheel damage and other wear and tear as it goes about its business.
The goal of all these missions is to find signs of life, either traces of what used to be there long ago, or real live organisms that might yet survive on what is now a very inhospitable planet, but was once lush with oceans, just like those here on Earth. Between three and four billion years ago, our solar system hosted two blue planets, and Mars, which is smaller, and thus cooled down first, might have developed living things long before Earth did. Proving that might demonstrate once and for all that the appearance of life on our planet was not a freak event unlikely to have occurred anywhere else among the stars, unless – and this is truly mind-boggling – we discover that the spontaneous appearance of animate matter may still have been a fluke, just one that occurred there instead of here. It’s entirely possible that living things from Mars could have made the trip between planets, embedded within rocks blown off the Martian surface by violent impacts, the traces of which are readily discernible all over the Red Planet. That little bits of another world might literally get blasted across the void and make it all the way to the surface of our planet may sound unlikely, but actually we know that it’s happened repeatedly – hundreds of pieces of Mars have been found scattered around the globe, particularly in barren places like Antartica, where they’re easier to find – and we now know that microbes are capable of surviving the rigours of space flight. They could well have developed first on Mars and then hitched a ride to Earth. Should we find living creatures hiding beneath the Martian surface, and they’re made of the same DNA sequences common to all terrestrial life, then, well, we’re probably all Martians, and the existence of life may still be a fluke, which migrated here from what might logically still be the only other place in the entire Universe that living things ever called home. Should that be the finding, it’ll be up to the astronomers, studying the many planets we’ve been able to discern orbiting other stars, to settle the matter. Or maybe other missions will one day find distinctive life forms elsewhere in the Solar System, perhaps on a moon circling Jupiter, or Saturn.
Maybe – just maybe – life landed both here and on Mars from somewhere else.
Perseverance was sent to land in a promising locale that used to be a vast lake, and it’s going to dig up samples using a drill to extract cylindrical cores from the Martian soil. The plan is to take about 40 such samples, each about the size of a piece of chalk, and seal them in little titanium tubes to maintain them in pristine condition, after which Perseverance is simply going to put them down on the surface and leave them there. The plan, amazingly, is to launch another mission down the road to go and retrieve them, and send them back to labs here on Earth for study. The Sample Retriever Lander, to be constructed in cooperation with the European Space Agency, should launch by 2028, and if all goes well it will deliver a rover that will be able to scoop up the tubes and put them into small rockets, which it will then launch into orbit around Mars to be intercepted by still another spacecraft that will collect them, and bring them all back to us, returning to Earth perhaps some time in 2031.
Perhaps less astounding, but even more fun, is the helicopter. Perseverance is testing technologies that might be highly useful to future exploration missions, and one of those is a little solar-powered helicopter named Ingenuity that’s going to attempt the first controlled flight on another planet. It’s just a little machine, weighing about four pounds, and it’s purely a technology demonstrator, there just to see if it’s even possible to get something to fly in the Martian atmosphere. It might not be. The air is awfully thin up there, 99% less dense than the stuff we’re used to, and not the best medium in which to generate aerodynamic lift, besides which it’s hellishly cold, to the point that something so small as Ingenuity might simply freeze solid. They’re going to give it a shot though, and if it works, wow. Imagine it: one day, much larger flying machines toting scientific instrument packages might be cruising at speed over all the most interesting places on the planet, performing reconnaissance for the plodding rovers below.
The idea just blows my mind.
It’s heartening, amid the wreckage and discord of the post-Trump era, with the nation in the grips of plague and natural disaster, its infrastructure crumbling, its people divided and suffering the effects of scandalously incompetent leadership, to see that Americans can still work their magic when they try. Thus far, nobody else has demonstrated anything like the acumen, the sheer scientific and technical prowess, inherent in the spectacularly successful series of NASA missions to Mars, and while the Chinese are snapping at America’s heels in this as in every arena, and are going to attempt to land their own rover later this year, it’ll be nothing like Perseverance, or Curiosity, for that matter. Nobody does it like NASA does it, and thus, while I suppose it’s a lot of baggage to pile on the back of a machine the size of a compact car, the shining success of the Perseverance mission is loaded at this point with symbolic significance that makes it so much more than a fascinating science project. As it navigates its way across the dried up river beds and evaporated lakes of far away Mars, it’s hard not to see it as proof that it’s too soon yet to be writing off our troubled neighbours to the south. The fools running Texas might not be able to keep the lights on, but just look at what the United States, and so far only the United States, can do. I mean, good Lord, they’re going to grab little bits of Mars, and bring them back here for study! Awesome! Maybe, by the time the first samples return, they’ll have pulled themselves back together and returned to form on lots of other fronts too. Maybe better days are just around the corner, with great things soon to be delivered by those who remain willing, like the best of the generations that preceded them, like the team that just sent this amazing machine all the way to Mars, to dare mighty things.