How SpaceX and NASA Are Choosing the First Human Landing Site on Mars

The entire human Mars program can be ended by a rock the size of a kitchen bin.

One rock?

One rock. Half a meter tall, under one landing leg, and a ship the height of a skyscraper tips over. That's why SpaceX's own rule for a landing site is that the chance of hitting anything taller than half a meter has to be under five percent.

So the first town on another planet gets picked by... gravel.

Gravel, ice and flatness. Hold that thought, because there's a number later that explains why the place humans actually land will probably be somewhere you've never heard of. October twenty-seventh, two thousand fifteen. Houston, the Lunar and Planetary Institute. Forty-five scientific abstracts on the table, each one an argument for a different patch of Mars. Each one saying... land the first humans HERE.

Forty-five pitches for the same job.

Forty-seven proposed sites in total, spread across almost the whole allowed range of latitude, longitude and elevation. And the thing nobody outside that room realizes is that the winning argument has nothing to do with beauty.

Okay, but let me be the idiot in the back. Why not Olympus Mons? Biggest volcano in the solar system. If I've flown two hundred million miles, I want the view.

The view doesn't keep you alive. In SpaceX's landing-site work presented at a lunar and planetary science conference in twenty twenty-one, the engineers wrote it plainly... latitude, elevation and load-bearing requirements quickly reduced the available areas.

Translate that for me.

You need enough air above you to slow down. Ground solid enough to hold the ship up. And ice you can dig. High ground is the worst possible place to park, because the air's too thin to brake in. So the map shrinks fast... Arcadia Planitia, Phlegra Montes, Utopia Planitia, Deuteronilus Mensae. Flat. Boring. Icy.

Boring is the brand.

The site also has to be radar reflective, so the ship can measure its own distance to the ground on the way down. And load bearing, so it doesn't sink. By May twenty twenty, fifteen candidate sites had been worked up in Arcadia Planitia alone.

Hang on. Who's taking those photos? SpaceX doesn't have an orbiter.

NASA does. In twenty nineteen, GeekWire reported that NASA's Mars Reconnaissance Orbiter was imaging SpaceX's candidate zones in Arcadia and Amazonis Planitia, with water in mind.

A government spacecraft scouting real estate for a private company. Very cooperative. For now.

SpaceX's principal Mars development engineer, Paul Wooster, told NASA's Mars analysis group exactly what they want... near-surface ice, few hazards like large rocks, and room to grow a sizeable outpost. Then he said something revealing. The ice sites are in the high mid-latitudes... but lower latitudes are preferred.

Why does latitude fight you?

That's the central trade of the whole Mars problem. Head toward the poles and the ice gets easy. That twenty fifteen workshop found that between forty and forty-five degrees, the ice is most continuous and the dirt you'd have to dig through is thinnest. Head for the equator and you get sun and warmth... but your water is buried, or gone.

Cold and wet, or warm and thirsty.

Exactly. And that's the number I promised you. The workshop invented a unit nobody outside the field talks about... the Exploration Zone. Not a landing pad. A circle roughly one hundred kilometers in radius around one central landing site.

A hundred kilometers. That's not a site, that's a commute.

It's a county. Habitat, plus every region of interest you'd ever want to drive to, reused by crew after crew after crew. You're not picking a parking spot. You're picking the only town humans will have on an entire planet, and everything they'll ever study has to be inside it.

So where does Jezero come into this? That's the rover crater.

Jezero was in that pile, in Houston, in twenty fifteen. Abstract ten thirty-four. Pitched as an Exploration Zone for polyhydrated sulfates you could use as a resource, mineral diversity, ancient habitability.

Wait. So it was being scouted as a human site before the rover ever went there.

Six years before. Perseverance touched down on February eighteenth, twenty twenty-one, inside a landing ellipse of about seven point seven by six point six kilometers. And it's been doing human reconnaissance ever since. More than two dozen rock samples. Proof of a stable lake, a delta, a river system. And it made oxygen on site... explicitly in preparation for human exploration.

Oxygen out of Martian air. That's the whole ballgame, isn't it?

It's the difference between a visit and a stay. And then July twenty twenty-four. A reddish rock in an ancient river valley called Neretva Vallis, nicknamed Cheyava Falls, covered in what the team called leopard spots. Organic carbon compounds, and minerals that most likely formed from biological processes.

Most likely? Say that part louder.

Carefully, though. The scientists are explicit that it could still have formed without life. The most compelling potential biosignature found so far... not proof. And it's sitting in a tube, waiting for a ride home.

Which is the argument for sending people.

That's the argument. One site has the science. Other sites have the ice. Nobody has found a place that scores perfectly, and as of today, no agency and no company has formally committed to a final human landing site. NASA calls it a multi-year process, and that process is still running.

So who's ahead?

On paper, SpaceX, because they've been grinding engineering constraints onto specific coordinates for years, with NASA's orbiter taking the pictures. But here's what I'd watch. Whoever picks the site writes the first chapter of Martian geography. The first street. The first name on a map that billions of people might one day live under.

And it'll be some flat grey plain nobody's heard of.

Almost certainly. The first human home on another world won't be chosen for how it looks from Earth. It'll be chosen because the rocks there were small enough.