Robert J. Sawyer

Fifty-five years ago, we got our first good look at the surface of Mars — a photo that figures prominently in my new novel The Oppenheimer Alternative. As I said five years ago, on the 50th anniversary of this picture from Mariner IV:

Possibly the saddest science photo ever. Our first close-up look at Mars, from Mariner 4, on July 15, 1965, showing not a twin of Earth but a dead, crater-scarred surface. No canals, no seasonal plant growth, no alien cities.

“Let’s skip the appetizers and get down to the giblets,” said von Braun, still boyish at fifty-three. “The key photo is this one, number eleven.” He moved it to the table’s center, and the other scientists craned to look at it. Oppie felt his heart jump. He heard Rabi suck in his breath, and Kitty muttered, “Shit.”

“That was taken at a distance of seventy-eight-hundred miles,” said von Braun, who stepped back now so the others could see the photo better. “East to west, it covers a hundred and seventy miles. North-south, one-fifty.”

“Where?” demanded Oppie. “What co-ordinates?”

Von Braun consulted a series of stapled sheets he had brought with him. “It’s centered on thirty-one degrees south and one-niner-seven degrees east.”

Oppie turned his attention to the giant 1962 Air Force map of Mars, flattening out its creases with his palm. He quickly found the spot. On the map, a canal cut diagonally across the middle of that area starting in the southwest and running up to the northeast as if flowing from Mare Cimmerium to Mare Sirenum.

And in the Mariner photo, maybe, just maybe, if he really, really, really willed himself to see it, there was a diagonal line, although at a less steep angle, running … no, not into a sea, or even a plain, but into —

There was nothing else it could be, was there?

— into a crater. Only one-half of its rim was clearly visible, like the bowed part of a capital D, but it dominated most of the frame. And the bloody thing wasn’t alone. Oppie quickly counted seven — no, eight! — other craters in photo eleven. Given the size of the area being portrayed, the D crater was perhaps eighty miles across, the one adjacent to it was maybe thirty, two were twenty, and the rest were ten down to as little as five.

Oppie knew that Mare Cimmerium was named in honor of the Cimmerians, a people Homer mentioned in the Odyssey who lived in perpetual darkness. And after three and a half centuries of looking at the red planet through telescopes, that darkness had finally lifted, and mankind was at last seeing the true face of its celestial neighbor.

It was heartbreaking.

It was like looking at the goddamned moon.

In photo eleven, there were small craters within large craters, and some craters overlapped and obliterated parts of others. And, once you’d seen them in this, the sharpest of the pictures, you couldn’t help seeing them in the other photos, too. Craters everywhere.

But no sign of water.

No sign of water erosion.

Just dusty death.

Even worse than that. Death implied there’d once been life, but this planet’s surface looked ancient, untouched for millions or billions of years. Barren, sterile.

With von Braun’s guidance, Oppie next located the spot on the Air Force map captured by picture eight. That area was bisected by Erinnys, one of Percival Lowell’s more prominent canals, which, according to him, flowed from the west end of Mare Sirenum to Titanum Sinus in Memnonia. But this photo, too, depicted nothing but craters, albeit none as large as the one that dominated picture eleven.

“And there’s more,” said von Braun.

“Oh, joy,” said Kitty.

“Mariner IV didn’t go into orbit,” said von Braun. “It was a fly-by mission. Still, it did pass behind Mars from earth’s point of view, and just before it did so — and just after it emerged on the other side — its S-band radio, beaming toward earth at twenty-three hundred megahertz, passed through the Martian atmosphere. There was no specific occultation experiment aboard, but we can make some reliable conclusions thanks to the amplitude and phase changes that were detected. Based on them, we were able to confirm that the Martian atmosphere is almost entirely carbon dioxide. That, of course, suggests that, despite our best hopes, the polar caps don’t contain any appreciable amount of frozen water — which could have been melted for drinking or irrigation, or electrolyzed into hydrogen and oxygen for fuel — but are almost exclusively dry ice.”

“Which is fun at a kid’s birthday party or to shatter a goldfish,” said Rabi, “but otherwise pretty damn useless.”

“Yes,” said von Braun, nodding. “And the occultation also let us get a handle on the density of the Martian atmosphere. It’s thin — even thinner than we’d thought. Somewhere between four and six millibars.” Earth’s was roughly a thousand millibars, one bar originally having been defined as earth’s sea-level atmospheric pressure. The red planet had an atmosphere about one-half of one percent as dense as earth’s — and what little of it there was consisted of poisonous CO₂. Oppenheimer felt light-headed.

“The bad news isn’t over yet,” said von Braun. “Mariner IV had a helium magnetometer aboard. As it approached Mars, we expected it to detect the planet’s magnetic field. The sooner it detected it — that is, the farther from Mars Mariner found it — the stronger the field must be. We knew Mars couldn’t have as strong a field as earth. But based on the planet’s mass and rate of rotation, we figured it might have a magnetic field about one-tenth as powerful as earth’s, and so we expected Mariner to encounter the shock front many hours before making its closest approach to the planet. Now, I won’t say we didn’t find anything. There was one little hiccup slightly after closest approach that might have been the shock front. If it was, well, then Mars has a magnetic moment 0.03 percent of earth’s — and if it wasn’t, then it’s even less, or perhaps totally nonexistent.”

Oppie found a chair and collapsed into it, stunned. With such a minuscule magnetic field, Mars couldn’t possibly have anything akin to earth’s Van Allen belts. That lack helped explain the incredibly tenuous Martian atmosphere Mariner IV had detected — nothing to deflect the ever-present solar wind from stripping it away. But it also meant that any life on the surface — be it native lichen or refugee humans — would be pelted by long-range alpha particles that were always spewing out of the sun. The surface of Mars wasn’t just sterile; it was constantly being sterilized.

Oppenheimer looked from person to person. Von Braun’s eyebrows and arms were lifted in the classic don’t-shoot-the-messenger plea. Rabi, frowning deeply, was chewing at the edge of his thumbnail. Kitty was shaking her head slowly left to right.

“Well,” said Oppie, when he could at last find his voice again, “that’s just devastating  …”

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