There it was: Glowering red on the dashboard of the sky like an astrological warning light next to the full Blood Moon Friday. Mars.
It was calling brightly out across 35.8 million miles of space, a gulf humans have yearned to cross for as long as they have known that the lights in the sky are places. This week, it is the closest it has been to Earth in 15 years.
That yearning has now been refreshed — if in fact it ever went away — by the discovery of a 12-mile-wide lake under the southern ice cap on Mars by the European Space Agency’s Mars Express orbiter. An oasis for interplanetary dreamers. Microbes are known to inhabit similar lakes on Earth, and so who knows? Could little Martian bugs be swimming around down there under a mile of ice that keeps the cosmic rays out and keeps the Martian water liquid?
Mars has always been the backyard of our imaginations, the place we might one day live or from where invaders would come in flying saucers to enslave us and steal our water. Our robots have already crossed that space again and again.
It is not crazy in astrobiology circles these days to hold the opinion that the life that now envelops Earth started on Mars and then some pilgrim microbe was brought here on an errant asteroid. We know now that the sky is an endless conveyor belt with cosmic riffraff shuffling debris from planet to planet, even star to star, as personified by Oumuamua, thewandering comet from outside our solar system that cruised blithely through the planets last winter. In the fullness of time, everything gets everywhere.
We could all be Martians, then, which could help explain the seemingly endless lure of the Red Planet. The dream of the exile to return to what might once have been Eden. Elon Musk has said he wants to die there, but he’s not ready to go there quite yet.
I grew up terrified as well as curious about the place, after I saw the previews of “Invaders From Mars.” The film showed a boy my age seeing a flying saucer go under a hillside, after which the townspeople, including his parents, were kidnapped and turned into robots. My parents never let me see the whole movie.
It paid homage to a part of a mythology that dated to the beginning of the century, of Mars being the dying home of a dying civilization of super smart beings — little green men — hunkered by canals bringing water from the poles. Those visions sprang from a misunderstanding of the work of the Italian astronomer Giovanni Schiaparelli, who in 1877 thought he saw long, thin lines he called canali, (channels in Italian) lacing the surface of Mars. Percival Lowell, a socialite and astronomer took the notion seriously and proceeded to map what he thought were cities and canals on the planet.
All that good science fiction melodrama vanished when spacecraft images showed the real planet, cratered and dustblown.
So here are a few hard facts. Mars is about half the size of Earth, so gravity is weaker there — only a third what is on Earth and so you could jump higher, that is if you could take a breath. The Martian atmosphere is mostly carbon dioxide and there is very little of it anyway, the pressure is less than one percent of air pressure here. Temperatures on the ground range from 86 degrees Fahrenheit to minus 190. A day there is 24 hours, 39 minutes and 35 seconds long and a year is 687 Earth days.
Mars is red because it is rusty. Martian dust is full of iron oxide.
It is, as a travel brochure would say, a land of dramatic contrasts, with the solar system’s biggest volcano, Olympus Mons, 15 miles high, and the longest canyon, Valles Marineris, 2,500 miles long and four miles deep.
As far as we know, it is inhabited mostly by our own robots, like the rovers and the Vikings we have sent there, and the wreckage of lost landers. Some 45 space missions — not all of which made it — have been launched toward Mars by humans. There are five on the docket, including efforts by China and the United Arab Emirates, planned for the summer of 2020.
If anybody else has been interested, if there is anything like an alien iPhone or one of those monoliths from “2001: A Space Odyssey” sitting on a rock somewhere, we wouldn’t necessarily have found it yet.
Out of all this exploration a new story has emerged, equally haunting. It is of a planet once splashed by oceans and carved by swiftly flowing rivers, a world warmed long ago by an atmosphere. But something happened and Mars lost its sparkling waters and its air.
Now there are only the naked shorelines, empty filaments of tributaries, silent rocks and occasional wet spots on cliff sides. If there was ever life here, the story goes, it died or went underground.
Instead of little green men, we are looking for microbes, which is O.K. with me. I get lonely easily and maybe microbes will be what passes for cosmic company.
The Vikings, which landed on Mars in 1976, were famously designed to look for life in the Martian soil. And scientists still argue about whether one of the four experiments actually got a positive result.
Since then any whiff of evidence for Martian life past or present has stirred the public and perhaps congressional enthusiasm for the space agency’s budget. In 1996 scientists said they had detected the fossil of a microbe in a meteorite from Mars in a news conference that came complete with a statement from President Bill Clinton. But few scientists accepted it.
In June, the Curiosity rover confirmed that there are small amounts of methane periodically emitted into the atmosphere in Gale Crater, where it spends its time. On Earth a lot of methane comes from biological activity, like cows burping, but pure geological processes can also make it.
The newly discovered underground lake, if it is confirmed by further observations, is just the latest in this parade of hopeful signs that we might have neighbors out there somewhere.
Lately much excitement about extraterrestrial life has been in the outer solar system where many of the moons of Jupiter, Saturn and the other gas giants have been found to be ocean worlds hiding under shells of ice. Some of them, like Jupiter’s Europa and Saturn’s Enceladus, seem to be squirting salty plumes of water and perhaps microbes out into space.
NASA is planning a probe to Europa and many astrobiologists have been pushing for a ride through the sprays of Enceladus or for a mission to send drones to explore the methane lakes of Titan, Saturn’s biggest moon. Nobody really knows what alien life would look like or what it would require.
As Jill Tarter of the SETI Institute in Mountain View, Calif., who has spent her whole life looking for ET, likes to say, we only know of one example of life in the universe. That is the mind-bogglingly complex web of DNA-based organisms on Earth.
“We are looking for No. 2,” she said.
We still don’t how or why life started on Earth or how prevalent it is in the universe. It is an article of faith among astronomers and hopeful astrobiologists that, given the right conditions,life will find a way.
The InSight spacecraft is heading to Mars to listen for marsquakes and study the planet’s structure.
In the next 50 years we will probably know whether Darwin’s test tube produced another result in our own neck of the cosmos, in our own solar system. Missions to Mars have been heading off every two years for decades now.
We won’t know for sure about Mars until somebody walks and drills on it. I used to think I would never live to see humans even back on the Moon, but that was before SpaceX began to do things with rockets — coming back and landing tail first — that I had only seen in old science fiction movies.
We might not find monoliths or an errant alien iPhone. We might only find dead microbes, or fossil imprints of them. But even that would be exciting, to know that nature had tried before.
But if they are alive — whatever that turns out to mean — then a kind of spiritual and intellectual reckoning will be on us. Depending on how wild or familiar these alien creatures are, we might have to decide whether our allegiance is to DNA-based organisms, or something even broader.
And we might have to decide whether microbes, or entire potential biospheres, have rights. If we decide to engage in the ultimate imperialist project, we could try to make Mars habitable for humans by heating the planet to melt the ice caps and release carbon dioxide — a greenhouse gas — from them and the red soil. The result would be a thick atmosphere that would keep things warm and wet, effecting intentional climate change.
This was the subject of an interactive exhibit at the American Museum of Natural History seven years ago, in which visitors could choose to rain bombs on the Martian surface, paint the ice caps black or plant the world with billowing smokestacks, which I did gleefully.
But trying to make Mars habitable for humans would take centuries, if not millenniums, and might not work, according to a report published Monday in Nature Astronomy.
Using data obtained by 20 years of orbiter and rover reconnaissance, Bruce Jakosky of the University of Colorado, Boulder, and Christopher Edwards of Northern Arizona University in Flagstaff, concluded that there is not enough carbon dioxide presently on the planet to thicken the atmosphere and warm it more than about 20 degrees Fahrenheit.
Terraforming Mars, they concluded, “will need technologies well beyond our current grasp.”
We have centuries, if not millenniums to sort this all out, as we must.
Everything we know about geology and astronomy tells us that Earth will someday become uninhabitable.
If the arc of cosmic history does bend back to the red planet, we could one day find ourselves in the metaphorical shoes of a family portrayed in Ray Bradbury’s classic “The Martian Chronicles.” They have fled nuclear war on Earth in a stolen rocket and taken up life among the ruins of the old, vanished Martian civilization.
To make up for the disruption, Dad offers to show his son a Martian. He takes him down to a canal.
They look in the water and see their own reflections.
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