WATER WHETS SPECULATION
Discovery of possible underground lake sparks talk of microbial life on the Red Planet
There is nothing new under the sun or on Mars. Even with the recent announcement of the discovery of underground water on the Red Planet, one way or another, we have been here before. “Water on Mars is not a novel idea,” said Dr. James B. Garvin, chief scientist of NASA’s Goddard Space Flight Center near Washington, D.C. He reminded me Mars was long thought to be a parched wasteland where eons ago oceans perhaps lapped against ancient shores — until 2008, that is, when NASA’s Phoenix Lander detected a layer of water. And then, just a few years later, a NASA orbiter circling Mars overhead discovered thawing ice deposits on mountain slopes. Where there’s ground ice, there’s the possibility of liquid water. And where there’s the possibility of liquid water, the conditions exist for life, however primitive. The last decade, then, has been something of a race to find signs of that life on Mars.
So when an Italian team of researchers published their article Radar Evidence of Subglacial Liquid Water on Mars in the journal Science, Garvin was anything but surprised about evidence suggesting a large underground lake — a mile across or more — trapped below the ice of the south pole. Not only that, but the team behind the article opined that “there is no reason to conclude that the presence of subsurface water is limited to a single location.” Could it be true? At first blush, this news appears to be a confirmed finding, the unassailable result of 31/2 years of soundings performed by a European spacecraft, Mars Express, between 2012 and 2015. At NASA, however, Garvin and others are not wholly convinced. “The Italians are all smart dudes,” he said, but added their results are far from definitive. They’ve detected something “stretching maybe a mile or more” and it may be liquid water.
“If you shine radar at water, it would be 40 times brighter than its surroundings. But this is only three times.”
Scientists are agreed that this is an “exciting anomaly” that might point to a buried dead sea on Mars — but it also could be sand or silt with some liquid between the grains or even perchlorate, a “super salt” capable of melting stubborn Martian ice. In that case, the subterranean “lake” might not be water at all, just a salty deposit. Garvin’s caution stems in part from NASA’s hesitancy to oversell discoveries. In 1984, the agency revealed with great fanfare the discovery of possible microfossils in a Martian meteorite collected here on Earth. The announcement seemed for a time to herald a new Age of Aquarius. This bit of ancient rock, called ALH8001, looked to be a time capsule hurled in our direction from Mars containing an amazing secret, that Mars once harboured forms of microbial life — and might still — and perhaps even more complex life forms. On further examination, doubts were raised. The meteorite had been lying on Earth on the slopes of the Alan Hills in Antarctica for quite some time and had perhaps become contaminated with life on Earth. It became difficult to prove that it contained a pristine sample of extraterrestrial life. Maybe we were just looking at ourselves. Thirty-five years later, ALH8001 still has its proponents, but scientific consensus about what, exactly, it contains or means no longer exists. Today, the most Garvin will say is the “lake” — if that’s what it is — “could be a source of microbial life.” The ability to study other planets has set in motion an evolution in thinking about planetary geology, a revolution not unlike that kickstarted by Galileo or other scientists studying natural phenomena. These observers see the same things as their scientific forebears — Aristotle, for instance — but they interpret it differently. It can lead scientists down unusual speculative pathways.
Garvin, a planetary geologist, wonders aloud if Mars somehow “follows playbooks different from ours.” And he said: “How do you use terra-centric standards to look for signs of life as agnostics tend to do? It raises the bar on ‘weird’ life on Mars being able to find a way to exist.” Even the definition of “life” is up for grabs. And perhaps life on Mars or elsewhere differ in some important respects to life on Earth. If we don’t recognize it as such, is it still life?
Elon Musk, the inventor, engineer and self-promoter, is keen to find out. Musk has already announced that SpaceX, the aerospace company he founded 16 years ago, plans to send a test vehicle to Mars as early as the first half of 2019. But to Musk, the hazards function mainly as incentives, if only to prove that he can overcome them. In addition to the requirements of rocketry and training a crew, just getting to Mars is a formidable undertaking. At its closest approach, Mars is about 55 million kilometres away. With the average distance between Earth and Mars coming in around 225 million kilometres, getting to the Red Planet would mean a journey of at least six months.
As Garvin puts it: “Musk wants to pioneer the Martian frontier. The problem is, physics isn’t free.” By which he means, as well as the distance and danger involved, there’s the immense expense. Garvin compares exploring that underground “lake” on Mars to the difficulties of exploring on Earth: “Let’s say this lake is a mile below the surface ... well, drilling that distance below the surface of the Earth costs a great deal. But drilling down a mile on Mars would tax the entire world economy for an uncertain benefit.”
A study published last month in the journal Science suggests a lake — possibly up to mile across or more — appears to be buried beneath the south pole of Mars, raising the possibility of finding life on the red planet. NASA/ESA/HUBBLE HERITAGE TEAM