Antarctica (15 page)

He has now been to Vida three times, to drill into the brine layer and beyond. Below fifty feet the drill hole quickly filled with salty slush but even though they went to one hundred feet, which ought to be the lake floor, they didn't find water. However, they did find unmistakable signs of a perfectly viable microbial world, living quite happily in the salty darkness.

And that could be the most intriguing aspect of Lake Vida: these creatures lurking within the ice could be a mirror of the very last Martians to survive. This, after all, would be the very final pool of anything resembling liquid water before a Martian lake finally froze solid.

‘This would be the last vestige of something living on Mars billions of years ago,' Peter said. ‘The last stand for life on Mars may have been a swim in a frozen lake.'

Mars might not even have needed a lake. In the soils here, researchers have found minuscule round worms called nematodes, and abundant bacteria. And anywhere with the slightest hint of moisture, they have also found tardigrades, or ‘water bears', the toughest animals on Earth. These grow up to a millimetre long, making the adults just barely visible to the naked eye. They are stubby and cute with four pairs of fat little legs, a vole-like snout, and the complexion of a gummy bear. You can (and in fact many researchers have) freeze them to within a whisker of absolute zero, boil them, dry them out or zap them with radiation and they simply shut down and wait for the ordeal to be over. For them, the Dry Valleys are a breeze. When any particular habitat becomes too dry for comfort, they replace the water in their bodies with a specialised form of sugar, adopt a shape like a microscopic beer barrel, and sit it out. They can do this, apparently, for decades, probably more.

Up on the glacier, Andrew Fountain from Portland State University in Oregon had found more hiding places for life. He was a big bearded bear of a man, and when I said that I was afraid of slipping on the glassy ice, even with crampons strapped to my bunny boots, he barked out a laugh. ‘Don't worry. You're a human fly now!' Andrew's main interest in the glaciers was figuring out how they were different from ones in warmer climates, and how they fed the lakes to keep them liquid. He had placed bamboo poles to measure how much snow accumulates, and gauges to measure the water trickling down the streams at the base. In one place, he had installed a closed-circuit security camera. ‘To make sure nobody steals the glacier?' ‘Yup,' said Andrew. ‘We're hoping we might see an alien landing.' (In truth the camera was there to watch for lumps of ice calving off the face.)

But there was also something else that he wanted to show me, another way that the creatures of the Dry Valleys cling to life, and to see it we'd have to climb. The sides of the glacier were steep—a feature, Andrew told me, of the cold ice, which flowed more sluggishly than ice in warmer regions. He showed me how to use my ice axe to hew out rough steps and together, clamped reassuringly on to the surface by our spiked crampons, we made our way up on to the main body of ice.

Up aloft the wind was biting; it picked up snow from the surface and flung it in our faces. We pulled up our scarves and in a muffled voice Andrew explained what he was looking for. To survive, life needed liquid water, and up here where the ice was at -4°F there was precious little of that. But in the few places where dirt and debris streaked the white ice, there was a chance. Where white ice reflects sunlight, dark soil soaks it up and can get hot enough to melt down into the ice. More snow and ice puts a lid on this deepening canister; sunlight still filters through the lid, keeping some liquid water in play, ready for any bacteria that are caught up in the soil when it blows up on to the glacier.

It sounded far-fetched, but Andrew started casting around until he spotted a slightly darker patch on the ice surface. He held out his hand for my ice axe and started jabbing at the ice with the axe head. Chips flew up into the air to mingle with the blowing snow and then, suddenly and shockingly, liquid water welled up in the hole. ‘Woo hoo!' he crowed. This was a big patch. Water began to appear in a wider area, then Andrew found smaller circles, broke them open, and water frothed out, filled with the bubbles that showed that microbes had found a way to grow, and breathe, and live. We were surrounded by champagne bottles of life, entombed aquaria that had been completely hidden in the ice. I noticed that the wind had dropped and there were hints of evening sun through the cloud. Andrew leaned on the ice axe and grinned. ‘There's debris like this on the polar ice cap of Mars,' he said. ‘You can see it on satellites, spiralling out from the centre. This could be another way to find life on Mars.'

We made our way back down the glacier and paused at the base. The sun had now fully broken through the clouds and we stared down the valley at the debris-strewn lake and snow-streaked mountains. I asked Andrew why he came here, but the question was almost rhetorical. He replied quietly. ‘It's “memory burn”,' he said. ‘You're back home and you smell something, the cleaning fluid they use in the dorms or kerosene, helo fuel, or you hear a Hercules taking off at Oregon airport and bang, you're back here. You close your eyes and you see this view, and you miss it. And you have to come back.'

 

Battleship Promontory, on the far side of the Dry Valleys, was a broad scoop of steep sandstone cliffs, a couple of hours' helicopter ride from McMurdo. About halfway up lay a wide ledge, several hundred metres deep, pocked with turrets and spires of sandstone and dark dolorite pebbles. From the air, I could see human footprints on patches of snow leading, ant-like, to a handful of brightly coloured tents. As the helo set down, Chris McKay climbed out of the biggest tent to meet me.

Chris McKay works at the NASA Ames Research Center in California and he's a veteran of the ice. He's been coming down here since 1980. He's a giant, standing nearly six feet six tall in his stockinged feet, so that I wondered how he could fold himself into one of these small tents. He spoke slowly and carefully and peppered his conversation with literary allusions. One minute he was referring to
The Iliad,
and the next he was quoting Lewis Carroll. (Talking about how strange the visible absence of life seemed when he first came down, he quoted ‘The Walrus and the Carpenter': ‘No birds were flying overhead—There were no birds to fly'. To Carroll, that was supposed to be nonsense, but to Chris here in the Dry Valleys it was an everyday reality.)

He told me that, unlike many other Antarctic veterans, he has never felt at home here. The lack of obvious life was always in his face, making it clear that he was somewhere alien. And yet, he knows more than most people about the myriad ways that creatures can eke out a living in this land that is utterly hostile to life.

Straight away he offered to show me around. He disappeared inside the main tent and re-emerged with a geological hammer. ‘I can't walk around without a hammer in my hand,' he said. ‘It would be like reading a book without holding a pen.'

From the air the cliffs looked golden, but close up the rocks were either grey or coated with a rust-like desert varnish where the iron in the dolorite had been weathered by wind and snow. But in places the rocks were pitted and mottled. ‘You see that?' said Chris. ‘It's almost like a disease.' This was the first sign that life had found an extraordinary new way to survive in the Dry Valleys. Chris picked up a lump of pitted sandstone and gently chipped off the outermost scale. Through the pale rock I could see a hint of green. Then he turned the rock over and smartly rapped it with his hammer, knocking off the corner. Running in a thread just below the surface was a bright emerald stripe, like a jewel. This stripe was made up of thousands of cyanobacteria, that were living, breathing and growing just as they do in drainpipes, ponds and puddles the world over. But these ones were different. They were doing all this
inside a rock.

As I was turning the emerald stripe over in my hands, Chris told me how they manage it. They stay frozen all winter. Summer comes, the rock warms above freezing and the creatures inside wake up. They are close enough to the surface, and the sandstone rock is just translucent enough, that they feel the first touches of sunlight. Snow melts in the sun and trickles inside to give a drop or two of water. And then it's a race to profit from all of this as quickly as possible, to make what Chris called a ‘mini rainforest' inside the rock. They have only a few hours a day for a few weeks of the year when the sun is warm enough to break through. And then the sunlight fades, and the bacteria sink back into sleep.

It might sound hard for them, said Chris, but this isn't such a bad life. ‘They're getting water, they're getting light, they're getting a warm enough temperature. The conditions here are either perfect for sleeping or perfect for growing. There's no confusion. It's a great job if you can get it. You sleep for eleven months then you work hard for one month of every year. And the great thing is you don't age in that eleven months of sleeping because you're frozen solid. So you can live a really long time.'

Why do they do it? In most parts of the Dry Valleys where you find them, the reason would be water or, rather, the lack of it. If they tried living on the surface of the rocks, these bacteria would dry out quickly in the wind. But here, the story was a little different. By a quirk of geography, Battleship Promontory was unusually warm and therefore unusually wet. The cliffs acted as a mirror magnifying and focusing the sun's rays. ‘At 1 p.m. the sun will be full on here, and here,' Chris said, pointing to the cliffs ahead and a patch of dolorite in front of us. ‘And then it's a cooker.'

We walked farther down to a cleft in the sandstone, a miniature suntrap, where ice was gleaming wetly and the rocks were dark with damp stains. He took another rock and broke it open. Sure enough, there was the emerald streak of life hiding inside. But then he pointed to the rock surfaces and I saw that the black stains were not just dampness but something clinging to the surface. Something that was alive.

‘What do you reckon?' Chris asked me. ‘Why do
these guys
[he pointed at the green streak] live underground when
these guys
[the black surface stain] are happy on the surface?' He looked at me expectantly and I shrugged, waiting for the punchline. There was obviously no problem in this little patch with dryness, so I couldn't see why anyone would need to live inside a rock here. But the trouble, it seemed, was with the intensity of sunlight. ‘They're both cyanobacteria,' Chris said. ‘The reason these ones are black instead of green is that they're excreting a pigment that absorbs UV light. Basically, they're putting on sunscreen.'

So these black surface blobs were sunbathing bacteria. I peered at them, intrigued. That explained how they coped with the intense summer light here, and this, said Chris, was the only place in the world where you could find them.

Now that we were in a hollow and the wind had dropped, the sun was baking. My parka began to seem ridiculous, even though the air temperature was technically far below freezing. I felt sleepy, and had a sudden urge to lie down and bask on one of the rocky surfaces. I knew what the cyanobacteria saw in this place. It wasn't even that hard to live here. Thanks to the weird combination of geometry and height, life really was a beach.

And yet, Chris had found his rock dwellers throughout the Dry Valleys. And similar rocks may also have provided one of the final refuges for life on Mars.

 

Just beyond Battleship Promontory lies another part of Antarctica's living Martian metaphor: a place where space itself comes to Earth. This is an area known as the Allan Hills for the few isolated mountains that poke their necks up through the ice. Apart from these, the surface up here on the edge of the vast East Antarctic Ice Sheet is mainly featureless. A helicopter pilot told me that in his first season he was detailed to take some researchers up into the Allan Hills and asked for a map. His boss took a blank sheet of paper, put a pencil dot in the middle and handed it to him.

But remote or not, this is one of the best places on Earth to find rocks from space. An astonishing amount of extra-terrestrial debris falls on the Earth every year. Some is in the form of dust that blazes brightly through the sky as a shooting star but burns itself up in the process. Once in a while there is also a really massive space rock, an asteroid, which collides with the Earth with devastating consequences. That's what did for the dinosaurs, and we humans could meet the same fate if we encountered a similarly unlucky strike. The really big hits like these carry so much energy that there's little or nothing left of them afterwards, just a mighty crater and a planet of dazed or dying creatures. In between these two extremes are moderately sized rocks, large enough that something survives the burning through the atmosphere, and small enough that they land relatively gently, and remain on the surface as an alien rock. It is these remnant rocks that we call meteorites.

Almost all meteorites come originally from the asteroid belt, a ring of potato-shaped rocks that marks a failed planet, between Mars and Jupiter. Jupiter formed so quickly and became so large that its gravity disturbed all the building blocks in its vicinity, and prevented them from forming a planet of their own. The asteroid belt is builders' rubble, left over from the creation of the Solar System. Rocks from there tell us about the birth of our planets, our Sun, and even about what came before.

But that's not the whole story. A very few, very rare meteorites come from more exotic locations. Antarctica has gathered more than its fair share of these precious alien visitors, along with their extraordinary insights about us, and our place in the world.

 

Ralph Harvey, a long-time meteorite hunter from Case Western Reserve University in Cleveland, Ohio, runs a programme called ANSMET (which stand for the Antarctic Search for Meteorites).
³
The programme is a strange beast, unique among all the science that takes place on the continent. It's funded by a combination of NASA, the NSF and the Smithsonian, and the field party always consists of volunteers. Though they are usually experts in meteorites, they themselves have nothing to gain. Anything they find must be bagged, logged and handed over to the authorities. They can then put in a proposal to study any of the meteorites they find, but will be treated like any other researcher: no special privileges, no queue jumping. And certainly no private collecting of samples.