I had come here mainly to see biologist Peter Doran from the University of Illinois in Chicago, who had promised to take me out on to the lake.2 This turned out to be a wide expanse almost filling the valley floor and running nearly all the way up to the steep sides of the Canada glacier. Around the edge was a ‘moat’ of clear, dark, glassy ice, but as I stepped gingerly over this I found myself on a frozen surface that looked nothing like I had imagined. I’d assumed it would be flat and white, but this was a tortured terrain of ice towers, pinnacles and hollows, streaked with patches of dark brown soil.
Some of the towers were almost at eye level; if I crouched down, I could peer into miniature ice caves with filigree walls, and what seemed to be an earthen floor. But I knew that beneath the soil was more ice, ten or twelve feet of it, capping the liquid lake beneath. In fact, the ice was so thick that there was no chance of accidentally breaking through into the lake, but we could still crash through a sliver of ice masking a pool of frigid surface meltwater, or break an ankle in a crack. Peter was taking no chances. ‘This is where it gets dicey. Follow my footsteps.’ He placed his feet carefully on the ice and I matched him meticulously, step for step.
As we walked, Peter told me that the dirt came in with the winter storms, and that the glacier up ahead plugged the end of the valley, and acted as a windstop, forcing the wind to drop its load of soil on to the ice. Where the soil landed, it formed an insulating layer, protecting some parts of the ice while the rest evaporated away into the dry air. Hence the towers and sculptures. Confounded by the unearthly landscape I asked Peter how he would describe it. He grinned, and said: ‘Mars-like’.
Peter had been studying Antarctic lakes for most of his career. He was tall and slim and precise. When you first met him he seemed flat, his voice dry and mechanical, his language scientific. But when he smiled, you could see the other side of his personality, the part that brought him down here. He had never been one to sit patiently in a lab looking through a microscope, always preferring the bigger picture, what he called the ‘flashy stuff’. He was a bit flashy himself. Peter came here because he read a paper about these strange frozen lakes that could be analogues for Mars. He was fascinated by places that don’t belong on Earth, and if you could add a pinch or two of adventure, so much the better.
It wasn’t enough for him to study the lakes from the outside. His first dive in an Antarctic lake came in the early 1980s, on an expedition to the Bunger Hills Oasis, near the Russian station of Mirny, on the other side of the continent from here. In fact it was the first time anyone had plunged into this particular lake. No one knew what to expect. Finding himself close to the bottom of the gloomy water, he sank into the soft mud, up to his waist. He had no idea whether he’d sink farther, or if he’d get safely out. As he told me about it, his eyes shone. ‘It was wild. It’s true discovery. I think that’s one of the things that attracts people to Antarctica. A lot of science has become routine, but here you’re genuinely exploring.’
He had now done dozens of Antarctic dives, but it was still far from routine. Out here in the middle of Lake Hoare, he showed me the dive hole we’d come to see: a neat circle melted through the ice, now filled with dark green water.
The first challenge in a dive was getting into the lake proper; the ice here was sixteen feet thick, making the entrance more of a tunnel than a hole. Though the water looked forbidding, he told me that it wasn’t as cold as you’d think. You could be down there for an hour and a half and be perfectly warm. You were wearing a dry suit, thick rubber gloves, a full-face mask with communications to the surface through a safety tether. When you made it to the lake itself you were free to wander, but you were also relying on the tether to see you safely home. Though some light did diffuse down through the ice, there was no beam coming through the hole to guide you back. There have been times when divers have lost their tethers. ‘That’s the scariest story I’ve ever heard,’ Peter said. ‘It would be like being buried alive. Or lost in space. Diving in the Dry Valley lakes is the closest thing to a space walk I’ll ever do.’
Unlike the myriad sea creatures back in McMurdo, the life here took the form of giant mats that look as though they’re woven of some sludgy seamless material. In fact, they were made from microscopic cyanobacteria, held together by a sticky mucus. One of the strangest aspects of this primitive life was that, though the mats formed on the sediment at the bottom of the lake, some 30 m below us, they also generated bubbles that lifted them up and made them float around like mocking ghosts. One mat, which Peter and his colleagues dubbed ‘the ghoul’, bore holes eerily reminiscent of a skull’s eye sockets and nose. Another, a shroud-like cylinder nearly two metres high, looked like a dead body rearing up from the depths. ‘I turned round and saw that lurking in the darkness. It makes you start at first, and then you realise there can’t be anything down there, there’s nothing moving, it’s all microbial. You make yourself swim through this stuff, but it’s bizarre, it’s really bizarre.’
And if he’s right, similar creatures might once have floated in the freezing lakes of Mars, before they finally dried up and blew into dust. Walking back over the crunchy lake surface, we saw scraps of these mats, like soggy yellow strips of chicken skin, embedded in the dirt and ice. I picked one up and rubbed until it disintegrated in my hands. As pseudo-Martians go, this wasn’t exactly glamorous, but it did prove that life could survive even in these harsh conditions. The annual average temperature here was zero and in the winter it could drop to 40° below. And yet, even today in the height of summer, when the temperature was a drop below freezing, there was enough direct sunlight to melt a little of the glacier beside the lake, sending a thin trickle of water to penetrate through the cracks in the ice. Peter and his colleagues have calculated that this trickle, running for just a few days a year, fuels the lake with enough heat to keep it liquid.
So that was one answer that research here has provided to the Martian question—you don’t have to have temperatures above freezing to maintain liquid water on the planet’s surface. The Dry Valleys show that cold is not necessarily dead.
Peter was also fascinated by another of the Dry Valley lakes: Lake Vida. This had an ice lid sixty feet thick, so thick that for decades scientists thought it was frozen solid. But when Peter took radar instruments to map the bottom he saw a strange reflection about fifty feet down, in a pocket about one mile long and a half-mile wide. It couldn’t be water. Down there the temperature should be around 10°F, and water would definitely freeze. But it could, perhaps, be brine. If so, it would be about as salty as water can get without turning to pure salt. That would be hard for anything living to take. But the lesson from the Dry Valleys was that life has a knack of finding a way.
One reason Peter cared was that these would be some of the most hostile conditions on Earth. ‘What are the extremes of life on this planet?’ he said. ‘How far can you push life before it doesn’t become life any more? Maybe life on Earth started like this. Maybe it will finish like this. Maybe this is the end.’
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.
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