I've just got back from a week's fieldwork in the Atacama Desert, Chile. The part of this massive, over 100,000 square kilometer area, desert we were in is one of the driest places on Earth - only the Antarctic Dry Valleys have a lower annual precipitation.
I was participating in a field campaign organised by the HOME (Habitability of Martian Environments) project with a German-based team of astrobiologists, microbiologists and astronomers. This project focuses on the Atacama as it is the most Mars-like environment we can study first hand. Here, they test theories of how microbial life may adapt and survive to the harshest hyper-arid, high-UV and high-salinity environments, as they may have on Mars. This group has just published, to a massive media reception, a study showing that microbial life can exist in a dormant state, underground, possibly for 1000's of years, even in the driest part of the desert - blooming after rare rainfall events. Maybe this is how life adapted to the gradually drying climate on Mars billions of years ago.
The desert was amazing, the landscape really was Martian. No signs or sounds of life (except for the occasional long-distance travelling vulture) and just reddish dry, dusty rocks and sands as far as the eye could see. It really did look just like the images coming back from Gale Crater on Mars - except for the bright blue sky.
We were in the desert to collect more samples to further this research and other work on hyper-arid soils and Martian analogs carried out by the many collaborators of the group. Unfortunately, it appeared as though the hyper-arid core of the desert had been a bit wet recently... Evidence of heavy rainfall and past standing bodies of water were everywhere. Even the pits, dug in previous years, that we had planned to sample from had been half infilled by water-transported debris - shifting this was to prove hard work and very time consuming.
|The hole, laser measurements showed it was 45 m down to the water|
|Practicing at camp|
After a fun evening teaching the rest of the group how to put on harnesses and use a gri-gri (autoblocking belay device) to descend and self-belay I rigged up a complex system of anchors (hammered in stakes), safety lines and knotted hand lines to re-ascend with. Then descended down the hole to test the system while everyone else watched. Desert dust clogged the ropes and belay device which made abseiling down difficult and jerky, dust and small rocks fell from the poorly consolidated side walls of the narrow hole. As I got deeper it got cold quickly. I stopped at 10 m to test how easily it was to get out again and pulled myself onto the 'rope ladder' hand line I'd made to climb back up on.
The Gri-Gri was completely seized up, dust had coated the thick 10 mm rope I'd bought to be extra safe and the extra friction meant it would take both hands to haul it through the belay device, I only had one free as the other was needed to take my weight off the rope I was on and onto the handline. This made reascending, safely, by the planned means impossible, ~If I had ascended the handline I would not have been able to self-belay at the same time so if the thin handline rope had snapped I wold have fallen.
I was stuck hanging 10 m deep, with a jammed Gri-Gri in the middle of the desert....Bollocks.
After trying everything I could to free myself (short of 10 m of vertical pruscking, which might have also jammed up and left me in even more of a tangle) while the group at the top grew understandably more anxious, I had to admit I'd fucked up and shout for a pull. Tying hand and foot loops in the second rope that had been set up I held on tight as 8 of my colleagues hauled me back into the light as I self belayed up my (now-unweighted and free moving) rope in case they dropped me. As they pulled me up the ropes cut into the soft sediment sending down a hail of dirt and stones - thankfully I was wearing a helmet as some of the chunks were big enough to do some damage.
Because of these unstable side walls it was decided that, rather than modify the technique used to avoid anyone getting stuck and going again, we should abandon the (w)hole idea as it was just too unsafe. I had seen some large rocks in the side walls as I went past and if they had fallen out and hit you at depth you'd be a gonner, helmet or not. So the hole remains unexplored and the depths of the Atacama keep their secrets, for now...
The failure at the deep hole meant that the only way to sample ancient sediments would be to dig. Much of the week was therefore spent digging, with pickaxe and spade - and on the last day, through harder layers - a jackhammer, and hauling buckets. This was hard, sweaty work, especially in the heat of the midday sun and the intense afternoon winds. A far cry from my usual day-to-day activity in the climate-controlled lab. It didn't take me long to come around to the German's habit of hydrating with 'isotonic' cervezas.
|Digging for Science|
By the end of each day we were knackered, we worked until just before sunset so there was enough light to sort out camp and build our fire. We had earned our barbecue and passed pisco around the campfire. Camping in the middle of the desert, we slept under the stars; the Milky way was the brightest I've ever seen it, we saw Jupiter rising, shooting stars, the International Space Station and even Mars.
|Our view from our sleeping bags each night|
Halfway through the week we had a rest day visiting the Very Large Telescope (VLT). Located on top of a flattened mountain at around 2500 m altitude, this is one of the most powerful telescopes in the world looking at some of the clearest skies. They don't lie, it is Very Large; 4 identical telescopes (each pretty big themselves) which work together collecting light to form a 'virtual telescope' around 130 m across. Before returning to camp, we stopped off back in Antagofasta to wash away the last few days of desert dust by swimming in the Pacific. That felt amazing, but the feeling didn't last long, the dust gets everywhere, I'll be finding it for weeks.
We only really got going with sampling in the last few days due to all of the digging and re-planning required first. Because I am interested in the organic molecules present in the sediments at minute amounts and others are interests in rare microbes, all of the sampling had to be carried out in as clean and sterile a way as possible. This is obviously not easy in the desert, especially when the afternoon winds pick up and you end up running 500 m after your face mask as it disappears into the distance... This was slow going and we were maybe not quite as productive as we had hoped. However, we sampled many interesting sediments which should have a good story to tell.
I nearly didn't have any samples to bring back at all. After checking my bags and making my way through security in Antagofasta airport I ('Samwell Roy-lay') was called back through security and taken into the back room by a serious looking security guy. The suspicious looking 'powders' wrapped in aluminium foil had unsurprisingly got security excited.
This is it, I thought, the latex gloves are going on....
Thankfully, we'd anticipated this and got a letter, explaining what the samples are and why I really don't want to open them in a dirty airport, translated into Spanish (thanks to the magic of Twitter), printed on official looking Imperial College London headed paper, signed and rubber stamped. This literally saved my ass.
While that is an experience I wouldn't want to repeat, working in the desert was an amazing experience. The geology is like nothing I'd ever seen before and I have a new understanding of how the subsurface may be in the hyper-arid Martian environment. It was great to be finally back in the field after so long stuck in the lab and offroading pickup trucks, sleeping under the stars and sitting late around the campfire with a great bunch of people was pretty awesome too.
|Camp under the stars|
Maybe they'll let me go back when I've worked my way through this bunch of samples, best get cracking...