A group of mountaineering medics are in position at a base camp on Mount Everest, ready to carry out tests that could lead to significant advances in medicine.
Establishing base camp has been a tough task
The Caudwell Xtreme Everest team from University College London plan to examine the effects of oxygen deprivation on the human body - a critical problem for patients in intensive care.
At the highest point on Earth, there is just one-third the amount of oxygen in the atmosphere that exists at sea level, which makes Everest an ideal place to learn more about this problem.
The researchers will carry out a variety of experiments on themselves and over 200 volunteer trekkers at base camp (5,300 metres).
A smaller team of scientists and mountaineers will climb to the summit in May, where they will take blood samples and repeat some of the tests to generate data in an even more extreme environment.
Oxygen treatment hope
Dr Mike Grocott said: "Low oxygen levels are pretty much a universal feature of patients who are very sick.
Mountaineering skills are essential
"Unfortunately it is quite difficult to separate out the effects of low oxygen back home on the wards from all the other things that are going on.
"Strange as it may seem, Everest is a brilliant model for looking at how humans adapt to low oxygen levels."
The researchers hope to generate hard data which proves people who acclimatise more effectively to a thin atmosphere are more efficient at using oxygen to generate energy.
"If we can do that, we can start to get a handle on the mechanisms by which people do that. And if you understand mechanisms, you can start to develop treatments.
"We would hope to be able look, in a few years' time, to developing treatments that allow people who are critically ill to use oxygen more efficiently."
Dr Grocott said setting up the base camp had been a huge task.
Dr Grocott hopes for revealing data
Teams of sherpas first started establishing the facility two months ago, and an advanced logistics team have been in place for nearly a month.
Now the site has around 80 tents, including two laboratory tents, tents specialising in logistics, medicine and communications, two tents for the media, and a completely separate facility for the arriving trekkers.
In total about 25 tonnes of equipment had been shipped in, much of it carried by porters or yaks up to base camp.
"We are really delighted. We have managed to set up a laboratory facility up here which essentially mirrors what we have in London.
"As a result we have finished the testing on arrival of the Xtreme team, and we are comfortable, having had the first set of trekkers through, that we can do the science on the 200-odd trekkers that will be coming up."
Crossing a crevasse calls for a steady nerve
Dr Grocott said the team had been acclimatising on some relatively low-lying peaks.
However, they have also ventured about a third of the way up the ice wall, a chaotic river of ice flowing down the mountain which separates base camp from where a second, higher outpost will be established.
In points, this involved using ladders to cross yawning crevasses in the ice.
"Because it is a river it is a very dynamic being, and bits of it tend to collapse on a relatively frequent basis," Dr Grocott said.
"So our approach to this is to go through as fast as possible, and as few times as possible.
"It is also a stunningly beautiful place, but we just don't have much time to stand around and be inspired."
The BBC's Horizon team will be following the Caudwell Xtreme Everest team throughout the expedition. You can follow the expedition progress through the Horizon website at bbc.co.uk/horizon.