Update: The SpaceX Dragon capsule splashed down safely at 12.22聽pm local time on 28 October, about 400 kilometres off the coast of California.
Original article, posted 26 October 2012
When the Dragon capsule, made by SpaceX of Hawthorne, California, splashes down in the Pacific Ocean on Sunday after a sojourn at the International Space Station (ISS), it will mark the end of the company鈥檚 first critical supply mission for NASA.
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But the return will also restore a capability lost since the space shuttle retired in July 2011 鈥� the means to bring science experiments and other cargo back to Earth.
鈥淲e鈥檙e now turning to the next step in space exploration, which is that commercial vehicles are bringing this stuff home,鈥� says , a nutritionist at NASA鈥檚 Johnson Spaceflight Centre in Houston, Texas, who is relying on SpaceX to bring back tubes of blood and urine used in monitoring astronauts鈥� health.
Until SpaceX鈥檚 trip, the only way for astronauts to get to and from the station was aboard Russia鈥檚 Soyuz capsules, but these don鈥檛 have enough room for equipment as well.
Uncrewed supply vehicles run by Russia, Japan and Europe also travel to the ISS, but they are designed to remove rubbish and then burn up in the atmosphere. So once the shuttle stopped operating in July 2011, no other craft could safely bring research materials back to Earth.
鈥淲e鈥檝e been anxiously awaiting a vehicle to bring this stuff home,鈥� Smith says.
He and his colleagues have been analysing the biochemistry of astronauts鈥� blood and urine for several years. These contain biomarkers that can reveal changes in and eye tissue, and so could allow astronauts to be monitored remotely and continuously, while in space.
Frozen samples
NASA prepared for the shuttle鈥檚 retirement by reserving freezer space on the ISS so they could continue collecting blood and urine samples from participating astronauts.
The Dragon capsule first journeyed to the space station in May, but that was a trial run. Its first official mission, in which it carried equipment for experiments aboard the space station, plus food, clothes and life-support gear, began on 7 October.
Dragon is and splash down in the Pacific Ocean the same day, where it will be retrieved.
It will be carrying 900 kilograms of scientific experiments, biological samples and failed equipment.
Space cucumbers
The cargo will include experiments 鈥� both part of the educational ; results from the European BioLab, which studies how , and a Japanese experiment called , a step towards the cultivation of plants there.
SpaceX鈥檚 capsule will also bring back used or damaged equipment, like expended life-support and crew healthcare systems, and spacewalk gloves that belonged to previous crew members.
Does it make any difference that a private company is doing this? Not to Smith. 鈥淲e鈥檝e been anxious for sample return, period,鈥� he says. 鈥淲e鈥檙e not picky about how it comes back.鈥� He adds: 鈥淚t isn鈥檛 a plus or a minus, just the way things are.鈥�
Chewed fingernails
But Smith is nervous about his samples staying cold. The blood and urine samples will be packed in special freezers or cold bags to make sure they stay below -30掳C from the time they leave the space station鈥檚 freezers on Friday to the time they get to Houston on Wednesday morning. If they thaw, the researchers will lose important information, he says.
鈥淲e have a very carefully orchestrated plan,鈥� he says. 鈥淏ut my heart rate will be up from the minute they take them out of the freezers on the station to the minute we put them in the freezers in my lab.鈥�
That鈥檚 a long time to bite your fingernails 鈥� but no longer than it was during the shuttle era. 鈥淚鈥檓 used to it,鈥� he says. 鈥淢y fingernails are pretty short.鈥�
