Aboard the final launch of the space shuttle Endeavour is one unusual addition: baby squid.
This is not because the astronauts want a change in their menu: the squid could help us understand how "good" bacteria behave in the microgravity of space. As Jamie Foster of the University of Florida in Gainesville, who is running the experiment, puts it: "Do good bacteria go bad?"
We already know that disease microbes grow faster and become more virulent if they are sent into space. In 2006 Salmonella bacteria were sent up on a space shuttle, and when they returned to Earth they were almost three times as likely to kill mice as normal. Escherichia coli also changes its behaviour.
These studies all focused on harmful bacteria. "This is the first to look at beneficial bacteria," Foster says.
Squid are cephalopods, a group of relatively intelligent animals that also includes octopuses and cuttlefish. Cephalopods have never been into space before – not in reality, at least.
Foster has arranged to send up the bobtail squid Euprymna scolopes, a Pacific species that carries a cargo of bacteria called Vibrio fischeri in its body. The microbes colonise young squid soon after the squid hatch and set up home in their light organs. The squid use the bacteria to generate light, which they shine downwards to ensure they don't cast a visible shadow.
This is a classic example of mutualism: the two species cooperate and each benefits. Humans have similar relationships with microbes, which help shape our immune and digestive systems, but thousands of species are involved with us rather than just one. "Humans are way too complex," Foster says.
Foster's experiment is simple. Newly hatched squid that have not yet encountered their bacterial partners will go up to orbit in tubes of seawater. 14 hours after launch, an astronaut will add the bacteria and give them 28 hours to colonise the squid. Then the squid will be killed and fixed solid, and brought back to Earth for examination.
Foster has some preliminary results from Earth-bound experiments that simulated microgravity and appeared to show problems with the uptake of bacteria by squid. If the shuttle study shows the same result, it would suggest that astronauts' relationships with their own microbes might also be affected in space. "We want to make sure the astronauts are healthy," she says.
Foster developed the experiment with Margaret McFall-Ngai of the University of Wisconsin-Madison, the Florida Space Grant Consortium and students from Milton Academy in Massachusetts and Merritt Island High School, Florida.