Fans of NASA’s Endeavour space shuttle are counting down with anticipation for Endeavour’s second launch attempt, currently slated for 8:56 a.m. EDT on Monday. The first launch attempt on April 29 ended a few hours before the planned liftoff when a heater in one of the ship’s onboard power generators failed.

Now the problem has been fixed, the weather seems to be cooperating, and if Endeavor is deemed go for launch on Monday, it will be carrying a peculiar live cargo: an intrepid three-inch creature named Euprymna scolopes, a.k.a., the Hawaiian bobtail squid.


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The squid are part of a microgravity experiment to determine the impact of space (if any) on beneficial bacteria, according to Jamie Foster of the University of Florida in Gainesville.

See, this species of squid has a built-in flashlight that uses bacteria as batteries to help navigate murky nighttime waters, hunt for prey, and hide from predators. There is a convenient little cavity on the squid’s underside that serves as home to colonies of bacteria known as Vibrio fischeri.

The cavity organ is lined with threadlike cilia that sweep bacteria from the surrounding water into the cavity, and the bacteria set up a colony. Once that colony reaches “critical mass,” they emit a telltale glow (bioluminescence). The glowing bacteria are surrounded by stacks of reflective plates to focus the light outward.

That light helps the squid hunt for prey in dark waters. It also provides camouflage from any organisms trying to eat him, because the squid doesn’t cast a telltale shadow on the ocean floor as a result of the moon’s rays shining down into the water. The squid can even control the “wattage” of this bio-flashlight, simply by limiting the amount of oxygen that reaches the cavity organ. (The bacteria need lots of oxygen for the chemical reaction that produces the light.)

So the squid get a handy flashlight, and the bacteria get a cozy home, and everyone wins. It’s a mutually beneficial relationship, similar to the manu microbes inhabiting human immune and digestive systems. But human beings “are way too complex” for this kind of experiment, Foster told New Scientist.

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It’s far simpler to launch a few baby squid (encased in tubes of seawater) into space aboard Endeavor, wait 14 hours, then add some bacteria into the mix. Those bacteria will have 28 hours to colonize before the squid meet their demise and return to earth for further study. Specifically, Foster will be looking for evidence that the microgravity environment interfered with the squid’s ability to be colonized by the bacteria. Previous terrestrial experiments in simulated environments show this might be the case.

Fear not, those baby squid will not have died in vain: the point of the experiment is to determine whether the microbes in human systems might also be adversely affected by the microgravity environment — and if so, to come up with ways to restore that mutually beneficial balance. Quoth Foster, “We want to make sure the astronauts are healthy.” Especially if we ever get around to sending that manned space mission to Mars.