Ralph O. Schill / ESA

A tardigrade, also known as a water bear, measures less than a millimeter (0.04 inch) in length but can withstand harsh environments and still thrive. The water bears are the stars of the show for the Planetary Society's Shuttle LIFE experiment on the shuttle Endeavour.

The eight-legged water bears have had to go back to the lab, and the energy bars better have a longer shelf life. But the big-ticket science item for the shuttle Endeavour's mission to the International Space Station, the $2 billion Alpha Magnetic Spectrometer, is just fine where it's at. We've heard a lot about the space spectrometer, which could crack the mysteries of antimatter and dark matter. but there are scores of smaller, quirkier experiments due to ride on Endeavour's final trip, whenever it happens.

Here are a few of the quirkier scientific and educational payloads:

Planetary Society

Bill Nye ("The Science Guy"), executive director of the Planetary Society, holds one of the microbe-filled Shuttle LIFE tubes with a set of tweezers.

Shuttle LIFE: The nonprofit Planetary Society is putting six types of microbes inside sealed tubes that will fly on Endeavour's middeck. The critters include eight-legged water bears, also known as tardigrades; Deinococcus radiodurans, one of the most radiation-resistant microbes known on Earth; Bacillus subtilis, a garden-variety strain of bacteria; Cupriavidus metallidurans, a type of bacteria that gobbles up heavy metals; the salt-loving microbe known as Haloarcula marismortui; and Pyrococcus furiosus, a critter that can withstand temperatures above 212 degrees Fahrenheit (100 degrees Celsius).

Sounds like the Planetary Society just recruited a League of Extraordinary Extremophiles.

The idea is to study how microbes that are adapted to different extreme environments on Earth do in the zero-G space environment. Planetary Society's Bruce Betts says this experiment is a "wet run" for a similar experiment that will fly on Phobos-Grunt, a Russian-Chinese mission due for launch to the Martian moon Phobos within the next year.

"It's like a dry run, but we actually get real science while we're at it," Betts told me.

After NASA postponed last week's scheduled launch of Endeavour, the Shuttle LIFE experiment was pulled off the shuttle along with other experiments on the middeck. Fresh tubes will go to the launch pad a couple of days before liftoff. "The good news for our experiment is that it's not much of an impact," Betts said. If these microbes can survive super-radiation and blazing temperatures, they should be able to handle a week or two hanging around the lab.

Student experiments: NASA has made room for several experiments set up by students, including one that studies seed germination in space and another that looks at the effects of microgravity on squid embryos. Then there's the STEM Bar, which will be flying on Endeavour as the result of a competition sponsored by the Conrad Foundation. STEM stands for "science, technology, engineering and mathematics," and the nutritional grain bar's creators hope that the space spotlight will help get kids back on Earth interested in STEM education.

The bar is made from oats, puffed rice and dried fruits, and has gone through NASA's space-food certification process for orbital consumption. One of the bar's developers, 15-year-old Shannon Diesch of the Battle Creek Area Mathematics and Science Center in Michigan, told me that such energy bars are among "the favorite things to eat up there" on the space station.

She and her 16-year-old sister, Mikayla, were at Kennedy Space Center for last week's launch attempt and gave me one of the bars for sampling. After leaving it in my suitcase for a week, to simulate the rigors of spaceflight, I shared the STEM Bar with three of my sweets-loving crewmates at the office. The verdict? Thumbs-up from all four of us.

ASI via NASA

The camera-equipped Astronaut Personal Eye is designed to float in zero-gravity and follow astronauts around, or serve as a remote-controlled eye in outer space.

Astronaut Personal Eye: One of the most James Bond-ish of the experiments is a "micro-aircraft" that could eventually follow astronauts around as they go about their activities inside or outside the space station. The camera-equipped, gyro-stabilized, thruster-powered gadget can be remote-controlled by an astronaut, to serve as a "personal eye" for observation. But NASA's info sheet on the device notes that problems may pop up: "In fact, the space environment may cause catastrophic events on micro-electronic components and devices, due to shocks and vibrations, high temperatures, ionizing radiations and electromagnetic fields." Be careful what you do with that thing, commander!

Lego bricks: Yes, those famous snap-together toys are due to go up on Endeavour, under the terms of an educational partnership between NASA and the Denmark-based Lego company. Astronauts will assemble a Lego workbench as well as a model of the space shuttle and the space station. NASA astronaut Cady Coleman has been designated as the first to take on the task, after getting some training from her 10-year-old son. The space-themed Lego kits are going on sale here on Earth this year.

Asian Seed: Japan's space agency is sending up a package of plant seeds that will be stored in the space station's Japanese Kibo laboratory for a month, and then sent back down to Earth for use in educational kits and gifts. The concept sounds similar to the "moon trees" that were grown from seeds taken into space by Apollo 14 astronaut Stuart Roosa in 1971. The locations for hundreds of those trees are currently unknown. Let's just hope the Japanese keep better track of where all their space seeds end up.

Update for 1:15 p.m. ET May 7: Pyrococcus furiosus can indeed survive temperatures above 100 degrees C, but I originally wrote that this was above water's boiling point. Which it would be at sea level. But in the deep-sea environment where the microbe lives, the pressures are so great that water does not boil at those temperatures. Thanks to Jonathan Eisen for pointing that out.

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