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NASA's Space Launch System (SLS) moon rocket creeps toward the pad aboard its mobile launch platform
NASA/Joel Kowsky

When NASA’s massive Space Launch System (SLS) rocket takes off on its first, uncrewed journey around the moon, currently scheduled for Aug. 29, most people will be paying attention to the 32-story machine itself—the largest rocket ever launched. Far fewer will be giving much thought to the yeast going along for the ride. But the little yeast are a very big deal.

Radiation in deep space poses a potentially deadly risk to human beings. Future moon bases and missions to Mars will expose astronauts to space radiation for months and even years at a time. To test how living things bear up under such danger, the SLS will be carrying a shoebox-sized CubeSat known as BioSentinel, which will be released from the rocket, fly past the moon and enter a six- to nine-month orbit around the sun. On board will be microscopic samples of yeast, which will be constantly exposed to the sizzling assault of high-energy cosmic rays and solar particles.

Some of the instruments aboard BioSentinel will measure the intensity of the radiation, while far smaller, finer ones—known as microfluidics cards, built to study extremely small amounts of liquids—will monitor the welfare of the yeast, sending the data they gather back to Earth. Yeast are hardly people, but when it comes to measuring such biological processes as growth, death, and DNA damage, they are a pretty good proxy. The samples aboard BioSentinel, which will have the distinction of flying farther in space than any organisms from Earth ever have before, will tell us a lot about the prospects of the astronauts who will one day follow.

But yeast won’t be the only passengers aboard the SLS when it takes off. The Orion crew capsule that will orbit the moon on the mission will be fairly stuffed with cargo—some of it practical, much of it sentimental. As CNN reports, the center seat of the spacecraft—the commander’s seat—will be occupied by a spacesuit-clad mannequin, which will rest against sensors in the seat to measure the acceleration and vibration a real astronaut will experience during the second, crewed flight of the SLS. The mannequin is affectionately dubbed Moonikin Campos. The first name was chosen by a public contest; the last name is a nod to Arturo Campos, a NASA electrical engineer who made essential contributions to the safe return of the near-disastrous Apollo 13 mission in 1970.

Flanking Moonikin in two other crew seats will be artificial human torsos, made of soft flesh-like material that will include more than 5,600 sensors and 34 detectors to test the radiation levels that real crew members will be exposed to in flight.

Also on board: A Snoopy plush toy—a nod to the Apollo 10 lunar orbital mission, which nicknamed its lunar module Snoopy; a pen nib used by Snoopy cartoonist Charles Schulz; a moon rock collected by the Apollo 11 crew; a space science badge from the Girl Scouts of America; a medal commemorating the Apollo 8 mission—the first crewed lunar orbital mission; and a small handful of tree seeds, which will be planted after the Orion spacecraft returns to Earth. That will continue a tradition begun by the Apollo 14 lunar landing mission, which also carried seeds that were later planted at various sites around the country, sprouting into much celebrated moon trees.

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Write to Jeffrey Kluger at

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