Imagine sending a tiny lab to deep space, only to learn the experiment never woke up. That’s pretty much what happened to NASA’s BioSentinel. The cereal box-sized satellite carried living yeast and flew past the Moon, according to NASA’s mission overview. The aim was to test the effects of deep-space radiation on living cells. But the yeast did not grow.
Why scientists sent yeast into deep space
Astronauts on the International Space Station orbit about 250 miles above the Earth. Earth’s magnetic field protects them from much of the radiation that can damage DNA in our cells and lead to serious health issues. Future crews venturing farther into space might not have that protection. They will be exposed to more dangerous radiation and will need heavy shielding. Scientists at NASA’s Ames Research Center in California’s Silicon Valley are making an early move with BioSentinel to find solutions for that problem.
Scientists often study "model organisms" that they know well. In the case of BioSentinel, NASA chose the same yeast that is used to make bread rise. The radiation found in deep space can cause double-strand breaks in DNA in yeast cells as well as human cells. Cells can repair this damage, and the repair process is quite similar in yeast and humans. A 2020 paper in IEEE Aerospace and Electronic Systems Magazine stated that this mission is the beginning of a new initiative. This initiative aimed to study the effect of deep space on Earth organisms through exposure beyond Earth’s magnetic field.
A cereal box-sized lab in deep space
BioSentinel launched on November 16, 2022, aboard Artemis I, the first flight of NASA’s Space Launch System rocket. It was one of 10 CubeSats on that ride. The satellite is a six-unit spacecraft and weighs about 30 pounds. After launch, it flew past the Moon and went into orbit around the Sun. NASA says it was designed to be the first long-duration biology experiment beyond the orbit of the space station, which circles Earth.
{{/usCountry}}BioSentinel launched on November 16, 2022, aboard Artemis I, the first flight of NASA’s Space Launch System rocket. It was one of 10 CubeSats on that ride. The satellite is a six-unit spacecraft and weighs about 30 pounds. After launch, it flew past the Moon and went into orbit around the Sun. NASA says it was designed to be the first long-duration biology experiment beyond the orbit of the space station, which circles Earth.
{{/usCountry}}The team triggered experiments remotely when the satellite was beyond the protective magnetic field of the Earth. They were going to wake up two strains of yeast at different points during a six- to twelve-month mission. One strain is common in nature. The other struggles to repair its own DNA. In the 2020 IEEE paper, the team said they planned to compare the growth and metabolism of normal yeast with yeast they engineered to be more sensitive to radiation. NASA also kept a reserve set of yeast samples in reserve to activate if the satellite encountered a solar particle event, which is a radiation storm from the Sun. The matching experiments were conducted on the ground and on the space station, where radiation is lower.
Why the yeast did not grow
Phase one of the mission started in December 2022 and ended in April 2023. The BioSensor, which is a mini laboratory designed to determine how live yeast reacts to radiation in space, was successfully used by the team in their four tests that lasted for two weeks each. However, they didn’t find any yeast growth. According to NASA, the team determined that the radiation in deep space was not the reason. The probable cause was that the yeast expired while waiting on Earth before the spacecraft launched.
What BioSentinel still offers
The mission didn’t end with the yeast. BioSentinel also carries a radiation detector to measure what kind of radiation hits the spacecraft, and how much. NASA extended the mission, and as of November 2025, the spacecraft was still collecting data in deep space. BioSentinel celebrated three years of continuous observations of radiation on November 16, 2025. At the time, it was more than 48 million miles from Earth. This matters because NASA said at the time that scientists expected strong solar activity to continue through 2026. Actual measurements from deep space are still useful since the solar radiation events can also be a threat to astronauts. The results from the missing yeast were a bust, but the radiation data still counts.