Programmed cell death and redox metabolism protect Chlamydomonas reinhardtii populations from the galactic cosmic environment on the Artemis-1 mission.

On the Artemis I mission, Chlamydomonas reinhardtii, a green unicellular flagellate alga, was exposed to the galactic cosmic environment. A new flight hardware termed "Moonshot" was designed, built, and flown. "Moonshot" performed flawlessly, and is available as flight-certified, flight-proven hardware for timed illumination and monitoring for flight and terrestrial applications. The Chlamydomonas strains were spotted on nutrient agar plates and flown on Artemis I in the new Moonshot hardware that provided six hours of light daily to synchronize the algal cell cycle and tracked temperature, power use, and gravity over time. Synchronous ground controls in identical hardware were run in parallel. The Artemis-1 flight of Chlamydomonas reinhardtii around the Moon with exposure to the galactic cosmic environment showed: (1) Flown samples exposed to cosmic radiation showed increased programmed cell death and decreased necrosis compared to ground control samples. (2) There was robust Chlamydomonas growth in both flown and ground control samples post flight. (3) Raman spectroscopy analysis showed that redox-protective terpenoid carotene pigments, known cell death mediators, were increased during flight around the moon. (4) Insertion of the Dsup tardigrade gene was protective both on the ground and in flight.