Cell Science-04 (CS-04)

Using Water Bears to Identify Biological Countermeasures to Stress During Multigenerational Spaceflight

Science Objective

The tardigrade – also known as a water bear – is a model organism for studying biological survival under the most extreme environmental stress conditions on Earth and in space. The objective of the Cell Science-04 investigation is to characterize the short-term and multigenerational survival of water bears by identifying genes required for adaptation and survival in high-stress environments. The findings of this study could be applied to understanding the stress factors of humans in the space environment and identifying countermeasures to protect astronauts from long-duration space missions.


The tardigrades will be cultured in the Bioculture System experiment hardware and launched to the International Space Station aboard the SpaceX-22 Commercial Resupply Services mission on June 3, 2021.

Experiment Description

Colorful photo of a tardigrade organism
Image: The tardigrade, Hypsibius exemplaris, a new model for space biology and understanding how organisms survive in extreme environments. Tardigrades will be cultured onboard the International Space Station over many generations. Photo Credit: Tagide deCarvalho
For most organisms, the stresses associated with spaceflight cause a variety of detrimental health effects. To foster a safe and productive long-term human presence in space, therapies and countermeasures to spaceflight-induced stress need to be developed. Tardigrades (water bears) are evolved to tolerate multiple extreme environments (polyextremophiles) restrictive to most life. In 2007, tardigrades were shown to survive and generally reproduce during an 11-day low-Earth orbit on the Foton-M3 Capsule. It has been speculated that the biological mechanisms in tardigrades have evolved to withstand extreme environments on Earth, which may be harnessed to protect against the stresses of spaceflight. This makes tardigrades a uniquely valuable model system for studying biological responses to spaceflight. Experimental and computational approaches to measure the effect of different environmental conditions on tardigrade gene expression will allow scientists to understand the mechanisms by which tardigrades protect themselves from various stresses.

This research team has also developed a reverse genetic approach, RNA interference, for tardigrades that allows them to directly investigate the role of a gene in conferring tolerance to an environment. These approaches are used by the team to study tardigrades’ initial, as well as multigenerational response to spaceflight, and use RNA interference to test the functionality of the genes identified in this study.  Several expression analyses will be conducted to compare station spaceflight time points, ground controls, and tardigrades exposed to other extreme stresses (e.g., desiccation, freezing, etc.). This approach allows the team to identify potential mediators of stress tolerance, which will serve as candidates for functional additional, future RNA interference experiments. These experiments will allow us to understand how these extremely hardy animals cope with prolonged exposure to space environments and help pave the way for a healthy and productive prolonged human presence in space.

Related Links

Space Station Research Explorer - Cell Science-04