Skip to page content Mission Information


Bacillus Spore Probiotics: Evaluation of Survival and Efficacy After Exposure to Deep-Space Radiation Simulating Long-Duration Human Exploration Missions (80NSSC20K1297)
Principal Investigator
Research Area:
Biomedical countermeasures
Species Studied
Scientific Name: Bacillus subtilis Species: Bacteria
Scientific Name: Lactobacillus acidophilus Species: Bacteria

Recent research has recognized humans as metaorganisms— multispecies consortia consisting of the human host and its associated microbial inhabitants commonly referred to as the microbiome. The subsequent flood of research in this field has led to a dramatic improvement of our understanding into how the host, its microbiome, and the environment interact to determine human health and disease. On Earth, probiotics have been shown to interact with the host and its GI microbiome to improve the immune response, protect against pathogens, and improve gut barrier function.

Long-duration missions in space expose astronauts to chronic stresses imposed by microgravity, ionizing radiation, and confinement. These aspects of space flight have been shown to alter astronaut physiology, affecting nearly every system including musculoskeletal, neurological, endocrine, cardiovascular, respiratory, excretory, cognitive, and immune systems. Development of effective countermeasures to maintain astronaut health and performance under the extreme conditions of deep space exploration is an actively ongoing NASA endeavor.

Research into changes to astronaut microbiomes has revealed evidence of both compositional and functional changes during long-duration space flight. Dysregulation of the astronaut immune system in space has been identified as a major contributor to numerous spaceflight syndromes. Further, The Design Reference Mission (DRM) for a Mars mission states that all nutrients sufficient for three plus years will be preserved and stored onboard, and no resupply activity or cultivation of fresh food is planned. This necessitates research into the stability and shelf-life of food items, supplements, and pharmaceuticals in space over the course of a Mars DRM. Probiotics stored as freeze-dried powders in capsules are a promising option for long-term stability. However, probiotics consisting of bacterial spores may serve as a better, albeit unexplored, option for long-duration missions due to their extreme longevity and documented resistance to ionizing radiation.

The hypothesis of this experiment was that exposure of probiotic bacteria to simulated space radiation would result in a decrease in survival and potency at a rate which can be empirically measured. Probiotics containing Bacillus spores were hypothesized to demonstrate enhanced long-term stability and potency compared to traditional Lactobacillus- or Bifidobacterium-containing probiotics.

This experiment had three specific aims.
(1) Select probiotic candidates to test.
(2) Expose probiotic samples to simulated Galactic Cosmic Radiation (GCRSim) and Solar Particle Events (SPESim) at Mars DRM-relevant doses.
(3) Characterize probiotic viability of pre- and post-irradiation probiotic samples and potency of these samples in simulated gastric and intestinal juices in vitro.

++ -- View more

Gastric juice
Microbial Viability

Data Information
Data Availability
Archive is complete. All data sets are on the Web site.
Data Sets + View data.

16S rRNA
Colony forming units (CFUs)
Viable cells
Viable spores

Mission/Study Information
Mission Launch/Start Date Landing/End Date Duration
Ground 05/01/2009 In Progress

Human Research Program (HRP) Human Research Roadmap (HRR) Information
Crew health and performance is critical to successful human exploration beyond low Earth orbit. The Human Research Program (HRP) investigates and mitigates the highest risks to human health and performance, providing essential countermeasures and technologies for human space exploration. Risks include physiological and performance effects from hazards such as radiation, altered gravity, and hostile environments, as well as unique challenges in medical support, human factors, and behavioral health support. The HRP utilizes an Integrated Research Plan (IRP) to identify the approach and research activities planned to address these risks, which are assigned to specific Elements within the program. The Human Research Roadmap is the web-based tool for communicating the IRP content.

The Human Research Roadmap is located at:

+ Click here for information of how this experiment is contributing to the HRP's path for risk reduction.

Additional Information
Managing NASA Center
Johnson Space Center (JSC)
Responsible NASA Representative
Institutional Support
National Aeronautics and Space Administration (NASA)
Proposal Date
Proposal Source
2019 HERO 80JSC019N0001-FLAGSHIP & OMNIBUS: Human Research Program Crew Health. Appendix A&B