In a groundbreaking experiment, researchers have successfully cultivated miso, a traditional Japanese condiment, in the microgravity environment of the International Space Station (ISS). This research, documented in a study published on April 2, 2025, in the journal *iScience*, sought to understand how fermentation processes behave differently in space compared to Earth. Miso, which is made from fermented soybeans and salt, provided an ideal subject for the team’s investigation into the impact of extraterrestrial conditions on food production, flavor development, and microbial activity.

The Experiment Design

The experiment was designed to assess fermentation’s viability in space, focusing on how microgravity and increased radiation affect microbial growth and the fermentation process. Co-lead author Joshua D. Evans from the Technical University of Denmark emphasized the importance of investigating these factors, highlighting how they could reshape culinary practices for future long-term space missions. The research aimed not only to expand the astronauts’ diet but also to improve their overall well-being during their time in space.

In March 2020, a specially prepared container of “miso-to-be” was dispatched to the ISS. The miso fermented in space for 30 days before returning to Earth, alongside two control batches that fermented under similar conditions on Earth—one in Cambridge, Massachusetts, and the other in Copenhagen, Denmark. The researchers equipped the fermentation environment with sensing boxes that monitored critical parameters such as temperature, humidity, pressure, and radiation to ensure optimal conditions for the fermenting process.

Analysis and Findings

Upon the return of the ISS miso, the research team conducted an extensive analysis of its microbial communities and flavor profiles. Surprisingly, they discovered that the fermentation was successful despite the unique environmental challenges presented by the ISS. However, it became clear that there were noticeable differences in the composition of bacterial communities among the different batches, with the ISS batch exhibiting distinct characteristics.

Maggie Coblentz, another co-lead author from the Massachusetts Institute of Technology, reflected on the implications of their findings, stating that the fermentation process observed on the ISS could offer insights into how microbial ecosystems can thrive in extraterrestrial environments. The acknowledgement of microbial agency in space raises compelling bioethical questions about the introduction of Earth-based organisms into other environments, prompting scientists and ethicists to reconsider how we approach space exploration.

Taste tests conducted by the research team revealed that while the ISS miso largely mirrored the aroma profiles and flavor characteristics of its Earth counterparts, subtle flavor variations existed. Most notably, the ISS miso was described by tasters as having a nuttier, more roasted flavor compared to the Earth samples. This finding highlighted the unexpected outcomes that can arise from introducing Earthly food production methods into the unpredictable realms of space.

Implications for Future Space Missions

The success of this experiment has significant implications for future space missions. Fermenting food in space could provide astronauts with a wider variety of nutritional options, potentially improving their quality of life during long-term missions. The findings also suggest that microbial fermentation can occur in space, opening up new possibilities for food production and preservation in extraterrestrial environments.

Moreover, the study underscores the potential for life to exist in space through the diversity of microbial communities. While the ISS is often seen as a sterile environment, the research shows that microbes and non-human life have agency in space, raising significant bioethical questions about the introduction of Earth-based organisms into other environments.

The successful fermentation of miso on the International Space Station marks a significant step forward in understanding how food production can be adapted to space environments. The nuttier, more roasted flavor of the ISS miso highlights the unique conditions of space and their impact on microbial activity and flavor development. As we continue to explore the possibilities of long-term space travel and colonization, experiments like these will be crucial in developing sustainable and enjoyable food systems for astronauts.