Shallow metabolic depression and human spaceflight: a feasible first step

Area of Science:

• Spaceflight physiology
• Metabolic engineering
• Biomedical engineering

Background:

• Synthetic torpor, a state of induced metabolic depression (MD), could address challenges in human spaceflight.
• Current research focuses on deep MD, which is not yet feasible for humans in space.
• Shallow MD offers a more achievable initial approach.

Purpose of the Study:

• To explore shallow metabolic depression as a viable first step toward synthetic torpor for spaceflight.
• To summarize perspectives from a NASA-hosted workshop on shallow MD applications.
• To propose a development plan for synthetic torpor in human spaceflight.

Main Methods:

• Defining shallow MD as an approximate 20% depression of metabolic rate.
• Discussing methods for safe induction, including acoustic/photoperiod stimulation and dexmedetomidine sedation.
• Examining habitual versus targeted application modes for shallow MD.

Main Results:

• Shallow MD is presented as a feasible near-term strategy for spaceflight.
• Various methods and application modes for inducing shallow MD were discussed.
• A multistep development plan toward synthetic torpor was proposed.

Conclusions:

• Shallow MD can provide health benefits for spaceflight crewmembers.
• It can reduce demands on spacecraft resources.
• It serves as a crucial testbed for developing deeper metabolic depression technologies for future missions.