Exploration class missions will be required to have an exercise device that is lightweight, has a small footprint, and is capable of providing enough physical stimulus and exercise variability to be an effective countermeasure against muscle and bone loss that results from the microgravity environment. Exploration exercise device prototypes should be evaluated on the ground and in-orbit for feasibility of use in microgravity for long and short duration exploration missions and efficacy of the device to maintain multi-system health and performance.

The European Enhanced Exploration Exercise Device (E4D) was selected as the exploration prototype device to be evaluated on ISS for efficacy and feasibility of use as a single multi-modality device for the exercise system for exploration missions. This effort supports the continued development, testing, and verification of E4D hardware and software, internal NASA integration (Human Health and Performance, ISS Vehicle Office, Engineering, and Flight Operations), and external integration across NASA, ESA, and the Danish Aerospace Company (DAC). Providing a feasibility and acceptability assessment from a physiological efficacy and hardware durability standpoint are critical for informing use and risk associated with use on exploration missions. Clearly defined objectives from end users, stakeholders, and Subject Matter Experts (SMEs) will be tested by crewmembers during acute use sessions and long duration use of the exercise device while on ISS. This effort will include a flight study where crewmembers will be asked to exercise using only the E4D during the duration of their mission and participate in a battery of physiological testing to evaluate the efficacy.

The E4D needs a vibration isolation stabilization (VIS) system that serves as a platform for the exercise hardware to protect the vehicle from loads imparted during exercise. Exploration forward VIS systems will need to protect the vehicle and provide sufficient stabilization for the exerciser during performance of all critical exercises. These enabling capabilities need to be achieved within exploration vehicle power, thermal, mass, and volume limitations.

In FY25, the E4D Training Unit completed assembly and testing, and was delivered to ESA where crew training and baseline data collection will be completed pre-flight. The VIS flight unit was launched on NG-21 and successfully installed in the Columbus module of ISS in December 2024. The E4D flight unit is scheduled to launch on NG-24 with an expected install in April 2026.

These efforts will develop requirements for Artemis, Gateway, and Mars exploration exercise systems. These requirements will include an understanding of exercise modality effects on crew health, software architectures that capture both the operational and performance enhancement perspectives, and ISS evaluations for feasibility of use in microgravity and efficacy of the device to maintain multi-system health and performance.

The E4D VIS system will protect the vehicle from imparted loads and provide sufficient stabilization for the exerciser during performance of all critical exercises.