Decompression Sickness Treatment Using a Pressure Suit After Loss of Spacecraft Atmosphere.

BACKGROUND: Loss of spacecraft atmosphere (LOA) during Earth-Moon transit may require up to 144 h of pressure suit operations. This work investigates the feasibility of DCS treatment in this paradigm and discusses the operational and engineering implications.METHODS: Three scenarios of LOA-induced DCS were considered: a permanent LOA secondary to a 0.25-in (0.64 cm) hole (unrecoverable cabin leak), a transient LOA, and a permanent LOA with early suit over-pressurization (beyond suit specification). Each was simulated in the context of the current Orion spacecraft operational concept with regards to atmosphere and anticipated cabin depress profile. Probability of DCS symptom resolution (P(SR)) was estimated using the previously derived Hypobaric DCS Treatment Model, with ΔP calculated from a Three Region Well-Stirred Tissue (3RWT) bubble dynamics model. Analysis was conducted and analogies drawn from experiences with the development and testing of the Orion Crew Survival System (OCSS).RESULTS: Maintaining 8 psia at 100% Fio2 following LOA resulted in an eventual halt and regression of bubble growth with a P(SR) of 87% (at 8 h, time to symptom onset (Ts) = 105 min, with ambulation). If cabin atmosphere was not restored and psia dropped to 4.3, bubble growth returned, but again eventually slowed and regressed over time (P(SR) = 75% at 21 h). If the leak is repaired within the 8-h period, 8 psid (psia = 22.7) resulted in P(SR) of greater than 95%. Similarly, if the suit was over-pressurized (12 psid/psia) within 3 h after LOA, P(SR) exceeded 95%.DISCUSSION: A launch/entry pressure suit represents a contingency option for DCS management in the event of LOA.Greene MR, Jacobs SE. Decompression sickness treatment using a pressure suit after loss of spacecraft atmosphere. Aerosp Med Hum Perform. 2020; 91(7):571-577.

The Variable Vector Countermeasure Suit (V2Suit) for space habitation and exploration.

The "Variable Vector Countermeasure Suit (V2Suit) for Space Habitation and Exploration" is a novel system concept that provides a platform for integrating sensors and actuators with daily astronaut intravehicular activities to improve health and performance, while reducing the mass and volume of the physiologic adaptation countermeasure systems, as well as the required exercise time during long-duration space exploration missions. The V2Suit system leverages wearable kinematic monitoring technology and uses inertial measurement units (IMUs) and control moment gyroscopes (CMGs) within miniaturized modules placed on body segments to provide a "viscous resistance" during movements against a specified direction of "down"-initially as a countermeasure to the sensorimotor adaptation performance decrements that manifest themselves while living and working in microgravity and during gravitational transitions during long-duration spaceflight, including post-flight recovery and rehabilitation. Several aspects of the V2Suit system concept were explored and simulated prior to developing a brassboard prototype for technology demonstration. This included a system architecture for identifying the key components and their interconnects, initial identification of key human-system integration challenges, development of a simulation architecture for CMG selection and parameter sizing, and the detailed mechanical design and fabrication of a module. The brassboard prototype demonstrates closed-loop control from "down" initialization through CMG actuation, and provides a research platform for human performance evaluations to mitigate sensorimotor adaptation, as well as a tool for determining the performance requirements when used as a musculoskeletal deconditioning countermeasure. This type of countermeasure system also has Earth benefits, particularly in gait or movement stabilization and rehabilitation.