2007, Piran, Slovenia

Gravitational Physiology
THERMOREGULATION AND PHYSIOLOGICAL DESIGN TO
SUPPORT ASTRONAUT COMFORT DURING EVA
Victor S. Koscheyev 1 , Gloria R. Leon 1 , and Aitor Coca 2
1 University of Minnesota, Minneapolis, Minnesota USA
2 NIOSH/NPPTL, Pittsburgh, Pennsylvania, USA
Principal investigator Victor S. Koscheyev
Contact person: kosch002@umn.edu
INTRODUCTION
There has been a relative lack of attention to aspects of human thermoregulatory
processes that influence comfort and therefore have an impact on the effectiveness of
protective equipment. There are specific tissues that comprise the heat transfer index
and differences in blood circulation through different body areas, for example, the
hand/torso temperature gradient. Further, there are other physiological protective
mechanisms against the cold such as the total/local reflex response to avoid massive
heat release from the body, and shivering to increase heat production. Because of the
significant influence of the thermal regulatory system on astronaut comfort and safety
both outside of and within the space vehicle or future planetary habitat, it is important
to focus on this system in advancing astronaut protection.
Through an extended program of research, our group developed a shortened liquid
cooling/warming garment and warming gloves based on physiological principles of
heat transfer. The physiological design of the garment evolved through research
identifying the body areas that are most effective in heat transfer, for example, highdensity
tissues, as well as utilizing the mechanism of blood circulation to deliver heat
to distal body areas. Further studies evaluated the efficacy of different types of tubing
bypasses within the garment to conserve energy and prolong thermal comfort in
emergency situations. The finger calorimeter studies addressed unresolved and
serious issues in space affecting the safety of the astronaut, i.e., the adequate
monitoring of astronaut thermal status during extravehicular activity (EVA) and
onboard the space vehicle, and the development of a simple and reliable method for
controlling the thermal status of the body during routine and emergency situations.
The specific aim of these latter studies was to design and test a miniaturized sensor
and monitoring system (finger calorimeter), applying experimental data assessing the
correlation between heat content in the body and heat flux density from the finger. A
prototype temperature/heat flux ring, attached to a transmitter and visual display
monitor, was constructed and calibrated. The finger calorimeter has the potential to
serve as the first index in an automatic thermal feedback system within the space suit.
Thus, a new generation of protective equipment designed on the basis of physiological
principles of heat transfer has been developed for space purposes.
RESULTS
Continued experiments and statistical analyses of the physiological data base were
carried out to assess the physiological boundaries in which finger temperature/heat
flux is informative in indicating thermal imbalance of the body, in order to establish
the parameters in which the finger temperature/heat flux ring will be effective. The
finger temperature (Tfing) comfort range within the vasomotor zone was from 28.5 to
33.5 o C. The functioning of the finger calorimeter was assessed by applying local
cooling on body areas remote (thigh) from or close (forearm) to the finger
35