U.S. prebreathe protocol

This paper identifies and describes the prebreathe protocol currently used by the U.S. Space Shuttle Program to provide astronauts the capability to safely perform extravehicular activity. A comparison of planned vs actual prebreathe experience through the STS-37 Mission is also provided.     

Past, present, and future: the U.S. EVA program

This paper provides an overview and summary of U.S. extravehicular activity accomplishments of the last 26 years, Space Shuttle missions having scheduled extravehicular activities to be performed over the next several years, extravehicular activities expected to be necessary to support Space Station Freedom assembly tasks and operations, and potential extravehicular activity roles of the NASA Space Exploration Initiative Program.     

The geomagnetic variation in the upper atmosphere

A brief review is given of the development of models of the geomagnetic variation in the thermosphere and exosphere, including some recent models based mainly on satellite-borne gas analyzer measurements. One recent model, derived from ESRO4 data, is described in detail and compared with the model in CIRA72. The limitations of this model are discussed. The model in the MSIS comprehensive model is also examined briefly. There appears to be a serious error in the amplitude of the exospheric temperature increase predicted by the MSIS model.     

Models of the geomagnetic effect in the earth's thermosphere

A study was made of the variations in exospheric temperature in the disturbed thermosphere as a function of geomagnetic latitude and local time and of the level of disturbance. Temperatures were derived from the N₂ densities measured by the gas analyzer aboard the polar-orbiting satellite ESRO 4. Results indicated two maxima in the temperature response in high geomagnetic latitudes that are probably associated with particle precipitation. These maxima occur near the poleward limit of the auroral belts, at about 9 and 0 hours of local magnetic time. There is also evidence of the effect of Joule heating due to the auroral electrojets in the morning and evening auroral belts. Enhancement of the temperature response in middle latitudes is observed throughout the night side and in a region centered in the late afternoon.