![]() However, in June 1997, there was rapid depressurization of the Spektr module of the Mir space station following a collision with a supply vehicle. The risks associated with depressurization of a suit or spacecraft are partially mitigated by micrometeoroid shielding in the suit and spacecraft modules. Treatment protocols involve re-pressurization, 100% oxygen therapy and, if necessary, over-pressurization of the spacesuit by use of a bends treatment adaptor. Astronauts are trained to recognize the symptoms of decompression sickness. Thus, before spacewalks, astronauts perform an oxygen pre-breathe protocol that reduces the level of nitrogen in the tissues. The transition from ambient pressure to vacuum during airlock depressurization causes considerable decompression stress to spacewalking astronauts. ![]() The Russian Orlan spacesuit is pressurized to 40 kPa. ![]() NASA’s suit for space-walks (extravehicular mobility unit) is pressurized to 29.5 kPa with 100% oxygen. 4 The pressure inside both spacecraft is regulated to 101.34 kPa (14.7 psi) and is equilibrated after docking and before hatch opening. Temperature is often the first cue that these transitions are imminent.Ī high vacuum exists outside the space shuttle and the International Space Station. Thermal mittens can also be used to provide insulation from high touch temperatures.ĭuring a spacewalk, it is easy to become focused on a task and lose awareness of an impending dusk or dawn, until surrounded by darkness or brilliant sunlight. Manually activated electric heaters in astronauts’ gloves may be used when the touch temperatures fall below –20☌. Heating the suit is a passive process resulting from accumulated body heat in the absence of active cooling. A manually controlled thermostat is used to control active cooling and regulate the temperature in the suit. 2ĭuring spacewalks, the personal life-support system of the spacesuit provides active cooling to dissipate the heat generated by high-metabolic workloads. Forty-five minutes later, during a night pass through earth’s dark shadow, temperatures can plunge to –100☌. When on the sun-lit side of the earth, the temperature on the spacecraft or space station can reach over 100☌. Much greater extremes occur outside the spacecraft. The crew controls the temperature in the crew compartment of the space shuttle and modules of the International Space Station, with an average temperature between 21 and 23☌. These spacecraft orbit the earth once every 90 minutes. Spacecraft in low orbit of the earth travel at Mach 25, or about 8 km per second. The development of new technologies to send people farther in space and keep them there longer is critical to the future of human space exploration. The International Space Station circles the earth at an altitude of more than 300 km in an environment characterized by high vacuum, microgravity, extremes of temperature, meteoroids, space debris, ionospheric plasma, and ultraviolet and ionizing radiation. Almost 50 years have elapsed since those initial flights, with remarkable progress in extending the duration of missions and the complexity of the objectives. ![]() The early space program progressed from suborbital missions lasting minutes to orbital flights lasting days, demonstrating that people can both survive and work in space. In an upcoming issue, a Dispatch from Space provides a personal look at space travel, and 2 other articles address the acclimation necessary for people to travel and live in space and the technological advances that can be applied to health care on earth. This article focuses on the specific challenges of the space environment. Human space exploration is dependent on robust spacecraft design and sophisticated life-support technologies, both of which are critical for working in the hostile space environment.
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