Space adaptation syndrome

Space adaptation syndrome

Space adaptation syndrome (SAS), or space sickness, is a condition experienced by around half of space travelers during adaptation to microgravity. [ Tony Quine (2007): "Addicted to space: An appreciation of Anousheh Ansari, Part II" appeared in "Spaceflight", a publication of the British Interplanetary Society (BIS), ISSN 0038-6340, Volume 49, Number 4, April 2007, page 144.] It is related to motion sickness, as the vestibular system adapts to weightlessness. [ "Why Do Astronauts Suffer From Space Sickness?"] ScienceDaily (May 23, 2008)]

Space sickness is caused by changes in gravitational forces, which affect spatial orientation in humans. According to "Science Daily", "Gravity plays a major role in our spatial orientation. Changes in gravitational forces, such as the transition to weightlessness during a space voyage, influence our spatial orientation and require adaptation by many of the physiological processes in which our balance system plays a part. As long as this adaptation is incomplete, this can be coupled to motion sickness (nausea), visual illusions and disorientation."

Space sickness was effectively unknown during the earliest spaceflights, as these were undertaken in very cramped conditions; it seems to be aggravated by being able to freely move around, and so is more common in larger spacecraft. Around 60 percent of all Space Shuttle crew members currently experience it on their first flight; the first case is now suspected to be Gherman Titov, in August, 1961 onboard "Vostok 2", who reported dizziness and nausea. However, the first significant cases were in early Apollo flights; Frank Borman on "Apollo 8" and Rusty Schweickart on "Apollo 9". Both experienced identifiable and fairly severe symptoms — in the latter case causing the mission plan to be modified.

As with motion sickness, symptoms can vary from mild nausea and disorientation, to vomiting and intense discomfort; headaches and nausea are often reported in varying degrees. About half of sufferers experience mild symptoms; only around 10% suffer severely. The most extreme reaction yet recorded was that felt by Senator Jake Garn in 1985 — after his flight, NASA astronauts began using the informal "Garn scale" [, pg 35, Johnson Space Center Oral History Project, interview with Dr. Robert Stevenson:

"Jake Garn was sick, was pretty sick. I don't know whether we should tell stories like that. But anyway, Jake Garn, he has made a mark in the Astronaut Corps because he represents the maximum level of space sickness that anyone can ever attain, and so the mark of being totally sick and totally incompetent is one Garn. Most guys will get maybe to a tenth Garn, if that high. And within the Astronaut Corps, he forever will be remembered by that."
] to measure reactions to space sickness. In most cases, symptoms last from 2–4 days.

Modern motion-sickness medications can counter space sickness, but are rarely used — it is thought that having space travelers adapt over the first day or two is preferable to a medicated (and drowsy) state during a mission. However, transdermal dimenhydrinate anti-nausea patches are typically worn during launch and landing by NASA crew members.

Mission-critical activities (especially EVA, during which vomiting could be fatal) are generally not scheduled for the first days of a mission, to allow crews to adapt to zero-g. Due to the danger posed by possible vomiting in an extravehicular suit, transdermal dimenhydrinate patches are also typically used during EVAs, as an additional backup measure.

ee also

*Human adaptation to space
*Human spaceflight


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