: In article <1993Apr29.121501@is.morgan.com>, jlieb@is.morgan.com (Jerry Liebelson) writes... : > I want to know what weightlessness actually FEELS like. For example, is : >there a constant sensation of falling?   Ron Baalke (baalke@kelvin.jpl.nasa.gov) replied: : Yes, weightlessness does feel like falling.  It may feel strange at first, : but the body does adjust.  The feeling is not too different from that : of sky diving.  I'm no astronaut, but I've flown in the KC-135 several times.  I'll tell you about my first flight.  At the on-set of weightlessness, my shoulders lifted and my spine straightened.  I felt a momentary panic, and my hands tried to grab onto something (like the strap keeping me firmly against the floor) to prevent me from falling; I remember conciously over-ruling my involuntary motions.  My ears felt (not heard) a rush and I could feel fluid moving in my head (like when you get up from bed while you have a cold).  At that point, I ceased to concentrate on my physiological response, since I had some science to do.  I was busy keeping my experiment going and keeping track of all the parts during the "return" of gravity and subsequent 1.8-G pull-out, so I didn't really pay attention to physiology at that time.  After about 5 parabolas, I discovered that I was performing one of the tricks I've discovered to keep myself from getting motion sickness; I was keeping my head very still and moving very slowly -- all except my hands and arms, which needed to be in rapid, concious motion for my experiment.  During the pull-out to parabola 5, my queasiness finally started to get to me, and I had to use one of those air-sickness bags.  I was basically useless for the rest of that flight, so I went to the seats in the back of the plane while my partner (whom I drafted for just this purpose) kept working on the experiment while I was ill. (He was a vetran Vomit Comet rider, one of those anomalous people who don't get sick on the thing.)  I didn't think of it as a "constant sensation of falling" so much as like swimming in air.  It's very close to the sensations I feel when I'm scuba diving and I turn my head down and fins up.  Jerry: : >And what is the motion sickness : >that some astronauts occasionally experience?   Ron: : It is the body's reaction to a strange environment.  It appears to be : induced partly to physical discomfort and part to mental distress. : Some people are more prone to it than others, like some people are more : prone to get sick on a roller coaster ride than others.  The mental : part is usually induced by a lack of clear indication of which way is : up or down, ie: the Shuttle is normally oriented with its cargo bay : pointed towards Earth, so the Earth (or ground) is "above" the head of : the astronauts.  About 50% of the astronauts experience some form of : motion sickness, and NASA has done numerous tests in space to try to : see how to keep the number of occurances down.  I'm a volunteer in JSC's Space Biomedical Laboratory where they do, among other things, some of the tests Ron mentions.  I was in one called the Pre-flight Adaptation Trainer, which consisted of a chair on a several-degree-of-freedom motion base with moving geometric visual aids.  The goal was to measure the victim's^H^H^H^H^H^H^H^H subject's responses and subjective physiological descriptions and see if repeated exposure to this environment could reduce future motion sickness symptoms.  Jerry --  I don't know of any former or active-duty astronauts who personally read this group.  I know that Bruce McCandless's office had been waiting anxiously for the Space Station Redesign option I posted last week, but I don't think Bruce reads the group himself.  -- Ken Jenks, NASA/JSC/GM2, Space Shuttle Program Office       kjenks@gothamcity.jsc.nasa.gov  (713) 483-4368