: 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