Conference 7.286::space

From: [email protected] (Peter E. Yee)
Date: 24 Jan 91 18:58:57 GMT
Organization: NASA Ames Research Center, Moffett Field, CA

Sarah Keegan
Headquarters, Washington, D.C.                   January 24, 1991
(Phone:  202/453-2754)
 
Jane Hutchison
Ames Research Center, Mountain View, Calif.
(Phone:  415/604-4968)


RELEASE:  91-11
 
UNDERWATER TESTS GATHER DATA TO HELP SPACESUIT DESIGN

     Scuba divers exercising on a unique underwater treadmill at 
NASA's Ames Research Center, Mountain View, Calif., may help 
scientists design better spacesuits for future astronauts working 
on the Moon or Mars.

     "We hope to answer the basic questions of how human movement 
and energy consumption will differ in the reduced gravity on the 
Moon and Mars," said the study's Principal Investigator Dava J. 
Newman, a doctoral candidate in aeronautical and astronautical 
engineering at the Massachusetts Institute of Technology.
 
     Newman and Co-investigator Dr. Bruce Webbon of Ames's 
Advanced Life Support Division also hope to learn at what speed 
humans change from walking to running and how much the joints 
move during various gaits.  Another objective is to determine 
what kind of gait is most effective in different gravity fields 
and what energy expenditures are associated with those gaits.
 
     Three men and three women, all certified scuba divers 
between 20 and 40 years old, are participating in the tests 
conducted on a treadmill designed by Newman for underwater use.
 
     Each experiment run consists of six 30-minute sessions.  The 
first session is a control experiment conducted outside Ames's 
Neutral Buoyancy Test Facility (NBTF).  The NBTF is a water-
filled cylindrical tank 9 feet deep and 11 feet in diameter. 

     Because water immersion is an effective technique to 
simulate reduced gravity, the remaining sessions take place 
inside the NBTF.  Five different gravity conditions, or "g's", 
are simulated:  zero g, one-sixth g, three-eighths g, two-thirds 
g and 1 g (normal Earth gravity).  

     By varying the number and placement of ballast weights 
distributed in seven regions on the diver's body, Newman can 
change the diver's buoyancy and thus simulate various 
gravitational conditions.
 
     Each diver wears a commercial diving face mask.  Air is 
provided through a supply hose from a surface tank.  Heart rate 
data and measurements of carbon dioxide exhaled and oxygen 
consumed by the diver indicate how hard the person is working 
under a specific workload and gravity field.
 
     During each test session, Newman controls treadmill speed 
while the diver keeps pace with the treadmill belt.  Each diver 
exercises at levels corresponding to 10 percent, 40 percent and 
70 percent of the maximum work he or she is able to perform as 
measured by maximum oxygen consumption.
 
     The treadmill is equipped with a platform that measures the 
force of each step, from which vertical speed and duration of 
each step can be calculated.  The degree and amount of leg, arm 
and torso movements are recorded on video.
 
     "Because humans have evolved under the influence of normal 
Earth gravity, their muscles and joints probably will respond 
differently under partial gravity," Newman said.  She hopes her 
research will provide basic information about these differences. 
 
     Newman believes such information may directly impact the 
design of advanced spacesuits and portable life support 
systems.  For example, designers need to know how much mobility 
astronauts' spacesuits should have to let them work most 
efficiently under various gravity forces.
 
     The study, which is scheduled for completion this spring, 
may lead to improved spacesuit thermal control systems by 
providing a basic measure of energy expenditures under various 
gravitational forces.

     Newman's tests also may lead to development of a training 
program to help astronauts simulate specific tasks and experience 
partial gravity prior to space flight.

	- end -
 
NOTE TO EDITORS:  Still photographs and a video to accompany this 
release are available by calling 202/453-8375.
 
 Photos:    B&W          Color
          91-H-48       91-HC-59

As I entered in a previous note, the Space Museum in Hutchinson,
Kansas has a very fine and comprehensive collection of space
suits, including a Soviet one.  Along with its other exhibits,
this collection is well worth the trip for space suit buffs
(pardon the expression).  Hutchinson is in south-central Kansas,
very close to Witchita.

    Just curious, how did Hutchinson Kansas become a site for a space
    museum or for that matter a site for a collection of suits?
    I like the collection at Houston.

Well, actually, besides being one of the greatest places in the
world, Kansas is home state to a number of astronauts/aviation
pioneers.  They supported having this museum, and are quite proud
of it.  My note, in the museum topic if I remember it right,
describes the museum in more detail.  Let me emphasize, that
while its not worth crossing the country for, it is a very fine
museum for those in neighboring states to visit.

    This query is motivated by the forthcoming mission STS-49 (Intelsat-IV
    rescue).

    Why is it necessary to change the cabin pressure of the Shuttle before
    making a space-walk? Doesn't this somewhat reduce the possibility of an
    emergency space-walk and hence flexibility of response to emergency
    situations?
    
    Is this also going to apply to Freedom? What do/did they do on Mir? Skylab?
    Apollo?

The space shuttle has a cabin pressure of around 15 PSI (pardon the units) with
a air mix more or less like sea level (e.g., nitrogen/oxygen).

A conventional space suit would not be usable at that pressure -- the astronaut
wouldn't be able to move (inflexible), and it also would increase the chances
of failures (aside: new "hard" spacesuits, much like the undersea "Jim" suits
may reverse this trend).

So, when you don a space suit and head outside, the air pressure must be
reduced to something around 5 PSI -- which pretty much means you need a
100% oxygen environment or you'd suffocate.  To get to that pressure you
have to do it slowly or you get "the bends" when the nitrogen starts
bubbling in your tissues.

Lowering the cabin pressure reduces decompression time -- useful in general
and also permits faster emergency responses.


Earlier American spacecraft were always used a low-pressure O2 environment,
so these steps weren't required.

I'm not familiar with the Russian program, but I think they use something
similar to what the shuttle uses now (I'm inferring this from the Apollo-Soyuz
mission).

- dave

From:	US1RMC::"[email protected]" "Henry Spencer" 11-JAN-1994 18:23:58.70
To:	[email protected]
CC:	
Subj:	NASA spacesuits grounded

One of my sources reports something very interesting indeed...  JSC
has grounded the shuttle spacesuits.  (Beached them, too -- no use in
the water tanks either.)  And the suits are considered essential
equipment for a shuttle flight -- for the sake of the emergency
payload-bay-door closing procedure, if nothing else -- so this means
the shuttle is grounded unless a fix is found quickly. 

The problem is that just before Christmas, there was a major suit
failure in the JSC water tank.  Nobody was hurt, but what was merely a
major emergency in the water tank would have been fatal in space. 

The suit shoulder joint has both mechanical parts, controlling the
motion of the arm with respect to the hard torso shell, and a bellows,
providing a flexible airtight seal.  What happened was that one of the
mechanical parts failed, in a completely new and unexpected way, and a
side effect was a large rip in the bellows.  We are talking about a
hole you could put your fist through.  In space, the suit's emergency
oxygen system could not possibly have coped. 

People are frantically trying to sort out what happened and why.  That
suit does have a slightly old version of the shoulder joint -- there
have been some improvements made since -- but it is not clear whether
that is significant.  The failure was in a part that was not thought
to be under significant load in normal use. 
-- 
Belief is no substitute                 | Henry Spencer @ U of Toronto Zoology
for arithmetic.                         |  [email protected]  utzoo!henry

From:	US1RMC::"[email protected]" "Henry Spencer" 13-JAN-1994 00:27:35.71
To:	[email protected]
CC:	
Subj:	(slightly) more on spacesuit grounding

The latest report (from a new source) is that they *think* the failure
is a combination of the old shoulder-joint design and the water-tank
environment.  The grounding has tentatively been lifted for suits with
the new joints, subject to some precautions.

From here, I can't tell how much of this is sound engineering judgement
and how much of it is wishful thinking.  It does sound like the problem
is not yet completely understood.
-- 
Belief is no substitute                 | Henry Spencer @ U of Toronto Zoology
for arithmetic.                         |  [email protected]  utzoo!henry

From:	US1RMC::"[email protected]" "Henry Spencer"  5-FEB-1994 19:42:02.32
To:	[email protected]
CC:	
Subj:	Wrap-up on that spacesuit failure

As folks may have gathered, NASA apparently thinks the pre-Christmas
suit failure in the water tank has been dealt with, given that the
shuttle was cleared for launch. 

Those who saw my earlier post may recall that the failing shoulder
joint was of a slightly obsolete design.  One of my sources says that
the modern design in fact includes a slight change meant to deal with
exactly this possible failure mode.  It was bundled in with a lot of
other minor changes, it wasn't considered important since the problem
had never actually shown up, and nobody thought it worth making a fuss
over. 
-- 
Belief is no substitute                 | Henry Spencer @ U of Toronto Zoology
for arithmetic.                         |  [email protected]  utzoo!henry