Space & Astronomy/Space and Astronomy (October 1993).iso/pc/text/spacedig/v08/v8_264.txt

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SPACE Digest                                      Volume 8 : Issue 264

Today's Topics:
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SPACE Digest                                      Volume 8 : Issue 240

Today's Topics:
               Re: Space suits
               Re: Space suits
               Re: Space suits
               Re: Space suits
               Re: Space suits
          What to do with the external shuttle tanks
        Re: What to do with the external shuttle tanks
        Re: What to do with the external shuttle tanks
         Re: Converting Ephemeris Time to GMT
         Re: Converting Ephemeris Time to GMT
----------------------------------------------------------------------

Date: 21 May 88 15:25:35 GMT
From: nyser!cmx![e-mail]  (Rangachari Anand)
Subject: Re: Space suits

In article <[e-mail]> [e-mail] (Steve Smith) writes:
>Many years ago, I saw an idea for a "spacesuit" that solved this
>problem elegantly.  It uses the fact that human skin is a very good
>gastight membrane.  It simply consists of a mechanical support layer
>that doesn't let the user swell up in vacuum.  Think of a *very* stiff
>body stocking.  A helmet finishes it off.  There are some obvious
>problems -- getting in and out would not be trivial, and there are
>parts of the human anatomy that would be difficult to handle (armpits,
>for example).

 Protection from vaccuum is not the only function of a space suit
 Thermal insulation and radiation insulation are also important.  I
 recently read in Spaceflight that even with the current space suits,
 EVA times have to be restricted to not more than a few hours so as to
 minimize exposure to radiation.

                                          R. Anand
                                         [e-mail]

------------------------------

Date: 20 May 88 16:08:18 GMT
From: mcvax!ukc!its63b![e-mail]  (ERCF08 Bob Gray)
Subject: Re: Space suits

Legs are not needed except for hooking your feet into some convenient
perch. Most of the actual moving about is done either by using your
hands or using a maneuvering unit of some sort. In a suit for serious
construction work in space, e.g. on a large space colony, there would
have to be a maneuvering unit attached to the suit.

On the basis of keeping the system as simple and as cheap as possible,
do away with the legs and torso and replace then with a simple cylinder.
Some sort of anchor would also be needed to hold the suit in place while
the occupant is working.

If the cylinder is wide enough, the occupant could withdraw their arms
from the sleeves to adjust instruments, feed, or just to scratch.

To improve the suit arms and gloves, make the occupant wear a long pair
of skin support gloves, put an air seal at the top of the wearer's arm
above the bicep, and pump most of the air out. The gloves can then be
designed to hold much less pressure, and be correspondingly more
flexible.  Make sure that the gloves are well thermaly insulated,
'though, things might get very hot in sunlight and very cold in shadow.

Suits of this basic design used to be used 150 years ago for underwater
salvage operations, before the invention of the diving suit.
    Bob.

------------------------------

Path: ucbvax!pasteur!ames!lll-tis!lll-winken!uunet!attcan!utzoo!henry
From: utzoo![e-mail] (Henry Spencer)
Newsgroups: sci.space
Subject: Re: Space suits
Keywords: non-anthropomorphic
Date: 22 May 88 01:14:09 GMT
Lines: 9
Apparently-To: [e-mail]

>   Hard suits...best of both worlds..

Well, better of both worlds.  The clear winner for the hassle-free
spacesuit is the "space activity suit" concept, in which the body of the
suit is just extra-stretchy fabric to supply pressurization, with the
skin in vacuum.  The idea has been tested in vacuum chambers; it works.
Unfortunately, NASA displays no interest in pursuing the scheme further,
even though it funded the original work and nobody has found any real
flaws.  If one were being cynical, one might suspect an overly-cozy
relationship between NASA and its current space-suit suppliers; it
wouldn't be the first time.

------------------------------

Date: 24 May 88 02:58:39 GMT
From: spar!snjsn1!trojan![e-mail]  (Charles Crapuchettes)
Subject: Re: Space suits

In article <[e-mail]> [e-mail] (Henry Spencer)
 writes:
>>   Hard suits...best of both worlds..
>
>Well, better of both worlds.  The clear winner for the hassle-free spacesuit
>is the "space activity suit" concept, in which the body of the suit is just
>extra-stretchy fabric to supply pressurization, with the skin in vacuum.
> . . .

In article <[e-mail]> [e-mail] writes:
>Small particles released with the liquids will suffer the same fate as
>Delta rocket paint flecks: fly around Earth for a few years and then
>either reenter or make craters in spacecraft windshields.

How long would an astronaut have to be EVA to have a 50% chance of being
injured by a chunk of crud (either artificial or man-made)?  Do harder
suits provide protection, or is the energy too high?

Anyone with hard facts?

InterNet:  [e-mail]  or  [e-mail]

------------------------------

Date: 24 May 88 04:33:44 GMT
From: ubvax!unisv![e-mail]  (Mike Van Pelt)
Subject: Re: Space suits

In article <[e-mail]> [e-mail] (Steve Smith) writes:
>Many years ago, I saw an idea for a "spacesuit" that solved this
>problem elegantly.  It uses the fact that human skin is a very good
>gastight membrane.  It simply consists of a mechanical support layer
>...  Suposedly, a large aerospace company (Avco-Everett?) built a model
>suit that was comfortable, inexpensive, and *far* more efficient than
>NASA's suits.  NASA rejected the idea with an excuse that translated
>"not invented here".
>
>Does anybody have any further information?

I heard a talk on space suit design a few years ago, and I asked about
this suit.  The speaker (don't remember his name, but he was involved in
the Apollo suit design) said that for satellite work, you'll be doing a
whole lot of outgassing, which is very bad for contaminating delicate
parts.

Sounds bogus to me.  They don't put satellites in a vaccum canister for
launch.  Probably (1) NIH and (2) not expensive enough.

That suit is supposedly very good for thermal control, too.  Given the
mechanical support, your skin does just as good a job of temperature
control as on earth.  Better, actually, as a little sweat provides a lot
more cooling in vacuum.

------------------------------

Date: 6 May 88 22:47:59 GMT
From: cadnetix.COM![e-mail]
Subject: What to do with the external shuttle tanks


    * All details from Boulder Daily Camera, 5/6/88; information
      used and quoted without permission *

    FACTS:

    In todays Boulder Daily Camera (5/6) there is an article about a
Boulder company that stands to benefit by a new amendment passed by the
space sub-committee (Congress).  The company is ETCO (External Tanks
Corp.) of Boulder.  ETCO was created by UCAR (Univ. Corp. for
Atmospheric Research, also of Boulder) to study and design ways of using
the ET in orbit.  ETCO is/was founded as a co-op between gov't and the
private sector; uses of the tanks are to be investor financed (yea!).
Final bit of factual info: the bill to authorize NASA to make use of the
ET was introduced by Rep. David Skaggs D-Colo.

    ME:

    Funny that a Boulder company could stand to benefit from this
bill, huh?  In any event, the bill is a good idea, no matter who is the
*financial* winner.  I know that uses of the ET has come up before in
this group, but it might be a good time to discuss it again - since it
just really might happen.  To start the ball rolling, here are a few
(well, 5) questions I have:

    1.  Does anyone in the know (Greg Woods at NCAR, others) know if
        the previous net discussion, amongst others I presume,
        influenced our Congress-critters/NASA to make use of the ET?
        Did it help?
    2.  The Camera article mentioned 20 to 30 experiments have been
        proposed to UCAR.  Care to give us any details, anyone?
    3.  Timeframe, if Congress/NASA is timely about adoption of the
        plan?
    4.  Does anyone have a summary of previous net proposals?
    5.  What about integration with the space station/ISF plans?

    Speaking for myself only...if anyone else has a better summary
of the amendment, speak up!

            -Tim

------------------------------

Date: 9 May 88 20:24:05 GMT
From: attcan!lsuc!spectrix!tmsoft!utgpu!utzoo![e-mail]  (Henry
 Spencer)
Subject: Re: What to do with the external shuttle tanks

>  1.  Does anyone in the know (Greg Woods at NCAR, others) know if the
>      previous net discussion, amongst others I presume, influenced
>      our Congress-critters/NASA to make use of the ET?  Did it help?

Unlikely.  The most significant influence was probably that the Reagan
space policy specifically called for NASA to provide ETs to private
companies wanting them, and this is uncontroversial enough to pass
Congress easily.

>  3.  Timeframe, if Congress/NASA is timely about adoption of the plan?

NASA is supposed to release a detailed policy document on it soon.  See
my latest AW&ST summary for some related news.  The main issue is that
any company wanting an ET in orbit has got to demonstrate to everyone's
satisfaction that the tank will not make an uncontrolled reentry.  This
is a non-trivial problem since the tanks are big and light, would end up
in quite a low orbit, and would naturally tend to orient themselves
broadside- on to air drag.

>    5.  What about integration with the space station/ISF plans?

If NASA were sensible, it would have provided for using an ET as
expansion space for the station.  It didn't.  And I'd say Space
Industries has enough problems with plain old ISF just now.

NASA is to spaceflight as            |  Henry Spencer @ U of Toronto Zoology
the Post Office is to mail.          | {ihnp4,decvax,uunet!mnetor}!utzoo!henry

------------------------------

Date: 17 May 88 01:25:41 GMT
From: [e-mail]  (Al Globus)
Subject: Re: What to do with the external shuttle tanks

My favorite use for external tanks: sports arena.

Note that the revenue from a major sporting event (Olympics, SuperBowl)
can be in the $100 millions range.

Put an aft cargo compartment on the tank so that modification work that
cannot be done on the ground can be done in a shirt sleeve environment.

First launch sets up the facility and presurizes the oxygen tank.

Next launch a Shuttle and a Soyuz simulataneously to dock with the
facility (this may be tricky).  The shuttle carries a pilot and
commander, a video technician, two American and two Soviet atheletes.
The Soyuz carries a Soviet pilot, one American and one Soviet athelete.

Take four days to train and aclimate.  Then have three or four games,
one per day with three on three teams, Americans vs Soviets.  I
guarantee VERY large audiences for at least the first game.

With proper marketing you just might be able to make some money.  In any
case, the initial potential income vastly exceeds any other space
venture.  You should take in hundreds of millions in the first week of
operation.

The scientist and engineers have had the orbital sandbox to themselves
for too long.  It's time for others to get in the action.

------------------------------

Date: 9 May 88 18:26:55 GMT
From: cfa![e-mail]  (Doug Mink)
Subject: Re: Converting Ephemeris Time to GMT

In article <[e-mail]>, [e-mail] (Kjartan R. Gudmundsson)
writes:
> I am working on a program which will give me on what days the moon is
> full.  I have a formula which gives the answer in Julian Ephemeris
> Days, and now I need a formula to convert these in to GMT.  A example
> with the formula shows that New Moon in February 1977 was on JD =
> 2443192.6525 or 1977 February 18 at 3 Hours 39.6 min (ET).

> If someone could give me this formula I would be thankful.

I run into this problem all the time doing occultation predictions.
Until recently, I've been working over a period of time during which
ET-UT could be closely approximated by a linear fit (it is an empirical
number whcih can only be accurately computed for the past).  I had
occasion to look at data over a period from the late 1940's to the
present, and no polynomial fit would work, so I built in a table of
ET-UT over a the period from which observations are most likely to be
used.  The fit back past the 1940's is based on the real ET-UT which I
didn't want to tabulate; ET-UT fluctuates strangely before 1930.  The
fit into the future fits the extrapolated data for the next two years
and should work for longer.  I use it through 1999 in my work.

Here is a program I wrote:

c*** March 24, 1988
c*** By Doug Mink

c--- Calculate ET - UT given seconds after 1/1/1950

    Subroutine JPDT (TSEC0, DT)

    Real*8 TSEC0
c            Date in format (yyyy.mmdd)
c            or if >3000.d0, seconds after 1/1/1950 0:00 et

    Real*8 DT
c            ET - UT in seconds

    Real*8 TSEC,YEAR,YDIFF,DIFF
    Integer*4 IYR

c  Table containing ET - UT in seconds from the Astronomical Ephemeris

    Real*4 DTTAB(40)
    Save DTTAB
    Data DTTAB/28.71,29.15,29.57,29.97,30.36,30.72,31.07,31.35,31.68,32.18,
     1           32.68,33.15,33.59,34.00,34.47,35.03,35.73,36.54,37.43,38.29,
     2           39.20,40.18,41.17,42.23,43.37,44.49,45.48,49.46,47.52,48.53,
     3           49.59,50.54,51.38,52.17,52.96,53.79,54.34,54.90,55.40,56.00/

    TSEC = TSEC0

c  Convert date to seconds after 1950.0101

    If (TSEC .lt. 3.d3) Then
       Call VCON (TSEC0,0.d0,TSEC)
       Endif

c  Convert to years since 1950 (divide by 365.25d0*8.64d4)

    YEAR = TSEC / 31557600.d0
    IYR = Idint (YEAR) + 2

c  Extrapolate into past using fit based on data from 1930 to 1950

    If (IYR .lt. 1) Then
        DT = 29.157184d0 + 0.589892348d0 * DYEAR + 7.701803d-3 * DYEAR*DYEAR
     1           - 4.7890824d-4 * DYEAR*DYEAR*DYEAR

c  Interpolate from table from the Astronomical Ephemeris (1987) (1949-1988)

    Elseif (IYR .lt. 40) Then
        DIFF = Dble (DTTAB(IYR+1) - DTTAB(IYR))
        YDIFF = YEAR - Dble (IYR-2)
        DT = Dble (DTTAB(IYR)) + (YDIFF * DIFF)

c  Extrapolate into future using fit based on data from 1975 to 1988

    Else
        DT = 28.76304734d0 + 0.719777265d0 * (YEAR)
    Endif

    Return
    End

------------------------------

Date: 10 May 88 05:52:00 GMT
From: [e-mail]
Subject: Re: Converting Ephemeris Time to GMT

While Dr. Mink's posting is quite accurate, as far as it goes, let me
just fill in some data for longer periods.

Actual observed differences in the two clocks over the last three
centuries are (all times in minutes):

1710 -0.2  1770 0.1   1870 0.0     1903 0.0   1940 0.4   1971 0.7
1730 -0.1  1800 0.1   1880 -0.1  1912 0.2   1950 0.5   1977 0.8
1750 0       1840 0.0   1895 -0.1  1927 0.4   1965 0.6 [Meeus]

For longer periods (centuries), Meeus suggests the approximation:

diff = 0.4992 * T**2 + 1.2053 * T + 0.41

where diff is the difference between the two clocks, in minutes, and T
is the time since 1900.0, in centuries.

Another useful and simple approximation is

diff = 0.015 * Y + 0.91,

where Y is the time since 1985, in years, and diff is again in minutes;
this approximation appears in the programs distributed by Allan Paeth.
This last one is within a few seconds for periods 1950-present.

Kevin

------------------------------

End of SPACE Digest V8 #240
*******************

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End of SPACE Digest V8 #264
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