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Subject: SPACE Digest V13 #055

SPACE Digest                                      Volume 13 : Issue 55

Today's Topics:
          Re: LO2/LH2 in Shuttle Payload Bay
          Re: LO2/LH2 in Shuttle Payload Bay
            What is cosmological constant?
         Re: Nuclear deep space power sources
           Re: Cameras in 0G, was: Re: MIR Vacation
             Re: Humanity's Launch Window
                HUBBLE REPORT
              Re: some questions
             Re: THE BLUE PLANET
              Ulysses Update - 01/15/91

Administrivia:

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

Date: 16 Jan 91 04:53:22 GMT
From: snorkelwacker.mit.edu!usc!wuarchive!cs.utexas.edu!news-server.csri.toronto.edu!utzoo![e-mail]  (Henry Spencer)
Subject: Re: LO2/LH2 in Shuttle Payload Bay

In article <[e-mail]> [e-mail] (Wales Larrison) writes:
>  Magellan, from my recollection, was never planned to use a
>Shuttle-Centaur. The use of the TOS stage was allowed when they
>removed the requirement to circularize the orbit at Venus ...

???  Wales, I think you need to check the references on this.  Magellan has
never used a TOS; it went up on an IUS.  And a quick look through the files
confirms my recollection:  Magellan was originally slated to be the first
NASA customer for Centaur G (as opposed to the bigger G-prime planned for
Ulysses and Galileo).  And Magellan, as opposed to its predecessor VOIR,
has always planned an elliptical orbit.

>[Ulysses] The Delta-VEGA maneuver used was a god-
>send to them.

Again, ???  Unless I am badly mistaken, Ulysses is going direct to Jupiter,
no delta-VEGA involved.  Only Galileo gets to bat around the inner system
for a while first.

>... Turns out Rockwell's Space Transportation Systems
>Division did a study on it in about 1987, which was supposedly the
>analysis which bumped the Centaur off Shuttle.

Hope you can turn that up; I am very interested to hear what it says.
--
If the Space Shuttle was the answer,   | Henry Spencer at U of Toronto Zoology
what was the question?                 |  [e-mail]   utzoo!henry

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

Date: 15 Jan 91 05:11:08 GMT
From: snorkelwacker.mit.edu!usc!elroy.jpl.nasa.gov!zardoz.cpd.com!dhw68k!ofa123![e-mail]  (Wales Larrison)
Subject: Re: LO2/LH2 in Shuttle Payload Bay

>So how did solid rockets -- which one would expect to weigh more,
>given their considerably lower specific impulse -- satisfy those
>weight limits for launching two out of the three original Shuttle-
>Centaur payloads? Both Ulysses and Magellan, originally both slated
>for S-C, flew their original flight plans, or close approximations
>thereto, with solids. How did those missions meet the weight limits
>if Shuttle-Centaur versions of those missions couldn't?

   Funny you should ask Henry.  If you check my previous posting
from yesterday I gave a brief synopsis of the history of the Galileo
mission with the C3 energy terms (as best as I could remember them)
from the different Galileo opportunities.  To summarize - the
original Galileo plan used a very favorable launch window in 1982
which would have used a Mars swingby maneuver to significantly
reduce the energy required in the orbit. By 1986 or so, this
favorable alignment of Earth, Mars, and Jupiter was lost, forcing
the mission to accomodate a much higher energy requirement.
  Magellan, from my recollection, was never planned to use a
Shuttle-Centaur. The use of the TOS stage was allowed when they
removed the requirement to circularize the orbit at Venus
(originally the mission planned for circularization of the
spacecraft in Venusian orbit).  Using the inclined elptical orbit
which Magellen is now in, allowed a dual use of the Radar mapping
antenna for Earth-pointing communications, which did reduce weight
and complexity of the mission.
   Ulyses (I still prefer ISPM) is a whole 'nother kettle of fish
however.  (Again, you must pardon me from working from memory - my
files got dumped when my company got out of the upper stage business
about 4 years ago).  The original mission plan for Ulyses was to use
the Galileo opportunity with a Mars swingby maneuver.  Their problem
was not only getting to Jupiter, but they needed somewhere around
15,000 fps velocity at Jupiter to do the 90 deg plane change, even
with a gravity assist by Jove. (:-) Their required C3 jumped to
about 70 km2/sec2, without the Mars assist, compared to about 55 for
Galileo. (They were only able to originally plan to do the mission
by greatly reducing their weight compared to Galileo).  With the
loss of the 1984 opportunity, they were really stuck.  Prior to the
Centaur decision all sorts of weird ideas were floating around -
like reducing the vehicle weight (again), or adding additional solid
stages on the IUS stack.  The Delta-VEGA maneuver used was a god-
send to them.
  BTW, I went into our corporate library and had the reference
librarian run a lit search on the Safety aspects of the Centaur
integration.  Turns out Rockwell's Space Transportation Systems
Division did a study on it in about 1987, which was supposedly the
analysis which bumped the Centaur off Shuttle.
  To make a long story short - I called the analyst who wrote the
report, and he's getting me a copy of the report.  Unfortunately, he's
out of town this week (I caught him on his way out the door to the
airport to DC), but we've set up a time to talk next week about the
issue.  Since the Centaur has been pulled from the orbiter, there
seemed more than willing to talk.
  I'll keep the net posted, as I find out more of what the analysis
showed.
------------------------------------------------------------------
Wales Larrison                             Space Technology Investor



--
Wales Larrison
Internet: [e-mail]
Compuserve: >internet:[e-mail]
--------------------------------------------------------------------------

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

Date: 15 Jan 91 22:36:17 GMT
From: bu.edu!rpi!zaphod.mps.ohio-state.edu!wuarchive!kuhub.cc.ukans.edu![e-mail]
Subject: What is cosmological constant?

Can someone give me a brief explanation of "cosmological constant"?
I have the understanding that this is a base energy density for
"empty" space; as opposed to a base energy level (vacuum energy level)
for "empty" space.  Is this correct?  To what would this base energy
level be due?  Uncertainty leading to a background cloud of paired
virtual particles?

Thanks.

Mike McGinnis                                 "Rust never sleeps."
Academic Computing Center                           -The Second Law of
University of Kansas                                 Thermodynamics
Lawrence, Kansas  66045

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

Date: 16 Jan 91 12:44:44 GMT
From: astroatc![e-mail]  (Joe Johnson)
Subject: Re: Nuclear deep space power sources


   i believe that most if not all of the deep space RTG's use
Plutonium 238 as the heat source. Pu 238 has a half-life of 86 years
and decays by emitting a 5.6 MeV alpha particle. According to my
source (Nuclear Heat Transport by M. M. El-Wakil) Pu 238 has a
density of 12.5 g/cm^3 which gives a peak power density of 6.9 W/cm^3
(this is the thermal power density, the electrical conversion
has not been taken into account).

joe

--
--------
[e-mail] | The cemeteries are full of indispensable
{...}!uwvax!astroatc!jjohnson      | men.   --Georges Clemenceau

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

Date: 15 Jan 91 21:04:16 GMT
From: sun-barr!newstop!exodus!concertina.Eng.Sun.COM![e-mail]  (Steve Hix)
Subject: Re: Cameras in 0G, was: Re: MIR Vacation

In article <[e-mail]>, [e-mail] (H.A.Shaw) writes:
>
>     Whats all this about modifications for 0G?  [...]
> [...] I have around 20,000 slides in my current collection and I've never
> knowingly lost a shot because of gravity.  What difference does gravity make?
>
> Maybe it makes using a tripod a little more tricky :-)
>
> This sounds like the $483 space rated hammer again to me!

As I (dimly) recall, space-rating a camera system has little do with
gravity.  The problems that concerned NASA had more to do with the
cameras operation in vacuum (outgassing, lubrication, thermal response,
etc.) than anything else.  Some chemicals outgassing from the camera
might have been a potential problem from a life-support angle, and
evaporating lubricants could leave you with a non-functioning paperweight
just when you didn't need one.

--
------------
  The only drawback with morning is that it comes
    at such an inconvenient time of day.
------------

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

Date: 15 Jan 91 22:05:48 GMT
From: netcom!teda![e-mail]  (Donald R. Bosart)
Subject: Re: Humanity's Launch Window

[e-mail] (Alan Silverstein) writes:
             Humanity's Launch Window

                 Alan Silverstein
                 January 14, 1991


>        *Thirty years*.  That's about how long humanity's ``launch
>        window'' has been open.  There are wonders beyond comprehension
>        awaiting us beyond our Earth.  To achieve a toehold, a foothold,
>        on those riches requires enormous investment.  It takes raw
>        materials and the technology to render them.  It takes many, many
>        people, at peace with each other in a stable society, wealthy
>        enough to make investments whose return is measured in
>        generations.
>

In an actual article, I would expect more concrete examples of the
benefits designed to mute space expansion critics...

>        Our precious Earth is crowded.  Our raw materials are being
>        consumed.  *Our launch window will close*.

This needs expansion, and justification; Club of Rome, etc.

>
>        *How long do we have?*  It is anyone's guess.  I think no more
>        than fifty years.  Perhaps much less.  After that -- no one, no
>        group, will have the resources, the time, the energy, to spare on

Maybe.  I think the more likely scenario is that another culture,
perhaps Japanese will cross the threshold.  I say this because we seem
too pre-occupied with militarism and the Europeans with happenings
east of them to have a PLAN for space.

It is also possible to imagine a partial collapse (50%-90%) of
humanity's world system, followed by "dark ages", followed by another
expansion which might retain enough technology and know-how to make
the leap to space.  This is supportable by historical and biological
evidence.  Of course, there were once dinosaurs too!

>
>        *Imagine it*.  Nine billion years for Earth.  An eighty year
>        launch window for humanity.  Now *that* is the big picture.
>        Perhaps, in the long run, it is the only perspective that counts.

A very good point!

--
-------------------------------------------------------------------------------
Donald R. Bosart                    Teradyne EDA West
!{decwrl, sun}!teda!bosart                5155 Old Ironsides Dr.
408-980-5264                        Santa Clara, CA. 95054

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

Date: 14 Jan 91 19:56:26 GMT
From: mcsun!ukc!mucs!liv-cs!liv![e-mail]  (Andrew Hartridge)
Subject: HUBBLE REPORT

Can anyone tell me (if it has been published yet) wether there is an
electronic form of the Hubble primary mirror investigation panel report.
If so can it be mailed or I can FTP it ???

      If not can someone tell me the Report Ref. Number so I can get
it on paper from the US Government Printing office (I presume it is
they who publish it?)
                     Thanks a lot
------------------------------------------------------------------------
|                          Andrew Hartridge                            |
| "How do you feel today... |                                          |
|                           | UUCP: !mcvax!ukc!liverpool.ac.uk!eeet176 |
| "Better ...... Better get | JANET:  eeet176 @ uk.ac.liverpool.ibm    |
|  bucket I'm gonna be sick |         ANDREWH @ uk.ac.nsfnet-relay     |
|  --- Mr Creosote          | Handel anywhere on the Internet : Rooh   |
------------------------------------------------------------------------

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

Date: 16 Jan 91 17:25:32 GMT
From: agate!bionet!uwm.edu!wuarchive!usc!jarthur!nntp-server.caltech.edu![e-mail]  (Robert Andrew Knop)
Subject: Re: some questions

[e-mail] (Earl W Phillips) writes:

>1) Once I know the lat, long location of my site, how
>do I translate these figures to decimal?

Do you mean something like:

lat = (deg + arcmin/60 + arcsec/3600)   degrees
long = [(deg + arcmin/60 + arcsec/3600)*(24/360)]   degres

?

-Rob Knop
[e-mail]

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

Date: 15 Jan 91 19:47:13 GMT
From: hpfcso!hpfcdc![e-mail]  (Alan Silverstein)
Subject: Re: THE BLUE PLANET

> ...THE DREAM IS ALIVE is now available on VHS cassette...

I saw it last month at Kennedy Space Center for about $13, if I remember
right.  Surprisingly reasonable prices on all the "space stuff" for sale
in the gift shop there.  Stiff paper posters, 16x20 (?), for $3, for
instance.

> ...most IMAX theatres don't show this thrilling feature much anymore,
> maybe because Challenger is such a big part of it.

It runs continuously at the IMAX theater at KSC for $2.75 (I think).
Such a deal.  It appeared they had edited it a little since I last saw
it in 1986, though.  Specifically I thought they showed a little more of
Judy Resnick earlier.

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

Date: 16 Jan 91 18:06:03 GMT
From: snorkelwacker.mit.edu!usc!elroy.jpl.nasa.gov!jato!mars.jpl.nasa.gov![e-mail]  (Ron Baalke)
Subject: Ulysses Update - 01/15/91


                        ULYSSES STATUS REPORT
                          January 15, 1991

     The following data was taken at 9AM (PST), January 14, 1991 on the
Ulysses spacecraft:

        Distance from Earth              72,188,104 miles (116,175,492 km)
        Distance from Jupiter           346,548,247 miles (557,715,343 km)
        Velocity relative to the Sun         67,976 mph       (109,396 kph)
        Velocity relative to the Earth       54,393 mph       ( 87,537 kph)

     On January 8, a nominal slew maneuver was performed.  On January 9, a
BAM (Solar Wind Plasma instrument) matrix I reconfiguration was carried out.
On January 10, Pseudo Spin scheduling tests were carried out.

     The Solar Aspect angle increased from 6.5 degrees on January 8 to 9.9
degrees on January 14.  The Sun-Probe-Earth  angle increased from 7.1 degrees
on January 8 to 10.4 degrees on January 14 when Opposition occurred. The angle
is now increasing again.

     A series of DSN (Deep Space Network) problems/errors occurred during this
first week of routine operations.  The data return was less than required.
Actions have been taken to reduce the operator errors but some degree of
station system failures must be expected in the future.  Operations since
January 11 have improved.

     Routine data gathering operations will continue together with experiment
reconfigurations as required.  Tape recorder operations based on recovering
data acquired during the 16 hours out of view periods are continuing on a
routine scheduled basis.
      ___    _____     ___
     /_ /|  /____/ \  /_ /|
     | | | |  __ \ /| | | |      Ron Baalke         | [e-mail]
  ___| | | | |__) |/  | | |___   Jet Propulsion Lab | [e-mail]
 /___| | | |  ___/    | |/__ /|  M/S 301-355        |
 |_____|/  |_|/       |_____|/   Pasadena, CA 91109 |

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

End of SPACE Digest V13 #055
*******************