Space & Astronomy/Space and Astronomy (October 1993).iso/mac/TEXT/SPACEDIG/V13_4/V13_492.TXT

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Subject: SPACE Digest V13 #492

SPACE Digest                                     Volume 13 : Issue 492

Today's Topics:
            Jonathan's Space Report, May 3
               Re: Gas Guns and Tethers
              Re: SPACE Digest V13 #470
     Re: Galileo Update On CNN  atmosphere probe question
              Re: SPACE Digest V13 #475
            Re: Terraforming Venus
  Re: Saturn V and Design Reuse: Saturn VI? (RBB: Real Big Booster)
     Re: slight problems with HLV's in general, Saturn or not...
             Terraforming Venus?
             Re: Saturn V vs. ALS

Administrivia:

    Submissions to the SPACE Digest/sci.space should be mailed to
  [e-mail].  Other mail, esp. [un]subscription requests,
  should be sent to [e-mail], or, if urgent, to
             [e-mail]

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

Date: 3 May 91 19:59:23 GMT
From: swrinde!elroy.jpl.nasa.gov!freedom!xanth![e-mail]  (Jonathan McDowell)
Subject: Jonathan's Space Report, May 3


Jonathan's Space Report

May 3 1991 (no.73)
----------------------------------------------------

Discovery was launched on mission STS-39 at 1133.14 UT
on Apr 28. The IBSS-SPAS satellite was deployed on May 1
at 0817 and retrieved at 2225 on May 2. The CRO-C subsatellite
was deployed on May 2 at 0128; the CRO-B subsatellite was
deployed on May 2 at 1803; the CRO-A subsatellite was deployed on
May 3 at 1210. Landing is scheduled for May 6.

Viktor Afanas'ev and Musa Manarov continue in orbit aboard the
Mir/Kvant/Kvant-2/Kristall/Soyuz TM-11/Progress M-7 complex.
Launch of Soyuz TM-12 is due for May 18, with the replacement
long stay crew of Anatoliy Artesbarskiy and Sergey Krikalyov.
Soyuz TM-12 will also carry as a passenger the British Project
Juno cosmonaut Helen Sharman, who will return with Afanas'ev and
Manarov in Soyuz TM-11.

Kosmos-2142, a navigation satellite, was launched by Kosmos R-14 from
Plesetsk on Apr 16 into a 1000 km orbit.

The fourth Meteor-3 weather satellite was launched by Tsiklon from
Plesetsk on Apr 24 into a 1200 km orbit.


___________________________________
|Current STS status:              |
|Orbiters                         |
|                                 |
|OV-102 Columbia         LC39B    |
|OV-103 Discovery     Earth orbit |
|OV-104 Atlantis        OPF Bay 2 |
|OV-105 Endeavour       Palmdale  |
|                                 |
|ML/ET/SRB stacks                 |
|                                 |
|ML3/STS-40/ET/OV-102   LC39B     |
-----------------------------------

20 years ago: 5 May 1971.  DSP F2 was launched by Titan 3C from Cape
Kennedy.  It was the first successful craft in the DSP early warning
satellite system, which watches for missile launches from stationary
orbit.  DSP F2 was stationed over the Indian Ocean.

30 years ago: 5 May 1961. The Mercury spaceship "Freedom Seven", with
astronaut Alan B. Shepard aboard, was launched on the suborbital
MR-3 mission by a Redstone booster. Shepard became the first U.S.
citizen to enter space; the flight lasted 15 minutes.

(c) 1991 Jonathan McDowell. Information in this report is obtained
from public sources and does not reflect the official views of NASA.

 .-----------------------------------------------------------------------------.
 |  Jonathan McDowell                 |  phone : [phone]                 |
 |  Space Science Lab ES65            | uucp:                                  |
 |  NASA Marshall Space Flight Center | bitnet :                               |
 |  Huntsville AL 35812               |  inter : [e-mail]  |
 |  USA                               |   span : ssl::mcdowell                 |
 '-----------------------------------------------------------------------------'

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

Date: 3 May 91 19:23:29 GMT
From: dog.ee.lbl.gov!hellgate.utah.edu!caen!ox.com!fmsrl7![e-mail]  (Ron Carter)
Subject: Re: Gas Guns and Tethers

In article <[e-mail]> [e-mail] writes:
[regarding capturing sub-orbital payloads with a tether]
>Theoretical problem 1) The centre-of-mass of the combined structure has
>instantaneously dropped closer to the earth's surface without the orbital
>velocity increasing. The result should be a lower orbit.

This is not a problem.  It requires only:
a.)    that the decrease in the size of the orbit be managable, or
b.)    the opposite end of the orbit be higher to compensate.

>Theoretical problem 2) Remember my "Summary:" line about no boostrapping?
>As the shuttle climbs the tether, the space-station+tether descend a bit.
>Since we're dealing with a closed system, the centre-of-mass must remain
>in the same orbit.

Yes, so?  Is an absolutely constant orbit a requirement?  For what?

>Practical problem 1) Conservation of angular momentum... Unless the
>shuttle matches velocity *VERY* closely with the station, the two bodies
>will be spinning around each other at some horrendeous rpm's by the time
>the shuttle has climbed all the way up the tether.

You are ignoring tidal effects on the tether, which tend to hold
it along the primary's radius.  After a payload capture, the
tether would swing back and forth relative to the radius like a
pendulum.  By proper control of the tether reel, these swings
can be damped.

>     The theoretical problems are where many "perpetual-motion machines"
>trip over reality. It takes X joules of work to lift a specific payload
>to a specific orbit.

If you'd take a detailed look at the energy and angular momentum
transfers, you'd realize that tethers don't offer a free lunch, or
a free launch.  What they give you is checking and credit, letting
you loan or transfer energy and angular momentum w/o using rockets.

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

Date: 3 May 91 00:22:03 GMT
From: dog.ee.lbl.gov!hellgate.utah.edu!caen!uakari.primate.wisc.edu!samsung!umich!umeecs!msi.umn.edu!cs.umn.edu!kksys!wd0gol!newave![e-mail]  (John A. Weeks III)
Subject: Re: SPACE Digest V13 #470

In article <[e-mail]> [e-mail] (Tommy Mac) writes:
> The computer that was used on the original Apollo Landings had only 64K of
> core memory.

> It's teeny sure, but they did it with tubes back then.  To give you an idea
> how that translates into lbs, a 40 BIT register that we have in a showcase
> here weighs about 20lbs.  That means that 64K of tube-memory would translate
> to, say 40000 lbs?  That can't be right!  It must be really heavy tho.
> That;s not even talking about the coooling system they needed.
> (That 40 bit job was about 2 cubic feet)

Think about the space 2 cubic feet would have to scale up to in order to
become 64K.  The 64K is main memory, where as a register would be part of
the CPU.  The Apollo CPU was solid state.  The memory was probably magnetic
core.  No tubes in either, but I bet the CPU still generated a bit of heat.
The magnetic core memory is surprisingly small, except when compared to
IC chip memory.

-john-

--
=============================================================================
John A. Weeks III               [phone]             [e-mail]
NeWave Communications                       ...uunet!tcnet!wd0gol!newave!john

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

Date: 4 May 91 07:51:16 GMT
From: agate!lightning.Berkeley.EDU![e-mail]  (Frank Crary)
Subject: Re: Galileo Update On CNN  atmosphere probe question

In article <[e-mail]> [e-mail] (robert.f.casey) writes:
>
>I saw part of this news report, too.  There was mention that if they can't
>get the antenna fixed, there will be no nice pictures.  But they can still
>do the atmosphere probe.  Are there cameras on this probe (didn't think so)?
>Data rate on the probe must be fairly low, then, if the antenna problem
>won't get in the way.  Will NASA "hear" the atmosphere probe directly from
>Jupiter without being relayed thru Galileo?

The Galileo atmospheric probe has no camera. All its data is transmitted by
a low power, omni-directional antenna. It is low power since it must run
off of the probe's bateries and omni-directional, since a directional
antenna could not keep an keep pointing in a constant direction, while
hanging from a parachute in possible gale-force winds. As a result the
probe has a very low data rate, even to the nearby orbiter. From Earth
the probe's signal would inaubable, so the orbiter must be there to
relay the signal. The good news is that, given the short transmission
time and low data rate, the orbiter can transmit via its low gain antenna
and/or store the data for later transmission.

                 Frank Crary
                 UC Berkeley

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

Date: 1 May 91 22:38:53 GMT
From: wuarchive!rex!rouge![e-mail]  (Fraering Philip)
Subject: Re: SPACE Digest V13 #475

In article <[e-mail]> [e-mail] writes:

>Sure dropping Jupiter for a 'few measly asteroids' would seem to be a waste.

>But dropping Jupiter for the most abundant, accessible resources and plantetary
>science specimens in the Solar System is a FANTASTIC idea.

>Remember that, unlike the Planets, we can (eventually) study every gram of the
>Asteroids, given the time and determinantion.  We will never study the interior
>of any of Jupiter's moons, let alone Jupiter.

>This not only means the Asteroids would make better scientific specimens, but
>also means we can recover all the heavy metals (i.e. gold, iron, lead, copper)
>that are forever hidden at the center of the other planets.

>And finding those heavy metals could be the incentive that private industry
>needs to get their butts busy building a space infrastructure.

>You would like to see a space infrasturcture wouldn't you?

>Tommy Mac
>Acknowledge-To: <18084TM@MSU>

Yes, but at present Galileo is a very lousy asteroid probe. You aren't going
to get much info from a bunch of 100 or so meters/sec flybys from a great
distance. Something a lot smaller than Galileo, with instruments more
appropriate to the task, could for less money than the replacement to
Galileo to Jupiter give us a lot better asteroid data.

Besides, for economic development, you'd want to look at the
near-earth asteroids.

Am I the only one here who understands that you won't get optimal
data using a planetary orbiter to look at asteroids?

--
Phil Fraering
[e-mail]
Joke going around: "How many country music singers does it take to
change a light bulb? Four. One to change the bulb, and three to sing
about the old one."

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

Date: 2 May 91 00:42:25 GMT
From: dog.ee.lbl.gov!hellgate.utah.edu!caen!sdd.hp.com!wuarchive!rex!rouge![e-mail]  (Fraering Philip)
Subject: Re: Terraforming Venus

In article <[e-mail]> [e-mail] (Mark A Wieczorek) writes:

>Also when people talk about bombarding either mars or venus with
>comets. Where are they going to come from and how are they going to
>get here?
>Is their any evidence that their actually is an oort cloud, or is this
>just a nice hypothesis?
>Mark Wieczorek

Yes, there actually is an Oort Cloud, and many of the comets were
there before they entered the inner solar system. However, over the
lifetime of the solar system, the Oort Cloud doesn't last very long,
so there is also a closer reservoir of comets called the Kuiper Belt,
past Neptune and Pluto, I don't really have the numbers handy. All the
scales I've seen the distances displayed on have been logarithmic in
nature; just past Neptune could be an orbit twice as large, as far as
some people are concerned. Neither of these places are very convienent
in terms of energy, but neither is terraforming Venus to begin with.

Terraforming the moons of Jupiter would probably be easier :-).


--
Phil Fraering
[e-mail]
Joke going around: "How many country music singers does it take to
change a light bulb? Four. One to change the bulb, and three to sing
about the old one."

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

Date: 5 May 91 02:46:32 GMT
From: skipper![e-mail]  (Mary Shafer)
Subject: Re: Saturn V and Design Reuse: Saturn VI? (RBB: Real Big Booster)

In article <[e-mail]> [e-mail] (Henry Spencer) writes:

>In article <[e-mail]> [e-mail] (/dev/null) writes:
>>No, life DOES NOT have a value that can be estimated.  The LEGAL
>>COSTS of a trial does not equate to a human life.

>Life may not have a value that can be estimated, in some theoretical sense,
>but for practical planning one *must* assign it some specific value.  There
>is *NO LIMIT* to how much you can spend making the hardware a little bit
>safer.  If you want to get anything done, sooner or later you have to say
>"enough".  Whether you like it or not, when you say that, you have set the
>value you put on life.

To provide a more explicit example of what Henry says, in the early
70s Caltrans (California Department of Transportation) set the value
of one life at $100,000.  The cost/benefit analysis had to reflect
this value: if a recommended action cost more than $100,000 times the
lives that would be saved in the first n years, the action would not
be taken.  That's why there are a lot of 4-way stops near schools and
few signals.

>"For perfect safety... sit on a fence and watch the birds." --Wilbur Wright

To quote something I said last year, "Perfect safety is for people who
don't have the balls to live in the real world."
--
Mary Shafer  [e-mail]  ames!skipper.dfrf.nasa.gov!shafer
           NASA Ames Dryden Flight Research Facility, Edwards, CA
                     Of course I don't speak for NASA
            "Turn to kill, not to engage."  CDR Willie Driscoll

--
Mary Shafer  [e-mail]  ames!skipper.dfrf.nasa.gov!shafer
           NASA Ames Dryden Flight Research Facility, Edwards, CA
                     Of course I don't speak for NASA
            "Turn to kill, not to engage."  CDR Willie Driscoll

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

Date: 2 May 91 18:08:41 GMT
From: hela![e-mail]  (Allen W. Sherzer)
Subject: Re: slight problems with HLV's in general, Saturn or not...

In article <[e-mail]> [e-mail] (unicorn) writes:

>AWST reported that one of the reason that the Russian heavy lift vehicle
>has not flow again is that there is no payload for it.

Agreed. Outside of SEI there is no current need for a 250K to LEO launcher.
However, if a cheap 100K pound to LEO launcher came up (like HL Delta or
Titan V) then I think we would see payloads. Space at GEO is getting
tight and large payloads means larger satellites which make better use
of the space available.

>I think that the
>US should com up with a list of prospective payloads for the first few
>years of the vehicles life.

In that case there are no payloads. Nobody in their right mind is
going to spend the money to develop the payloads with no way to
launch them.

If Von Braun had that attitude there would have been no Apollo 11. The
work on the F-1 engine began long before a need for it (apollo) was
identified.

   Allen

--
+---------------------------------------------------------------------------+
|Allen W. Sherzer |        Allen's tactics are too tricky to deal with      |
|   [e-mail]   |             -- Harel Barzilai                           |
+---------------------------------------------------------------------------+

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

Date: 2 May 91 16:48:43 GMT
From: cadence![e-mail]  (Jon Monsarrat x6227)
Subject: Terraforming Venus?

> [e-mail] (Philip Fraering) writes:
>
> Terraforming the moons of Jupiter would probably be easier :-).

Wait, do Jupiter's moons (like Ganymede) have enough gravity
to support an atmosphere even if supplied with impacted comets?

Thanks to any responders!

-Jon Monsarrat
 [e-mail]

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

Date: 28 Apr 91 23:59:52 GMT
From: unisoft!fai!sequent!crg5![e-mail]  (Nick Szabo)
Subject: Re: Saturn V vs. ALS

In article <[e-mail]> [e-mail] (Richard Caley) writes:

>Besides, there is nothing sacred about one payload per rocket.

Sharing works only where there is a common destiation orbit and time
of deployment.  There are many orbits of interest -- GEO, low polar, SSO,
Molniya, equatorial, 28 degree, 60 degree, 5 Lagrange points, various deep
space trajectories -- and many possible planes within some of those orbits.
Unless the two spacecraft just so happen to share a common destination _and_
a common time of deployment, and just so happen to fit together in the
payload shroud, sharing a launcher can be a severe handicap.  Furthermore,
sharing requires specialized payload interfaces which decrease the payload
well below the specified maximum launch mass, and increase price due to
the customized hardware.  At this point, sharing probably only makes sense
for some GEO-bound satellites and microsatellites systems with multiple
spacecraft per plane (eg Iridium).


--
Nick Szabo                [e-mail]
"Living below your means allows you to live better than living above your
means." -- Dave Boyd    The above opinions are my own and not related to
those of any organization I may be affiliated with.

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

End of SPACE Digest V13 #492
*******************