Space & Astronomy/Space and Astronomy (October 1993).iso/mac/TEXT/SPACEDIG/V11_1/V11_117.TXT

Internet Message Format | 1991-07-08 | 18KB

Return-path: <[e-mail]>
X-Andrew-Authenticated-as: 7997;andrew.cmu.edu;Ted Anderson
Received: from beak.andrew.cmu.edu via trymail for +dist+/afs/andrew.cmu.edu/usr11/tm2b/space/[e-mail] (->+dist+/afs/andrew.cmu.edu/usr11/tm2b/space/space.dl) (->ota+space.digests)
          ID </afs/andrew.cmu.edu/usr1/ota/Mailbox/QZwpYem00VcJEK7E4G>;
          Tue,  6 Mar 90 01:31:08 -0500 (EST)
Message-ID: <[e-mail]>
Reply-To: [e-mail]
From: [e-mail]
To: [e-mail]
Date: Tue,  6 Mar 90 01:30:33 -0500 (EST)
Subject: SPACE Digest V11 #117

SPACE Digest                                     Volume 11 : Issue 117

Today's Topics:
    Re: Magellan Update - 03/02/90 -- now reprogramming spacecraft
           Payload Status for 03/05/90 (Forwarded)
              Astronomy network
   Re: where spacecraft expertise (was Magellan Update - 03/02/90)
              Re: Challenger Last Words
          Re: Spacecraft drives and fuel efficiency
          Re: Spacecraft drives and fuel efficiency
             Re: Large antennas in orbit
             Space Mailing List?
          Re: Spacecraft drives and fuel efficiency
           Re: Funding Is Not The  Problem
----------------------------------------------------------------------

Date: 5 Mar 90 18:18:11 GMT
From: cs.utexas.edu!ut-emx![e-mail]  (Anita Cochran)
Subject: Re: Magellan Update - 03/02/90 -- now reprogramming spacecraft

In article <[e-mail]>, [e-mail] (Tom Neff) writes:
> I'm curious about something in general.  One of the geniuses of the space
> program, I won't say just the US's although that's what we mostly hear
> about, is our ability to improvise and tinker with launched probes,
> especially in software, to overcome unexpected obstacles.  Voyager is
> rich with examples, and now we read about similar heroics with Magellan
> and Hipparcos and Galileo.
>
> The question is, are the lessons learned and the tricks we come up with
> DOCUMENTED and passed on to future spacecraft designers?  Or do they
> languish in a few geniuses' brains until they retire, or get buried in
> the guts of some endless moldering rack of mission paperwork or stacked
> magtapes in a department office somewhere?


Yes, these things are documented and remembered.  As anyone who has ever
worked with NASA can attest, NASA doesn't do ANYTHING without copious
amounts of documentation.  A mission generates file cabinets worth of
documentation.  And we don't uplink anything to a spacecraft until it
is fully tested out on the ground-system and documented.  This results
in very safe operations and the ability to fix things but means we
cannot operate in anything like real time.

As an example, I am involved with the Comet Rendezvous/Asteroid Flyby (CRAF)
mission.  If we decided one day that we want to point to a particular
feature on the comet and cycle through 5 filters, it will be a minimum
of 4 weeks from the time we request it until the time it is uplinked
and executed.  Obviously, this takes away sponteneity!  First and
foremost is spacecraft safety.  We scientists are trying to shorten
the time but we are not winning the battle.




--
 Anita Cochran  uucp:  {noao, ut-sally, ut-emx}!utastro!anita
                arpa:  [e-mail]
                snail: Astronomy Dept., The Univ. of Texas, Austin, TX, 78712
                at&t:  [phone]

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

Date: 5 Mar 90 22:35:40 GMT
From: trident.arc.nasa.gov![e-mail]  (Peter E. Yee)
Subject: Payload Status for 03/05/90 (Forwarded)

Daily Status/KSC Payload Management and Operations 03-05-90



- STS-31R HST (at VPF) -

MILA/CTV checks and HST diode retest were completed Friday.
Today VPF to MILA interface checks will be performed and
HST closeout operations will continue.  MMSE preps for P/L
transfer to the pad will also continue today.


- STS-32R SYNCOM/LDEF (at SAEF-2)

LDEF deintegration continues.


- STS-35 ASTRO-1/BBXRT (at O&C) -

Velcro patch installation and MLI closeout were worked
Friday and will continue today.  Also the CITE SIP panel
will be removed today and canister preps for P/L transfer
to the OPF will continue.


- STS-40 SLS-1 (at O&C) -

The systems test was active Friday and will continue today.
Experiment functional checks will also continue today.  On
Saturday the O2N2 panel was changed out and the CCTV over-
head cable was also partially installed.  On Sunday all
three AP101SL computers were changed out.


- STS-42 IML (at O&C) -

Racks 3 and 9 staging operations were worked Friday.  Racks
3, 5, 9, and 11 staging operations were worked Saturday.
Today racks 3, 4, 9, and 11 staging operations are scheduled.


- STS-45 Atlas-1 (at O&C) -

Pallet keel installation was active Saturday.  Today, ortho-
grid hardpoint installations are scheduled.


- HST M&R

ORUC cable system installation will continue today.

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

Date:     Mon, 05 Mar 1990 11:57 EST
From: DAVID SIMMONS <[e-mail]>
Subject:  Astronomy network
To: <[e-mail]>

     I have seen several references to a 'sci.astro' dealing with
subjects of astronomy. Does anyone have the address for it?

     David Simmons

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

Date: 5 Mar 90 23:10:56 GMT
From: [e-mail]  (Eugene Miya)
Subject: Re: where spacecraft expertise (was Magellan Update - 03/02/90)

This is a good question.
Lots of this stuff gets documented in project notebooks, programs, tapes,
etc.  Lots of it stays in people's heads.  Lots of this stuff is one of
of kind.  A good example in software is when you look at COSMIC
software distribution stuff: you will find the availability in forms like
old H-P magnetic cards, punched cards and card images.  What do you
keep and what do you throw away?  A few people do write articles
and books which appear in conference proceedings for AIAA meetings etc.
(Less so ACM/IEEE, a different circle of interest.)

When you are flying a project the term "Fire fighting drill (exercise)"
is frequently used.  It refers to working at the "heat" of the moment
when you might not have time TO DOCUMENT this stuff.
THE PROBLEM is that budgets are not written in a long term fashion to
move data of this kind.  Data is taken, written down, like Apollo 17
radar data, but its stored on 200 BPI tape, or the odd 556 BPI JPL tape, etc.
There is no money for format conversion, anything more than boxing and
wherehousing the old manuals, etc.

This is also good.  There are old inappropriate methods of doing these
kinds of software and hardware fixes, you take the problems on a case by
case basis.  Like Indiana Jones once said, "I don't know, I'm
making it up as a go."  The Agency generally believes it all
averages out.  It tries to avoid single person/resource failure.
It eventually reinvents the wheel several times over.
I'd hate to have a new hire have to learn 360 assembly code from
some old COSMIC listing to get every detail of some dumb fix.

Evolution: isn't simply the adding of new features, it's taking them away.

Another gross generalization from

--eugene miya, NASA Ames Research Center, [e-mail]
  resident cynic at the Rock of Ages Home for Retired Hackers:

  "You trust the `reply' command with all those different mailers out there?"
  "If my mail does not reach you, please accept my apology."
  {ncar,decwrl,hplabs,uunet}!ames!eugene
  Do you expect anything BUT generalizations on the net?
  [If it ain't source, it ain't software -- D. Tweten]

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

Date: 5 Mar 90 18:28:58 GMT
From: att!cbnewsj![e-mail]  (r.craig.montero)
Subject: Re: Challenger Last Words

As I recall, Aviation Week (of course) provided an edited transcript
of the transmissions that were sent from the vehicle from about T-5 minutes
until they ceased (the expletives
were deleted). According to that transcript, the pilot utterred "Uh, oh"
as the last recorded transmission from the vehicle. Based on the time
it was after the fireball began and was probably a response to seeing
the fireball. The transcript appeared in one of the special post accident
issues. Av Week published its transcript BEFORE NASA decided it wasn't
going to release the information.

Craig Montero
AT&T Bell Labs

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

Date: 6 Mar 90 00:23:03 GMT
From: zaphod.mps.ohio-state.edu!swrinde!cs.utexas.edu!jarvis.csri.toronto.edu!helios.physics.utoronto.ca!ists!yunexus!utzoo![e-mail]  (Henry Spencer)
Subject: Re: Spacecraft drives and fuel efficiency

In article <[e-mail]> [e-mail] (Brian or James) writes:
>...just how bad would a plausible M-AM explosion be? If we're
>talking the annihilation of several micrograms, that's roughly about
>twenty tons of of TNT going Boom, which is very annoying if you happen
>to be standing next to it, but survivable at moderately short ranges.

Bear in mind, also, that a worst-case explosion of a large chemical
rocket, e.g. Saturn V or shuttle, is in the low kiloton range.  It's
not an accident that the nearest viewing areas are 3 miles away...
--
MSDOS, abbrev:  Maybe SomeDay |     Henry Spencer at U of Toronto Zoology
an Operating System.          | uunet!attcan!utzoo!henry [e-mail]

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

Date: 5 Mar 90 16:26:54 GMT
From: mailrus!jarvis.csri.toronto.edu!utgpu!watserv1!watdragon![e-mail]  (Owner of Many System Processes)
Subject: Re: Spacecraft drives and fuel efficiency

Followup to:
Distribution:
Organization: U. of Waterloo, Ontario
Keywords: That Darned Antimatter
From: [e-mail] (Brian or James)
Path: watyew!jdnicoll

 While I'd agree that sitting next to a matter-antimatter annihilation would
likely be uncomfortable, I notice that his posting doesn't seem to include
estimations of the magnitude of the problem. If a 'Challenger' style mishap
would sterilise all of Florida (for example), then the risk would probably
outweight the possible gains. On the other hand, if the explosion were to
cause damage on the scale of that SRB fuel plant that blew up or
Bohpol (I think that's misspelled, for which my apologies) then I think
that the risk would fall into the range that humans have historically
tolerated (especially in someone else's back yard).So the question
would be, just how bad would a plausible M-AM explosion be? If we're
talking the annihilation of several micrograms, that's roughly about
twenty tons of of TNT going Boom, which is very annoying if you happen
to be standing next to it, but survivable at moderately short ranges.
I don't know how much of a problem the gamma EMR is going to be, but my
copy of 'The Effects of Nuclear Weapons' (April 1962 AEC edition,
the one with the neat circular sliderule) indicates that gamma EMR tends
to get absorbed pretty quickly in an atmosphere. Granted, any lifeform
that is unlucky enough to be close to ground zero may have kids with
tendrils, but how many is that going to be, given that prudence seems
to indicate not locating M-AM facilities in crowded areas (Rather like
petrolium in some ways). EMP could be a true pain, given to proliferation
of EMP vulnerable hardware, but again, what range is the EMP going to
have effect at?
 Comment by people with better expertise in this area (Any insurance
agents out there?) invited eagerly, of course, but this seems to be
another one of Mr. Maroney's postings making comprehensive statements
about undeveloped technologies without providing evidence to back up
his views. It's curious to see hin show such horror at antimatter use
given his enthusiasm for fusion reactions, some of which have much
higher productions of undesired byproducts.

                        JDN

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

Date: 6 Mar 90 00:01:15 GMT
From: calvin.spp.cornell.edu![e-mail]  (John Sahr)
Subject: Re: Large antennas in orbit

In article <[e-mail]> [e-mail] (John Roberts) writes:
[]
>The local gravitational gradient places a limit on the maximum size of
>a space structure of a given strength. ("Size" here refers to the maximum
>difference in distance to the center of the earth.) My calculations indicate
>that a good approximation for "small" objects is that the gravitational
>gradient will be roughly equal to the local acceleration due to gravity
>times two, divided by the distance to the center of the earth. The number
       ^^^ should be three ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ okay for LEO

>is given in inverse seconds squared, which is multiplied by the length of the
>object to get meters per second squared. Thus for LEO, the gravitational
>gradient is about 2.7E-6 s^-2.
[]
>                           [e-mail]

acceleration (a) of a body in circular orbit:

                          G R_e^2
    a(r) = W^2 r  -  ---------  (radial direction)
                            r^2

where W is the angular frequency = 2 pi/T, T = orbital period; G =
strength of gravitation acceleration at the ground, 9.8 m/s^2;

                                             G R_e^2
W evaluated at equilibrium a(r) = 0 -> W^2 = -------
                                               r^3

                       da      G R_e^2              G R_e^2
radial gradient = a' = -- =  2 -------- + W^2 =  3 ---------
                       dr        r^3                  r^3
                             A                   A
                             |                   |

So, John Roberts is almost correct, except that he left out the
centrifugal contribution to the radial force.  If you plug in the
numbers, you get 1.5 times his 2.7e-6, or about 4.0e-6 s^-2.
--
John Sahr,                   | Electrical Engineering - Space Plasma Physics
[e-mail] | Cornell University,         Ithaca, NY  14853

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

Date: 5 Mar 90 19:19:20 GMT
From: elroy.jpl.nasa.gov!usc!brutus.cs.uiuc.edu!uakari.primate.wisc.edu!uflorida!beach.cis.ufl.edu![e-mail]  (Mark Kilby)
Subject: Space Mailing List?


I am an infrequent reader of this newsgroup.  Could someone enlighten me as
to what the Space Mailing List is.

Thanks in advance!

Mark
[e-mail]

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

Date: 5 Mar 90 18:57:13 GMT
From: elroy.jpl.nasa.gov!usc!cs.utexas.edu!jarvis.csri.toronto.edu!utgpu!watserv1!watdragon![e-mail]  (Owner of Many System Processes)
Subject: Re: Spacecraft drives and fuel efficiency

.edu>
Sender:
Reply-To: [e-mail] (Brian or James)
Followup-To:
Distribution:
Organization: U. of Waterloo, Ontario
Keywords:

 My previous posting failed to mention whose article I was replying to.
I was refering to Mr. Maroney's comments.
                            JDN

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

Date: Mon, 5 Mar 90 15:03:16 CST
From: [e-mail]
Subject: Re: Funding Is Not The  Problem

>> agate![e-mail]  (William Baxter)

>> There is strong pressure for bureaucracies like NASA or DoD and their
>> contractors to push into development prematurely, rather than doing the
>> necessary research.

And why does that pressure exist, Mr. Baxter?  It's not simply
because "development contracts are much more lucrative than research
contracts".  That's certainly a good reason for a contractor to
prefer development to research, but it hardly seem to cover the
issue, since it's not the contractors who put out the RFPs.

That pressure exists primarily because it's easier to get Congress to
spring for something 'concrete' than it is to get them to fund
research, and in particular it exists within DoD both because of the
because of the way DoD is forced to do business with regard to
funding things and because DoD isn't usually allowed to fund
'research' unless it is intended to apply directly to a follow on
production system.

Apply the fix where it needs to go; at the point of control of the
purse strings, i.e. Congress.

[Other than that minor nit, I agree with much of what you have to
say.  However, I don't think that targetting specific programs is
the answer, either.]

>> ARPA: web@{garnet,brahms,math}.Berkeley.EDU
>> UUCP: {sun,dual,decwrl,decvax,hplabs,...}!ucbvax!garnet!web

==============================================================================
| Fred McCall  ([e-mail]) | My boss doesn't agree with anything  |
| Military Computer Systems           | I say, so I don't think the company  |
| Defense Systems & Electronics Group | does, either.  That must mean I'm    |
| Texas Instruments, Inc.             | stuck with any opinions stated here. |
==============================================================================

>> P.S.
>> Is this a sentence? -->                          As is, it would
>> >appear, assuming that any disagreement with their opinions
>> >automatically means that the person disagreeing must have whatever
>> >their particular generalized stereotype for the attitudes of 'the
>> >enemy' is.

P.S. -
No, it isn't, but the meaning when taken with the preceding sentence
(of which it should have been a clause) seems fairly clear.  If it
really left you confused, let me know and I'll explain it.

And if you can show me a dozen or so examples of you pointing out
grammar, spelling, or punctuation discrepancies by people who
*didn't* disagree with you about something, I'll change my opinion
that you bringing this up is just an obfuscatory debating tactic
intended to misdirect from the issues.

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

End of SPACE Digest V11 #117
*******************