Space & Astronomy/Space and Astronomy (October 1993).iso/mac/TEXT/SPACEDIG/V11_4/V11_478.TXT

Internet Message Format | 1991-07-08 | 16KB

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/0aNpFry00VcJIBR04f>;
          Sat,  2 Jun 1990 01:54:00 -0400 (EDT)
Message-ID: <[e-mail]>
Precedence: junk
Reply-To: [e-mail]
From: [e-mail]
To: [e-mail]
Date: Sat,  2 Jun 1990 01:53:33 -0400 (EDT)
Subject: SPACE Digest V11 #478

SPACE Digest                                     Volume 11 : Issue 478

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

Today's Topics:
                  HST future
          Re: Saturn V:  Center S-I Engine shutdown?
           Re: light pollution exaggeration
                Re: Radiation
              Re: space station software
      Information sources for frequent space questions (1 of n)
----------------------------------------------------------------------

Date: 1 Jun 90 15:57:00 GMT
From: zaphod.mps.ohio-state.edu!brutus.cs.uiuc.edu!ux1.cso.uiuc.edu!ux1.cso.uiuc.edu!uxa.cso.uiuc.edu![e-mail]
Subject: HST future


Is it expected that the Hubble Space Telescope will eventually perform as
originally designed in spite of the initial problems?

If not, what are its limitations?

Thank you,
Dan

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

Date: 1 Jun 90 04:43:19 GMT
From: attcan!utgpu!utzoo![e-mail]  (Henry Spencer)
Subject: Re: Saturn V:  Center S-I Engine shutdown?

In article <[e-mail]> [e-mail] (Mark Perew) writes:
>...Part of this section tells how the center first stage engine
>(S-I?) shutdown as planned while the other four continued running
>until staging occured.
>
>I have never heard of this before.  I am a bit puzzled as to why
>the first stage would have been designed to work this way...

A quick look through the usual references does turn up a mention or
two of the early shutdown of the center engine, but no explanation.

>I have managed to come up with two possible reasons.  First, that
>the engine was shutdown for the passage through Max-Q and that the
>S-I (unlike the S-IVB) was not restartable...

The F-1 engines in the S-1C (to give the correct designations) were
not restartable, but center-engine shutdown was only about 15 seconds
before staging, which sounds a bit late for max Q.  Possible, but I'm
skeptical.

>Second, that sufficient
>propellant mass had been used that the thrust to weight ratio would
>have turned the crew into hull pizza if they didn't shut down an
>engine.  Of course, I wonder if the second is correct if the
>equivalent result couldn't have been acheived by throttling the
>engines down.  But, I seem to recall reading somewhere that these
>particular engines were not throttleable...

I would guess that this is right answer:  reducing thrust to limit
G load on either the astronauts or the upper-stage structures.  If I
had to guess, I'd guess the limiting factor was the second-stage
structure.  Acceleration wasn't especially high at first-stage cutoff
compared to later stages, so I don't think the astronauts were the
limiting factor.  The second stage, on the other hand, was a demanding
structural job to begin with and got much worse when it had to bear
the brunt of weight-reduction demands.  (The S-IVB third stage was
already in production when weight problems became apparent, so it
couldn't be messed with much, and weight reductions in the second
stage paid off much more than reductions in the first stage.)

None of the Saturn V engines -- F-1 in the first stage, J-2 in the
upper stages -- was throttleable.  In fact, the only throttleable
engine in the whole Saturn-V-Apollo assembly was the LM descent engine.
Throttling generally is a nasty added problem that rocket engineers
prefer to avoid whenever possible; apart from the mechanical means
for doing it, it demands stable operation over a wide range of
conditions rather than just a narrow bracket around one nominal
point, plus stable transitions from one setting to another, and this
considerably complicates design and testing.
--
As a user I'll take speed over|     Henry Spencer at U of Toronto Zoology
features any day. -A.Tanenbaum| uunet!attcan!utzoo!henry [e-mail]

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

Date: 29 May 90 19:17:22 GMT
From: skipper![e-mail]  (Al Bowers)
Subject: Re: light pollution exaggeration

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

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

>>But you seem to forget that hardly anything can be seen through the smog
>>of the cities and megalopolises that will cover our planet within 5 to 10
>>years. ...

>Mark, would it be too much to ask that you check these numbers before
>posting them?  Even 50 to 100 years is too soon for something like that
>to happen except in fairly small areas.

Actually significant portions of the southwest United States are
unusable now.  Mt. Wilson was closed down for some time (the only
_real_ research going on now is solar astronomy), Mt. Palomar is still
fighting off San Diego and Kitt Peak is feeling the effects of Tucson.

>I've seen the moons of Jupiter from my apartment window, using just my
>old cruddy binoculars -- and this is in downtown Toronto, not the worst
>case but *not* a good one.

I agree that some very worthwhile observations can still be done, but
complacency is the problem.  With a little work on the part of our
civic officials (the correct use of lighting) and a little fore
thought much improvment can be made.  I agree there was some measure
of exageration made, but the effect is real.  A better test might be
M33 with your binoculars?

--
Albion H. Bowers  [e-mail]  ames!elxsi.dfrf.nasa.gov!bowers

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

Date:         Fri, 01 Jun 90 16:04:20 CDT
From: John Nordlie <[e-mail]>
Subject:      Re: Radiation

It was mentioned that radiation hard chips (memories) were much
more expensive than 'standard' chips.  Could anyone put a dollar
figure to that please?  A compairison between the two types for
the same memory size would be helpful.  Do you need all rad-hard
chips in your satellite (CPU, timers, buffers, etc.), or just
the memories?

I would also like some info on the U of Surrey sats now in orbit.
I was building a receiveing setup for UOSat 1, when the damned
thing burned up.  What is needed to receive the new sats?

--------------------------------------------------------------------
Disclaimer: Why bother?  I'm not controversial.
            --John Nordlie

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

Date: 1 Jun 90 03:14:31 GMT
From: eagle![e-mail]  (Teddy Fabian)
Subject: Re: space station software

In article <[e-mail]> [e-mail] (Thomas A. Bitterman) writes:
>
>    Does anyone out there have some information on the computer
>systems to be used in Space Station Freedom?  In particular:


I'll try to provide some information.. but realize, I'm not an expert, and my
opinions are my own...



>
>1) Who will be the vendor? (IBM, Unisys, DEC, NEC)  Is there some sort
>    of nationality restriction for security reasons?



if you believe the ads that appearred in trade magazines about a year ago
or so, you would have seen IBM PS/2 class machines on a 100mb fiber ring
being advertised as the "same machine and network that will fly on the
Space Station..."

I don't know if this is true though..  nothing I've seen refers directly
to workstations onboard the stations, or to computers onboard..

I imagine that ultimately the decision will be made based on what the
intended functionality of the particular system is.. and of what
hardware is available (and bid, proposed, and/or designed into) the
habitation and science modules...

I think that the only firm guideline at this time is that a working
group of NASA engineers along with engineers from each Work Package
Contractor meet on a fairly regular basis to discuss a common user
interface (CUI) for the workstations...


>
>2) What language will be used?  If not Ada, why not?


Ada is the language that was chosen as the primary language to be
used as part of the Software Support Environment (SSE)..  I assume
that the folks responsible for developing the various control systems
are using ADA... I've not heard otherwise..

as for other software being developed for non-flight related
activities such as testing and analysing data, I've seen a mix of
Fortran, C, Pascal, APL, and whatever else the particular engineer
knows how to code...


>
>3) Who will write the software?  Will it be farmed out, or written in-
>    house, or both?


Flight related control software (assuming I understand what that is) is
being developed through a contract that was awarded about two years ago
to Lockheed.  The contract (SSE) calls for a number of Software Production
Facilities (SPF) to be put in place at each NASA site and Work Package
Contractor.. I beleive 6 or 7 of these machines are currently installed..

People at each of the SPF sites (either existing Civil Service or Contractor
employees) would be the primary folks responsible for doing the
programming...


Non-fight related software (mostly administrative and management) is
being developed through a contract that was awarded about two and a half
years ago to Boeing.  The contract, Technical and Management Information
System (TMIS), is supposed to provide for a technical database of information
used to build the Space Station which will be available for futre
reference... and to provide for automation functions (email, networking,
workstations, application tools, etc.) for the day to day work in
developing the Space Station...

Current implementations are either being coded by Boeing (or their
subcontractors), NASA Civil Service people, or other contractor employees
or are based around commercial off the shelf software...


>
>4) How will software maintenance be carried out?  Will there be on-site
>    programmer/debuggers?  Does NASA need volunteers? :-)


software maintenance where?? on the Station??  I doubt it..

more than likely, there will be Engineering Support Centers set up either
at some or all of the NASA sites..  Work Package Contractor and Civil
Service employees would  staff these centers during missions, and would
have the responsibility of maintaining and monitoring the onboard
systems..  but plans I've heard about for this type of thing are still
to far into the future, and/or constantly being affected by budget cuts..


as for volunteers.. I don't think you'ld get very far voluntering...
you'ld be better off, if you're serious, getting your degree (if you
don't have one) and apllying to NASA or one of the Contractor companies..



>
>5) Even with rad-hard chips, there is going to be some program degradation.
>    What is the state of the art in fault-tolerant programming?


no idea... sorry....


>
>I apologize if its rather early in the life of the project to ask these
>questions.  However, early on is probably the best time to get these
>details straight.  Inquiring computer scientists want to know!


so do Computer Scientists who are working on the project already...

   [smirk]

>
>|||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
>| thomas bitterman                         aka: [e-mail]    |
>|                                                                           |
>| "Good morning, Dave. How are you feeling?" -HAL                           |
>| Disclaimer: My right to bear assault weapons ensures they'll never take   |
>|             me alive...  hahahahaha!                                      |
>|||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||


--
----------------------------------------------------
Thanks,    Ted Fabian   NASA Lewis Research Center
           [e-mail]      *my opinions
           [e-mail]      *are my own..
--
----------------------------------------------------
Thanks,    Ted Fabian   NASA Lewis Research Center
           [e-mail]      *my opinions
           [e-mail]      *are my own..

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

Date: 1 Jun 90 11:01:06 GMT
From: amelia![e-mail]  (Eugene N. Miya)
Subject: Information sources for frequent space questions (1 of n)

Many space activies center around large Government or International
Bureaucracies.  In this country that means NASA.  If you have basic
information requests: (e.g., general PR info, research grants, data,
limited tours, and ESPECIALLY SUMMER EMPLOYMENT (typically resumes
should be ready by Jan. 1), etc.), consider contacting the nearest
NASA Center to answer your questions.

EMail typically will not get you any where, computers are used by
investigators, not PR people.  The typical volume of mail per Center is
a multiple of 10,000 letters a day.  Seek the Public Information Office
at one of the below, this is their job:

NASA Headquarters (NASA HQ)
Washington DC 20546

NASA Ames Research Center (ARC)
Moffett Field, CA 94035
[Mountain View, CA, near San Francisco Bay, you know Silicon Valley 8-) ]

Ames Research Center
Dryden Flight Research Facility [DFRF]
P. O. Box 273
Edwards, CA  93523

NASA Goddard Space Flight Center (GSFC)
Greenbelt, MD 20771
[Outside of Washington DC]

NASA Lewis Research Center (LeRC)
21000 Brookpark Rd.
Cleveland, OH 44135

NASA Johnson Manned Space Center (JSC)
Houston, TX 77058

NASA Kennedy Space Flight Center (KSC)
Titusville, FL 32899

NASA Marshall Space Flight Center (MSC)
Huntsville, AL35812

NASA Langley Research Center (LaRC)
Hampton, VA 23665
[Near Newport News, VA]

Not a NASA Center, but close enough:
Jet Propulsion Laboratory [JPL/CIT]
California Institute of Technology
4800 Oak Grove Dr.
Pasadena, CA 91109

There are other small facilities, but the above major Centers are set up
to handle public information requests.  They can send you tons of information.

Specific requests for software must go thru COSMIC at the Univ. of Georgia,
NASA's contracted software redistribution service.  You can reach them
at [e-mail].  If this gives you problems, tell me.

NOTE:  Foreign nationals requesting information must go through their
Embassies in Washington DC.  These are facilities of the US Government
and are regarded with some degree of economic sensitivity.
Centers cannot directly return information without high Center approval.
Allow at least 1 month for clearance.  This includes COSMIC.

EUROPEAN SPACE AGENCY        (O) 202/488-4158
955 L'Enfant Plaza S.W., Washington, D.C.  20024

 Arianespace Headquarters
 Boulevard de l'Europe
 B.P. 177
 91006 Evry Cedex
 France

ARIANESPACE, INC. (O) 202/728-9075
1747 Pennsylvania Avenue, NW, Suite 875, Washington, DC  20006

SPOT IMAGE CORPORATION           (FAX) 703/648-1813    (O) 703/620-2200
1857 Preston White Drive, Reston, VA 22091

National Space Development Agency (NASDA), 4-1 Hamamatsu-Cho, 2 Chome
          Minato-Ku, Tokyo 105, Japan

SOYUZKARTA
45 Vologradsij Pr., Moscow 109125, USSR

SPACE COMMERCE CORPORATION (U.S. agent for Soviet launch services)
504 Pluto Drive, Colorado Springs, CO  80906   (O) 719/578-5490
69th flr, Texas Commerce Tower, Houston, TX 77002  (O) 713/227-9000

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

End of SPACE Digest V11 #478
*******************