Space & Astronomy/Space and Astronomy (October 1993).iso/mac/TEXT_ZIP/spacedig/V16_1/V16NO197.ZIP/V16NO197

Internet Message Format | 1993-07-13 | 11KB

Date: Thu, 18 Feb 93 05:06:41
From: Space Digest maintainer <[e-mail]>
Reply-To: [e-mail]
Subject: Space Digest V16 #197
To: Space Digest Readers
Precedence: bulk


Space Digest                Thu, 18 Feb 93       Volume 16 : Issue 197

Today's Topics:
                  FGS Info (RE: HST repair mission)
                       Nobody cares about Fred?
                      PEGASUS QUESTION (2 msgs)
                             Space Icons

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Date: Wed, 17 Feb 1993 18:15:20 GMT
From: [e-mail]
Subject: FGS Info (RE: HST repair mission)
Newsgroups: sci.space

In article <[e-mail]>, [e-mail] (Pat) writes:
> In article <[e-mail]> [e-mail] (Gary Coffman) writes:
>>half smiley, look up GE's TIMs program.) As to software, I don't know
>>which instrument is responsible for fine pointing, but if it is one
>>that is left off of Jr, then some redesign is definitely required.
>>
>
>
> Guidance comes from thhe Fine guidance system.  A series of three banana
> shaped ccd, which tap light off the WF/PC?  My understanding is the
> FGS is considered almost a separate science instrument on it's own.
>
>

The Fine Guidance Sensors (FGS) are located in the focal plane structure and
placed at right angles to the optical path of the telescope.  They have
"pick-off" mirrors that deflect the incoming light into the apertures.  Each of
 the three apertures cover a 90 degree sector of the telescope's outer
portion of the field of view.  Each of the sensors have a large 60 arcmin^2
field of view to search for and track stars.  These fields do not interfere
or overlap with any of the other instruments.

Once the two target-acquisition FGSs lock onto guide stars, the third FGS can
perform astrometric operations on targets within the field of view of that
FGS.  This is how they can be used as a separate science instrument.

Kent Reinhard
Space Telescope Science Institute

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

Date: 17 Feb 93 21:21:34 GMT
From: "Allen W. Sherzer" <[e-mail]>
Subject: Nobody cares about Fred?
Newsgroups: sci.space

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

>>Now before Doug whines about Intelsat, if NASA had engaged in such a
>>program of practice he would have a point. They didn't and he doesn't.

>First you whine about the Intelsat rescue.  "No value," he says, "Cheaper to
>send up a new satellite."

Which was correct. NASA rescued the satellite because they thought it would
be good PR. If they thought (as they should have) that EVA was important
they would have been doing far more of it a long time ago.

That is why I said you would have a legitimate point *IF* NASA was engaged
in regular EVA.

In fact, even here it is a bit strained. It turns out that the astronauts
say they where so busy with the work they didn't have time to try and learn
from the experience.

>During the course of the mission, they find there ARE some differences between
>ground simulations and The Real Thing.
>So, NASA adds EVA time whenever it can on future Shuttle missions.

Too little too late.

I assume from past postings Doug, that you are not an engineer or at
best a student so I'll explain why this is important. In design it is
inevitable that mistakes will be made. It also turns out that the later
mistakes are found, the more expensive it is to fix those mistakes. Therefore
good engineers spend a lot of effort finding errors as soon as possible.

Now with a large space station requiring several times the existing EVA
experience base to assemble, assembly itself becomes a large risk area.
The prudent thing to do is to begin very early in the project conducting
LOTS of experiments on orbit and coorelating them with ground based
efforts (like water tank simulations and task models). NASA failed to
do this and now it is starting to look like there may (suprise suprise)
be more problems than NASA anticipated. Instead of anticipating problems
early on, they wait for the end of the project. This is one reason why
the station is so expensive. Better risk reduction up front and we would
have had a station we can afford.

>NASA realizes it has some shortcomings.  It now does EVAs and people such as
>yourself start bitching about how useless it is to have two astronauts haul each
>other around in the Shuttle cargo bay.

At this stage in the game, it is indeed too late. In 1984, that would have
been a great experiment to try.

I applaud these initial experiments they are doing but it should be obvious
that they should have done more sooner. Asking why in hell it took so long
to do the obvious is a reasonable question.

>So tell me, Mr. Sherzer, what is the REAL reason why you don't like NASA?

Parts of NASA I like a lot. When I was in aerospace I read a lot of the
NASA aeronautical work. It was all first rate stuff and we are far better
for it. Manned space (which I think is very important) doesn't spend my
money very wisely. Examples abound; asside from Shuttle and Fred we
can look at:

1. The wake shield facility. NASA cost models say it should cost $93 million
to build. A private company is building the exact same thing for $11 million.

2. Spacehab. NASA costing says it should cost $1.12 billion. A private
company is building the exact same thing for $115 million.

3. DCX. NASA says eight years and about a billion $$. MacDac says $60
million and two years.


>Were you denied a job there?

Never applied to NASA. I was offered a space station job (at a 15%
increase in pay) but turned it down. No, I'm not upset because I
didn't get a job.

>Astronaut slot?

Again, no. I would have been a good pilot (95+ percentile on the Air
Force Pilot Aptitude Test) but my eyes are terrible. So I have never
applied. I long ago accepted that I will never fly spacecraft or high
performance aircraft. No regrets.

>It is obvious you have an axe to
>grind, beause they're incapable of meeting your standards of perfection.

I am holding them to the 'reasonable man' standard, not perfection. I
think the abuses described above are very good reasons not to like the
job NASA is doing and to expect a lot better. Why don't you?


  Allen

--
+---------------------------------------------------------------------------+
| Allen W. Sherzer | "A great man is one who does nothing but leaves        |
|  [e-mail]     |  nothing undone"                                       |
+----------------------118 DAYS TO FIRST FLIGHT OF DCX----------------------+

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

Date: 17 Feb 93 19:18:51 GMT
From: clifford bettis <[e-mail]>
Subject: PEGASUS QUESTION
Newsgroups: sci.space

[e-mail] writes:

>Lawrence Curcio ([e-mail]) wrote:

>: [...] while taking advantage of at least some of airplane's velocity.

>Although pointing the vehicle in the right direction helps somewhat,
>adding a couple of hundred kph doesn't really do you that much good.
>The airplane's velocity is not a sizeable fraction of orbital
>velocity.
I disagree very much. Starting a rocket from a moving start does
wonders for its final velocity. If I recall correctly, there have been
schemes for putting a rocket on wheels and rolling it down a u-shaped
track and firing up the engines at its lowest point. People often
object that one shouldn't gain anything by this since whatever you
gain in kinetic energy you lose in potential energy. But one must
remember that a rocket has to carry its fuel along with it and as
measured from the earth produces a lot more horse power when its
moving with respect to the earth (even though the thrust is the same).
Cliff Bettis
[e-mail]

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

Date: Wed, 17 Feb 1993 19:31:32 GMT
From: Paul Dietz <[e-mail]>
Subject: PEGASUS QUESTION
Newsgroups: sci.space

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

>> Although pointing the vehicle in the right direction helps somewhat,
>> adding a couple of hundred kph doesn't really do you that much good.
>> The airplane's velocity is not a sizeable fraction of orbital
>> velocity.

> I disagree very much. Starting a rocket from a moving start does
> wonders for its final velocity. If I recall correctly, there have been
> schemes for putting a rocket on wheels and rolling it down a u-shaped
> track and firing up the engines at its lowest point.


Perhaps more significant for airlaunch than the rather small velocity
gain is the lower atmospheric pressure.  This enables one to put a
larger nozzle on the first stage, improving Isp, or operate the first
stage at lower pressure, reducing the weight of the casing (for
solids).

    Paul F. Dietz
    [e-mail]

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

Date: Wed, 17 Feb 1993 17:53:10 GMT
From: [e-mail]
Subject: Space Icons
Newsgroups: sci.space

[e-mail] wrote:

:      I have several astronomy and Space related files in Windows,that
: were without icons.I'd like to get some icons to use for them and wonder
: if anyone can tell me where I can obtain some, either by FTP or a
: program offered by some company?

I maintain an archive of space-related graphics on the anon-FTP server
at ames.arc.nasa.gov.  Take a look at:
  ames.arc.nasa.gov:/pub/SPACE/LOGOS/README

-- Ken Jenks, NASA/JSC/GM2, Space Shuttle Program Office
      [e-mail]  [phone]

     "...back to the moon, back to the future,
      and, this time, back to stay." -- George Bush

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


From: Bill Higgins-- Beam Jockey <[e-mail]>
Newsgroups: sci.space
Subject: Dogs and Mice (was Re: Book Computers/AI in Shuttle-SSF)
Message-Id: <[e-mail]>
Date: 17 Feb 93 07:00:58 GMT
Article-I.D.: fnalf.1993Feb17.130058.1
References: <[e-mail]> <[e-mail]>
Organization: Fermi National Accelerator Laboratory
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Nntp-Posting-Host: fnalf.fnal.gov
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Source-Info:  Sender is really [e-mail]

In article <[e-mail]>, [e-mail] writes:
> Our safety guys get
> all worried about laser light blinding astronauts.  (I could tell
> stories about the problems getting an optical mouse flown inside the
> crew compartment.  The safety gang went a little bonkers about the
> brightness of the LED inside the mouse.)

This suggests that the old Groucho Marx quote:

"Outside of a dog, a book is man's best friend.
Inside of a dog, it's too dark to read."

may not be true for mice.

Bill Higgins, Beam Jockey              | Comet Swift-Tuttle is
Fermi National Accelerator Laboratory  | Mama Nature's way of
Bitnet:           [e-mail]  | saying it's time to
Internet:       [e-mail]  | get off the planet.
SPAN/Hepnet:           43011::HIGGINS  |   --Dale Amon

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End of Space Digest Volume 16 : Issue 197
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