Space & Astronomy/Space and Astronomy (October 1993).iso/mac/TEXT_ZIP/spacedig/V13_6/V13_650.ZIP/V13_650

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Subject: SPACE Digest V13 #650

SPACE Digest                                     Volume 13 : Issue 650

Today's Topics:
               Re: satellite refuelling
               Re: satellite refuelling
                 Space Stamps
           Re: Galileo Antenna (was Re: Amputation)
  Re: Refueling satellites (was Re: Self-sustaining infrastructures)
           Re: Galileo Antenna (was Re: Amputation)
          Re: space news from April 8 AW&ST
      Private Research (was Re: Fred vs. Exploration...)
              Latest Scoup on Dead Fred
           Re: Rational next station design process

Administrivia:

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

Date: 30 May 91 21:52:57 GMT
From: sequent!muncher.sequent.com![e-mail]
Subject: Re: satellite refuelling

In article <[e-mail]> [e-mail] (Allen W. Sherzer) writes:
>
>>You missed another option, which is to decrease the payload mass in
>>order to allow more stationkeeping fuel for the same launcher.
>
>That is a viable option right now. No new technology would be needed.
>The fact that it isn't done indicates that it is not a good tradeoff.

Huh?  It is done all the time.  SOP, in fact.  The real fact is that it
is the central planners, not the satellite builders and operators,
who are pushing refueling capability.   This indicates that refueling
is not a good tradeoff.


>>For most satellites, the cost of a refueling mission will not be
>>significantly smaller than the cost of launching a new generation, more
>>capable satellite.
>
>Depdend on the cost. If I can refuel the satellite for less than $100M
>it is likely to be worth it.

Assume that the statistical critical component lifetime is 50% longer than
the fuel lifetime (the difference is probably much less, but what the hey).
Increasing the lifetime of a $200M satellite with half the capability
of a replacement by 50% is worth $50 million.  Furthermore, the refueling
schemes I've seen would, I suggest, cost $500M per shot, which is
uneconomical by a factor of 10.  A technology requiring large amounts
of R&D and industry-wide change should _improve_ things by a factor of 5 or
more.

BTW, nobody has yet posted the specific information needed to estimate
cost and market, including:

* The target market: proposed orbits and satellites to be serviced
* Component lifetime & failure rate vs. fuel lifetime statistics
* Cost of redesigning satellites for refueling
* R&D cost of refueling infrastructure, amortized over market
* Cost of refueling missions

Until we get this information it just sounds like more hot air from
the centrally planned "infrastructure" pushers.



--
Nick Szabo                [e-mail]
"If you understand something the first time you see it, you probably
knew it already.  The more bewildered you are, the more successful
the mission was." -- Ed Stone, Voyager space explorer

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

Date: 31 May 91 00:29:46 GMT
From: cis.ohio-state.edu!zaphod.mps.ohio-state.edu!wuarchive!rex!uflorida!mailer.cc.fsu.edu!prism![e-mail]  (Matthew DeLuca)
Subject: Re: satellite refuelling

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

>Huh?  It is done all the time.  SOP, in fact.  The real fact is that it
>is the central planners, not the satellite builders and operators,
>who are pushing refueling capability.   This indicates that refueling
>is not a good tradeoff.

That fact that satellite builders do not (you say) support refuelling
projects is not in the least surprising; the current system of replacing
satellites when they run out of fuel requires a constant supply of new
satellites, hence a constant incoming revenue.

Satellite operators, on the other hand, will likely support whatever
costs less; since costs are passed on to the consumer in most cases it
would make sense to do whatever costs less, from a consumer point of view.
At this point in time it is fairly unlikely that we could refuel sats on
a regular basis for less than the cost of new ones, but that may change
later on.  With some very moderate technological advances, it's not
implausible to think of an automated 'refuelling drone' that could
drift along the geosync belt tanking up satellites.  Refuelling is not
a 'central planning' issue, as you seem to imply, but a cost-benefit
issue.  If it costs less, do it.
--
Matthew DeLuca
Georgia Institute of Technology      "I'd hire the Dorsai, if I knew their
Office of Information Technology      P.O. box."  - Zebadiah Carter,
Internet: [e-mail]    _The Number of the Beast_

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

Date: 30 May 91 21:41:36 GMT
From: pro-magic.cts.com![e-mail]
Subject: Space Stamps

I have a plate block of one of the early walk in space missions.  It shows
in two stamps adjoined a space suited figure on the left stamp and the
capsule on the right with the lifeline going between the stamps.

This is a block of 5 joined stamps (10 stamps in all) with a face value of
5 cents each and a serial number on the top right edge.

Anyone know if this is worth anything?

Anyone interested in them?

My dad apparently purchased them before he passed away and in going through
his things I came across this block.
------------------------------<<<Mike Ungerman>>>----------------------------
                           Proline:  mikeu@pro-magic
                 Internet: crash!pnet01![e-mail]
                  UUCP: (..uunet!tarpit!bilver!pro-magic!mikeu)
                  Arpa:  crash!pnet01!pro-magic![e-mail]
       Voice: 407-366-5840 | Prodigy: JSNP58A | Compuserve: 71326,31

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

Date: 27 May 91 16:37:35 GMT
From: agate!bionet!uwm.edu!zaphod.mps.ohio-state.edu!swrinde!elroy.jpl.nasa.gov!euclid.jpl.nasa.gov![e-mail]  (Peter Scott)
Subject: Re: Galileo Antenna (was Re: Amputation)

In article <[e-mail]>, [e-mail] (Chris Jones) writes:

> [...]  As has been pointed out, though, there are many
> possibilities, and JPL seems to be taking a very cautious approach to resolving
> the problem (as well they might, since they do have time, and don't want to
> make things worse by hasty action).

Quite.  Latest gossip is that unless they positively figure out how
to fix it by Gaspra, they'll leave it the way it is until Earth II.
The problem is likely due to heat warping, and they'll want it warmed
up again before they try anything, so when they get back to Earth
they'll turn it to toast it good.  I wondered whether the 200-mile
flyby might shake it up a little, but the people I was talking with
didn't know.  There is atomic oxygen at that height, but at 15 mps,
it's not going to have time to rust :-)  If they decide to wait, the
biggest problem will be cold-welding in the meantime.  There are many
unusual ideas floating around.  Apparently the best guide to how the
antenna has actually deployed is the radiation pattern, and there
is this lobe that some people are talking about being able to use for
burst transmissions...

(Disclaimer: I don't know anyone on the Tiger Team; this is all
nth-hand.)

--
This is news.  This is your       |    Peter Scott, NASA/JPL/Caltech
brain on news.  Any questions?    |    ([e-mail])

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

Date: 27 May 91 16:46:25 GMT
From: news-server.csri.toronto.edu!utzoo![e-mail]  (Henry Spencer)
Subject: Re: Refueling satellites (was Re: Self-sustaining infrastructures)

In article <[e-mail]> [e-mail] (Christopher Neufeld) writes:
>   On the subject of refueling satellites, can anybody tell us whether
>the fuel tank is usually kept in the spun or despun section of a
>satellite with both?

Spin-stabilized comsats typically put everything in the spinning section
except the main antennas and support for them.  Scientific satellites vary,
but the general "spin everything possible" approach is fairly constant.
Anything moved from spun to de-spun section reduces the attitude stability
provided by spin.

Another consideration is that you can get by with fewer thrusters if they
are mounted on the spinning section, because to thrust in direction X,
you just wait until the spin carries the thruster around to point in that
direction.

>Some tanks are equipped with a forcing membrane to
>feed the fuel. Are any fed centrifugally, possibly with a gas injector
>to maintain a constant pressure?

I *think* the spin-stabilized birds generally use centrifugal feed.  I
could be wrong, as there might be some difficulty with getting gas in the
lines before spin was started.

In any case, Chris makes a good point here:  refuelling a spin-stabilized
satellite is going to be tricky, perhaps impossible.  The general trend
is towards three-axis-stabilized birds, but spinners are still in use and
in production.
--
"We're thinking about upgrading from    | Henry Spencer @ U of Toronto Zoology
SunOS 4.1.1 to SunOS 3.5."              |  [e-mail]  utzoo!henry

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

Date: 27 May 91 16:59:37 GMT
From: spot.Colorado.EDU![e-mail]  (ALVIN KENNETH F)
Subject: Re: Galileo Antenna (was Re: Amputation)

In article <[e-mail]> [e-mail] (Chris Jones) writes:
>
>This particular design is the same as is
>used for TDRS satellites, I recall.  It wasn't changed between the
>Shuttle-Centaur direct flight plan and the Shuttle-IUS VEEGA flight plan, save
>for the addition of the sun shield and the delay in deploying it.  The unusual
>aspect of Galileo's mission is the length of time the antenna is kept
>undeployed, and I'm sure there is concern that this caused or contributed to
>the deployment problem.  As has been pointed out, though, there are many
>possibilities, and JPL seems to be taking a very cautious approach to resolving
>the problem (as well they might, since they do have time, and don't want to
>make things worse by hasty action).

The antenna's design used TDRSS as a baseline, but the unique characteristics
of the mission eventually led to some major redesigns.  I believe the antenna
was designed and built in the 1980-1982 time frame.  I used to work in the
engineering group at Harris responsible for the design and fabrication of
that system (and the TDRSS antennae); I recall seeing a picture of the full
spacecraft with antenna deployed on the cover of Aviation Week about 4 years
ago (the system was delivered to JPL before I started at Harris in '83), and
the mesh and cords near the outside diameter of the dish appeared quite
damaged.  There was a lot of speculation at home about what might have
happened to it (definitely not the condition it was in when delivered); does
anyone know whether that was the actual spacecraft in that cover photo
(as opposed to a structural test model), and, if so, was the antenna launched
in that same condition?

>Chris Jones    [e-mail]    {uunet,harvard,world}!ksr!clj

Ken Alvin       [e-mail]

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

Date: 28 May 91 13:32:29 GMT
From: pilchuck!seahcx!phred![e-mail]  (Peter Jarvis)
Subject: Re: space news from April 8 AW&ST

In article <[e-mail]> [e-mail] (Henry Spencer) writes:
>
>.... [Hmm, I wonder if they've thought about the problems
>of nuclear clustering?  One has to beware of interactions between reactors,
>since they are unshielded and right beside each other.]
>
They are in the business of thinking about such problems.

>NASA is interested in Timberwind but is wary of public outcry and suspects
>that commitment to a specific advanced reactor design is premature.  [They
>would prefer to spend half a decade studying it first, as usual.]......
>
You don't just slap something like this together and launch it.


Peter Jarvis............

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

Date: 30 May 91 01:42:10 GMT
From: rochester![e-mail]  (Brian Yamauchi)
Subject: Private Research (was Re: Fred vs. Exploration...)

In article <[e-mail]> [e-mail] (Doug Mohney) writes:
>In article <[e-mail]>, [e-mail] (Herman Rubin) writes:

>>Almost all of the pure research done in this country before WWII, the great
>>bulk of it privately funded, went into the public domain.

>So? WWII was 50 years ago. The times, they are a changin'. Currently, the
>makers of AZT are being sued for their patent rights to that drug. Why? Much of
>the research and testing was done in NIH labs without renumeration. Not in
>the private sector.
>
>Companies will hold close to their wallets any information which will make them
>a buck. This is the capitalist way.

Companies will want to hold on to rights to their specific product
designs (whether AZT should fall into this category is a separate
issue), but that doesn't mean that they won't distribute their
research results (both basic and applied).

A quick flip through this year's IEEE Robotics & Automation Conference
proceedings reveals papers from researchers at IBM, Hughes, Phillips,
Siemens, Mitsubishi, Canon, Lockheed, Rockwell, Martin-Marietta, and
IntelliCorp.

>>In article <[e-mail]>, [e-mail] (Doug Mohney) writes:
>>
>>> I can't
>>> see any private set of individuals gathering up $1 billion for two
>>> Voyager-class probes, nor maintaining infrastructure for 15+ years to collect
>>> all the data.

I do agree with you here.  It's unlikely that private companies will
fund expensive science missions with no near- or medium-term benefits
for the company, and it's unlikely that private non-profits will have
the resources to fund billion dollar missions.

Personally, I think all three types of organizations can produce
valuable R&D: venturesome private firms can develop new technologies
with possible immediate commercial benefits (OSC's Pegasus, AMROC's
hybrid boosters), non-profits can develop low-cost/high-risk systems
with possible long-term science/engineering benefits (SSI's lunar
prospector, WSF's solar sail race, PlanSoc's Mars snake), and
(well-run) government agencies/contractors (JPL) can run the larger,
more expensive space exploration missions (Galileo, CRAF, Cassini,
Mars rover).
--
_______________________________________________________________________________

Brian Yamauchi                University of Rochester
[e-mail]        Department of Computer Science
_______________________________________________________________________________

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

Date: Thu, 30 May 91 00:25:29 PDT
From: [e-mail] (Jim Bowery)
To: crash![e-mail]
Subject: Latest Scoup on Dead Fred

The latest inside scoup on the space station fight:

Today, in a members-only meeting of the Science, Space and
Technology Committee, the has-beens concocted a strategy
to save Space Station Fred.

Next week, during the House floor fight, a prominent has-been,
probably George Brown, will introduce a floor amendement
to the VA, HUD and Independent Agencies appropriation bill.
This amendment will slash 3% off the budget of ALL non-veterans
programs, and give the resulting $1.5 billion dollars to NASA
to save Fred.

When the amended appropriations bill goes to conference with the
Senate, Senate members of the conference committee will insist
that NASA stay within its funding cap.  At this point, the
House will compromise with the Senate and give back $1.5 billion
dollars from NASA's budget.

Here is where it gets cute:  They'll take the $1.5 billion from
space science instead of Fred.  By acting in conference, they
can do it by fiat and off the record so no one can see who did what
to who.
-----------------------------------------------------------------------------
Jim Bowery      619/295-3164               The Coalition for
PO Box 1981                                   Science and
La Jolla, CA 92038                             Commerce
-----------------------------------------------------------------------------

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

Date: 29 May 91 03:28:01 GMT
From: van-bc!rsoft!mindlink![e-mail]  (Nick Janow)
Subject: Re: Rational next station design process

[e-mail] (Dave Smith) writes:

> How is space engineering going to get any better unless we do some?  Computer
> simulation is not enough, we all know this.  Neither is building small
> unmanned probes.  Have you any proposals for doing space engineering without
> building a station?

Certainly.  I propose that governments fund basic research in robotics, AI and
automation (including teleoperation).  They should also fund basic research
into materials science, materials and mechanical engineering (welding,
preventing vacuum welding, etc).  This will require microgravity services
(transportation, power, communications, etc).  This will provide a stable
return on investment in launch technologies and orbital facilities
(microgravity modules, etc) which will encourage private R&D.  The improvements
gained from this work will improve the technologies and decrease the cost.
This positive feedback should lead to even more R&D and experience in space
engineering.  Eventually, the expertise and infrastructure will be there to
build a manned station at a reasonable cost.

Before you embark on a major engineering project, it's wise to spend some time
and effort building the tools you'll need to do the job efficiently.

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

End of SPACE Digest V13 #650
*******************