Space & Astronomy/Space and Astronomy (October 1993).iso/mac/TEXT/SPACEDIG/V10_1/V10_196.TXT

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Subject: SPACE Digest V10 #196

SPACE Digest                                     Volume 10 : Issue 196

Today's Topics:
         Re: Payload Status for 10/30/89 (Forwarded)
     Hubble Space Telescope powered for tests at KSC (Forwarded)
              Moon Colonies / Ant Tanks?
         Re: Powersat options II: Magnetism?
               Re: Terraforming
            Re: Moon Colonies / Ant Tanks?
              Re: Manned Jupiter Mission
                 Re: Computer
              Re: Manned Jupiter Mission
 Re: Manned Jupiter Mission (was Re: Condensed CANOPUS - August 1989)
         Re: Powersat options II: Magnetism?
----------------------------------------------------------------------

Date: 31 Oct 89 14:15:08 GMT
From: frooz!cfa250![e-mail]  (Jonathan McDowell)
Subject: Re: Payload Status for 10/30/89 (Forwarded)

From article <[e-mail]>, by [e-mail] (Peter E. Yee):
> [No, don't ask we what all the acronyms mean.  This is the raw daily payload
> status coming out of KSC. -PEY]
 .. Aww, lets have a go anyway...

> - STS-31R HST (at VPF) -
HST: Hubble Space Telescope
VPF: Vertical Processing Facility?
STS-31R: What does the R mean? I suspect it means 'revised' or 'remanifested', ie
there was an earlier STS-31 mission whose payload got reassigned to another mission.
But I've never seen this before. Can anyone help?

> environmental and ECS unit monitoring.
ECS: Environmental Control System (in this context - can also mean European Comm. Sat. !)

> - STS-35 ASTRO-1/BBXRT (at O&C) -
BBXRT: Broad Band X-ray Telescope, a NASA-Goddard experiment.
O&C: Hmm, dunno this one. How about: "Operations and Checkout"? or
maybe something like "Ordnance and Cargo"? "Oxford and Cambridge"?

> was located in the PGSA-1 motor area, removed, and the

PGSA: More difficult still. My guess is that A is almost certainly
Assembly; P could be Propulsion but I don't think there is any on
this payload, so how about Precision Guidance and Steering Assembly?

> - STS-40 SLS-1 (at O&C) -
SLS: Spacelab Life Sciences

> Installation of the MVAK servo unit was completed, and the
> experiment RAU and code plug was installed.  Assessment of the
Whew! Guess I have to give up at this point. I know RAU is something
electronic that everyone else on the net will know. MVAK is weird -
what does the K stand for? Missing Valuable Automobile Keys? .....


... Jonathan, in a slightly silly mood..

`

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

Date: 31 Oct 89 21:02:20 GMT
From: trident.arc.nasa.gov![e-mail]  (Peter E. Yee)
Subject: Hubble Space Telescope powered for tests at KSC (Forwarded)


  George H. Diller                                    Oct. 28, 1989
  Kennedy Space Center

  HUBBLE SPACE TELESCOPE POWERED FOR TESTS AT KSC


       The Hubble Space Telescope (HST) has passed a significant
  milestone toward launch with the first "power-up" of the
  spacecraft at the Kennedy Space Center.  This initiates a series
  of functional checks of onboard science instruments and systems
  which are scheduled to continue through the end of January.

       Power was applied to the telescope via satellite from the
  HST control facility at Lockheed in Sunnyvale, Ca. at 12:15 a.m.
  Eastern time on Saturday, Oct. 28.  The link terminates at a 30-
  foot receiving antenna especially installed at KSC's Vertical
  Processing Facility to support the upcoming telescope testing.  A
  return data stream confirmed to controllers that the power was
  on, and that the satellite link will be returning test data to
  Sunnyvale during a total of 35 scheduled test days.

       Undergoing performance evaluation will be five science
  instruments, the telescope's pointing control system, fine
  guidance sensors, the communications and data handling system
  with associated tape recorders, and the power system.

       In addition, another 12 days of tests are scheduled with the
  HST Payload Operations Control Center at the Goddard Space Flight
  Center in Greenbelt, Maryland.  They will directly simulate on-
  orbit activity using the telescope via the satellite link.

       Finally, the telescope will undergo the routine tests for
  payloads flown on the Space Shuttle, verifying its readiness to
  be integrated with the Space Shuttle Discovery.  These tests will
  take about four days.

       Based on the current manifest, the Hubble Space Telescope is
  scheduled to be transported to the launch pad on March 9, 1990;
  placed in the payload bay of Discovery on March 12; and launched
  no earlier than March 26.

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

Date: 31 Oct 89 23:13:10 GMT
From: bfmny0![e-mail]  (Tom Neff)
Subject: Moon Colonies / Ant Tanks?

Oh by the way, if you have to burrow underground to survive in a
Moon colony, why bother to go?  Why not just build underground
colonies here?  Sure is easier to ship stuff here.  If you have
to spend your whole life in the basement, how much does it matter
which basement?

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

Date: 31 Oct 89 17:42:01 GMT
From: cs.utexas.edu!mailrus!jarvis.csri.toronto.edu!utgpu!utzoo![e-mail]  (Henry Spencer)
Subject: Re: Powersat options II: Magnetism?

In article <[e-mail]> we have:
>I am posting this for a friend...
>... beaming a couple
>megawatts of power into the atmosphere, no matter what the intensity, will
>alter the whole planets ecology...

Nonsense.  The sun already beams many terawatts of power into the
atmosphere.  Effects from a few gigawatts (powersats would be up in the
gigawatt, not megawatt, range) should be minor and very localized.  The
actual intensity of the proposed beams is comparable to that of sunlight.

>Microwaves would do a lot of damage to the
>weather, at least on a local level, and there is always the fear of someone
>pointing the thing at my house, either by accident or by design.

See above regarding "damage to the weather".  As for pointing the thing
at your house, (a) the proposed designs are incapable of being pointed
at anything that doesn't actively cooperate, and (b) while having one
pointed at your house would not be healthy in the long run, it wouldn't
do anything spectacular in the short run.

>What I propose, and have worked on very little ...
>... is to use collected power in orbit to pulse a magnetic field at a low
>(50-120Hz) frequency...

In other words, transmitting power at VLF rather than SHF frequencies.
This is almost certainly a really bad idea.  The biological effects of low
frequencies are much less (!) well understood, and it's hard to beam them
well -- you will inevitably affect a large part of the Earth, rather than
one small area.  (You will also have very large losses, with much of your
power output escaping into space.)

>...ElectroMagnetic Pulse
>(EMP) will be low, because EMP requires a large change in magnetic field
>intensity before in can do much damage...

Powering things from it also requires large changes in magnetic field
before it can yield much power.  You can't have it both ways.

>Also, the magnetic field is not
>degraded much for travelling in an atmosphere, unlike microwaves or lasers.

The microwave band proposed for powersat use is not significantly hit by
atmospheric absorption.  (This *would* be a problem for lasers.)
--
A bit of tolerance is worth a  |     Henry Spencer at U of Toronto Zoology
megabyte of flaming.           | uunet!attcan!utzoo!henry [e-mail]

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

Date: 31 Oct 89 18:03:26 GMT
From: pacific.mps.ohio-state.edu!zaphod.mps.ohio-state.edu!gem.mps.ohio-state.edu!wuarchive!brutus.cs.uiuc.edu!samsung!shadooby!mailrus!jarvis.csri.toronto.edu!utgpu!utzoo![e-mail]-state.  (Henry Spencer)
Subject: Re: Terraforming

In article <[e-mail]> [e-mail] (John Roberts) writes:
>For settlement of other star systems, there are several unknowns:
>  - It is not *known* that we will ever develop a practical means of human
>    travel over interstellar distances.

If you are willing to stipulate travel times of a significant fraction of
a lifetime, it is known about as certainly as it can be without actually
doing it.  There are a dozen propulsion ideas that are likely to work well
enough, and new ones are coming up all the time.  It used to be gospel
that interstellar travel faced horrendous obstacles and its practicality
was very unclear.  In the last decade or so, it's become clear that this
*just isn't so*.  Starflight is not that hard, if you're willing to spend
lots of money and be very patient.

>  - It is not known whether any star systems within reach have planets with
>    size and chemical composition similar to earth.

True, but.  We will have much more information on the general incidence of
planets nearby within a couple of decades.  (Here again, what used to be
thought of as impossibly hard is now looking easier by the day.)  Getting
information about smaller planets and their composition will be trickier,
but the obvious approach is to go there (by proxy) and see.  Any attempt
at interstellar colonization would naturally be preceded by unmanned probes.

Note also that unless some fundamental problem with the "space colony"
concept is found, habitable planets may be relatively unimportant.  Space
is, in many ways, a much more convenient place to live.  Debris belts
may be much more important than planets -- and we already have direct
observations of them around nearby stars.
--
A bit of tolerance is worth a  |     Henry Spencer at U of Toronto Zoology
megabyte of flaming.           | uunet!attcan!utzoo!henry [e-mail]

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

Date: 1 Nov 89 04:21:31 GMT
From: mailrus!jarvis.csri.toronto.edu!utgpu!utzoo![e-mail]  (Henry Spencer)
Subject: Re: Moon Colonies / Ant Tanks?

In article <[e-mail]> [e-mail] (Tom Neff) writes:
>Oh by the way, if you have to burrow underground to survive in a
>Moon colony, why bother to go?  Why not just build underground
>colonies here?  Sure is easier to ship stuff here.  If you have
>to spend your whole life in the basement, how much does it matter
>which basement?

If you have to ask, you aren't ever going to know.
--
A bit of tolerance is worth a  |     Henry Spencer at U of Toronto Zoology
megabyte of flaming.           | uunet!attcan!utzoo!henry [e-mail]

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

Date: 31 Oct 89 16:52:50 GMT
From: cs.utexas.edu!helios!photon![e-mail]  (Harold E Mueller)
Subject: Re: Manned Jupiter Mission

In article <[e-mail]> [e-mail] (Joe Voros) writes:
>In article <[e-mail]>, [e-mail] (Brian Yamauchi) writes:
>One problem is that HAL does not yet exist  :-)
>--
>Joe Voros, Physics Dept, Monash University, Clayton, VIC, 3168, Australia.

I most certainly do, and would be happy to go along!

Hal Mueller                  [e-mail]
Grad Student, CS Dept.       n270ca@tamunix (Bitnet)
Texas A&M University, College Station, TX 77843

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

Date: 31 Oct 89 17:30:58 GMT
From: usc!henry.jpl.nasa.gov!elroy.jpl.nasa.gov![e-mail]  (Steve Groom)
Subject: Re: Computer

In article <[e-mail]> [e-mail] (S Schaper) writes:
[ referring to the future use of "modern" processors for flight hardware,
in particular a version of the 8086 ]
>I'd opt for 80860's that are rad-hardened, or 88k's in parallel...

Of course you would.  Believe me, the people responsible for flight
software would too.  The problem is that it's not a trivial task to
design and produce rad-hard parts.  You don't just whip up a special
version of a chip in a few months and stick it in a spacecraft.  That's
why a rad-hard version of the 8086 is just now being discussed for use,
because has taken this long to produce it.

Personally, I'd rather see them using a SPARC :-)

--
Steve Groom, Jet Propulsion Laboratory, Pasadena, CA
[e-mail]  {ames,usc}!elroy!stevo

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

Date: 31 Oct 89 18:07:37 GMT
From: mailrus!jarvis.csri.toronto.edu!utgpu!utzoo![e-mail]  (Henry Spencer)
Subject: Re: Manned Jupiter Mission

In article <[e-mail]> [e-mail] (Terry Hancock) writes:
>    [radiation shielding] Mostly what you're worried about
>are sporadic outbursts of solar activity (not the continuous level of
>radiation)...

Unfortunately, not so.  Solar flares can be handled with a small "storm
shelter" area, occupied only during danger periods.  The big shielding
problem, when one starts considering really long stays in space, is
cosmic rays.  For that, one needs continuous shielding of all inhabited
areas.

The same is true, for slightly different reasons, for penetrating Jupiter's
Van Allen belts.  There the radiation is so intense that you cannot afford
to play games with it; full-time all-directions shielding is needed.
--
A bit of tolerance is worth a  |     Henry Spencer at U of Toronto Zoology
megabyte of flaming.           | uunet!attcan!utzoo!henry [e-mail]

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

Date: 31 Oct 89 17:25:42 GMT
From: visdc![e-mail]  (John E Van Deusen III)
Subject: Re: Manned Jupiter Mission (was Re: Condensed CANOPUS - August 1989)

In article <[e-mail]> [e-mail]
(Henry Spencer) writes:
>
> Manned Jupiter missions could *really* *really* use better propulsion
> than chemical rockets.  Otherwise the travel times start getting
> really troublesome.

First construct a large planetary transport in orbit; complete with moon
rock shielding, trees, you name it.  Then give it a nudge a la Galileo.
After it comes around for the second time, intercept it with a high-
performance, crew-carrying, orbital shuttle and make the comparatively
quick journey in comfort and safety.
--
John E Van Deusen III, PO Box 9283, Boise, ID  83707, [phone]

uunet!visdc!jiii

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

Date: 31 Oct 89 23:30:41 GMT
From: telesoft![e-mail]  (Roger Arnold @prodigal)
Subject: Re: Powersat options II: Magnetism?


Forget about pulsed magnetic fields for transmitting power; you're
only talking about very low frequency electromagnetic waves in
place of microwaves, and there are good technical reasons why low
frequencies are a lousy choice for power transmission.

A lot of messages lately have begun with "sigh!".  This could be
another one.  It's depressing to see people posting messages and
getting emotionally exercised about issues where they clearly don't
know what they're talking about, but carry on as if they did.  It's
not that individuals don't have a right to be fools, it's just SUCH
A WASTE!  There are so many real issues that are worth getting worked
up about, and mostly they go begging.  Those who get off on causes
don't seem to care to take the time or effort to understand the real
issues.  "Another gross generalization from.." oh, sorry Eugene.

Herewith, a very short primer on the standard model for SPS power
transmission and safety:

o  The power density in the center of the beam at the rectenna site
   is about 25% of the power density of direct sunlight.  It's
   certainly not recommended, but you could walk through the beam,
   without suffering any obvious or immediate ill effects.  Maybe a
   slight feverish feeling, from a rise in body temperature, if you
   stayed in the beam more than ten minutes.  Long term effects are
   another matter.  You could do serious damage to the lenses of your
   eyes; they're efficient absorbers of microwave energy, and are not
   efficently cooled by the bloodstream.  People who work in the
   vicinity of high power microwave transmitters show a statistically
   significant increase in frequency of cataracts.

o  Despite the low power density in the beam, the rectenna would
   still collect about six times the average power per area covered
   as an array of solar cells.  That's because of high conversion
   efficiency, and a steady, 24 hour source from a fixed direction.

o  A powersat rectenna would pass 95% of incoming sunlight through
   its mesh, and shield the area below it from microwaves.  You could
   use the area under the rectenna for agriculture, or leave it to
   the natural desert flora and fauna.  Contrast that to the "silicon
   deserts" of solar power farms.

o  If powersats provided all of the world's electrical power, the
   total input of SPS beam power would be something like .01% of solar
   input.  Virtually none of that energy would be absorbed by the
   atmosphere.  The effect on the thermal balance of the earth would
   be a fraction of what it would be if the same energy were derived
   from solar power.  Reason: to oversimplify a bit, solar power
   captures energy that would otherwise be reradiated.  Of course,
   solar power, in turn, has far less impact on the thermal balance
   than power derived from fossil fuels.

o  The power density in an SPS beam is limited by beam optics.  There
   is simply no way that the beam could be "intensified", without
   building a larger transmitting antenna.

o  An SPS power beam is formed by phase conjugation of a pilot beam
   from the rectenna site.  If you don't know what that means, don't
   worry about it.  The bottom line is "no pilot beam, no power beam".
   The SPS transmitting antenna is essentially an amplifying retro-
   reflector for the pilot beam.  It's physically impossible, given
   the antenna design, for the power beam to be directed anywhere
   except back at its receiving rectenna.  Weapons potential: zilch.

o  Could you design the system differently, so that it could be used
   as a weapon?  Of course.  But there already exist vastly more cost
   effective weapons systems, if that's what you're into.

- Roger Arnold                ucsd!telesoft!roger

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

End of SPACE Digest V10 #196
*******************