Date: Sat, 18 Jul 92 04:59:59
From: Space Digest maintainer <digests@isu.isunet.edu>
Reply-To: Space-request@isu.isunet.edu
Subject: Space Digest V15 #011
To: Space Digest Readers
Precedence: bulk
Space Digest Sat, 18 Jul 92 Volume 15 : Issue 011
Today's Topics:
Antimatter (was propulsion questions) (2 msgs)
Chemical unit operations in space
FTL drives
Mir diary pt.2
Need Testers for MS Windows Astronomy Program (2 msgs)
Now, where at last ? (Re: apollo 10)
Phobos-UFO-pic,what do You think about it ?
Propulsion questions (2 msgs)
Re.: Need Testers for MS Windows Astronomy Program
Red stripe in Apollo spacesuits
Space Transportation Infrastructure Costs (Was Re: Inter
Space Transportation Infrastructure Costs (Was Re: Interstates)
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----------------------------------------------------------------------
Date: Fri, 17 Jul 1992 12:33:15 GMT
From: Nick Haydock <nick@bustard.inmos.co.uk>
Subject: Antimatter (was propulsion questions)
Newsgroups: sci.space,sci.physics
Hi
I have brought this question over into sci.physics
because I think this question belongs there, and
re-directed followups back there.
On sci.space there is a discussion about spacecraft
propulsion systems, in particular ones using antimatter
annihilation to generate the power source. Can anyone
tell me just how much energy (Joules please) would
be generated if 0.5 grams of X is annihilated with
0.5 grams of anti-X. with the different products
generated in the process does it make a defference
what we pick for X ( protons, electrons, whatever ).
Nick
" Now look, I speak 34 languages fluently,
gibberish isn't one of them. " - D.Mouse
------------------------------
Date: Fri, 17 Jul 1992 15:24:28 GMT
From: Henry Spencer <henry@zoo.toronto.edu>
Subject: Antimatter (was propulsion questions)
Newsgroups: sci.space
In article <1992Jul17.123315.28475@inmos.co.uk> nick@inmos.co.uk () writes:
> ...tell me just how much energy (Joules please) would
> be generated if 0.5 grams of X is annihilated with
> 0.5 grams of anti-X.
E = mc^2. Annihilation of 0.001kg of stuff produces 0.001*3e8^2 Joules,
i.e. 9e13 J.
>with the different products
> generated in the process does it make a defference
> what we pick for X ( protons, electrons, whatever ).
Not in the long run. It all ends up as energy eventually (unless you
believe neutrinos have mass, in which case a miniscule fraction of it goes
into neutrino mass). Electrons plus positrons gives gamma rays; protons
plus antiprotons is more complex, but eventually most ends up as gamma rays,
plus a little bit carried by neutrinos.
In the short run it can make a considerable difference. Gamma rays are
hard to handle. The proton-antiproton reaction produces mostly pions.
Neutral pions are useless -- impossible to control and very short-lived.
But charged pions live long enough to travel several m, enough to be
steered by a magnetic nozzle in a compact engine. They decay, mostly,
to muons. *Those* live long enough to travel 1-2 km, which is lots for
any reasonable engine. Eventually they decay to electrons and positrons,
which annihilate. There are losses every step of the way, but using pions
gives you 70-80% of the available energy temporarily in a useful form,
and even muons give you something like 60%.
There has been some speculation that reacting antiprotons with heavy
nuclei might tend to give you charged fragments that would be better.
I haven't heard any firm results.
No matter how you slice it, there are going to be a lot of gamma rays
flying around.
--
There is nothing wrong with making | Henry Spencer @ U of Toronto Zoology
mistakes, but... make *new* ones. -D.Sim| henry@zoo.toronto.edu utzoo!henry
------------------------------
Date: Thu, 16 Jul 1992 10:27:11 GMT
From: Nick Szabo <szabo@techbook.com>
Subject: Chemical unit operations in space
Newsgroups: rec.arts.sf.science,sci.space,sci.engr.chem
In article <1992Jul15.065617.27597@ccu1.aukuni.ac.nz> ecmtwhk@ccu1.aukuni.ac.nz (Thomas Koenig) writes:
An excellent article on an important subject. This topic may be
more important than any other for space colonization; it is key to
developing space industry to the point where we can build and fund
the space settlements.
>- Distillation columns. These rely on counterflow of gas and liquid
> and on a large surface between the two, both provided for by gravity
> and geometry (either plates, with bubbles rising/spray descending
> or packed columns with liquid drops coming down and gas going
> up).
One possibility is maintaining a pressurized flow of spray through a
gas. Another is using surface forces, eg flow of a liquid
from wet to dry through a wick or across a packed column surface.
It is easy to get large surfaces for vacuum distillation. We might
also use other separation methods, eg membranes.
>- Gas / liquid chemical reactors (see above)
Microgravity could be a big advantage for slow reactions where we need
the gas and liquid to be thoroughly mixed. In some cases we can
use acoustic levitation instead of chemical reactor walls to avoid
contamination. We can use pressurized inert or near-inert gas (eg N2)
to move liquids, as is done in many liquid rockets.
>- After separating solids from liquid or gas, most conventional filters/
> centrifuges/whatever rely on the stuff actually falling down after-
> wards.
Remove the stuff ultrasonically or electrostatically. Electrostatic
dust removal from a gas is a common operation; in microgravity we
might even be able to get rid of the filters in many situations.
>- Transportation of solids on conveyer belts is not going to work
Magnetic and electrostatic conveyence works much better, as does
just shoving the stuff off and catching it at the other end.
We can transport across short or long distances in three dimensions
without heavy machines.
>... and so on... just take a look at Perry's Chemical Engineering
>Handbook and figure which unit operations rely on gravity.
In general, we certainly have to do things quite differently in
microgravity. Most chemical processes naively extrapolated into
space will not work.
Upon redesign, in some cases we will find we can do things much more
effectively (eg electrostatic dust removal, electrophoresis, containerless
processing), in some cases we remain severely handicapped. We already have
several chemical reactors designed for microgravity, including fuel
cells, some life support equipment and of course rocket engines. As we
strive do more things in space, eg space manufacturing and native materials
processing, we will learn much more about how to take advantage of
microgravity and avoid the pitfalls (oops, naive extrapolation of
gravity-dependent metaphor... :-)
>Most of the workarounds I can think of rely on centrifugal force, which
>would wreck micro - g conditions, as anyone who has ever watched a
>centrifuge vibrate on its foundations will probably tell you.
We need to design a despun segment dynamically connected to a spun
segment without transferring vibration. I wonder how close the Galileo
spacecraft comes to this? The other problem is moving stuff between the
two segments. Brain busters, but nothing fundamentally impossible that
I can see.
>Conclusions: to build a chemical factory in orbit, build a rotating one
>with about 10 m/s^2 of acceleration (but make it big, current distillation
>columns are up to 50 m high);
Spin the facility with a tether; we can shrink the distillation column
by jacking up the gravity level.
--
szabo@techbook.COM Public Access User --- Not affiliated with TECHbooks
Public Access UNIX and Internet at (503) 644-8135 (1200/2400, N81)
------------------------------
Date: Fri, 17 Jul 1992 12:54:33 GMT
From: Ian Taylor <se_taylo@rcvie.co.at>
Subject: FTL drives
Newsgroups: sci.space
In article <a5d14b07@Kralizec.fido.zeta.org.au> derek.wee@f820.n680.z3.fido.zeta.org.au (Derek Wee) writes:
>
> Just out of interest, I'm compiling a list of the FTL drives used in
>science fiction stories and computer games.
One of my all time favorites is the Infinite Probability Drive
described in Douglas Adam's `Hitchhiker's Guide'.
This works on the principle that there is a small but finite probability that
you and your starship exist everywhere in the universe at any given moment.
The drive simply ;-) maximises the probablity of being in the place you desire.
+-- I -------- fax +43 1 391452 --------------------- voice +43 1 391621 169 --+
| T a y l o r Alcatel-ELIN Research, 1-7 Ruthnergasse, Vienna A-1210 Austria |
+-- n ---- ian@rcvie.co.at --- PSI%023226191002::SE_TAYLOR --- 20731::ian -----+
All opinions subject to change without notice (Signature Release 3 Version 3)
------------------------------
Date: 17 Jul 92 14:02:11 GMT
From: TIMOTHY FREER <tfreer@metz.une.edu.au>
Subject: Mir diary pt.2
Newsgroups: sci.space
MIR DIARY Pt.2 (Aug89 to Jul92)
-------------------------------
This diary continues on from my first posting, listing major events
during manned operations with the Mir space station between August 1989 and
July 1992. Once again the listing includes all launches to Mir, all
dockings, port transfers, spacewalks, undockings and re-entries, that
occured during this period. All dates are in GMT, and are reasonably
accurate.
I trust that you will find this diary a usefull reference for major
Mir space station activities. If you have any corrections, please post
them to me.
-----------------------------------------------------------------------------
Mir diary pt.2 (Aug89 to Jul92).
-----------------------------------------------------------------------------
1989.
-----------------------------------------------------------------------------
23 AUG Progress M launched.
25 AUG Progress M docks with Mir's extreme forward port.
05 SEP Soyuz TM-8 launched with Alexsandr Viktorenko and Alexsandr
Serebrov aboard.
07 SEP Soyuz TM-8 docks with Kvant-1's rear port.
26 NOV Kvant 2 launched by Proton rocket.
01 DEC Progress M undocks and is directed into the atmosphere to burn-up.
02 DEC Kvant-2 aborts attempted docking with Mir.
06 DEC Kvant-2 docks with Mir's extreme forward port.
08 DEC Kvant-2's 'Ljappa' manipulator is used to transfer Kvant-2 to the
upper port on Mir's forward docking unit.
12 DEC Soyuz TM-8 transfered to Mir's extreme forward port by Viktorenko,
and Serebrov.
20 DEC Progress M-2 launched.
22 DEC Progress M-2 docks with Kvant-1's rear port.
----------------------------------------------------------------------------
1990.
----------------------------------------------------------------------------
09 JAN Viktorenko and Serebrov make a 2 hour, 56 minute spacewalk to
install sensors outside the Mir core module.
11 JAN Viktorenko and Serebrov make a 2 hour, 54 minute spacewalk to
retrieve French instruments and to prepare the extreme forward
docking port for the arrival of Kristall.
26 JAN Viktorenko and Serebrov install camera equipment outside Kvant-2
in a 3 hour, 2 minute spacewalk.
01 FEB Viktorenko and Serebrov make a 4 hour, 59 minute spacewalk.
Serebrov makes first test of 'Space Motorcycle'.
05 FEB Viktorenko and Serebrov make a 3 hour, 45 minute spacewalk.
Viktorenko tests 'Space Motorcycle'.
09 FEB Progress M-2 undocks and is directed into the atmosphere to burn-up.
11 FEB Soyuz TM-9 launched with Anatoli Solovyov and Alexsandr Balandin
aboard.
13 FEB Soyuz TM-9 docks with Kvant-1's rear port.
18 FEB Soyuz TM-8 undocks and re-enters with Viktorenko and Serebrov
aboard.
21 FEB Soyuz TM-9 transfered to Mir's extreme forward port by Solovyov
and Balandin.
28 FEB Progress M-3 launched.
03 MAR Progress M-3 docks with Kvant-1's rear port.
27 APR Progress M-3 undocks and is directed into the atmosphere to burn-up.
05 MAY Progress 42 launched (last of original design).
07 MAY Progress 42 docks with Kvant-1's rear port.
27 MAY Progress 42 undocks and is directed into the atmosphere to burn-up.
28 MAY Soyuz TM-9 transfered to Kvant-1's rear port by Solovyov and
Balandin.
31 MAY Kristall launched by Proton rocket.
06 JUN Kristall's docking with Mir is postponed because of problems with
Kristall's orientation motors.
10 JUN Kristall docks with Mir's extreme forward port.
11 JUN Kristall's 'Ljappa' manipulator is used to transfer the module to
the lower port on Mir's forward docking unit opposite Kvant-2.
03 JUL Soyuz TM-9 transfered to Mir's extreme forward port by Solovyov,
and Balandin.
17 JUL Solovyov and Balandin make a 7 hour spacewalk to repair damaged
insulation blankets on Soyuz TM-9. Problems experienced in
re-entering Kvant-2.
26 JUL Solovyov and Balandin make a 3 hour, 31 minute spacewalk to close
jammed hatch on Kvant-2, and complete repairs to Soyuz TM-9.
01 AUG Soyuz TM-10 launched with Gennadi Manakov and Gennadi Strekalov
aboard.
03 AUG Soyuz TM-10 docks with Kvant-1's rear port.
09 AUG Soyuz TM-9 undocks and re-enters with Solovyov and Balandin
aboard.
15 AUG Progress M-4 launched.
17 AUG Progress M-4 docks with Mir's extreme forward port.
?????? Progress M-4 undocks and is directed into the atmosphere to
burn-up.
27 SEP Progress M-5 launched.
29 SEP Progress M-5 docks with Mir's extreme forward facing port.
?????? Manakov and Strekalov make unsuccesfull spacewalk to repair
Kvant-2's damaged hatch.
28 NOV Progress M-5 undocks and is directed into the atmosphere to
burn-up. Recoverable capsule re-enters.
02 DEC Soyuz TM-11 launched with Viktor Afanaseyev, Musakhi Manarov,
and Toyohiro Akiyama (Japan) aboard.
04 DEC Soyuz TM-11 docks with Mir's extreme forward facing port.
10 DEC Soyuz TM-10 undocks and re-enters with Manakov, Strekalov, and
Akiyama aboard.
---------------------------------------------------------------------------
1991.
---------------------------------------------------------------------------
07 JAN Afanaseyev and Manarov repair Kvant-2's damaged hatch in
a 5 hour, 18 minute spacewalk.
14 JAN Progress M-6 launched.
16 JAN Progress M-6 docks with Kvant-1's rear port.
23 JAN Afanaseyev and Manarov make spacewalk to install an extendable
boom on Kvant-2's exterior.
26 JAN Afanaseyev and Manarov complete installment of equipment in a
6 hour, 20 minute spacewalk.
15 MAR Progress M-6 undocks and is directed into the atmosphere to burn-up.
19 MAR Progress M-7 launched.
21 MAR Progress M-7 unsuccesfull in docking attempt because of computer
error.
23 MAR Progress M-7 passes within five metres of Mir during second docking
failure caused by malfunctioning Kurs rendevous system.
26 MAR Soyuz TM-11 transfered Afanaseyev and Manarov to Kvant-1's rear
port to test Kurs system.
28 MAR Progress M-7 docks with Mir's extreme forward port.
25 APR Afanaseyev and Manarov make a 3 hour, 34 minute spacewalk to
collect samples and photograph the Kurs antenna.
07 MAY Progress M-7 undocks and is directed into the atmosphere to burn-up.
18 MAY Soyuz TM-12 launched with Anatoli Artsebarski, Sergei Krikalyov,
Helen Sharman (United Kingdom) aboard.
20 MAY Soyuz TM-12 docks with Mir's extreme forward facing port.
26 MAY Soyuz TM-11 undocks and re-enters with Afanaseyev, Manarov and
Sharman aboard.
28 MAY Soyuz TM-12 transfered to Kvant's rear port by Artsebarski and
Krikalyov.
30 MAY Progress M-8 launched.
01 JUN Progress M-8 docks with Mir's extreme forward port.
25 JUN Artsebarski and Krikalyov make a 4 hour, 58 minute spacewalk to
repair Kurs antenna.
29 JUN Artsebarski and Krikalyov make a 4 hour, 58 minute spacewalk to
deploy a U.S cosmic ray detector.
15 JUL Artsebarski and Krikalyov make a 5 hour, 50 minute spacewalk to
begin building a space girder.
19 JUL Artsebarski and Krikalyov make fourth spacewalk.
23 JUL Artsebarski and Krikalyov make fifth spacewalk.
27 JUL Artsebarski and Krikalyov make sixth spacewalk.
16 AUG Progress M-8 undocks and is directed into the atmosphere to
burn-up. Experiment to deploy baloon from freighter failed.
20 AUG Progress M-9 launched.
23 AUG Progress M-9 docks with extreme forward port.
30 SEP Progress M-9 undocks and is directed into the atmosphere to
burn-up. Recoverable capsule re-enters.
02 OCT Soyuz TM-13 launched with Alexsandr Volkov, Tokhtar Aubakirov
(Khazakstan), and Franz Viehbock (Austria) aboard.
04 OCT Soyuz TM-13 docks with Mir's extreme forward facing port.
10 OCT Soyuz TM-12 undocks and re-enters with Artsebarski, Aubakirov
and Viehbock aboard.
15 OCT Soyuz TM-13 transfered to Kvant-1's rear port by Volkov and
Krikalyov.
17 OCT Progress M-10 launched.
19 OCT Progress M-10 aborts docking sequence.
21 OCT Progress M-10 docks with Mir's extreme forward port.
----------------------------------------------------------------------------
1992.
----------------------------------------------------------------------------
20 JAN Progress M-10 undocks and is directed into the atmosphere to
burn-up. Recoverable capsule re-enters.
25 JAN Progress M-11 launched.
27 JAN Progress M-11 docks with Mir's extreme forward port.
20 FEB Volkov and Krikalyov make a 4 hour, 12 minute spacewalk to
install and retrieve instruments. Objectives curtailed by Volkov's
spacesuit malfunction.
13 MAR Progress M-11 undocks and is directed into the atmosphere to
bur-up.
14 MAR Soyuz TM-13 transfered to Mir's extreme forward port by Volkov
and Krikalyov.
17 MAR Soyuz TM-14 launched with Alexsandr Viktorenko, Alexsandr Kaleri,
and Klause-Dietritch Flade (Germany) aboard.
19 MAR Soyuz TM-14 docks with Kvant-1's rear port.
25 MAR Soyuz TM-13 undocks and re-enters with Volkov, Krikalyov and
Flade aboard.
19 APR Progress M-12 launched.
?? APR Progress M-12 docks with Mir's extreme forward port.
27 JUN Progress M-12 undocks and is directed into the atmosphere to
burn-up.
30 JUN Progress M-13 launched.
02 JUL Progress M-13 unsuccesfull in docking attempt.
04 JUL Progress M-13 docks with Mir's extreme forward port.
-----------------------------------------------------------------------------
-----------------------------------------------------------------------------
N.B This diary lists all events up until 4 JUL 92. I am quite certain
that I have included all launches, dockings, spacewalks, and
re-entries. The only important events that I am not sure of are
launchings of micro-satellites (if any) that may have taken place
from Mir's airlocks. I wuold be gratefull to anyone who can tell
me of such events.
Bye for now Tim.
------------------------------
Date: 17 Jul 92 10:43:39 GMT
From: M.L.Cook3@lut.ac.uk
Subject: Need Testers for MS Windows Astronomy Program
Newsgroups: comp.windows.ms,comp.windows.ms.programmer,sci.astro,sci.space,sci.edu,comp.ibm.pc.misc
I've had the problem with mail being returned as well...
Martin.
------------------------------------------------------------------------------
| ___ ___ ___ ________ | Martin Cook, Dept. Computer Studies, |
| /_ /| /__/| /_ /| /_______/| | Loughborough University of Technology, |
| | | | | | | | | | |__ __|/ | Loughborough, Leicestershire, LE11 3TU,|
| | | |__ | | |_| | | | | | | United Kingdom. |
| | |/__ /| | |/__| | | | | | | |
| |_____|/ |_______|/ |__|/ | e-mail: M.L.COOK3@UK.AC.LUT (UK) |
| | M.L.COOK3@LUT.AC.UK (Elsewhere)|
------------------------------------------------------------------------------
------------------------------
Date: 17 Jul 92 12:25:43 GMT
From: kevin mcfadden <kevin@sherman.pas.rochester.edu>
Subject: Need Testers for MS Windows Astronomy Program
Newsgroups: comp.windows.ms,comp.windows.ms.programmer,sci.astro,sci.space,sci.edu,comp.ibm.pc.misc
Ditto. Add me to the list as well.
Kevin McFadden
kevin@sherman.pas.rochester.edu
Univ. of Rochester
Bausch & Lomb Hall Rm 206
Rochester, NY 14627
------------------------------
Date: 16 Jul 92 18:55:58 GMT
From: Bruce Watson <wats@scicom.AlphaCDC.COM>
Subject: Now, where at last ? (Re: apollo 10)
Newsgroups: sci.space
Satellite Situation Report, NASA, Project Operations Branch, Code 513,
Goddard Space Flight Center, Greenbelt, MD, USA 20771 is published
quarterly and is available to interested persons.
It lists 1969 043C LM/descent in orbit around the moon and 1969 043D
LM/ascent in orbit about the sun, but there are errors in this
publication.
------------------------------
Date: Fri, 17 Jul 92 08:43:08 GMT
From: Stefan Hartmann <leo@zelator.in-berlin.de>
Subject: Phobos-UFO-pic,what do You think about it ?
Newsgroups: alt.alien.visitors,sci.space,alt.paranormal,sci.skeptic
Hi,
I have just posted the Phobos2 Ufo-picture in JPEG format in
alt.binaries.pictures.misc
What do You all think about it ?
Best regards Stefan Hartmann.
email to: leo@zelator.in-berlin.de
--
*************************************************************
* Stefan Hartmann This is how to contact me: *
* EMAIL: leo@zelator.in-berlin.de *
* Phone : ++ 49 30 344 23 66 FAX : ++ 49 30 344 92 79 *
*************************************************************
------------------------------
Date: 17 Jul 92 12:09:22 GMT
From: John Roberts <roberts@CMR.NCSL.NIST.GOV>
Subject: Propulsion questions
Newsgroups: sci.space
-From: tjn32113@uxa.cso.uiuc.edu (Thomas J. Nugent)
-Subject: Re: Propulsion questions
-Date: 16 Jul 92 18:42:39 GMT
-Organization: University of Illinois at Urbana
-rdouglas@cs.wpi.edu (Rob Douglas) writes:
->We were sitting around discussing this and not getting any where, so I decided
->to ask the experts.
-Well, I don't know if I'm an expert, but this is an area of strong interest,
-and I did give a well-received talk on these topics last week.
->1) If a space ship used a fusion reactor for propulsion, how would that work?
->Doesn't there have to be something sent out the back of the ship, so
->that the ship has to conserve momentum and move forward? If so, then the
->amount of forward acceleration is limited by the weight carried by the ship
->at the start, and there is no way to have a very long term propulsion source.
-Just like in regular rockets, you need a nozzle to provide thrust to the
-rocket from the exhaust. What happens (or will happen) in a fusion rocket is
-as follows: you cause (by whatever means) fusile material to fuse; this
-releases alot of energy; you add (or already have sitting there) some
-propellant which picks up energy from the fusion reaction; then you deflect
-the expanding plasma (it's energetic enough to cause all your propellant
-to become a plasma) with an electromagnetic nozzle; and thru the nozzle,
-force is imparted to the ship. An electromagnetic nozzle is basically a
-superconducting ring (or rings) with a _large_ current flowing in it.
-Due to some conductive properties of plasma, it magnetic field formed by
-the superconducting ring 'deflects' the plast, imparting force to the ring
-which is attached to the ship. Neat, huh?
Don't forget the MHD generator you run your exhaust through to get all the
megawatts you need to run the rest of the system.
If your fusion reaction produces nothing but heat and helium, and if all the
heat energy goes into kinetic energy of the exhaust, then I believe from an
energy / delta-v standpoint, you can't do better than using all the fused
helium from the fusion reaction as your rocket exhaust, and no additional
inert reaction mass. With a fixed-size fuel tank, you might increase your
delta-v by bringing along another tank of reaction mass (i.e. hydrogen),
but you would do even better by filling that second tank with more fuel.
However, fusion is a little more complicated than that, with subatomic
particles and high-energy photons generated, and pure fusion exhaust might
vaporize your rocket engine, so there could be real-world advantages to
using extra reaction mass. Also, regular hydrogen is considerably cheaper
than fusion fuel, so adding reaction mass is likely to give you greater
delta-V *per dollar*.
->2) Does this problem also work for matter-antimatter propulsion systems? Do
->you need a significant mass of both to destroy in order to propel the ship
->forward?
-Yes. Actually, the original idea for antimatter rockets was to use light
-itself as exhaust, using electron-positron annihilation to produce gamma-rays.
-Only problem is, gamma-rays have this annoying tendency to penetrate most
-matter, and not reflect from it very well (which is what you want - to reflect
-the light out the back).
The main problem with a photon drive is that it's ruinously wasteful of power
compared to a matter reaction drive. (A very rough calculation is that the
entire electrical production of Earth would give a thrust of only about
4000 pounds, a tiny fraction of the thrust of conventional chemical rocket
engines.) The breakeven point compared to use of reaction mass is when your
fuel supply is "pure energy" (half antimatter, half ordinary matter). But
nobody's proposing anything like that within the next century. The cost of
antimatter production is so high that this predominates over all other factors.
"Current" antimatter proposals are for tiny amounts of antimatter reacted
with huge quantities of normal matter.
->3) How does a solar sail work, then? Are there any existing models of a solar
->sail which have been shown to work?
-Solar sails work by reflecting sunlight.
Solar sails get around the energy problem because they don't supply their
own energy. In this case, not having to bring along any reaction mass is the
big advantage. 10000000 watts of sunlight gets you up to 1/15 newton (1/4
ounce) of thrust, including the additional kick from reflection.
John Roberts
roberts@cmr.ncsl.nist.gov
------------------------------
Date: 17 Jul 92 07:18:02 EDT
From: Chris Jones <clj@ksr.com>
Subject: Propulsion questions
Newsgroups: sci.space
In article <92Jul16.214235.18316@acs.ucalgary.ca>, jsbell@acs3 (Joshua Bell) writes:
>In article <BrHvz6.EC9@news.cso.uiuc.edu> tjn32113@uxa.cso.uiuc.edu (Thomas J. Nugent) writes:
>
>> Also, back
>>in the 60's the idea was actually proved (unintentionally I suspect) by
>>some weather satellite/balloon which was in orbit but had some aluminized
>>mylar balloon about 30 ft across. Can't remember what it was called,
>>but supposedly light pressure affected the perigee of its orbit by some
>>500 km!
>
>Dunno where this stands on the fact-fiction continuum (someone
>out there's bound to know for sure :),
The two Echo satellites, which were passive communications reflectors about 30
METERS (not feet) across (and were extremely visible from the ground), fit this
description. One or both of them decayed significantly more quickly than
expected, reportedly due to solar wind combined with increased atmospheric drag
due to the a solar maximum.
but I'd read/heard that
>one of the early Venus orbiters, out of fuel for stationkeeping,
>was reprogrammed with instructions to rotate its solar pannels to
>do limited solar sailing (solar tacking?) to maintain its orbit
>for a little while longer. Confirmation anyone?
This was mentioned most recently in this group in the article
<BrHtC3.29y@zoo.toronto.edu> by Henry Spencer. It was Mariner 10, which was
not an orbiter. It was primarily a mission to Mercury, although it flew past
the moon and Venus, using the latter's gravity to deflect its orbit into a 176
day orbit passing by Mercury. The significance of the period is that it was
twice as long as Mercury's period, so Mariner 10 passed by Mercury on every
orbit. Due to encounter maneuvering and orbital correction necessitated by
Mercury's gravity, the limiting factor on the number of encounters turned out
to be the on board fuel. There were three encounters, and the time between the
second and third was spent with almost no fuel left. Much of the attitude
control during this orbit was done using the differential solar pressure on the
solar panels, which were individually steerable.
--
Chris Jones clj@ksr.com
------------------------------
Date: Friday, 17 Jul 1992 14:43:57 CET
From: PKRISTIA@ESOC.BITNET
Subject: Re.: Need Testers for MS Windows Astronomy Program
Newsgroups: sci.astro,sci.space
My post bounced too.
Please count me in as a tester.
Poul
------------------------------
Date: 17 Jul 92 13:30:39 GMT
From: DURDA <dddurda@pine.circa.ufl.edu>
Subject: Red stripe in Apollo spacesuits
Newsgroups: sci.space
And now we've finally gotten to the problem of what happens when there
are more than two astronauts out on EVA. When Pierre, Rick, and Tom were
capturing the Intelsat satellite we saw a red stripe, a red _dashed_
stripe, and _no_ stripe.
--Dan
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Daniel D. Durda
Department of Astronomy
University of Florida
durda@astro.ufl.edu
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Date: Fri, 17 Jul 1992 12:23:23 GMT
From: "Allen W. Sherzer" <aws@iti.org>
Subject: Space Transportation Infrastructure Costs (Was Re: Inter
Newsgroups: sci.space
In article <13513@mindlink.bc.ca> Bruce_Dunn@mindlink.bc.ca (Bruce Dunn) writes:
>> Allen W. Sherzer writes:
>> Or consider this idea I have been tossing about inside my head:
>> 1. The Feds form a non-profit company and for five to ten years invest in
>> it what they now spend on the Shuttle (about $5B/year)....
> Add two steps:
>7. Send up a solar powered electrolysis unit and a cryogenic storage tank
> farm. Sell the cryogenic propellants produced to those wishing to go
> beyond low earth orbit.
No problem. We need to do something with it all anyway. Fuel may or may not
be the best use.
>8. As the cryogenic propellants in orbit are exhausted, pay for replenishment
> water or matching amounts of hydrogen and oxygen from any source,
> including extraterrestrial sources.
I don't think this step is needed. The market and its growth should be
fairly predictable so reliable plans can be made. All you need to is find
and mine your ET source. The company buys first come first served from
those who deliver to LEO; they don't care where you get the water. Delivery
from Earth or Phobos is all the same to them.
Although I will grant that down the road some sort of incentive for
extraterrestrial sources may be desirable.
To me the real question is how to phase something like this out. Ending
it too soon could wipe out suppliers but ending it too late will make
it an incentive for corruption. Any ideas?
Allen
--
+---------------------------------------------------------------------------+
| Allen W. Sherzer | "If they can put a man on the Moon, why can't they |
| aws@iti.org | put a man on the Moon?" |
+----------------------280 DAYS TO FIRST FLIGHT OF DCX----------------------+
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Date: 17 Jul 92 14:23:48 GMT
From: "Dr. Norman J. LaFave" <lafave@ial4.jsc.nasa.gov>
Subject: Space Transportation Infrastructure Costs (Was Re: Interstates)
Newsgroups: sci.space
In article <1992Jul16.125608.20325@iti.org>, aws@iti.org (Allen W. Sherzer) writes:
>
> In article <14JUL199218084223@judy.uh.edu> seds%cspar.dnet@Fedex.Msfc.Nasa.Gov writes:
>
> >instead of fighting about manned vs unmanned we could jointly promote the
> >development of a transportation infrastructure that will greatly lower
> >the cost of manned space for their purposes and unmanned space for ever grander
> >tours of ever farther places. I make a suggestion that those on here with
> >expertise begin to post your ideas for lowering transportation costs.
>
> Instead of more talk, let's *DO* something. A big push will be needed
> to keep the SSRT program alive. It is a moderately risky program but
> offers the best chance yet to make significant reductions in launch
> costs. Let's quit talking and do something.
>
> Allen
>
> --
> +---------------------------------------------------------------------------+
> | Allen W. Sherzer | "If they can put a man on the Moon, why can't they |
> | aws@iti.org | put a man on the Moon? |
> +----------------------281 DAYS TO FIRST FLIGHT OF DCX----------------------+
>
>
and let's not forget about NASP. I believe that this program has unlimited
potential and has provided vital technology to the SSRT program.
Dr. Norman J. LaFave
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End of Space Digest Volume 15 : Issue 011
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