Space & Astronomy/Space and Astronomy (October 1993).iso/mac/TEXT/SPACEDIG/V09_5/V9_500.TXT

Internet Message Format | 1991-07-08 | 7KB

Return-path: <[e-mail]>
X-Andrew-Authenticated-as: 7997;andrew.cmu.edu;Ted Anderson
Received: from corsica.andrew.cmu.edu via trymail for +dist+/afs/andrew.cmu.edu/usr1/ota/space/[e-mail] (->+dist+/afs/andrew.cmu.edu/usr1/ota/space/space.dl) (->ota+space.digests)
          ID </afs/andrew.cmu.edu/usr1/ota/Mailbox/oYbpo:y00UkVEEF04o>;
          Wed, 21 Jun 89 05:16:58 -0400 (EDT)
Message-ID: <[e-mail]>
Reply-To: [e-mail]
From: [e-mail]
To: [e-mail]
Date: Wed, 21 Jun 89 05:16:51 -0400 (EDT)
Subject: SPACE Digest V9 #500

SPACE Digest                                      Volume 9 : Issue 500

Today's Topics:
             EMI/EMC TEST FACILITY WANTED
         Re: DO IT YOURSELF SPACE PROBES PT.2
                Let's go back
----------------------------------------------------------------------

Date: 15 Jun 89 20:52:59 GMT
From: agate!sag4.ssl.berkeley.edu![e-mail]  (Earl Powell)
Subject: EMI/EMC TEST FACILITY WANTED


The Space Sciences Laboratory of the University Of California, Berkeley is
looking for a California vendor and/or facility do EMC testing on it's
ATLAS 1 payload (FAUST). The test should be to MSFC-SPEC-521A, (Electromagnetic
Compatibility Requirements on Spacelab Payload Equipment) section 4.

This testing is a requirment of our verification plan.

Your help is appreciated.
Thank you
Earl Powell, Project Manager Faust

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

Date: 15 Jun 89 15:03:52 GMT
From: mcvax!ukc!etive![e-mail]  (Bob Gray)
Subject: Re: DO IT YOURSELF SPACE PROBES PT.2

In article <[e-mail]> [e-mail] (William Lewis) writes:
>In article <[e-mail]6> [e-mail] writes:
>>phases of the mission. [Query, did the Phobos probes fail because of the use
>>of cheap components, human error, both or neither?]

>   I don't remember the reason for the other probe's failure, although I
>think it was a probe failure and not an Earth failure... (?)

A space exibition featuring some of the results from Phobos 2
opened at the Science Museum in London last week. In what
they called an exclusive report, C4 news interviewed some of
the Soviet scientists responsible for the Phobos mission.

Three very strange details of the mission were revealed.

First, a number of the images taken of an area near the
equator in the infra-red clearly show an area covered with a
series of regular rectangular features about two miles across.
One of these images was shown in the report, and is in the
exhibition. (Anyone in London reading this who has been to
the exhibition and care to comment?)

Second, one of the images shown features the shadow of what
could only be one of the Martian moons. Except that there
wasn't any moon in the place and time it would have to have
been to cast the shadow.

Third, Phobos 2 was transmitting an image to Earth when the
signal died. In the words of one of the scientists
interviewed, it "showed something that shouldn't have been
there". The report interpreted this to mean that the last
image shows some debris in the same orbit as the moon
Phobos, and that it was collision with this that destroyed
Phobos 2. The Soviets haven't released this image.

The report tried hard to avoid being identified with the
"little green men" and "faces on Mars" group, but I am
surprised that the "newspapers" which regularly feature that
type of article haven't caught onto this story yet.
    Bob.

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

Date: 13 Jun 89 07:55:43 GMT
From: amdcad!weitek!sci![e-mail]  (Dave Rickel)
Subject: Let's go back

The 20th anniversary is coming up in a month.  To celebrate, the Smithsonian's
AIR AND SPACE June/July issue was dedicated to Apollo.  Anyway, it started
me wondering just what you'd need to get there again.  Using my CRC and a
calculator, i came up with the followin numbers (again, i'm good at making
simple arithmetic mistakes; if you find some, send me email):

Delta v        which

5.383 km/sec    Earth Orbit (500 km) to escape velocity (i was too lazy to
        figure a lunar transfer trajectory, this should be reasonably
        close)
1.360 km/sec    Lunar transfer to Lunar Orbit (100 km) (this is too high--
        it's to get from a hyperbolic orbit into lunar orbit)
1.363 km/sec    Lunar Orbit to Lunar Surface (this is too low--it doesn't
        count delta-v wasted fighting lunar gravity)
0.292 km/sec    Three minutes hover at the lunar surface (this is to make up
        for the previous entry being too low)
2.480 km/sec    Lunar transfer to Lunar Surface (if we don't want to go into
        a lunar orbit before hitting (crashing if the engines don't
        restart) into the moon) (again, this doesn't figure delta-v
        wasted fighting lunar gravity--add in the hover time).


The 5.4 km/sec figure is nasty; it sounds like we need LOx/LH.  Oh well.
When they come back to earth, they can use aerobraking, and either go into
LEO or do a direct reentry.

Let's do this in a big way, like in the A. C. Clarke stories.

Let's look at a cargo moonship first.  Say it's supposed to softland 20 tons
on the moon; the 20 tons to include engines and guidance and landing gear and
so on.  Clearly, that'd take the shortest path--blast from LEO directly to the
moon.  5.4 + 2.5 + .3 = 8.2 km/sec delta v.  The SSMEs have an Isp of 4.464
km/sec in vacuum; say we can get 4.4 km/sec.  That's a mass ratio of about
6.45 (wet weight to dry weight).  Call it 131 tons fuel,  4 tons tanks,
20 tons for the rest of the moonship; 155 tons total.  That allows a bit of
slop.  We could send up two dry cargo ships per shuttle load (i think--it
has about a 45 ton capacity, doesn't it?).  Fuel is, of course, a problem.
It seems the solution would be to ship up fuel as water to an orbiting cracker/
refigerator (use expendables for this).

I guess that of the 20 tons eventually soft-landed, 15 tons could be useful
payload.

Oh well.  The return trip is much simpler.  Let's say we take off 20 tons
from the moon, the 20 tons again including engines and guidance and all that
stuff.  This is 2.5 + .2 = 2.7 km/sec delta v.  Call it 18 tons fuel, .5
tons tanks, for a wet weight of 39 tons.

So.  One ship could be a return vessel (and a bit of fuel), another could be
more fuel for the return vessel, and one could be astronauts.  Probably on the
order of six  astronauts.  Send up ten vessels (three return, three fuel,
three astronauts, one general-purpose cargo) resupply periodically, always
send enough fuel in the resupply ships to keep at least one of the return
vessels fully fueled, in case of accidents.


Let's see.  At $6M/metric ton to LEO, that's about $3 billion for a set of
three moon ships.  Not including materials or development (there is a quote
from WIERD SCIENCE that would be appropriate here.  Something along the lines
of "Shut up.  I know what reality is.  This is fantasy.").


david rickel
decwrl!sci!daver

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

End of SPACE Digest V9 #500
*******************