Space & Astronomy/Space and Astronomy (October 1993).iso/mac/TEXT/SPACEDIG/V12_4/V12_459.TXT

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Subject: SPACE Digest V12 #459

SPACE Digest                                     Volume 12 : Issue 459

Today's Topics:
        Re: Cost comparison: Apollo/Saturn vs. Shuttle
            Capsule parachute reliability
    Former astronaut Scott Carpenter to attend Chicago Hobby Show
     Re: Deep Space Network use (Was: Ulysses Update - 10/06/90)
           Re: disposal of N-waste into sun
               Re: Magellan/Venus Info
     North and South off Earth [was Magellan/Venus Info]
            Re: Manned/unmanned tradeoffs
               Re: Atmospheric nitrogen

Administrivia:

    Submissions to the SPACE Digest/sci.space should be mailed to
  [e-mail].  Other mail, esp. [un]subscription notices,
  should be sent to [e-mail], or, if urgent, to
             [e-mail]

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

Date: 14 Oct 90 18:22:54 GMT
From: uceng!minerva![e-mail]  (Daniel Mocsny)
Subject: Re: Cost comparison: Apollo/Saturn vs. Shuttle

In article <[e-mail]> [e-mail] (John McKernan) writes:
>And if we want to get a few men
>up into LEO all we need to do is put a simple capsule on one of our
>cheap private boosters. Remember, a capsule is a simple thing, at least
>compared to other space hardware. It's just a few retro rockets, O2
>bottles, and parachutes.

This reminds me of something I have wondered about:

What is the reliability of the parachutes used in space capsules?

From my exposure to sport skydiving, I recall a figure of about 1
parachute malfunction in 300 dives for skilled parachutists. (That is
why they need reserve chutes. The reserve chute is similarly
reliable, meaning that the parachutist can expect to "bounce" in
1 out of 300^2 dives or so.)

Do space capsule designers plan to lose 1 in 300 flights to parachute
malfunctions? Do they have reserve chutes and procedures to cut-away
malfunctioning main chutes? Or are capsule chutes inherently more
reliable than the sport parachutist's gear?



--
Dan Mocsny                Snail:
Internet: [e-mail]    Dept. of Chemical Engng. M.L. 171
      [e-mail]        University of Cincinnati
513/751-6824 (home) 513/556-2007 (lab)    Cincinnati, Ohio 45221-0171

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

Date: 14 Oct 90 19:17:09 GMT
From: world!ksr![e-mail]  (Chris Jones)
Subject: Capsule parachute reliability

In article <[e-mail]>, dmocsny@minerva (Daniel Mocsny) writes:
>
>What is the reliability of the parachutes used in space capsules?
>           Do they have reserve chutes and procedures to cut-away
>malfunctioning main chutes? Or are capsule chutes inherently more
>reliable than the sport parachutist's gear?
>
I'm pretty sure Mercury and Gemini had a reserve chute for their one main
chute.  Apollo had three main chutes, and I don't know if they had any in
reserve.  I know it was possible to land safely using only two chutes, because
at least one of the flights did just that.

As for the Soviets, I assume the Vostok cosmonauts had their own personal
reserve chute to go with the personal chute.  It wouldn't surprise me to learn
that Voskhod had no reserve chute since that whole project was a slapped
together headline grabber, and the fact that they flew without a launch escape
system or space suits shows that crew safety was going to be sacrificed to meet
mission goals.  I know Soyuz has a reserve chute.  The one fatality attributed
to parachute failure (Vladimir Komarov in Soyuz 1) is said to have occurred
after he opened his reserve chute following the failure of his main chute.
Details are sketchy, but many accounts have the capsule spinning in an attempt
to keep it stabilized, and the spinning possibly contributing to the parachute
failure.

As to your last point, I think they probably are more reliable than sports
chutes.  If would certainly expect them to be packed more carefully.

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

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

Date: 8 Oct 90 18:29:21 GMT
From: att!cbnewsd![e-mail]  (R. M. Jungclas)
Subject: Former astronaut Scott Carpenter to attend Chicago Hobby Show


Former American astronaut Scott Carpenter will be attending the model
rocket demonstration launch between noon and 1 p.m.  and will be
on Saturday Oct. 20th and at the Chicago Hobby Show (Estes booth #1235)
from 5 p.m. to 9 p.m. Friday, Oct. 19th, from 10 a.m. to 11:30 am. and
2:30 p.m. to 6 p.m. on Saturday, October 20th and from 10 a.m. to noon
and 1 p.m. to 3 p.m. on Sunday Oct. 21st.

Further details may be found in "rec.models.rockets".

R. Michael Jungclas                    UUCP:      att!ihlpb!rjungcla
AT&T Bell Labs - Naperville, IL.       Internet:  [e-mail]

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

Date: 14 Oct 90 17:22:12 GMT
From: unmvax!nmt.edu![e-mail]  (Daniel Briggs)
Subject: Re: Deep Space Network use (Was: Ulysses Update - 10/06/90)

In article <[e-mail]> [e-mail]
(Henry Spencer) writes:
>In article <[e-mail]> [e-mail]
>(Perry G Ramsey) writes:
>>The VLA (Very Large Array) radiotelescope near Socorro, New Mexico
>>was pressed into service for Voyager's Neptune pass.
>
>And several others.  A large fraction of the Free World's total radiotelescope
>aperture was pointed at Voyager for the Neptune encounter.

Not so much as you might think, Henry.  Besides the normal DSN
antennas (which are fairly large, even by todays standards), I believe
that there were only three non-DSN stations involved.  Namely, the
VLA, Parkes Australia, and Usuda Japan.  At one point, the Parkes
antenna was 64 m diameter, with a wire mesh surface.  While this
doesn't inspire great confidence of terrific X band performance, (the
Voyager downlink was at about 3.5 cm), it may have been upgraded and
my information out of date.  I'm afraid that I have never heard of
Usuda before, so I don't have any information on it.  (I couldn't find
it in the '90 Astronomical Almanac, so it's either listed under a
different name, or it could be a non astronomical site.)  The point
is, that while several large radio telescopes were used for the
Voyager Neptune encounter, it was far short of 'A large fraction of
the Free World's total radiotelescope aperture.'  I think this
statement is starting to grow to folklore proportions, since I have
heard it from several other people before.

--
This is a shared guest account, please send replies to
[e-mail] (Internet)  ["Life's a Beech, and then you Dive."]
Dan Briggs / NRAO / P.O. Box O / Socorro, NM / 87801  (U.S. Snail)

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

Date: 8 Oct 90 22:38:51 GMT
From: wuarchive!zaphod.mps.ohio-state.edu!rpi!dali.cs.montana.edu!milton![e-mail]  (Lamont Granquist)
Subject: Re: disposal of N-waste into sun


[..discussion on sun-dive vs. solar escape methods of N-waste disposal del..]

How about dumping the N-waste into the trojan points 60 deg. head of and
behind the moon in its orbital path.  Would this be a very stable orbit or
would there be a high probability of the N-Waste escaping from the trojan
point due to outside forces (sun, asteroids, comets, etc...)?  and what
would be the radiation risk in the area around the trojan points and on the
moon?

would it be possible to collect waste in the trojan points and then
periodically send a large asteroid from the belts to capture all the trash
and sling-shot the whole mess around the sun and out of the system?

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

Date: 14 Oct 90 18:19:19 GMT
From: unmvax!nmt.edu![e-mail]  (Daniel Briggs)
Subject: Re: Magellan/Venus Info

In article <[e-mail]> [e-mail]
(Ron Baalke) writes:
>In article <[e-mail]> [e-mail]
>(Henry Spencer) writes:
>>In article <[e-mail]> [e-mail]
>>(Ron Baalke) writes:
>>>... Also, there is a universal convention
>>>on planets other than Earth that the longitude will be measured in the
>>>opposite direction that the planet rotates.  Venus rotates backwards...
>>
>>Sorry, no, this is not universally agreed on, for a different reason:
>>there is a difference of opinion on which is the north pole.  Various
>>groups are on opposite sides of the question.
>
>Since Venus axis tilt is nearly straight up and down, its North pole is
>assumed to be pointing in the same direction as that of the Earth's, even
>though this would mean Venus rotates backwards.

I've got to side with Henry on the question regarding poles.  What Ron
is assuming is essentially the IAU definition of 'North Pole'.  (The
North pole of a planet points north of the ecliptic.)  This definition
can cause violent controvery at meetings.  Many people think that this
definition is just plain wrong.  (Usually these are people whose job
includes studying the planet in question, rather than just cataloging
the orbital parameters.  The IAU definition makes bookkeeping simpler,
at cost of screwing up the planetary physics.)  Bottom line: Ron's
definition is the most common one, but it is by no means universal.

I don't happen to know how longitiude is defined, although a thought
occurs to me.  Isn't Ron's definition of longitude independent of
which direction is north?  The spin of the planet is independent of
the coordinate system in which you measure it.  You can change the
numerical sign of the spin by swapping which pole you call north, but
that also changes the coordinate system to which you refer the number.
The end result would be that any given spot on the planet is assigned
the same numerical longitude, no matter which pole definition you use.
(This is only speculation on my part, BTW.)

--
This is a shared guest account, please send replies to
[e-mail] (Internet)  ["Life's a Beech, and then you Dive."]
Dan Briggs / NRAO / P.O. Box O / Socorro, NM / 87801  (U.S. Snail)

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

Date: 14 Oct 90 15:52:28 GMT
From: van-bc!ubc-cs!news-server.csri.toronto.edu!utgpu!watserv1!maytag!watdragon!watyew![e-mail]  (Brian or James)
Subject: North and South off Earth [was Magellan/Venus Info]


    If you were to stand on the surface of Venus with a magnetic compass
in your hand, would 'north:compass' be the same as 'north:clockwise convention',or the opposite? I know Venus doesn't have a strong magnetic field, so
it might not be useful for this. For that matter, the north magnetic pole
might not be anywhere near the north/south axis of rotation pole. Just
look at Uranus.

                                James Nicoll

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

Date: 8 Oct 90 22:26:57 GMT
From: uceng![e-mail]  (daniel mocsny)
Subject: Re: Manned/unmanned tradeoffs

While we are on the subject of dealing with time delays, I
wonder if anyone has considered hiring whales to teleoperate
bulldozers on the Moon.

The speed of nerve signal propagation is not very high in
biological systems. I seem to remember an upper limit in the
low hundreds of feet per second, for the fastest (myelinated)
axons. (Anybody know the actual numbers?)

That would mean that very large animals, such as the biggest
cetaceans, would run into round-trip teleoperation delays on the
order of 1 sec for moving, say, their hindmost extremities. This
would seem to create some peculiar problems for coordination,
because different parts of the whale's body would have
noticeably different propagation delays. The whale must be
aware of this, because it also senses its environment with
sonar, which is probably faster than its tactile nerves.
I.e., a sperm whale doing battle with a giant squid probably
senses collisions first by sonar before it feels them, if the
contact areas are far from its brain. As far as I know,
whales can deal with this problem and be very successful in
their environments anyway.

The longest animals which have lived (the sauropods) apparently
coped with propagation delays by off-loading a portion of their
control to a large nerve ganglion located about halfway back
along the spine. Perhaps a tail that was too slow to react was
a competitive disadvantage to a sauropod. The sauropod could
have had its tail stepped on, or munched on, and reacted too
slowly to avoid injury.

[e-mail]

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

Date: 14 Oct 90 17:50:33 GMT
From: world!ksr![e-mail]  (Chris Jones)
Subject: Re: Atmospheric nitrogen

In article <[e-mail]>, roberts@CMR (John Roberts) writes:
>
>>From: Richard Ristow <[e-mail]>
>>Subject:      Re: gravity and atmosphere (nitrogen
>
>>>For that matter, we don't know for sure that long-term absence of major
>>>quantities of nitrogen doesn't have some obscure harmful effect.
>
>>I suggest that for planetary atmospheres (as opposed to short-term breathing
>>and managed biospheres) the absence of nitrogen has a harmful effect that's
>>far from obscure:  atmospheric nitrogen is the substrate from which combined
>>nitrogen is produced by biological and abiological 'fixing' processes
>>(the former mainly an enzyme chain in certain prokaryotes, the latter
>>including nitrogen oxydation in lightning strokes).
>
>Good point, but that in itself does not not imply that a full 78% will be
>required.

I don't have a reference, but I recall reading that we may be paying a penalty
for having so much nitrogen in the air.  As divers know, nitrogen impairs
judgement, an effect that increases as the partial pressure of nitrogen
increases.  For this reason, it is dangerous to dive using compressed air much
below 200 feet.  Experiments have been done substituting some other gas for
nitrogen at 1 atmosphere, and the results show that we're all walking around a
little more sluggish and stupid than we would be if nitrogen weren't so
prevalent.  (Of course, modifying the atmosphere in any major way is likely to
have effects on living organisms we haven't even begun to consider yet, so it
may very well be that an earth-like atmosphere is the ideal for all you
terra-former-wannabes out there.)
--
Chris Jones    [e-mail]    {world,uunet,harvard}!ksr!clj

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

End of SPACE Digest V12 #459
*******************