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sci.space FAQ - Controversial questions
Archive-name: space/controversy
Last-modified: $Date: 92/09/02 14:48:06 $
CONTROVERSIAL QUESTIONS
These issues periodically come up with much argument and few facts being
offered. The summaries below attempt to represent the position on which
much of the net community has settled. Please DON'T bring them up again
unless there's something truly new to be discussed. The net can't set
public policy, that's what your representatives are for.
WHAT HAPPENED TO THE SATURN V PLANS
Despite a widespread belief to the contrary, the Saturn V blueprints
have not been lost. They are kept at Marshall Space Flight Center on
microfilm.
The problem in re-creating the Saturn V is not finding the drawings, it
is finding vendors who can supply mid-1960's vintage hardware (like
guidance system components), and the fact that the launch pads and VAB
have been converted to Space Shuttle use, so you have no place to launch
from.
By the time you redesign to accommodate available hardware and re-modify
the launch pads, you may as well have started from scratch with a clean
sheet design.
WHY DATA FROM SPACE MISSIONS ISN'T IMMEDIATELY AVAILABLE
Investigators associated with NASA missions are allowed exclusive access
for one year after the data is obtained in order to give them an
opportunity to analyze the data and publish results without being
"scooped" by people uninvolved in the mission. However, NASA frequently
releases examples (in non-digital form, e.g. photos) to the public early
in a mission.
RISKS OF NUCLEAR (RTG) POWER SOURCES FOR SPACE PROBES
There has been extensive discussion on this topic sparked by attempts to
block the Galileo and Ulysses launches on grounds of the plutonium
thermal sources being dangerous. Numerous studies claim that even in
worst-case scenarios (shuttle explosion during launch, or accidental
reentry at interplanetary velocities), the risks are extremely small.
Two interesting data points are (1) The May 1968 loss of two SNAP 19B2
RTGs, which landed intact in the Pacific Ocean after a Nimbus B weather
satellite failed to reach orbit. The fuel was recovered after 5 months
with no release of plutonium. (2) In April 1970, the Apollo 13 lunar
module reentered the atmosphere and its SNAP 27 RTG heat source, which
was jettisoned, fell intact into the 20,000 feet deep Tonga Trench in
the Pacific Ocean. The corrosion resistant materials of the RTG are
expected to prevent release of the fuel for a period of time equal to 10
half-lives of the Pu-238 fuel or about 870 years [DOE 1980].
To make your own informed judgement, some references you may wish to
pursue are:
A good review of the technical facts and issues is given by Daniel
Salisbury in "Radiation Risk and Planetary Exploration-- The RTG
Controversy," *Planetary Report*, May-June 1987, pages 3-7. Another good
article, which also reviews the events preceding Galileo's launch,
"Showdown at Pad 39-B," by Robert G. Nichols, appeared in the November
1989 issue of *Ad Astra*. (Both magazines are published by pro-space
organizations, the Planetary Society and the National Space Society
respectively.)
Gordon L Chipman, Jr., "Advanced Space Nuclear Systems" (AAS 82-261), in
*Developing the Space Frontier*, edited by Albert Naumann and Grover
Alexander, Univelt, 1983, p. 193-213.
"Hazards from Plutonium Toxicity", by Bernard L. Cohen, Health Physics,
Vol 32 (may) 1977, page 359-379.
NUS Corporation, Safety Status Report for the Ulysses Mission: Risk
Analysis (Book 1). Document number is NUS 5235; there is no GPO #;
published Jan 31, 1990.
NASA Office of Space Science and Applications, *Final Environmental
Impact Statement for the Ulysses Mission (Tier 2)*, (no serial number or
GPO number, but probably available from NTIS or NASA) June 1990.
[DOE 1980] U.S. Department of Energy, *Transuranic Elements in the
Environment*, Wayne C. Hanson, editor; DOE Document No. DOE/TIC-22800;
Government Printing Office, Washington, D.C., April 1980.)
IMPACT OF THE SPACE SHUTTLE ON THE OZONE LAYER
From time to time, claims are made that chemicals released from
the Space Shuttle's Solid Rocket Boosters (SRBs) are responsible
for a significant amount of damage to the ozone layer. Studies
indicate that they in reality have only a minute impact, both in
absolute terms and relative to other chemical sources. The
remainder of this item is a response from the author of the quoted
study, Charles Jackman.
The atmospheric modelling study of the space shuttle effects on the
stratosphere involved three independent theoretical groups, and was
organized by Dr. Michael Prather, NASA/Goddard Institute for Space
Studies. The three groups involved Michael Prather and Maria Garcia
(NASA/GISS), Charlie Jackman and Anne Douglass (NASA/Goddard Space
Flight Center), and Malcolm Ko and Dak Sze (Atmospheric and
Environmental Research, Inc.). The effort was to look at the effects
of the space shuttle and Titan rockets on the stratosphere.
The following are the estimated sources of stratospheric chlorine:
Industrial sources: 300,000,000 kilograms/year
Natural sources: 75,000,000 kilograms/year
Shuttle sources: 725,000 kilograms/year
The shuttle source assumes 9 space shuttles and 6 Titan rockets are
launched yearly. Thus the launches would add less than 0.25% to the
total stratospheric chlorine sources.
The effect on ozone is minimal: global yearly average total ozone would
be decreased by 0.0065%. This is much less than total ozone variability
associated with volcanic activity and solar flares.
The influence of human-made chlorine products on ozone is computed
by atmospheric model calculations to be a 1% decrease in globally
averaged ozone between 1980 and 1990. The influence of the space shuttle and
Titan rockets on the stratosphere is negligible. The launch
schedule of the Space Shuttle and Titan rockets would need to be
increased by over a factor of a hundred in order to have about
the same effect on ozone as our increases in industrial halocarbons
do at the present time.
Theoretical results of this study have been published in _The Space
Shuttle's Impact on the Stratosphere_, MJ Prather, MM Garcia, AR
Douglass, CH Jackman, M.K.W. Ko and N.D. Sze, Journal of Geophysical
Research, 95, 18583-18590, 1990.
Charles Jackman, Atmospheric Chemistry and Dynamics Branch,
Code 916, NASA/Goddard Space Flight Center,
Greenbelt, MD 20771
Also see _Chemical Rockets and the Environment_, A McDonald, R Bennett,
J Hinshaw, and M Barnes, Aerospace America, May 1991.
HOW LONG CAN A HUMAN LIVE UNPROTECTED IN SPACE
If you *don't* try to hold your breath, exposure to space for half a
minute or so is unlikely to produce permanent injury. Holding your
breath is likely to damage your lungs, something scuba divers have to
watch out for when ascending, and you'll have eardrum trouble if your
Eustachian tubes are badly plugged up, but theory predicts -- and animal
experiments confirm -- that otherwise, exposure to vacuum causes no
immediate injury. You do not explode. Your blood does not boil. You do
not freeze. You do not instantly lose consciousness.
Various minor problems (sunburn, possibly "the bends", certainly some
[mild, reversible, painless] swelling of skin and underlying tissue)
start after ten seconds or so. At some point you lose consciousness from
lack of oxygen. Injuries accumulate. After perhaps one or two minutes,
you're dying. The limits are not really known.
References:
_The Effect on the Chimpanzee of Rapid Decompression to a Near Vacuum_,
Alfred G. Koestler ed., NASA CR-329 (Nov 1965).
_Experimental Animal Decompression to a Near Vacuum Environment_, R.W.
Bancroft, J.E. Dunn, eds, Report SAM-TR-65-48 (June 1965), USAF School
of Aerospace Medicine, Brooks AFB, Texas.
USING THE SHUTTLE BEYOND LOW EARTH ORBIT
You can't use the shuttle orbiter for missions beyond low Earth orbit
because it can't get there. It is big and heavy and does not carry
enough fuel, even if you fill part of the cargo bay with tanks.
Furthermore, it is not particularly sensible to do so, because much of
that weight is things like wings, which are totally useless except in
the immediate vicinity of the Earth. The shuttle orbiter is highly
specialized for travel between Earth's surface and low orbit. Taking it
higher is enormously costly and wasteful. A much better approach would
be to use shuttle subsystems to build a specialized high-orbit
spacecraft.
[Yet another concise answer by Henry Spencer.]
THE "FACE ON MARS"
There really is a big rock on Mars that looks remarkably like a humanoid
face. It appears in two different frames of Viking Orbiter imagery:
35A72 (much more facelike in appearance, and the one more often
published, with the Sun 10 degrees above western horizon) and 70A13
(with the Sun 27 degrees from the west).
Science writer Richard Hoagland has championed the idea that the Face is
artificial, intended to resemble a human, and erected by an
extraterrestrial civilization. Most other analysts concede that the
resemblance is most likely accidental. Other Viking images show a
smiley-faced crater and a lava flow resembling Kermit the Frog elsewhere
on Mars. There exists a Mars Anomalies Research Society (sorry, don't
know the address) to study the Face.
The Mars Observer mission will carry an extremely high-resolution
camera, and better images of the formation will hopefully settle this
question in a few years. In the meantime, speculation about the Face is
best carried on in the altnet group alt.alien.visitors, not sci.space or
sci.astro.
V. DiPeitro and G. Molenaar, *Unusual Martian Surface Features*, Mars
Research, P.O. Box 284, Glen Dale, Maryland, USA, 1982. [Apparently the
first lengthy consideration of the Face published. Does anybody know
what it costs?]
R.R. Pozos, *The Face of Mars*, Chicago Review Press, 1986. [Account of
an interdisciplinary speculative conference Hoagland organized to
investigate the Face]
R.C. Hoagland, *The Monuments of Mars: A City on the Edge of Forever*,
North Atlantic Books, Berkeley, California, USA, 1987. [Elaborate
discussion of evidence and speculation that formations near the Face
form a city]
M.J. Carlotto, "Digital Imagery Analysis of Unusual Martian Surface
Features," *Applied Optics*, 27, pp. 1926-1933, 1987. [Extracts
three-dimensional model for the Face from the 2-D images]
M.J. Carlotto & M.C. Stein, "A Method of Searching for Artificial
Objects on Planetary Surfaces," *Journal of the British Interplanetary
Society*, Vol. 43 no. 5 (May 1990), p.209-216. [Uses a fractal image
analysis model to guess whether the Face is artificial]
B. O'Leary, "Analysis of Images of the `Face' on Mars and Possible
Intelligent Origin," *JBIS*, Vol. 43 no. 5 (May 1990), p. 203-208.
[Lights Carlotto's model from the two angles and shows it's consistent;
shows that the Face doesn't look facelike if observed from the surface]
NEXT: FAQ #13/15 - Space activist/interest/research groups & space publications
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