Archive-name: space/controversy Last-modified: $Date: 93/04/01 14:39:06 $  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.       HOW THE CHALLENGER ASTRONAUTS DIED      The Challenger shuttle launch was not destroyed in an explosion. This is     a well-documented fact; see the Rogers Commission report, for example.     What looked like an explosion was fuel burning after the external tank     came apart. The forces on the crew cabin were not sufficient to kill the     astronauts, never mind destroy their bodies, according to the Kerwin     team's medical/forensic report.      The astronauts were killed when the more-or-less intact cabin hit the     water at circa 200MPH, and their bodies then spent several weeks     underwater. Their remains were recovered, and after the Kerwin team     examined them, they were sent off to be buried.       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. $18 by mail.      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]