Nasa Goddard Space Flight Center example essay topic

People arguing over shuttle costs on the net are usually arguing from different assumptions and do not describe their assumptions clearly, making it impossible to reach agreement. To demonstrate the difficulty, here are a range of flight cost figures differing by a factor of 35 and some of the assumptions behind them (all use 1992 constant dollars). $45 million - marginal cost of adding or removing one flight from the manifest in a given year. $414 million - NASA's average cost / flight, assuming planned flight rates are met and using current fiscal year data only. $1 billion - operational costs since 1983 spread over the actual number of flights. $900 million - $1.35 billion - total (including development) costs since the inception of the shuttle program, assuming 4 or 8 flights / year and operations ending in 2005 or 2010.

$1.6 billion - total costs through 1992 spread over the actual number of flights through 1992. For more detailed information, see the Aviation Week Forum article by Roger A. Pi elke, Jr. : 'Space Shuttle Value Open To Interpretation', July 26, 1993, pg. 57. 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 Federal Archives in East Point, GA also has 2900 cubic feet of Saturn documents.

Rocket dyne has in its archives dozens of volumes from its Knowledge Retention Program. This effort was initiated in the late '60's to document every facet of F-1 and J-2 engine production to assist in any future re-start. The problem in re-creating the Saturn V is not finding the drawings, its finding vendors who can supply mid-1960's vintage hardware (like guidance system components), and the fact that the launch pads and VABhave 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. Other references: Several AIAA papers delivered in recent years discuss reviving the Saturn V. For example, AIAA paper 92-1546, 'Launch Vehicles for the Space Exploration Initiative'.

This paper concluded that a revived Saturn V was actually cheaper than the NLS vehicle. An overview of the infrastructure still available to support production of a 1990's Saturn V and how that vehicle might be used to support First Lunar Outpost missions can be found in the December 1993 issue of Spaceflight, published by the British Interplanetary Society. 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 19 B 2 Rtg, 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,'s how down 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, Unive lt, 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, DC, 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 (S RBs) 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 model ling 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 / GIS S), Charlie Jackman and Anne Douglass (NASA / Goddard SpaceFlight 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 a relaunched 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. An expanded discussion of this issue, citing several case studies, maybe found at web 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. Survival Under Near-Vacuum Conditions in the article 'Barometric Pressure,' by C.E. Billings, Chapter 1 of Bioastronautics Data Book, Second edition, NASA SP-3006, edited by James F. Parker Jr. and Vita R. West, 1973.

HOW THE CHALLENGER ASTRONAUTS DIED The Challenger shuttle 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 medical / forensic report by Joe Kerwin's team confirmed what was already suspected for other reasons: at least some of the crew were not only alive, but conscious, for at least a few seconds after the orbiter broke up.

The forces of the breakup were not violent enough for a high probability of lethal injury, and some of the emergency-escape air packs had been turned on manually. However, unless the cabin held pressure -- which could not be determined positively, but seems unlikely -- they almost certainly were unconscious within seconds, and did not recover before water impact. They did not have oxygen masks (the emergency-escape packs held air, not oxygen, for use in pad emergencies) and the cabin apogee was circa 100,000 ft. The circa 200 MPH water impact was most certainly violent enough to kill them all. It smashed the cabin so badly that Kerwin's team could not determine whether it had held pressure or not.

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. The Kerwin report was discussed in Aviation Week and other sources at the time. World Spaceflight News printed the full text.

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: 35 A 72 (much more face like in appearance, and the one more often published, with the Sun 10 degrees above western horizon) and 70 A 13 (with the Sun 27 degrees from the west). The feature, about 2.5 km across, is located near 9 degrees longitude, +41 degrees N latitude, near the border between region Arabia Terra and region Acid alia Planitia. 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 (see address for " Mars Research' below) to study the Face.