Planetary Envlronmehts

Interplanetary spacecraft designers face environmental problems that may be unique even in what is, after all, a rather specialized field. Flyby spacecraft, such as Pioneers 10 and 11 and Voyagers 1 and 2, may encounter radiation environments greatly exceeding those in near-Earth space. The Mariner 10 mission to Mercury required the capability to cope with a factor of 10 increase in solar heating compared to Earth orbit, whereas Voyager 2 at Neptune received only about 0.25% of the illumination at Earth. In addition to these considerations, planetary landers face possible hazards such as sulfuric acid in the Venusian atmosphere and finely ground windblown dust on Mars. Spacecraft intended for operation on the lunar surface must be designed to withstand alternating hot and cold soaks of two weeks duration and a range of 200 K.

It is well beyond the scope of this text to discuss in detail the environment of each extraterrestrial body, even where appropriate data exist. Spacecraft system designers involved in missions where such data are required must familiarize themselves with what is known. Because the desired body of knowledge is often lacking, ample safety margins must usually be included in all design calculations.

References

1 Bedingfield, K. L., Leach, R. D., and Alexander, M. B., "Spacecraft System Failures and Anomalies Attributed to the Natural Space Environment," NASA Ref. Pub. 1390, Aug. 1996.

2Engels, R. C., Craig, R. R., and Harcrow, H. W., "A Survey of Payload Integration Methods," Journal of Spacecraft and Rockets, Vol. 21, 1984, pp. 417-424.

3U.S. Standard Atmosphere, National Oceanic and Atmospheric Administration, NOAA S/T 76-1562, U.S. Government Printing Office, Washington, DC, 1976.

4Slobin, S. D., "Atmospheric and Environmental Effects," DSMS Telecommunications Link Design Handbook, Doc. 810-005, Rev. E, Jet Propulsion Lab., Pasadena, CA, Jan. 2001.

5Hale, N. W., Lamotte, N. O., and Garner, T. W., "Operational Experience with Hypersonic Flight of the Space Shuttle," AIAA Paper 2002-5259, Oct. 2002.

6Campbell, W. A., Marriott, R. S., and Park, J. J., "Outgassing Data for Selecting Spacecraft Materials," NASA Ref. Pub. 1124,1990.

7Baumjohann, Wā€ž and Treumann, R. A., Basic Space Plasma Physics, Imperial College Press, London, 1986.

8Frezet, M., Daly, E. J., Granger, J. P., and Hamelin, J., "Assessment of Electrostatic Charging of Satellites in the Geostationary Environment," ESA Journal, Vol. 13, 1989, p. 91.

9Leach, R. D., and Alexander, M. B., "Failures and Anomalies Attributed to Spacecraft Charging," NASA Ref. Pub. 1375, Aug. 1995.

I0Ferguson, D. C., "Interactions Between Spacecraft and Their Environments," National Aeronautics and Space Administration, Glenn Research Center, Cleveland, OH, 1993; also Proceedings, ALAA Aerospace Sciences Meeting, Reno, NV, January 1993.

11 Whorton, M. S., Eldridge, J. T., Ferebee, R. C., Lassiter, J. O., and Redmon, J. W., Jr., "Damping Mechanisms for Microgravity Vibration Isolation," NASA TM-1998-206953, Jan. 1998.

12May, T. C., and Woods, M. H., "Alpha-Particle-Induced Soft Errors in Dynamic Memories," IEEE Transactions on Electron Devices, Vol. ED-26, No. 1, 1979, pp. 2-9.

13Cunningham, S. S., "Cosmic Rays, Single Event Upsets and Things That Go Bump in the Night," Proceedings of the AAS Rocky Mountain Guidance and Control Conference, Paper AAS-84-05, 1984.

14Cunningham, S. Sā€ž Banasiak, J. A., and Von Flowtow, C. S., "Living with Things That Go Bump in the Night," Proceedings of the AAS Rocky Mountain Guidance and Control Conference, Paper AAS-85-056, 1985.

l5Bouquet, F. L., and Koprowski, K. F., "Radiation EiTects on Spacecraft Materials for Jupiter and Near-Earth Orbiters," IEEE Transactions on Nuclear Science, Vol. NS-29, No. 6,1982, pp. 1629-1632.

l6Frisch, B., "Composites and the Hard Knocks of Space," Astronautics and Aeronautics, Vol. ?, pp. 33-38.

""Meteoroid Environment Model-1969," NASA SP-8013.

18Cour-Palais, B., "Hypervelocity Impact in Metals, Glass, and Composites," International Journal of Impact Engineering, Vol. 5, 1987, pp. 221-237.

"international Academy of Astronautics, "Position Paper on Orbital Debris," Paris, France, Nov. 2001.

20Kessler, D. J., and Cour-Palais, B. G., "Collision Frequency of Artificial Satellites: The Creation of a Debris Belt," Journal of Geophysical Research, Vol. 83, No. A6, 1978, pp.

21 Liou, J., Matney, M. J., Anz-Meador, P. D., Kessler, D. J., Jansen, M., and Theall, J. R., "The New NASA Orbital Debris Engineering Model ORDEM 2000," NASA/TP-2002-210780, May 2002.

22Tan, A., and Zhang, D., "Analysis and Interpretation of the Delta 180 Collision Experiment in Space," Journal of the Astronautical Sciences, Vol. 49, OcL-Dec. 2001, pp. 585-599.

23National Research Council, Orbital Debris: A Technical Assessment, National Academy Press, Washington, DC, 1995.

24National Research Council, "Protecting the Space Station from Meteoroids and Orbital Debris," Washington, DC, Jan. 1997.

Problems

3.1 At its atmospheric entry interface of h ā€” 122 km altitude, the space shuttle air-relative velocity is about 7.9 km/s. The angle of attack at that time is typically about 40 deg, and the planform area is 367 m2. What is the drag acceleration (see Chapter 4) at the entry interface under standard atmosphere conditions?

3.2 On a particular day at Cape Canaveral, the air pressure and temperature are measured and found to be 101,000 N/m2 and 298 K, respectively. What is the density, and what is the density altitude? Assume Rgas = 287.05 J/kg ā€¢ K for air (see Chapter 6).

3.3 What is the expected number of impacts on the space shuttle during a two-week mission at 400 km circular orbit altitude and 51.6 deg inclination by debris particles greater than 4 mm in size? For particles greater than 1 cm? Assume the planform area of 367 m2 to be the relevant target area.

3.4 How much flight time should the space shuttle fleet expect to accumulate before experiencing an impact by a micrometeoroid of 0.1 g or greater mass, assuming an average orbit of 400-km altitude?

3.5 The Global Positioning System (GPS) satellite constellation operates in 63-deg inclination orbits at approximately 11,000 n mile altitude. Give a rough estimate of the expected total radiation dose from protons and electrons for these satellites assuming a nominal ten-year mission.

3.6 Consider a plot of acceleration spectral density (ASD) such as in Fig. 3.17. Note that this is a graph of log10 ASD vs log 10io/hz- Assuming simple harmonic oscillation, what is the slope (dB/octave) of a curve of constant displacement on such a plot?

3.7 Calculate the average acceleration loading due to random vibration, gnns. for the curve of Fig. 3.17.

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Getting Started With Solar

Getting Started With Solar

Do we really want the one thing that gives us its resources unconditionally to suffer even more than it is suffering now? Nature, is a part of our being from the earliest human days. We respect Nature and it gives us its bounty, but in the recent past greedy money hungry corporations have made us all so destructive, so wasteful.

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