NASA Scientific and Technical Aerospace Reports

necessary hazard reports, EVA procedures, and ISS flight rules required for operating ISS in a safe and productive manner.
Author (revised)
International Space Station; Spacecraft Charging; Probability Theory; Risk
20040111076 Air Force Research Lab., Hanscom AFB, MA, USA
High-Level Spacecraft Charging at Geosynchronous Altitudes: A Statistical Study
Lai, Shu T.; Tautz, Maurice; 8th Spacecraft Charging Technology Conference; March 2004; 12 pp.; In English; See also
20040111031; No Copyright; Avail: CASI; A03, Hardcopy
We present the results of a statistical study on high-level spacecraft charging at geosynchronous altitudes. Below the
critical temperature T* for a surface material, no spacecraft charging occurs. The spacecraft charging potential data are
obtained from the ion line of the ion energy spectrum. If the ion line can not be clearly identified, the data point is flagged.
We do not use flagged data in our analysis. Since T* depends on the surface material and since each satellite has its own
surface material or materials, each satellite is expected to have its own critical temperature. The coordinated space
environmental parameter data of the Los Alamos National Laboratory (LANL) geosynchronous satellites include spacecraft
charging data measured on several geosynchronous satellites in eclipses and in sunlight over years. We have obtained
statistical results of T* for each satellite studied and found that, beyond T*, the high level spacecraft potential increases almost
linearly with the ambient electron temperature. Amazingly, the critical temperature in sunlight remains the same as in eclipse,
agreeing with the monopole-dipole differential charging model. This work offers a useful method not only for predicting the
onset of spacecraft charging in eclipse and in sunlight but also for predicting highlevel spacecraft charging potential with
reasonable accuracy at any given ambient electron temperature in the geosynchronous environment.
Author
Altitude; Spacecraft Charging; Statistical Analysis; Geosynchronous Orbits
20040111078 Utah State Univ., Logan, UT, USA
Observations of Vehicle Surface Charging in Dusty Plasma
Barjatya, Aroh; Swenson, Charles M.; 8th Spacecraft Charging Technology Conference; March 2004; 14 pp.; In English; See
also 20040111031; No Copyright; Avail: CASI; A03, Hardcopy
The NASA Sudden Atom Layer (SAL) rocket was launched in February of 1998 from Puerto Rico into an approximately
5 km thick sodium layer that peaked at 94 km altitude. This layer was observed from ground based sodium lidar as well as
the Arecibo Radar. The instrument payload consisted of a charged dust detector, an electric field probe, a DC Langmuir probe,
and a RF impedance probe. The instruments experienced an anomalous charging event as the rocket passed through this
sodium layer. We present here an analysis of the DC Langmuir probe data and the RF impedance probe data to compute the
amount of vehicle charging attributed to charged dust. Possible scenarios that could lead to the observed charging effects on
the instruments are investigated using a novel SPICE model. The model development and its features are also presented in
this paper.
Author
Spacecraft Charging; Dusty Plasmas; Sounding Rockets
20040111085 Nara National Coll of Technology, Nara, Japan
Electron-Beam-Induced ESD Triggering Discharge Tests of Solar Arrays for Space Use
Fujii, Haruhisa; Koakutsu, Hideaki; 8th Spacecraft Charging Technology Conference; March 2004; 11 pp.; In English; See
also 20040111031; No Copyright; Avail: CASI; A03, Hardcopy
This paper deals with the electron-beam irradiation experiments concerning the arcing discharge on the solar array. It is
very important to investigate this discharge phenomenon and offer a guideline to design solar arrays with high reliability. We
used a pair of real GaAs solar cells on a substrate as a sample. The sample was biased to -9kV and the electron beam of the
energy of 10keV was irradiated to the sample. On that condition, the voltage from DC battery was applied to the gap between
the cells. The detrimental arcing did not occur even at the gap voltage of about 80V, although a few hundreds of ESD took
place. Therefore, the high voltage use of solar array, for example 100V, is thought not to cause sustained arcing discharge to
destroy the satellite system if arrays are designed to lower the maximum voltage between cell strings with reasonable distance.
Author
Electron Beams; Solar Arrays; Electrostatic Charge; Irradiation; Arc Discharges
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