NASA Scientific and Technical Aerospace Reports

The NASA supported project ‘Modeling of Cometary Atmospheres’ has been quite successful in broadening our
understanding of the cometary environment. We list peer reviewed publications and conference presentation that have been
made as a result of studies performed under this project. Following the list we present details of a selection of the results.
Author
Cometary Atmospheres; Ion Distribution; Magnetohydrodynamics
20040111967 NASA Johnson Space Center, Houston, TX, USA
The LEO Particulate Environment as Determined by LDEF
See, Thomas H.; Zolensky, Michael E.; Hoerz, Friedrick; Bernhard, P.; Leago, Kimberly S.; Warren, Jack L.; Sapp, Clyde A.;
Foster, Tammy R.; Kinard, William H.; [1993]; 11 pp.; In English; Original contains color and black and white illustrations;
No Copyright; Avail: CASI; A03, Hardcopy
The Meteoroid & Debris Special Investigation Group has been studying the low-Earth orbit particulate environment by
examining and documenting impact craters that occurred on the Long Duration Exposure Facility (LDEF) during its 5.7 year
stay in orbit.
Author
Debris; Long Duration Exposure Facility; Low Earth Orbits; Meteoroids; Particulates
20040120953 Computer Sciences Corp., Huntsville, AL, USA
Atmospheric Models for Aerocapture Systems Studies
Justus, C. G.; Duvall, Aleta; Keller, Vernon W.; December 19, 2003; 5 pp.; In English; AIAA Atmospheric Flight Mechanics
Symposium, 16-19 Aug. 2004, Providence, RI, USA
Contract(s)/Grant(s): NAS8-60000; No Copyright; Avail: Other Sources
Aerocapture uses atmospheric drag to decelerate into captured orbit from interplanetary transfer orbit. This includes
capture into Earth orbit from, for example, Lunar-return or Mars-return orbit. Eight Solar System destinations have sufficient
atmosphere for aerocapture to be applicable - three of the rocky planets (Venus, Earth, and Mars), four gas giants (Jupiter,
Saturn, Uranus, and Neptune), and Saturn’s moon Titan. These destinations fall into two groups: (1) The rocky planets, which
have warm surface temperatures (approx. 200 to 750 K) and rapid decrease of density with altitude, and (2) the gas giants and
Titan, which have cold temperatures (approx. 70 to 170 K) at the surface or 1-bar pressure level, and slow rate of decrease
of density with altitude. The height variation of average density with altitude above 1-bar pressure level for the gas giant
planets is shown. The periapsis density required for aerocapture of spacecraft having typical values of ballistic coefficient (a
measure of mass per unit cross-sectional area) is also shown. The aerocapture altitudes at the gas giants would typically range
from approx. 150 to 300 km. Density profiles are compared for the rocky planets with those for Titan and Neptune.
Aerocapture at the rocky planets would occur at heights of approx. 50 to 100 km. For comparison, typical density and altitudes
for aerobraking operations (circularizing a highly elliptical capture orbit, using multiple atmospheric passes) are also indicated.
Author (revised)
Atmospheric Models; Aerocapture; Aerobraking; Planetary Atmospheres
20040121084 NASA Marshall Space Flight Center, Huntsville, AL, USA
Computed Tomography and its Application for the 3D Characterization of Coarse Grained Meteorites
Gillies, Donald C.; Engel, H. P.; Carpenter, P. K.; [2004]; 1 pp.; In English; Microscopy and Microanalysis 2004 Conference,
1-5 Aug. 2004, Savannah, GA, USA; No Copyright; Avail: Other Sources; Abstract Only
With judicious selection of parameters, computed tomography can provide high precision density data. Such data can lead
to a non-destructive determination of the phases and phase distribution within large solid objects. Of particular interest is the
structure of the Mundrabilla meteorite, which has 25 volumes, percent of a sulfide within a metallic meteorite. 3D digital
imaging has enabled a quantitative evaluation of the distribution and contiguity of the phases to be determined.
Author
Meteorites; Tomography; Three Dimensional Models; Microscopy
20040121128 Aviation Week and Space Technology, USA
Making Tracks at JPL
Covault, Craig; Aviation Week and Space Technology; June 21, 2004; Volume 160, No. 25, pp. 66-67; In English; Original
contains black and white illustrations; Copyright; Avail: Other Sources
The President’s commission on manned and unmanned lunar and Mars exploration is calling for redefinition of the U.S.
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