NASA Scientific and Technical Aerospace Reports

stabilized GEO spacecraft via an improved radiative force model. The macro-model approach for the Tracking and Data Relay
Satellites (TDRSS), models the spacecraft area and reflectivity properties using an assembly of flat plates to represent the
spacecraft components. This ‘box-wing’ approach has been adapted for the UNIX version of the Goddard Trajectory
Determination System (GTDS) at the MIT/Lincoln Laboratory. This thesis presents background and mathematical
development of the macro-model approach. This thesis also describes software development and testing, including
incorporation of a one-panel spacecraft model along with the full macro-model. A model for Earth albedo and Earth infrared
radiation and related software development is also described. Additionally, this thesis gives details about the TDRSS macromodel,
and explains the development of a macromodel for the NASA Geosynchronous Operational Environmental Satellites
(GOES) I-M spacecraft. Results of simulated data testing using the improved radiative force models are presented. The real
data testing detailed in this thesis is an investigation into improving GEO orbit determination using the new force models along
with observation data from the Space Surveillance Network (SSN). For the TDRSS spacecraft, HANDS optical observations
are used in conjunction with the SSN data. NOAA ranging observations are included in some of the tests for the GOES-10
spacecraft. The spacebased visible (SBV) observation model has also been incorporated into GTDS, and SBV observations
are included in the orbit determination testing. The results of this thesis give a better understanding of the process of
determining precise orbits for GEO spacecraft with the box-wing model and SSN observation7
DTIC
Artificial Satellites; Earth Orbits; Geosynchronous Orbits; Orbit Determination; Solar Radiation
20040111738 Pittsburgh Univ., Pittsburgh, PA
Acquisition of Hyperthermal Atomic Oxygen Source
Yang, Judith C.; Aug. 11, 2004; 7 pp.; In English
Contract(s)/Grant(s): F49620-02-1-0198
Report No.(s): AD-A425922; AFRL-SR-AR-TR-04-0446; No Copyright; Avail: CASI; A02, Hardcopy
The objective of this grant was the acquisition of a hyperthermal atomic oxygen (AO) source that is of critical importance
to a Multi-University Research Initiative (MURI) on the fundamental mechanisms of materials degradation in the low earth
orbit (LEO). ("Simulations of Fundamental Degradation Process in Space Environments", PI: J. C. Yang, MURI
Contract #: F49620-O1-1-0336). A Physical Sciences, Inc. (PSI) FASTTM (Fast Atom Sample Tester) source was specially
designed for portability with an ultra-high vacuum exposure chamber and delivered to University of Pittsburgh in October
2003. The portability of this FASTTM AO source allows the utilization of unique experimental tools located at different sites.
This system has now been improved so that the best base vacuum is 4x1O(-9) torr. A room temperature sample stage has been
built, a dual head quartz crystal monitor (QCM) system has been installed for in situ weight loss. A sensitive Mettler balance
was purchased in order to measure total weight changes. All of these items have been installed and working since May 2004.
Present experiments are being performed on Si, Al, Ag and Au single crystals and thin films.
DTIC
Earth Orbits; Oxygen; Oxygen Atoms
20040120869 Morgan Research Corp., Huntsville, AL, USA, NASA Marshall Space Flight Center, Huntsville, AL, USA
Atmospheric Models for Aeroentry and Aeroassist
Justus, C. G.; Duvall, Aleta; Keller, Vernon W.; June 15, 2004; 8 pp.; In English; 2nd Planetary Probe Workshop, 23-26 Aug.
2004, Moffett Field, CA, USA; Original contains color illustrations
Contract(s)/Grant(s): NNM04AA02C; No Copyright; Avail: CASI; A02, Hardcopy
Eight destinations in the Solar System have sufficient atmosphere for aeroentry, aeroassist, or aerobraking/aerocapture:
Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune, plus Saturn’s moon Titan. Engineering-level atmospheric models
for Earth, Mars, Titan, and Neptune have been developed for use in NASA s systems analysis studies of aerocapture
applications. Development has begun on a similar atmospheric model for Venus. An important capability of these models is
simulation of quasi-random perturbations for Monte Carlo analyses in developing guidance, navigation and control algorithms,
and for thermal systems design. Characteristics of these atmospheric models are compared, and example applications for
aerocapture are presented. Recent Titan atmospheric model updates are discussed, in anticipation of applications for trajectory
and atmospheric reconstruct of Huygens Probe entry at Titan. Recent and planned updates to the Mars atmospheric model, in
support of future Mars aerocapture systems analysis studies, are also presented.
Author
Atmospheric Models; Solar System; Aeroassist; Aerobraking; Aerocapture; Guidance (Motion)
24