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data smoother. A number of safeguards that allow the incremental phasing in of autonomy and alleviate the potential for
mission-impacting anomalies from the on- board autonomous system are discussed. A comparison of the maneuvers planned
onboard using the EO-1 autonomous control system to those from the operational ground-based maneuver planning system
is presented to quantify our success. The maneuvers discussed encompass reactionary and routine formation maintenance.
Definitive orbital data is presented that verifies all formation flying requirements.
Author
Formation Flying; Autonomy; Spacecraft Control
20030025243 NASA Goddard Space Flight Center, Greenbelt, MD, USA
Evaluation of an Ultra-Low Power Reed Solomon Encoder for NASA’s Space Technology 5 Mission
Li, K. E.; Xapsos, M. A.; Poivey, C.; LaBel, K. A.; Stone, R. F.; Yeh, P-S.; Gambles, J.; Hass, J.; Maki, G.; Marguia, J.; [2003];
10 pp.; In English; Hardened Electronics and Radiation Technology (HEART) Conference, 10-13 Mar. 2003, Albuquerque,
NM, USA; Original contains black and white illustrations; No Copyright; Avail: CASI; A02, Hardcopy
This viewgraph presentation provides information on radiation tests on encoders intended for a constellation of
microsatellites. The encoders use CMOS Ultra-Low Power Radiation Tolerant (CULPRiT) technology. The presentation
addresses power consumption, radiation dosage, and Single Event Upset (SEU).
CASI
Microsatellites; Coders; Microelectronics; Radiation Dosage; Energy Consumption
20030025265 NASA Goddard Space Flight Center, Greenbelt, MD, USA
Libration Orbit Mission Design: Applications of Numerical & Dynamical Methods
Bauer, Frank, Technical Monitor; Folta, David; Beckman, Mark; [2002]; 17 pp.; In English; International Conference on
Libration Point Orbits and Applications, 10-14 Jun. 2002, Girona, Spain; Original contains black and white illustrations; No
Copyright; Avail: CASI; A03, Hardcopy
Sun-Earth libration point orbits serve as excellent locations for scientific investigations. These orbits are often selected
to minimize environmental disturbances and maximize observing efficiency. Trajectory design in support of libration orbits is
ever more challenging as more complex missions are envisioned in the next decade. Trajectory design software must be further
enabled to incorporate better understanding of the libration orbit solution space and thus improve the efficiency and expand
the capabilities of current approaches. The Goddard Space Flight Center (GSFC) is currently supporting multiple libration
missions. This end-to-end support consists of mission operations, trajectory design, and control. It also includes algorithm and
software development. The recently launched Microwave Anisotropy Probe (MAP) and upcoming James Webb Space
Telescope (JWST) and Constellation-X missions are examples of the use of improved numerical methods for attaining
constrained orbital parameters and controlling their dynamical evolution at the collinear libration points. This paper presents
a history of libration point missions, a brief description of the numerical and dynamical design techniques including software
used, and a sample of future GSFC mission designs.
Author
Earth Orbits; Microwave Anisotropy Probe; Numerical Analysis; Trajectory Control
20030025267 NASA Goddard Space Flight Center, Greenbelt, MD, USA
First Results from a Hardware-in-the-Loop Demonstration of Closed-Loop Autonomous Formation Flying
Gill, E.; Naasz, Bo; Ebinuma, T.; [2003]; 2 pp.; In English; 26th Annual AAS Guidance and Control Conference, 5-9 Feb.
2003, Breckenridge, CO, USA; Copyright; Avail: CASI; A01, Hardcopy
A closed-loop system for the demonstration of formation flying technologies has been developed at NASA s Goddard
Space Flight Center. Making use of a GPS signal simulator with a dual radio frequency outlet, the system includes two GPS
space receivers as well as a powerful onboard navigation processor dedicated to the GPS-based guidance, navigation, and
control of a satellite formation in real-time. The closed-loop system allows realistic simulations of autonomous formation
flying scenarios, enabling research in the fields of tracking and orbit control strategies for a wide range of applications. A
sample scenario has been set up where the autonomous transition of a satellite formation from an initial along-track separation
of 800 m to a final distance of 100 m has been demonstrated. As a result, a typical control accuracy of about 5 m has been
achieved which proves the applicability of autonomous formation flying techniques to formations of satellites as close as 50
m.
Author
Autonomy; Feedback Control; Formation Flying; Hardware-In-The-Loop Simulation; Systems Engineering; Satellite Design
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