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e modeled for the Leonardo constellation mission, but is intended to be adaptable to any constellation mission. To develop
a common software architecture. the controllers will only model very high-level responses. For instance, after determining that
a maneuver must be made. the MADECC system will output B (Delta)V (velocity change) value. Lower level systems must
then decide which thrusters to fire and for how long to achieve that (Delta)V.
Author
Attitude Control; Automatic Control; Autonomy; Information Systems
20030025352 NASA Goddard Space Flight Center, Greenbelt, MD, USA
Internet Technology for Future Space Missions
Hennessy, Joseph F., Technical Monitor; Rash, James; Casasanta, Ralph; Hogie, Keith; October 2002; 9 pp.; In English;
International Telemetering Conference 2002, 21-24 Oct. 2002, San Diego, CA, USA; Original contains black and white
illustrations
Contract(s)/Grant(s): GS-35F-4381G; S-43981-G; Copyright; Avail: CASI; A02, Hardcopy
Ongoing work at National Aeronautics and Space Administration Goddard Space Flight Center (NASA/GSFC), seeks to
apply standard Internet applications and protocols to meet the technology challenge of future satellite missions. Internet
protocols and technologies are under study as a future means to provide seamless dynamic communication among
heterogeneous instruments, spacecraft, ground stations, constellations of spacecraft, and science investigators. The primary
objective is to design and demonstrate in the laboratory the automated end-to-end transport of files in a simulated dynamic
space environment using off-the-shelf, low-cost, commodity-level standard applications and protocols. The demonstrated
functions and capabilities will become increasingly significant in the years to come as both earth and space science missions
fly more sensors and the present labor-intensive, mission-specific techniques for processing and routing data become
prohibitively. This paper describes how an IP-based communication architecture can support all existing operations concepts
and how it will enable some new and complex communication and science concepts. The authors identify specific end-to-end
data flows from the instruments to the control centers and scientists, and then describe how each data flow can be supported
using standard Internet protocols and applications. The scenarios include normal data downlink and command uplink as well
as recovery scenarios for both onboard and ground failures. The scenarios are based on an Earth orbiting spacecraft with
downlink data rates from 300 Kbps to 4 Mbps. Included examples are based on designs currently being investigated for
potential use by the Global Precipitation Measurement (GPM) mission.
Author
Internets; Protocol (Computers); Space Missions; Space Communication; Applications Programs (Computers)
20030025363 NASA Goddard Space Flight Center, Greenbelt, MD, USA
Jason-1 Precise Orbit Determination from GPS Tracking: Method, Performance and Calibration of the Lc Phase
Center Offset
Luthcke, Scott B.; October 2002; 1 pp.; In English; Jason-1/TOPEX/Poseidon Science Working Team, 21-23 Oct. 2002, New
Orleans, LA, USA; No Copyright; Avail: Other Sources; Abstract Only
Jason-1, launched on December 7, 2001, is continuing the time series of centimeter level Ocean topography observations
as the follow-on to the highly successful TOPEX/POSEIDON (T/P) radar altimeter satellite. The precision orbit determination
(POD) is a critical component to meeting the Ocean topography goals of the mission. T/P has demonstrated that the time
variation of Ocean topography can be determined with an accuracy of a few centimeters, thanks to the availability of highly
accurate orbits based primarily on SLR+DORIS tracking. The Jason-1 mission is intended to continue measurement of the
Ocean surface with the same, if not better accuracy.
Author
Calibrating; Global Positioning System; Orbit Determination; Tracking (Position)
20030025663 NASA Goddard Space Flight Center, Greenbelt, MD, USA
Satellite GN and C Anomaly Trends
Robertson, Brent; Stoneking, Eric; [2003]; 15 pp.; In English; 2003 AAS Guidance and Control Conference, 5-9 Feb. 2003,
Breckenridge, CO, USA
Report No.(s): AAS-03-071; No Copyright; Avail: CASI; A03, Hardcopy
On-orbit anomaly records for satellites launched from 1990 through 2001 are reviewed to determine recent trends of
un-manned space mission critical failures. Anomalies categorized by subsystems show that Guidance, Navigation and Control
(GN&C) subsystems have a high number of anomalies that result in a mission critical failure when compared to other
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