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Purdy, Craig L.

Publications and source records attributed to Purdy, Craig L..

5 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS2003

TOPEX NASA Altimeter Operations Handbook, September 1992

This operations handbook identifies the commands for the NASA radar altimeter for the TOPEX/Poseidon spacecraft, defines the functions of these commands, and provides supplemental reference material for use by the altimeter operations personnel. The main emphasis of this document is placed on command types, command definitions, command sequences, and operational constraints. Additional document sections describe uploadable altimeter operating parameters, the telemetry stream data contents (for both the science and the engineering data), the Missions Operations System displays, and the spacecraft and altimeter health monitors.

Hancock, David W., III↗
NASA NTRS2001

JEM-EF Space Station Carrier System

The NASA/GSFC Shuttle Small Payloads Projects Office (SSPPO) is developing a carrier system for accommodating scientific and applications payloads on the Japanese Experiment Module - Exposed Facility (JEM-EF). The carrier structure provides for flexible mounting of payload instrumentation in nadir, zenith, or limb-viewing positions. Avionics capability will be provided to accommodate up to four payloads with independent power and signal connections. The JEM-EF carrier builds on over 15 years of experience in developing and operating the "Hitchhiker" carriers used on the Space Shuttle. This paper describes the carrier system, potential payload configurational and related GSFC activities.

Daelemans, Gerard J.↗
NASA NTRS1993

Prelaunch performance of the NASA altimeter for the TOPEX/POSEIDON project

Validation of in-orbit performance has demonstrated the ability of satellite radar altimetry to measure mesoscale absolute dynamic sea surface topography and to measure the variation in the general circulation on the largest spatial scales. Measurements of basin scale mean circulation, however, have been corrupted by system inaccuracies. The TOPEX/POSEIDON radar altimeter satellite applies recent advances in remote sensing instrumentation to reduce long wavelength measurement errors to dramatically lower levels. The TOPEX altimeter measures the range to the ocean surface with 2-cm precision and accuracy through the use of both Ku- and C-band radars, a high pulse repetition frequency, an agile tracker, and absolute internal height calibration. Dual pulse bandwidths for both frequencies make it possible to quickly acquire the surface and begin tracking after crossing the land/ocean boundary. This paper presents the altimeter requirements and the elements of the altimeter design that have resulted in meeting these requirements. Prelaunch test data, based on the use of a Radar Altimeter System Evaluator to simulate the backscatter from the ocean surface, are presented to demonstrate that the TOPEX altimeter will meet these requirements and provide the data necessary to the understanding of basin scale mean circulation.

Marth, Paul C.↗
NASA NTRS1991

NASA radar altimeter for the Topex/Poseidon Project

The Topex/Poseidon Project is a joint U.S. and French mission to develop and operate an earth-orbiting satellite with sensors capable of making accurate measurements of sea level. The NASA Radar Altimeter (NRA), a fifth-generation U.S. altimeter, will provide the primary measurement for the Topex/Poseidon altimetric mission. This paper presents the requirements, altimeter fundamentals, design description, integration and test program, primary elements of ground processing, and assessment for the dual-frequency NRA.

Zieger, Alfred R.↗