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Prototype Test Results for the Single Photon Detection SLR2000 Satellite Laser Ranging SystemNASA's aging Satellite Laser Ranging (SLR) network is scheduled to be replaced over the next few years with a fully automated single photon detection system. A prototype of this new system, called SLR2000, is currently undergoing field trials at the Goddard Space Flight Center in Greenbelt, Maryland to evaluate photon counting techniques and determine system hardware, software, and control algorithm performance levels and limitations. Newly developed diode pumped microchip lasers and quadrant microchannel plate-based photomultiplier tubes have enabled the development of this high repetition rate single photon detection SLR system. The SLR2000 receiver threshold is set at the single photoelectron (pe) level but tracks satellites with an average signal level typically much less than 1 pe. The 2 kHz laser fire rate aids in satellite acquisition and tracking and will enable closed loop tracking by accumulating single photon count statistics in a quadrant detector and using this information to correct for pointing errors. Laser transmitter beamwidths of 10 arcseconds (FWHM) or less are currently being used to maintain an adequate signal level for tracking while the receiver field of view (FOV) has been opened to 40 arcseconds to accommodate point ahead/look behind angular offsets. In the near future, the laser transmitter point ahead will be controlled by a pair of Risley prisms. This will allow the telescope to point behind and enable closure of the receiver FOV to roughly match the transmitter beam divergence. Bandpass filters (BPF) are removed for night tracking operations while 0.2 nm or 1 nm filters are used during daylight operation. Both day and night laser tracking of Low Earth Orbit (LEO) satellites has been achieved with a laser transmitter energy of only 65 microjoules per pulse. Satellite tracking is presently limited to LEO satellites until the brassboard laser transmitter can be upgraded or replaced. Simultaneous tracks have also been observed with NASA s SLR standard, MOBLAS 7, for the purposes of data comparison and identification of biases. Work continues to optimize the receive optics; upgrade or replace the laser transmitter; calibrate the quadrant detector, the point ahead Risley prisms, and event timer verniers; and test normal point generation with SLR2000 data. This paper will report on the satellite tracking results to date, issues yet to be resolved, and future plans for the SLR2000 system.
Document ID
20040171398
Acquisition Source
Goddard Space Flight Center
Document Type
Conference Paper
Authors
Zagwodzki, Thomas W.
(NASA Goddard Space Flight Center Greenbelt, MD, United States)
McGarry, Jan F.
(NASA Goddard Space Flight Center Greenbelt, MD, United States)
Degnan, John J.
(Sigma Space Corp. Lanham, MD, United States)
Cheek, Jack W.
(Raytheon Information Technology and Scientific Services)
Dunn, Peter J.
(Raytheon Information Technology and Scientific Services)
Patterson, Don
(Honeywell Technology Solutions, Inc.)
Donovan, Howard
(Honeywell Technology Solutions, Inc.)
Date Acquired
August 22, 2013
Publication Date
January 1, 2004
Subject Category
Communications And Radar
Meeting Information
Meeting: 2004 AMOS Technical Conference
Location: Maui, HI
Country: United States
Start Date: September 13, 2004
End Date: September 17, 2004
Distribution Limits
Public
Copyright
Other

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