FORTE ScienceSpacecraft Structure | Coordinated radio-frequency and optical | Optical | Radio-frequency | Satellite Operation | Sferic Array | Weather | AGU Presentations
The FORTE (Fast On-orbit Recording of Transient Events) satellite was launched on 29 August 1997 and has been in continuous operation since. FORTE's successful launch and engineered robustness were a result of several years of dedicated work by the joint Los Alamos National Laboratory/ Sandia National Laboratories project team, led through mission definition, payload and satellite development, and launch by Dr. Stephen Knox.
FORTE is in a circular, 800-km-altitude orbit inclined 70 degrees from the Earth's equator. FORTE carries a suite of instruments each individually useful, and together exceedingly useful, for the study of lightning. The optical payload, built by Sandia, comprises (1) a fast-time-response photodiode detector (PDD) sampling an 80-degree field-of-view throughout the visible and near-IR and sampled every 15 microseconds, and (2) a 128 x 128 pixel CCD array imager (LLS) whose square image is inscribed in the PDD fov, and whose input is the bright narrow-band-filtered line emission at 0.77 microns wavelength. The radio-frequency payload, built by Los Alamos, comprises (1) a multi-band-coincidence trigger with perpetual recording of power background in all 16 trigger subbands (each 1 MHz wide), (2) a wideband (300 Megasamples/sec) RF receiver operating in any of three positions within the VHF, and (3) a pair of medium-bandwidth (50 Megasamples/sec) simultaneous RF receivers also operating anywhere in the VHF. The RF payload derives its signals from either of two active monopoles, or alternatively from two mutually orthogonal, multi-element, passive, moderate-gain log-periodic antennas on a nadir-directed deployed boom.
Both the RF and optical payloads are configurable for signal-triggered or for time-triggered digitization. There are also options for cross-triggering of PDD and LLS and for cross-triggering of PDD and the RF payload. There is ample memory on board (the RF memory is by far the largest at 160 Megabytes) for thousands of events to be stored and then downloaded. The downloading is done up to several times per day, at both Sandia and the University of Alaska.
This section on FORTE science presents the ongoing analysis and synthesis of FORTE results and of joint results from FORTE and other sensor systems, including NLDN, the Los Alamos Sferic array, and the LMS VHF TOA system.
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