SCIENTIFIC AND TECHNICAL AEROSPACE REPORTS

A Biweekly Publication of the National Aeronautics and Space Administration
VOLUME 43, ISSUE 19 - SEPTEMBER 23, 2006

14 GROUND SUPPORT SYSTEMS AND FACILITIES (SPACE)
Includes launch complexes, research and production facilities; ground support equipment, e.g., mobile transporters; and test chambers and simulators.

Also includes extraterrestrial bases and supporting equipment.

For related information see also 09 Research and Support Facilities (Air).

20050210122 NASA Goddard Space Flight Center, Greenbelt, MD, USA

LEO Download Capacity Analysis for a Network of Adaptive Array Ground Stations

Ingram, Mary Ann; Barott, William C.; Popovic, Zoya; Rondineau, Sebastien; Langley, John; Romanofsky, Robert; Lee, Richard Q.; Miranda, Felix; Steffes, Paul; Mandl, Dan; [2005]; 7 pp.; In English; SERP 2005, 27-30 Jun. 2005, Las Vegas, NV, USA Contract(s)/Grant(s): NAG5-13362.; Copyright; Avail: CASI; A02, Hardcopy

To lower costs and reduce latency, a network of adaptive array ground stations, distributed across the USA, is considered for the downlink of a polar-orbiting low earth orbiting (LEO) satellite. Assuming the X-band 105 Mbps transmitter of NASA s Earth Observing 1 (EO-1) satellite with a simple line-of-sight propagation model, the average daily download capacity in bits for a network of adaptive array ground stations is compared to that of a single 11 m dish in Poker Flats, Alaska. Each adaptive array ground station is assumed to have multiple steerable antennas, either mechanically steered dishes or phased arrays that are mechanically steered in azimuth and electronically steered in elevation. Phased array technologies that are being developed for this application are the space-fed lens (SFL) and the reflectarray. Optimization of the different boresight directions of the phased arrays within a ground station is shown to significantly increase capacity; for example, this optimization quadruples the capacity for a ground station with eight SFLs. Several networks comprising only two to three ground stations are shown to meet or exceed the capacity of the big dish, Cutting the data rate by half, which saves modem costs and increases the coverage area of each ground station, is shown to increase the average daily capacity of the network for some configurations. Author

Earth Observing System (EOS); Low Earth Orbits; Cost Reduction; Antenna Arrays; Ground Stations; Artificial Satellites

Source: NASA.