New antenna systems for NASA satellites

USA Today (Society for the Advancement of Education), August, 2005

Sophisticated signal processing techniques and simple proof-of-principle antenna arrays built from PVC pipe, aluminum foil, and copper wire could revolutionize the way NASA obtains data from its Earth-observing satellites. If the adaptive array system being studied by NASA and Georgia Institute of Technology, Atlanta, researchers ultimately proves feasible, it dramatically could decrease the cost of building and maintaining ground stations. Ultimately, that could make information from the space agency's Earth-observing satellites more widely and rapidly available.

"The dream would be to provide total global coverage with these antenna systems and to network the systems together to make these NASA information services available to anybody sitting at a computer, almost like video-on-demand," explains Mary Ann Ingram, a professor in Georgia Tech's School of Electrical and Computer Engineering. "Timely information from Earth-observing satellites could be useful in many ways, such as directing operations to fight a forest fire, for instance."

Information from satellites such as Earth Observing-1 (EO-1) now is downlinked to various 11 -meter dishes, primarily in the Arctic Circle, where sub-zero temperatures create maintenance and reliability issues for their complex aiming mechanisms. Typically, satellites like EO-1 are in contact with these antenna systems between five and eight times per day for 10 minutes at a time. The present systems cost approximately $4,000,000 each, and require resident crews to operate as well as maintain them constantly.

The NASA/Georgia Tech project envisions replacing these with a network of inexpensive antenna arrays that would have no moving parts and use sophisticated software--instead of careful aiming--to gather data from the satellites. The network could lower operational costs while improving information access.

"When people use cell phones to make calls, there are no moving parts on the antennas," notes Dan Mandl, mission director for NASA's EO-1 program at Goddard Space Flight Center near Washington, D.C. "What I would like to do is build a continuous cell-like network around the world that would provide almost unlimited opportunities to downlink data."

Mandl compares NASA's existing downlink system to old-fashioned pay phones located off expressway exits. "If you witness an accident, you can open your cell phone and call for assistance," he says. "But if you don't have a cell phone, you have to get off the highway at the next exit and hunt for a pay phone. What we would like to do is give these satellites the equivalent of cell phones to allow anytime, anywhere contact."