Ask Dr. SETI ®
Dear Dr. SETI:
The Doctor Responds:
Regardless of their baseline (the distance between them), two identical antennas in an array will have never more than twice the capture area of a single one (hence no more than 3 dB more gain). So two antennas with a long baseline will have the beamwidth and resolving power (but not the sensitivity) of a single antenna as large as that baseline.
On the other hand, interferometry holds much promise for the second stage of SETI, signal verification. When a single antenna has detected a candidate signal, an interferometer array can be used to verify that it is indeed of extra-terrestrial origin, and to help identify the specific star from which it emanated. Once The SETI League's Project Argus network achieves critical mass (that would be at perhaps 1000 participating stations; we have only 57 right now) we can start planning our global inerfometer array.
Project ELBA (Extremely Long Baseline Array) will ultimately interconnect all participating Argus stations into the world's largest phased array. This will require a common time and frequency reference for all participants, to atomic-clock accuracy. We expect that oscillators slaved to the constellation of Global Positioning Satellites (GPS) will do the trick, and are in fact developing the technology right now. Stay tuned for details.
entire website copyright © The SETI League, Inc.
this page last updated 28 December 2002
Top of Page