That is why Drake (author of Drake eqn, now director of SETI) is searching for ET in the radio and optical rather than proposing to develop technology to travel there. Sagan's proposal to go to Mars, etc was for purely scientific exploration, not as a prelude to spread our seed across the galaxy.
Virtually all astronomers believe that ET will NOT drive up in a spaceship; he/she/it/? will send us a signal (hence SETI), IF he chooses.
The signal will have to be deliberate, powerful and carefully planned; a TV broadcast (a la Contact) won't do it. Even Arecibo Observatory doing ionospheric/planetary radar probably wouldn't do it (too sporadic) even though AO could easily communicate with a comparable facility a good fraction of the distance across the Milky Way (IF we knew it was there; hence SETI). But even a round-trip "hello/how are you?" to the nearest star would take 6+ years....
Drake's estimate from his eqn a year ago was either about 1K or 10K (I forget which). I wonder how far he would reduce the estimate after Sept 11?
(former radio astronomer at AO)
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That is why Drake (author of Drake eqn, now director of SETI) is searching for ET in the radio and optical rather than proposing to develop technology to travel there. Sagan's proposal to go to Mars, etc was for purely scientific exploration, not as a prelude to spread our seed across the galaxy. Virtually all astronomers believe that ET will NOT drive up in a spaceship; he/she/it/? will send us a signal (hence SETI), IF he chooses. The signal will have to be deliberate, powerful and carefully planned; a TV broadcast (a la Contact) won't do it. Even Arecibo Observatory doing ionospheric/planetary radar probably wouldn't do it (too sporadic) even though AO could easily communicate with a comparable facility a good fraction of the distance across the Milky Way (IF we knew it was there; hence SETI). But even a round-trip "hello/how are you?" to the nearest star would take 6+ years.... Drake's estimate from his eqn a year ago was either about 1K or 10K (I forget which). I wonder how far he would reduce the estimate after Sept 11? (former radio astronomer at AO)