SETI Search for Extra Terrestrial Intelligence. ASTR 1420 Lecture 20 Sections 12.3. History. Guglielmo Marconi (1874-1937) 1 st cross-Atlantic radio communication Nikola Tesla (1856-1943) inventor of AC current
They both claimed to hear a radio signal from alien worlds. In fact, they both heard atmospheric “whistlers”
In 1924, when the Mars was close to Earth, a large campaign to hear a signal from Mars…
Destined to fail. Why?
? which radio frequency ?
Three possible types of alien signals
to reach out to many homes…
We can detect only an intended signal from aliens at this point.
what communication protocol?
We sent out a radio signal
using the world’s largest
antenna (Arecibo) in 1974
1,679 bits in a 3-minute message
1,679 = a multiple of two prime numbers (23, 73).
M13 : 21000 light-years away, a globular cluster with ~1 million stars!
Build a telescope on the hidden side of the Moon!?
SETI@Home (2-3% of data)
(diameter = 16km)
At 100 Ly away with an Arecibo-like receiver: omni-directional signal requires to be 66,000 MW, while a beam signal to be only 0.0033MW.
Instead of sending a signal, advanced aliens might have visited US already and buried their instruction somewhere in the Solar System!
energy usage upto 1017 Watts
energy usage up to 1026 Watts
energy usage of 1037 Watts
Seen from the USS Enterprise bridge
The Enterprise in orbit around the Dyson sphere