R* = the average rate of star formation in our galaxy
fp = the fraction of those stars that have planets
ne = the average number of planets that can potentially support life per star 'that has planets'
fl = the fraction of planets that could support life that actually develop 'life at some point'
fi = the fraction of planets with life that actually go on to develop 'intelligent life'
fc = the fraction of civilizations that develop a technology that releases 'detectable signs of their existence into space'
L = the length of time for which such civilizations release detectable 'signals into space'
SETI@home and Astropulse are funded by grants from the National Science Foundation, NASA, and donations from SETI@home volunteers. AstroPulse is funded in part by the NSF through grant AST-0307956.
