The Drake equation is a tool used by scientists engaged in the Search for Extraterrestrial Intelligence (SETI). It is used to estimate N, the number of potentially contactable, technologically advanced civilizations presently in existence in the Milky Way Galaxy. It is usually expressed as N=Rx fs xp x SLX Six ft x L The terms in the equation are defined as: • N, the number of civilizations in the Milky Way Galaxy • R, the rate of formation of Sun-like stars in the Milky Way Galaxy • fs, the fraction of Sun-like stars with planets ● др. the average number of habitable planets per star • L. the fraction of habitable planets that have life • f₁, the fraction of life forms that evolve intelligence • fr. the fraction of intelligent species that develop advanced technology and choose to send messages into space L, the average lifetime of technologically advanced civilizations Suppose that using the current estimates of the terms in the Drake equation results in a best estimate for N of 1000 civilizations Now suppose that recent observations suggest new values for two of the variables. The value for fs is now 0.5 times its previou estimate and L. is now 5 times its previous estimate. How many civilizations would now be estimated as detectable in the Galaxy?

The Drake equation is a tool used by scientists engaged in the Search for Extraterrestrial Intelligence (SETI). It is used to estimate N, the number of potentially contactable, technologically advanced civilizations presently in existence in the Milky Way Galaxy. It is usually expressed as N=Rx fs xp x SLX Six ft x L The terms in the equation are defined as: • N, the number of civilizations in the Milky Way Galaxy • R, the rate of formation of Sun-like stars in the Milky Way Galaxy • fs, the fraction of Sun-like stars with planets ● др. the average number of habitable planets per star • L. the fraction of habitable planets that have life • f₁, the fraction of life forms that evolve intelligence • fr. the fraction of intelligent species that develop advanced technology and choose to send messages into space L, the average lifetime of technologically advanced civilizations Suppose that using the current estimates of the terms in the Drake equation results in a best estimate for N of 1000 civilizations Now suppose that recent observations suggest new values for two of the variables. The value for fs is now 0.5 times its previou estimate and L. is now 5 times its previous estimate. How many civilizations would now be estimated as detectable in the Galaxy?