The equation is N=R*fp ne fl fl fc L, according to Steve Ford, in an article for the SETI league, where:
Dr. Drake's solution to the Drake Equation estimates 10,000 civilizations in the Milky Way capable of communicating with our planet. Although there are many detractors, who say the equation's "f" factors are currently unknown, and estimates of their values span too wide a range, making the estimate no more than a guess; the Drake Equation is generally accepted by the scientific community. 

Dear Readers,
I am not a scientist. I am a fan of science. So far be it from me to second guess some of the most brilliant minds on the planet. But in my eternal quest for knowledge of space and time we have to hear as many points of view as possible. With that in mind, here are a couple more opinions regarding the Drake Equation.
V. Porterfield
I am not a scientist. I am a fan of science. So far be it from me to second guess some of the most brilliant minds on the planet. But in my eternal quest for knowledge of space and time we have to hear as many points of view as possible. With that in mind, here are a couple more opinions regarding the Drake Equation.
V. Porterfield
http://en.wikipedia.org/wiki/Drake_equation
This article is about Frank Drake's equation. For other uses, see Drake equation (disambiguation).
The Drake equation is a probabilistic argument used to estimate the number of active, communicative extraterrestrial civilizations in the Milky Way galaxy. The equation was written in 1961 by Frank Drake not for purposes of quantifying the number of civilizations,[1] but intended as a way to stimulate scientific dialogue at the world's first SETI meeting, in Green Bank, West Virginia. The equation summarizes the main factors which scientists must contemplate when considering the question of other radiocommunicative life.[1] The Drake equation has proved controversial since several of its factors are currently unknown, and estimates of their values span a very wide range. This has led critics to label the equation a guesstimate, or even meaningless.
This article is about Frank Drake's equation. For other uses, see Drake equation (disambiguation).
The Drake equation is a probabilistic argument used to estimate the number of active, communicative extraterrestrial civilizations in the Milky Way galaxy. The equation was written in 1961 by Frank Drake not for purposes of quantifying the number of civilizations,[1] but intended as a way to stimulate scientific dialogue at the world's first SETI meeting, in Green Bank, West Virginia. The equation summarizes the main factors which scientists must contemplate when considering the question of other radiocommunicative life.[1] The Drake equation has proved controversial since several of its factors are currently unknown, and estimates of their values span a very wide range. This has led critics to label the equation a guesstimate, or even meaningless.
(Submitted September 24, 1997)
What are the chances of life existing outside our solar system?
The Answer
This is a question that astronomers first started to quantify in the early 1960s. In 1961, a radio astronomer named Frank Drake developed an equation to stimulate discussion of the Search for Extraterrestrial Intelligence (SETI). This equation, which is now called the Drake equation, states that the number of communicating civilizations in our galaxy likely depends on a number of factors which must combine to yield a habitable planet where life has the chance develop to a certain level of technological knowhow. These factors include the rate of formation of stars like the Sun, the fraction of those with planets, the fraction of Earthlike planets, the fraction of such planets where life develops, the fraction of those where the life becomes intelligent, the fraction of intelligent species who can communicate in a way we would detect, and the lifetime of the communicating civilizations. As you may imagine, there is a lot of debate about reasonable values for most of these factors. As we learn more about the likelihood of planets around other stars, we are able to better estimate one of these parameters. For the other parameters, the estimates vary widely. Frank Drake's own current estimate puts the number of communicating civilizations in the galaxy at 10,000.You can find out more about the Drake Equation from
http://www.setileague.org/general/drake.htm
http://seds.lpl.arizona.edu/~rme/drake.html
Cheers,
Padi Boyd
for the Ask an Astrophysicist
Questions on this topic are no longer responded to by the "Ask an Astrophysicist" service. Seehttp://imagine.gsfc.nasa.gov/docs/ask_astro/ask_an_astronomer.html for help on other astronomy Q&A services.
What are the chances of life existing outside our solar system?
The Answer
This is a question that astronomers first started to quantify in the early 1960s. In 1961, a radio astronomer named Frank Drake developed an equation to stimulate discussion of the Search for Extraterrestrial Intelligence (SETI). This equation, which is now called the Drake equation, states that the number of communicating civilizations in our galaxy likely depends on a number of factors which must combine to yield a habitable planet where life has the chance develop to a certain level of technological knowhow. These factors include the rate of formation of stars like the Sun, the fraction of those with planets, the fraction of Earthlike planets, the fraction of such planets where life develops, the fraction of those where the life becomes intelligent, the fraction of intelligent species who can communicate in a way we would detect, and the lifetime of the communicating civilizations. As you may imagine, there is a lot of debate about reasonable values for most of these factors. As we learn more about the likelihood of planets around other stars, we are able to better estimate one of these parameters. For the other parameters, the estimates vary widely. Frank Drake's own current estimate puts the number of communicating civilizations in the galaxy at 10,000.You can find out more about the Drake Equation from
http://www.setileague.org/general/drake.htm
http://seds.lpl.arizona.edu/~rme/drake.html
Cheers,
Padi Boyd
for the Ask an Astrophysicist
Questions on this topic are no longer responded to by the "Ask an Astrophysicist" service. Seehttp://imagine.gsfc.nasa.gov/docs/ask_astro/ask_an_astronomer.html for help on other astronomy Q&A services.