The Search for Extraterrestrial Life Will Succeed

In recent years, we always heard about outer space mysteries, like people who have seen UFOs in the sky. They have dreamt about the aliens that have kidnapped them (Schroeder), the strange crop circle was first found in London (Taylor) and scientists assume that there is evidence of life on Mars (European Space Agency). Actually, human beings have searched for extraterrestrial intelligence (SETI) for more than four decades. The entire sky and thousands of nearby stars have been observed and studied several times. However, scientists still cannot declare any conformations to show that extraterrestrial life has been detected. Some researchers support Copernican's assumption that the signals of extraterrestrial life will be found but not now. It takes time to wait for the right time and location to detect the signals. Others think it is a multi-generational project; there is still a long way to go. With improvements of both telescopes and digital electronics in SETI, scientists believe that we will succeed in this search in the future. (Easton, 2010)

Approach

There are two factors that show it is a long-term search and difficult to find sought-for phenomenon. For one thing, how many times will aliens show up? This is not something that human beings can determine; it is an objective condition that we cannot control right now. The other factor is how fast we can scan the universe at the right time. For example, if we scan the sky in US, while the signal is in Australia, we won't detect it. We may miss the important phenomenon we are searching for. Frank Drake, who is the member of the search for extraterrestrial intelligence (SETI) field, came up with an equation. Drake's equation calculates N, the number of contemporaneous, galactic transmitting sites, is like alien societies. So the N is bigger when there are more aliens.

Travelling to planets to find the answer is possible but very difficult. So far, we don't have enough advanced technology to support us to go wherever we want. It is also easy to miss some transmitters if we transfer our search from waiting to taking actions. There are myriad uncertain stellar choices; we could not study on every one of them. It is a good advance but also risky. It takes time and money if we are not sure there is a life signal on the target planet.

Numbers of stars to search

Based on the range estimate for N which is 104 - 106 from Drake's Equation, scientists came to a conclusion that the nearest transmitter is 200 – 1,000 light-years away. There are ~1011 target stars located within this distance. They can be categorized as F, G or K-type stars and M-dwarfs stars. These are all the stars qualified to search. However, there are ~1% short-lived and massive stars that are not taken into our consideration. That means we can search 99% our galaxy to find out signals. There is possible life