Is anybody out there?

A CAMERA so sensitive that it could spot a flea walking across a car headlight from three kilometres away may just solve the biggest question of all time: are we alone in the universe?

The launch of the Kepler satellite, a mission to discover earth-like planets orbiting sun-like stars, is scheduled for early Saturday morning (Irish time). It may prove that there are thousands, increasing the chances that there is life out there in space. Yet it may show earth-like planets are very rare, making life here very special indeed.

Among the first to learn the answer to this age-old question could be Castlebar native Dr Maura Rabbette. Based at the US National Aeronautics and Space Administration’s Ames Research Centre, she is a research scientist on its Kepler mission.

Rabbette will analyse the streams of data flowing from the satellite and learn whether there are many planets like ours. She is understandably enthusiastic about the mission and will be at Cape Canaveral in Florida when the satellite launches tomorrow.

“What is so exciting is that, for the first time in human history, we will find out if there are earth-like planets that could support life,” she said a few days before the launch. “The Kepler mission is to find those planets, to find planets that can support life. If we find none, this is also a very profound finding. It means that the presence of life is very rare indeed.”

Kepler is an unusual mission for a number of reasons. One is the fact that the spacecraft will not be orbiting the Earth. Rabbette described how it will be left trailing behind Earth, gradually getting further and further away until it is 72.4 million kilometres away after four years.

The idea is to move clear of the earth so the Kepler’s view of the sky is never blocked, Rabbette says. Equally surprising is the fact that the satellite will be focused on a fixed point in the Cygnus-Lyra region of our Milky Way galaxy. Its view will not vary and will encompass more than 100,000 stars in its fixed field of view. “Kepler is going to look at the stars and isn’t going to blink for four years,” says the astrophysicist, who joined Nasa in 1997.

The reason for this relates to the most important elements of the Kepler mission, its 1.4-metre telescope and the most sensitive camera system – 95 megapixels – ever launched into orbit, according to Rabbette. “This is a very, very powerful telescope with a very sensitive camera.”

These will detect what are known as “transits”, when an orbiting planet passes in front of a star that lies in the satellite’s line of sight. Transits will cause a periodic dimming of the star’s light and Kepler will spend four years “staring” at 100,000 stars to watch for this.

The level of change is about the same as that previously mentioned flea crossing the car headlight three kilometres away, she says, sensitive indeed.

Kepler will beam back hundreds of “terabytes” of data, a terabyte representing 10 followed by 12 zeroes. It will be loaded on to supercomputers and, as part of the Ames team, Rabbette helped develop software that will search through all this data for the dimming signatures that represent a planet transiting a star.

This is only the beginning, however. It will identify if it is a rocky, earth-like planet and calculate its size. The team will be able to say if the planet occupies the “habitable zone”, not too hot or too cold to support life, and will know its surface temperature.

It will take several years to catalogue at least three transits for each planet found and Nasa hopes to locate at least 50 earths, or hundreds more if they include “super-earths” up to twice our size.

Rabbette urged other Irish graduates to apply to Nasa for similar space programme opportunities, and said she would assist.