Beam me up, Michel: a Swiss professor leads the hunt for extraterrestrial life.

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Star Trek's Mr. Spock may never have been to Switzerland but he could well have made a friend in Michel Mayor, the Swiss astronomer at the forefront of the search for earth-like planets that could support life outside our solar system.

The 65-year-old scientist at the University of Geneva shot to fame some 12 years ago when he discovered 51 Pegasi B, the first planet outside the solar system (an exoplanet) orbiting a normal star--which means that the star and the planet were created at the same time.

This discovery was groundbreaking because, for the first time ever, the possibility of life on another planet became real instead of mere fodder for science fiction writers. However, Mayor says that 51 Pegasi B is too hot to host life.

Since his discovery, the search for extraterrestrial life, or at least planets capable of sustaining it, has truly begun.

Earlier this year, Mayor's Swiss team further challenged key competitors on a U.S.-based team, with the discovery of two possible contenders.

To support life as we know it, a planet must have a solid surface, water and an atmosphere. Mayor's two discoveries have generated the greatest public interest and excitement to date.

The two are believed to be rocky and, potentially, within a forgiving distance of the sun they orbit--not too far and not too close to red dwarf Gliese 581 (a weaker form of star than our sun).

But Mayor thinks one planet, Gliese C, could be too close to the sun, therefore too hot, while the other, Gleise D is more likely suitable to have liquid water its atmosphere is thick enough.

At the heart of Mayor's success is his team's use of the HARPS--High Accuracy Radial Velocity Planet System at the European Space Agency's Southern Observatory in La Silla, Chile. Mayor describes the HARPS as, "a huge optical instrument that measures speed and variation in speed of stars, night after night".

By looking at its oscillation due to the gravitational pull--and with a few calculations--"you derive the period, mass and orbit of its planets," he tells Swiss News.

Mayor helped to develop the HARPS along with a French team in 2003. Rather than taking a cash payment for their invention, the Swiss team agreed to use the Observatory for 500 nights over the next five years.

The HARPS is kept under the vast telescope. The astronomers spend their time, not with their eye glued to the telescope as many would imagine, but down in the Observatory's basement monitoring computers collecting the data transmitted by the HARPS.

Remaining at home

Swiss-educated Mayor has remained committed to staying in his native Switzerland--in contrast to many European academics who have turned to American research institutes in the quest for greater resources. He credits the satisfactory funding he has received from both the Swiss National Science Foundation, which promotes research in Switzerland, and the University of Geneva.

"I have always been very satisfied and cannot complain," he says. "The only difference is that in the U.S. one can access satellites while in Europe there is no such opportunity, but on the other hand as part of ESO [European Southern Observatory] one has access to the great telescopes in Chile, so I have never felt the need to go abroad."

Mayor tells Swiss News that while his professional motivation stems from the scientific desire to understand the formation of planetary systems, he cannot deny a personal curiosity about the potential for life in space.

Galactic task

The hunt for exoplanets capable of supporting life is not easy, especially because methods used tend to yield the opposite of what is being searched for, says Mayor.

The basic reason for this is that unlike the stars they orbit, the planets arc faint and hard to spot. Their presence is thereby detected, or rather inferred, only by the effects they trigger.

The most common way to find a planet, says Mayor, is to identify a star that wobbles--caused by the gravitational pull of one or two orbiting planets. Detectable planets are often too close to their stars because proximity increases the wobble. Also, to be certain that a new exoplanet has been found, planet hunters want to see two complete orbits--and a planet's duration of orbit depends on its distance from its star.

Moreover wobbling is most visible when the star is relatively small or the planet is big, characteristics that do not lend themselves to a natural system of life support.

The final complication in such searches is that they favour the discovery of stars that are similar in age to our sun, which is about 4.5 billion years old. A younger star--a mere billion years old or so--has a very active atmosphere with magnetic eruptions, which makes it hard for astronomers to make observations.

The calmer red dwarf stars are popular with planet hunters. They are much smaller than the sun and, because they burn at lower temperatures, last a long time. Unfortunately, their cooler temperature means that the habitable areas are closer to their suns and tend to be tidally locked--showing the same side to their sun at all times. And this creates a very special climate which is still difficult to study, notes Mayor.

These difficulties mean that nearly all the exoplanets found so far are enormous, too hot, and revolve quickly around stars that are smaller and darker than the sun. They are therefore unlike the planets in our solar system, and only one of those--Earth--is known to have life.

Gazing towards the future

Detecting more hospitable exoplanets is the aim of a European satellite COROT, launched in December 2006. The satellite is also able to probe into the interiors of stars by studying star quakes on their surfaces--similar to the way geologists learn about the Earth's interior by studying earthquakes.

Two further satellite missions are on the drawing board to search for signs of life on planets that have already been found or new planets still to be found.

America's Terrestrial Planet Finder and Europe's Darwin, which will consist of a network of several satellites, could be scanning the universe in a decade. Both projects are still at an early stage, but astronomers would like to use them to identify 'biomarkers' such as oxygen in the atmospheres of exoplanets.

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Mayor, who just retired from teaching at the University of Geneva and is the principle investigator at the Southern Observatory in Chile, believes such projects will be crucial in perpetuating the search for extraterrestrial life.

Asked whether he expects Darwin will be up and running in his lifetime, Professor Mayor says he believes so, "because I am still in good health," but adds it will take some 15 years before the satellite system will be deployed.

There you have it. It may be some time before Mayor and his colleagues find genuine counterparts to our mythical green men, but a taste of Mr. Spock's universe may be closer than we think.