Searching and researching the sky
Exoplanet hunters are not ever satisfied. At the University of Arizona, they are developing a new type of search that could greatly improve the localization of terrestrial planets with advantageous conditions to biological life, like water in a liquid state.
This artist’s conception shows NASA’s Wide-field Infrared Survey Explorer, or WISE, mapping the whole sky in infrared. The mission will unveil hundreds of thousands of asteroids, and hundreds of millions of stars and galaxies.
Terrestrial planets which belong to nearby stars are often surrounded by a cloud of dust that embraces both the star and the planet. Our solar system, for example, has a cloud of dust that consists mainly of debris left by mutual impacts between asteroids or comets, when passing close to the Sun. Today’s technology, however, makes it possible to detect clouds of dust only when they are very bright, which is a few thousand times brighter than ours. Unfortunately, very bright clouds create enormous difficulties in finding out the planets within them. The observational strategy would be to be able to locate very faint dust clouds, where to look for small-sized planets. It is thought that with this search system, the number of other lands around the Galaxy will increase tremendously. A cloud of dust around a star is, in fact, with good probability, composed of rocky debris and warns of the possible presence of terrestrial planets. Observations so far obtained show that this situation is very frequent. We have a space telescope dedicated to this mission that it was weak in carefully chosen clouds areas in the sky. The staff technologists are developing a tool that can detect clouds of dust only ten times (instead of thousands of times) brighter than the Sun. It would be like being in Australia and trying to capture the image of a lighthouse located in San Francisco’s famous and terrible fog of that city. These are the minimum conditions required. In fact, a cloud a thousand times brighter than our Sun would be comparable with that of the same central star. It is easy to look at, but hopeless to find planets inside. The research group is performing tests with the large binocular telescope in Arizona to prove the ability of the hardware and convince NASA to accept a mission worth of billions of dollars. NASA wants to be sure of being able to “see” a planet that acquires directly a spectrum to derive from the celestial body temperatures and the presence of water.
To achieve this we must build a telescope with extremely extraordinary characteristics, able to observe the light from the planet immersed in background flare of dust cloud. First, though, we must greatly reduce the brightness of the central star. The technique needed to do so is provided by binocular tool that is already operational in Arizona. By combining the light from each telescope you can erase the light of central star through the technique of interferometry. Under these conditions it becomes visible through an extremely weak cloud. The purpose of the ongoing technology research is to lower the stellar luminosity of 10,000 times. The technique has already been used, with two big Keck Telescopes in Hawaii, to reveal the dust disk of the star Fomalhaut, located 25 light-years away. To be more exact, the VLT European Interferometer had discovered a very bright cloud close to the star mail. Keck observations have detected another, much weaker, revolve disk at a distance from the star that is similar to the asteroid belt. This is most likely in dynamic interaction with some rocky and small planets undiscovered. It is an ambitious and expensive mission, with no doubt. But there is a question: finding habitable lands nearby worth the expense?