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An infrared space telescope that will make a three-dimensional map of the Universe has just launched. Astronomers plan to study everything from asteroids to galaxies with the telescope.

Japan's Institute of Space and Astronautical Science (JAXA) launched the orbiting telescope from the Uchinoura Space Center in Japan at 06:28 local time on 22 February. Dubbed ASTRO-F, the satellite has been nicknamed Akari, meaning 'light', since the launch.

Stars and galaxies are born within clouds of dust that obscure them from optical telescopes. But infrared light shines through the dust, showing astronomers what is happening inside the clouds. "That's where all the action is," says Michael Rowan-Robinson, an astronomer from Imperial College London, and part of the Akari team.

The Spitzer Space Telescope already probes the infrared Universe. But Spitzer focuses on tiny points in the sky, allowing it to spot distant stars or record nearby objects in great detail.

In contrast, Akari "will do a much shallower survey, but it will cover the whole sky", explains Rowan-Robinson. This means it should be able to spot interesting things that the Spitzer telescope can then look at in detail, says Michael Werner, an astronomer at the Jet Propulsion Laboratory in Pasadena, California.

From birth to death

As well as star births, Akari should capture a host of other objects and events that emit infrared light. "It will see everything from asteroids in our own Solar System to galaxies most of the way back to the Big Bang, along with everything in between," says Richard Savage, an astronomer at the University of Sussex, UK.

This should include failed stars called brown dwarfs and the dim glow of dead stars. Both types of object could make up part of the missing mass, dubbed dark matter, that keeps the Milky Way from flying apart as it spins round. A thorough survey should help to measure their contribution to the missing mass.

The telescope will also look for planetary systems within 1,000 light years of Earth.

Second look

The first infrared sky survey was done by the IRAS satellite in 1983, but the technology has improved so much that astronomers wanted a second look. Rowan-Robinson hopes that Akari will see at least twice as far as IRAS, and provide much better images.

Akari will spend two months checking out its systems, and then about six months surveying the whole sky. A further ten months has been allocated to look at specific objects in more detail, before the telescope's liquid-helium coolant is expected to run out.

Akari was developed by JAXA, the European Space Agency (ESA), and researchers in the United Kingdom and the Netherlands.

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