By Edwin Cartlidge, Rome, Italy
Rome, the birthplace of nuclear physicist Enrico Fermi, is this week hosting a conference dedicated to discussing results from the NASA satellite that bears his name. Some 400 scientists have gathered in the Italian capital to discuss what the Fermi Gamma-Ray Space Telescope, launched in June 2008, can tell us about all manner of extreme celestial events – from the accretion of matter by supermassive black holes and ultra-energetic events known as gamma-ray bursts to the hypothesized collision of dark-matter particles.
First up on to the vast stage of the echoey Aula Magna at La Sapienza University was NASA’s Elizabeth Hays, who gave an overview of Fermi’s progress to date. Hays says she was happy to report that Fermi’s operations were “becoming almost mundane”, now that the satellite has been circling the Earth for over 1000 days, completing more than 16,000 orbits in that time, and collecting vast quantities of gamma-ray data in the process. (There is even now a Fermi app for the iPhone/iPad.)
Some of the gamma rays collected by Fermi have their origins on Earth, with Hays pointing out that radiation generated by charged particles during thunderstorms created something of a minor storm of their own on the Web with nearly half a million views of a NASA video explaining the process (see video above). Fermi’s principal source of gamma radiation is, however, outer space, and it surveys almost the whole sky in three hours, making increasingly detailed studies of bright sources and attempting to pinpoint the nature of weaker ones.
The first catalogue of distinct gamma-ray sources revealed by Fermi was released about a year ago and researchers have been working furiously to get a second, more precise catalogue published. As Dave Thompson of NASA’s Goddard Space Flight Center explained, this has taken a lot longer to produce than expected but he argues that when it comes out later on this month it will represent a “major revision” of the old catalogue, listing some 1888 active galactic nuclei and other gamma-ray sources.
Many of those who have made the trip to Rome will also be hoping that another high-profile – and very expensive – astroparticle mission will finally get to make the trip into space in the next few days or weeks. That mission is the cosmic-ray observatory known as the Alpha Magnetic Spectrometer, which is expected to launch on 16 May on the space shuttle Endeavour. As speaker Giovanni Bignami of the University of Pavia put it, “we are keeping our fingers crossed”.
Edwin Cartlidge is a science writer based in Rome