A suite of cameras that will scan the skies for exoplanets moved closer to reality on 5 April, when NASA chose it for launch in 2017 under the agency’s Astrophysics Explorer programme.
The Transiting Exoplanet Survey Satellite (TESS) will search for small planets passing in front of, and temporarily blocking the light of, nearby bright stars. It will be the first space-based mission that hunts such planetary transits over most of the sky; earlier satellites such as CoRoT and Kepler had more limited fields of view.
“On average, TESS target stars will be about ten times closer than are the Kepler target stars,” says the mission’s principal investigator, George Ricker of the Massachusetts Institute of Technology (MIT) in Cambridge. That means the TESS stars will be brighter than Kepler stars, and easier to follow up on any tantalizing hints.
The cameras aboard TESS are also most sensitive at wavelengths of 600–1,050 nanometres, compared with Kepler’s 400–850 nanometres. Ricker says that gives TESS a better chance at detecting rocky planets around cooler stars such as M dwarfs.
NASA’s Explorer satellites are capped at a cost of US$200 million. The most recent launch in this line of missions was the NuSTAR X-ray probe, which went up in June 2012.
In addition to backing TESS, the agency said on 5 April that it will pursue a $55-million Explorer “mission of opportunity”, which is a detector that will be mounted on the International Space Station. NICER (the Neutron Star Interior Composition Explorer) will measure the variability of X-rays coming from cosmic sources such as rotating neutron stars. Changes in the timing of the radiation are thought to reveal information about their interiors. NICER is led by Keith Gendreau of NASA’s Goddard Space Flight Center in Greenbelt, Maryland.
Both TESS and NICER are slated to be launched in 2017.