NASA’s Near-Earth Object Wide-field Infrared Survey Explorer (NEOWISE) has sent back the first test images from its 16-in (40-cm) telescope and infrared cameras as it is prepared for its new mission. Intended to seek out potentially dangerous asteroids and help in selecting a near-Earth object as part of the space agency’s asteroid retrieval effort, NASA says NEOWISE will be a powerful tool for discovering, cataloging and understanding the asteroids in the inner Solar System.
Among the first deep space imagery sent back by the unmanned probe was of an asteroid named (872) Holda, which was discovered in 1917. It has a diameter of 26 mi (42 km) and resides in the asteroid belt between Mars and Jupiter. NASA says that the images will allow scientists and engineers back on Earth to assess the quality of NEOWISE’s observations.
Launched on December 14, 2009, NEOWISE started life as the WISE space telescope, tasked with producing a full-sky survey in search of dim objects, such as brown dwarfs, in the infrared spectrum. Its ultra-sensitive telescope was supercooled down to as low as 7.6° K (-446° F/-266° C) by inserting it inside a cryostat containing solid hydrogen. WISE’s main mission ended when its hydrogen ran out and it was eventually decommissioned in February 2011 after receiving a four-month mission extension, but it was brought back online in September for its new mission after 31 months of hibernation.
It sits in a solar-synchronous orbit 525 km (326 mi) above the Earth, circling the globe once every 95 minutes. Now renamed and recommissioned, its new three-year mission focuses on the search for asteroids that might pose a threat to Earth, or that may be targeted for an asteroid exploration mission as part of the US asteroid initiative. NASA anticipates that the unmanned probe will find up to 150 new near-Earth objects (NEO) and will study the size, albedo and thermal properties of 2,000 more. In order to cool the telescope to the needed temperature, the telescope will be aimed at deep space periodically to allow heat to radiate away.
"NEOWISE not only gives us a better understanding of the asteroids and comets we study directly, but it will help us refine our concepts and mission operation plans for future, space-based near-Earth object cataloging missions," says Amy Mainzer, principal investigator for NEOWISE at NASA's Jet Propulsion Laboratory (JPL) in Pasadena, California. "The spacecraft is in excellent health, and the new images look just as good as they were before hibernation. Over the next weeks and months we will be gearing up our ground-based data processing and expect to get back into the asteroid hunting business, and acquire our first previously undiscovered space rock, in the next few months."