WISE Captures Key Image Of Comet Mission’s Destination

NASA's Wide-field Infrared Survey Explorer, or WISE, caught a glimpse of the comet that the agency's EPOXI mission will visit in November. The WISE observation will help the EPOXI team put together a large-scale picture of the comet, known as Hartley 2. "WISE's infrared vision provides data that complement what EPOXI will see with its visible-light and near-infrared instruments," said James Bauer, of NASA's Jet Propulsion Laboratory, Pasadena, Calif. "It's as if WISE can see an entire country, and EPOXI will visit its capital." WISE's infrared vision will allow the telescope to get a new estimate of the size of the comet's nucleus, or core, as well as a more thorough look at the sizes of dust particles that surround it. This information, when combined with what EPOXI finds as it gets closer to Hartley 2, will reveal how the comet has changed over time.

On Nov. 4, the EPOXI mission, which uses the already "in flight" Deep Impact flyby spacecraft, will reach its closet approach to Hartley 2. The spacecraft will examine the dusty, icy body in detail as it flies by, providing the best, extended view of a comet in history. WISE and several other ground- and space-based telescopes are participating in the viewing, working together to tackle mysteries about our solar system's origins that are frozen inside comets. For stargazers, opportunities to view the comet are possible throughout October. On Wednesday, Oct. 20, Hartley 2 will reach its closest approach to Earth since it was discovered in 1986. The comet will be approximately 11 million miles away and should be visible with the naked eye near the constellation Perseus if viewed in dark skies.

Observers will need binoculars or telescopes from urban areas in the Northern Hemisphere. Southern Hemisphere stargazers can see the comet later in the month. WISE captured its view of the comet during an ongoing scan of the sky in infrared light. The mission has been busy cataloging hundreds of millions of objects, from comets to distant, powerful galaxies. In late September, it used up its frozen cryogen coolant as expected and began a new phase of its survey. Called the NEOWISE Post-Cryogenic Mission, it primarily focuses on finding additional asteroids and comets. To date, the WISE mission has observed more than 150,000 asteroids and 110 comets, including Hartley 2.

NASA's WISE Mission Warms Up But Keeps Chugging Along

After completing its primary mission to map the infrared sky, NASA's Wide-field Infrared Survey Explorer, or WISE, has reached the expected end of its onboard supply of frozen coolant. Although WISE has 'warmed up,' NASA has decided the mission will still continue. WISE will now focus on our nearest neighbors the asteroids and comets traveling together with our solar system's planets around the sun. "Two of our four infrared detectors still work even at warmer temperatures, so we can use those bands to continue our hunt for asteroids and comets," said Amy Mainzer of NASA's Jet Propulsion Laboratory in Pasadena, Calif. Mainzer is the principal investigator of the new phase of the mission, now known as the NEOWISE Post-Cryogenic Mission.

It takes its name from the acronym for a near-Earth object, NEO, and WISE. A cryogen is a coolant used to make the detectors more sensitive. In WISE's case, the cryogen was frozen hydrogen. WISE launched Dec. 14, 2009, from Vandenberg Air Force Station in California aboard a Delta II launch vehicle. Its 16-inch infrared telescope scans the skies from an Earth-circling orbit crossing the poles. It has already snapped more than 1.8 million pictures at four infrared wavelengths. Currently, the survey has covered the sky about one-and-one-half times, producing a vast catalog containing hundreds of millions of objects from near-Earth asteroids to cool stars called "brown dwarfs" to distant, luminous galaxies.

To date, WISE has discovered 19 comets and more than 33,500 asteroids, including 120 near-Earth objects, which are those bodies with orbits that pass relatively close to Earth's path around the sun. More discoveries regarding objects outside our solar system, such as the brown dwarfs and luminous galaxies, are expected. "The science data collected by WISE will be used by the scientific community for decades," said Jaya Bajpayee, the WISE program executive in the Astrophysics Division of NASA's Science Mission Directorate at the agency's Headquarters in Washington. "It will also provide a sky map for future observatories like NASA's James Webb Space Telescope."