SAN FRANCISCO — A NASA advisory panel is recommending that the Wide-field Infrared Survey Explorer (WISE) mission end in October as originally planned instead of continuing to search for comets, asteroids and stars during a three month extended phase.
While the WISE mission is expected to produce significant results, NASA’s 2010 Astrophysics Senior Review Committee said there was not adequate scientific justification to continue the mission once the spacecraft depletes its supply of hydrogen used to cool the onboard telescope and detectors. The WISE spacecraft built by Ball Aerospace & Technologies Corp. of Boulder, Colo., carries an infrared telescope built by the Space Dynamics Laboratory of Logan, Utah, that is designed to detect the faint glow of distant objects with instruments chilled to the point where they produce no detectable infrared light.
The original plan for the 10-month WISE mission, which was launched in December and managed by the Jet Propulsion Laboratory in Pasadena, Calif., includes one month for on-orbit checkout, followed by a six-month survey of the entire sky in four wavelengths of infrared light. During the last three months of the original mission, the WISE team plans to conduct a second survey covering half the sky in those four infrared wavelengths.
Because the spacecraft and telescope remain in excellent condition, Ned Wright, WISE principal investigator and a professor at the University of California, Los Angeles, proposed a three-month extension of the mission to complete the second half of the second sky survey in two of the four infrared wavelengths because those images could be captured even when the hydrogen supply is exhausted and the instruments can no longer be chilled. That additional three-month project, known as Warm WISE, would have added $6.5 million to the program’s $320 price tag, according to NASA spokesman J.D. Harrington. WISE mission officials also proposed spending $8 million on an Extended Source Catalog, a detailed database of large objects, such as galaxies and interstellar clouds of gas and dust, revealed in WISE imagery but not of primary concern to astronomers looking at specific stars or comets.
Currently, WISE is producing approximately 7,500 images a day in each of four infrared wavelengths. That original mission “should produce a catalog and image atlas of great utility to the entire astronomical community,” according to the report of the NASA review panel. “Although it is impressed with the promise of the cryogenic mission, the Senior Review Committee did not find adequate scientific justification in the proposal for the cost of either the Warm Extension or the Enhanced Data Products.”