Great news for asteroid surveys from WISE and Arecibo

JPL issued a press release today announcing that the WISE mission will be carrying on surveying the sky even though it has run out of coolant. This is a huge surprise, given that NASA's 2010 Astrophysics Senior Review Committee did not recommend to extend the mission beyond its primary, cryocooled one, according to this space.com story. Without any more solid hydrogen cooling its detectors, WISE is now blind to two of its four infrared wavelengths. But the remaining two wavelengths happen to be good ones for mapping cold objects within our solar system, including asteroids and comets.

I saw an update on WISE's comet survey at today's Division of Planetary Sciences meeting. They've already discovered 19 comets (including 3 cases of new cometary activity on previously known bodies); they've also discovered 5 Centaurs and observed 13 others.

I also ran into radio astronomer Lance Benner in the hallway and asked for an update on radio observations of near-Earth asteroids. He said they're very busy observing Hartley 2 (the target for Deep Impact's November 4 encounter), and that they've recently been funded to do more near-Earth asteroid followup than they've been able to do for quite some time. Optical astronomers measure the challenge of their targets in visual magnitude, with magnitudes below minus 20 being really faint. Radio astronomers measure the challenge of their targets using "signal-to-noise ratio," a measure of how difficult it is to pick the body the background "hiss." Lance told me they're now routinely observing near-Earth objects down to a signal-to-noise ratio of 20, which is a much smaller number than has prevailed recently. Yay!