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Breaking: WISE mission misleads public with confusing comet stats
event July 18, 2010 comment 20 Comments

In my day work I am no stranger to government bureaucracies and “programs” manipulating information about their activities until it suits them to do otherwise.  The WISE mission is no different.

In March of this year David Shiga wrote an obviously informed article revealing early results of the WISE mission (below).  Six weeks into WISE’s work, someone revealed to Shiga (I don’t think it is press release material, but prove me wrong) that 16 NEO’s had been identified, and strangely, these objects were in comet-like inclined orbits (making them comets).  Then, this week, six month later, we get an update from the JPL mission team reporting a total of 15 new “comets” have been found, and 25,000 new “asteroids.”

What happened to the original 16 objects with inclined orbits?  Are they now just lumped in with asteroids?  How many of the “asteroids” orbits are inclined (making them comets)?.

The WISE mission is massaging, or least showing no consistency, in their use of the terms comet and asteroid in their press releases or private communication with the media.  I am sure the public will be able to sort this out in six more months as promised in the JPL press release.  But the opaque and clumsy treatment of this important quasi-public information in the popular press in the meantime is disappointing.

I would love for a reader or two to provide insight and clarification regarding these matters.  I do not, for instance, monitor or quite understand the Minor Planet Center. Perhaps all this info is being fed to “Harvard” and WISE feels no responsibility to elaborate in a press releases regarding the finer points of astronomical nomenclature.  Or, maybe you sense the same manipulation-without-explanation  I do…

Besides all those asteroids, WISE has also sighted 15 new comets. It has spied hundreds of potential brown dwarfs — stellar objects that are bigger than a planet but much smaller than a star — and confirmed the existence of 20 of them, including some of the coldest ever known.

Alicia Chang, Associated Press, July 16, 2010

In its first six weeks of observations, it has discovered 16 previously unknown asteroids with orbits close to Earth’s. Of these, 55 per cent reflect less than one-tenth of the sunlight that falls on them, which makes them difficult to spot with visible-light telescopes. One of these objects is as dark as fresh asphalt, reflecting less than 5 per cent of the light it receives.

Many of these dark asteroids have orbits that are steeply tilted relative to the plane in which all the planets and most asteroids orbit. This means telescopes surveying for asteroids may be missing many other objects with tilted orbits, because they spend most of their time looking in this plane.

David Shiga, March 5, 2010, New Scientist

So far, WISE has observed more than 100,000 asteroids, both known and previously unseen. Most of these space rocks are in the main belt between Mars and Jupiter. However, some are near-Earth objects, asteroids and comets with orbits that pass relatively close to Earth. WISE has discovered more than 90 of these new near-Earth objects. The infrared telescope is also good at spotting comets that orbit far from Earth and has discovered more than a dozen of these so far.

JPL press release summarizing WISE findings so far, July 16, 2010

Dark, dangerous asteroids found lurking near Earth

David Shiga, March 5, 2010, New Scientist

An infrared space telescope has spotted several very dark asteroids that have been lurking unseen near Earth’s orbit. Their obscurity and tilted orbits have kept them hidden from surveys designed to detect things that might hit our planet.

Called the Wide-Field Infrared Survey Explorer (WISE), the new NASA telescopelaunched on 14 December on a mission to map the entire sky at infrared wavelengths. It began its survey in mid-January.

In its first six weeks of observations, it has discovered 16 previously unknown asteroids with orbits close to Earth’s. Of these, 55 per cent reflect less than one-tenth of the sunlight that falls on them, which makes them difficult to spot with visible-light telescopes. One of these objects is as dark as fresh asphalt, reflecting less than 5 per cent of the light it receives.

Many of these dark asteroids have orbits that are steeply tilted relative to the plane in which all the planets and most asteroids orbit. This means telescopes surveying for asteroids may be missing many other objects with tilted orbits, because they spend most of their time looking in this plane.

Fortunately, the new objects are bright in infrared radiation, because they absorb a lot of sunlight and heat up. This makes them relatively easy for WISE to spot.

Ex-comets

“It’s really good at finding the darkest asteroids and comets,” said mission team member Amy Mainzer of NASA’s Jet Propulsion Laboratory in Pasadena, California, at the Lunar and Planetary Science Conference in Houston, Texas, on Thursday.

WISE is expected to discover as many as 200 near-Earth objects – but astronomers estimate that the number of unknown objects with masses great enough to cause ground damage in an impact runs into the tens of thousands.

Richard Binzel of the Massachusetts Institute of Technology says the dark asteroids may be former comets that have long since had all the ice vaporised from their exteriors, leaving them with inactive surfaces that no longer shed dust to produce tails. He points out that many comets have very tilted orbits, and comets visited by spacecraft have been observed to have very dark surfaces.

Alicia Chang asteroid comet dark comet David Shiga dead comet NASA Peter Eisenhardt WISE wise mission