In 2005, after NASA's Deep Impact spacecraft had completed its objective of slamming an impactor probe into the nucleus of Comet Tempel 1, mission scientists began plotting their next move.

The spacecraft that had released the probe and documented its cometary collision was intact, with fuel to spare, leaving it well equipped to rendezvous with another comet in the inner solar system. Comets preserve some of the primordial materials from the early solar system, and the rare close look offers planetary scientists a glimpse of conditions that prevailed billions of years ago. The prospect of visiting another comet without having to build and launch a new spacecraft—getting two missions for little more than the price of one—seemed too good to pass up. The only question: Where to?

The best option, it seemed, was a comet called 85P/Boethin. The little-known object, named for its discoverer, Leo Boethin, a priest in the Philippines, would be drawing close to Earth in 2008. Boethin's timely orbit would provide an opportunity for NASA to visit another comet without having to fund the Deep Impact mission for more than a few additional years.

The only catch: Comet Boethin had not been sighted in almost 20 years. In fact, it had been seen on only two occasions—at its 1975 discovery and on its subsequent orbit around the sun, in 1986. Boethin's roughly 11-year elliptical orbit placed it in the class of so-called short-period comets. But when it was due to make another pass through the inner solar system in 1997, Boethin was inconveniently positioned on the opposite side of the sun from Earth, precluding astronomers from getting another look at it.

In the years leading up to 2008, when Boethin was to return once more, astronomers designing the extended Deep Impact mission, called EPOXI (Extrasolar Planet Observation and Deep Impact Extended Investigation), moved to locate the comet again. But despite a few promising leads, the trail went cold, and mission scientists opted to send Deep Impact to a backup target instead.

The mission ultimately succeeded, but Comet Boethin was never found. And after an exhaustive search, which engaged some of the largest telescopes on Earth and in orbit, the researchers have declared the comet gone for good. It most likely disintegrated sometime after the last known sighting in 1986, but astronomers may never know exactly when, where or how Boethin met its demise. Its unexpected disappearance delayed the payoff of EPOXI mission by two years and added millions to the price tag.

In a forthcoming issue of the journal Icarus, astronomer Karen Meech of the University of Hawaii at Manoa's Institute for Astronomy and her colleagues describe the laborious, ultimately futile search for Boethin. From 2005 to 2007 the hunt engaged several of the world's most powerful observatories, including in Chile the 8.2-meter Very Large Telescopes (VLT), the 8.1-meter Gemini South Telescope, the twin 6.5-meter Magellan telescopes and two four-meter telescopes at the Cerro Tololo Inter-American Observatory; in Hawaii, they employed the 8.3-meter Subaru Telescope and the 3.6-meter Canada–France–Hawaii Telescope. They even turned to space, harnessing the observing power of the orbiting Spitzer Space Telescope. Later the astronomers looked in vain for a debris trail in the data collected in 2010 by NASA's Wide-Field Infrared Survey Explorer satellite.

"I was almost embarrassed to say how much telescope time we had because the eight- and 10-meter-class telescopes are very precious resources," Meech says. "If you're really lucky, you might get a night of eight-meter time."

Meech even considered marshaling robotic planetary spacecraft for the campaign. "I was actually looking at the facilities in orbit around Mars," she says. "Could we turn around Mars Odyssey or something else to look for it?" She soon learned that such maneuvers were possible in principle but that Mars orbiter cameras were ill equipped to detect such a faint object.

The fact that none of the telescopes spotted the comet can only mean one thing: "It had to have broken up," Meech says. "Because of the interest in this comet, everyone was looking for it."

13 Comments

1. 1. JoeMerchant 07:40 PM 10/23/12

   Fall apart, or get deflected to a different orbit? Is it really that impossible to conceive of a near-miss pass by another Kupier belt object?

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2. 2. Chuck Darwin 11:48 AM 10/24/12

   I, for one, welcome our new, comet-eating overlords.

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3. 3. sparcboy 02:34 PM 10/24/12

   LOL! The aliens are jacking with NASA!

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4. 4. ErnestPayne 04:45 PM 10/24/12

   One of the last acts of David Hemmings? Now you see it now you don't. Thanks for the story.

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5. 5. jack.123 06:31 PM 10/24/12

   If its in a new orbit,is there a possibility that it is now on a Earth crossing path?Could it now be hiding behind the Sun then coming from that direction?Which would then be unseen till it is upon us.How big is this thing?Is this the reason they spent so much time and resources trying to find it?Is its arrival date 12-21-2012?A whole lot of unanswered questions.How the hell do you lose a comet?

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6. 6. lesizz 07:25 PM 10/25/12

   They could rename it the "Jimmy Hoffa" comet

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7. 7. Grumpyoleman 07:55 AM 10/26/12

   The Ferengi got it, like they captured the Mars Orbiter.
   

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8. 8. iWind 08:18 AM 10/26/12

   First the xenon goes missing, now a comet's gone missing - there's definitely something going on here!

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9. 9. Quinn the Eskimo 10:39 PM 10/27/12

   My feeling is that the Klingons used it for target practice.
   
   Or, it was launched by one of the Shuttles. We all know how those missions worked out.

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10. 10. myron 10:43 AM 10/29/12

    All comments from our intellectual colleagues seem to miss the obvious possibility of NASA's 'impactor probe' being the culprit for the comet's disappearance. "slamming" into the comet's core could have triggered a gradual disintegration, or even an orbital deviation into the Sun. Who knows anyway !?

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11. 11. Postman1 in reply to myron 09:41 PM 10/29/12

    myron - that was a different comet hit with the impactor.

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12. 12. Phoenix59 in reply to myron 08:51 PM 10/30/12

    Read the article again. The impactor probe was sent into Comet Tempel, not the missing Comet Boethin.

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13. 13. m allworth 01:35 PM 10/31/12

    maybe it just disintegrated - how big/stable was it in the first observations/
    
    Best wishes,
    
    Marg.

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