Too much plume promise

NASA hype over mooncrash may have clouded value of real data

For weeks, NASA had been publicizing the plan to give the moon a one-two punch: crashing a used-up NASA rocket and its small mother craft, LCROSS. NASA billed the impact as a major observing event that even backyard astronomers could enjoy. Press releases and news articles quoted NASA officials saying that, in the crash’s immediate aftermath, short-lived plumes would rise far enough above the permanently shadowed lunar crater Cabeus to be seen with a 12-inch or maybe even a 10-inch telescope.

Guess what. The plumes weren’t clearly visible, even with some of the most powerful telescopes astronomers have available. (At the time of this writing, astronomers are still analyzing the Hubble data and they don’t yet know whether the orbiting observatory glimpsed any spray of debris.) Even LCROSS, which had a front row seat for the crash of its rocket, observed no plume.

Yet during a press briefing only a few hours after the crashes, NASA scientists pronounced the moon blasts a roaring success. Scientists seemed taken aback when reporter John Johnson Jr. of the Los Angeles Times lofted the first, hardball question: Why call the mission a success when there was no plume?

LCROSS mission scientist Anthony Colaprete of NASA Ames immediately launched into an explanation that was scientifically accurate. LCROSS did indeed record critical and highly significant data — a thermal flash and changes in ultraviolet and visible-light spectra — that are likely to show whether the crater contains frozen water, the whole point of the mission. Other telescopes also recorded changes in the intensity of light at various wavelengths that could also help determine the presence of water or of its fragment, the hydroxyl radical OH.

Colaprete was right. But it would have been nice if he had begun his answer by at least acknowledging that indeed the predictions for the plumes weren’t borne out. The hype before the event was considerable, and it may have made the actual data less appreciated by journalists, the public and even some scientists.

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