It turns out, says NASA's Ames Research Center, that the LCROSS lunar impact mission, which it ran, did kick up a plume of debris after all. It just wasn't bright enough to show in the live images streamed at the time of impact on Oct. 9. Perhaps it wasn't large or dense enough to catch much sunlight over the edge of the permanently-shadowed Cabeus crater where the Centaur rocket crashed, with the LCROSS satellite watching as it followed.
But if you combine several overlapping images from parts of the visible spectrum, and crank up the contrast, you get the image below. The red circle was added by NASA.
Click on the image to enlarge, or HERE for full resolution. NASA says that 15 seconds after impact, the debris had flown up to 3-4 km (2-3 miles) in every direction. Keep in mind that for lack of a lunar atmosphere, the flying particles did not form a debris "cloud" around the impact site; instead, each particle probably followed a roughly parabolic path from where the booster crashed.
"We are blown away by the data returned," said Anthony Colaprete, LCROSS principal investigator and project scientist, in a release you can find HERE. "The team is working hard on the analysis and the data appear to be of very high quality.”
"There is a clear indication of a plume of vapor and fine debris," said Colaprete. “Within the range of model predictions we made, the ejecta brightness appears to be at the low end of our predictions and this may be a clue to the properties of the material the Centaur impacted.”
As for what this means to the search for usable lunar ice, Colaprete and his team still cannot say. The refining of an image does not change the spectrometer data, which will tell them the chemical composition of the lunar soil they hit.