Countdown to LCROSS Impact

Tomorrow (Friday, Sept. 11th, 2009) at 10am PDT, the LCROSS team will announce the chosen permanently-shadowed, lunar South Pole crater for the impact of the Centaur upper stage of the launch vehicle. The lucky crater selected has been deemed the ideal target for evaluating if water ice exists at the lunar south pole. Anthony Colaprete, LCROSS principal investigator, will make the announcement and you can catch it live on NASA TV.

The impact is scheduled for October 9, 2009 at 4:30am PDT. At that time, the kinetic impactor (the size of a large sports utility vehicle) will slam into the Moon at over 9,000 km/h (5,600 mph), according to the NASA LCROSS website (following image courtesy of the LCROSS site):

Inevitably, a small group of folks are quite upset about the idea of disturbing the lunar environment. I suspect they are afraid of disturbing the underground moon squirrels. Such is the chance we take in the name of exploration.

The LCROSS website has strategically set up a FAQ to address some of these concerns. Here is one sentence that puts things into perspective:

"The LCROSS impact will excavate a crater approximately 20 meters in diameter, or about one-trillionth the total permanently shadowed area. It is safe to say the LCROSS impact will not have a lasting effect on lunar water, if it does indeed exist."

The Imagery

The scientists are drawing conclusions on which crater to target based on a wealth of valuable imagery, data, and analysis that has been provided by space agencies from around the globe. JAXA Kaguya (Selene) spacecraft lunar imagery and data has been used to create highly accurate digital elevation models (DEMs) of the South Pole, which were used by the NASA/Goddard Space Flight Center Scientific Visualization Studio to create the following images (Shackleton Crater is in the center of the images below):

Even better, they made a video visualization showing the permanently shadowed craters:


The following image was produced by NASA's Jet Propulsion Laboratory using the Deep Space Network's Goldstone Solar System Radar. The left image is computer generated based on radar reflectance data, and the color image on the right is the highest resolution topography map to date of the moon's south pole.

ESA's SMART-1 spacecraft also collected valuable imagery and data of the lunar south pole. Here is an image of some of the permanently shadowed craters provided by ESA:

There are also a wealth of images from the early days of Moon exploration, including the following images restored from Lunar Orbiter IV, taken in 1967. These images show most of the craters being considered for the LCROSS impact:

Of course there are a wealth of other images and data -- but there's a start.

Follow Along!

LCROSS is on Twitter and Facebook. The flight director is blogging on the mission. There is also a Google Group dedicated to Observation events (or backyard amateur observation tips) for the October 9, 2009 impact.

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