Astronomers Will Train Big MMT Telescope on Moon During 2009 Impact

Feb 06, 2009 By Lori Stiles
LCROSS mission
An artist's illustration shows the LCROSS mission shepherding a satellite releasing its SUV-sized rocket toward the moon. (Credit: NASA)

( -- Astronomers will use the powerful University of Arizona/Smithsonian MMT Observatory on Mount Hopkins, Ariz., to search for lunar water ice when NASA fires a 2-ton rocket into a polar crater on the moon later this year.

Water is a crucial resource on the moon because it would not be practical to transport to space the amount of water needed for human and exploration needs.

NASA selected a team of MMT Observatory and UA Steward Observatory astronomers as one of four ground-based telescope teams to observe the moon on impact with its Lunar CRater Observation and Sensing Satellite mission, known as LCROSS, in August or later.

The LCROSS mission is a small companion mission to the Lunar Reconnaissance Orbiter, scheduled to launch from Cape Canaveral in spring 2009. LCROSS will separate from the lunar orbiter soon after launch.

Astronomers Will Train Big MMT Telescope on Moon During 2009 Impact
The 21-foot diameter MMT Observatory on Mount Hopkins, Ariz. (Credit: Howard Lester, MMTO)

The piggybacking LCROSS mission consists of a shepherding spacecraft and a rocket weighing as much as a large SUV that will hit the moon at about 5,600 mph, excavating a crater about a third as wide as a football field and about as deep as the deep end of a swimming pool.

Instruments aboard the shepherding spacecraft are designed to search for evidence of water ice on the moon as the rocket collides with a permanently shadowed crater near one of the moon's poles.

Researchers predict that impact debris plumes reaching 30 miles high will be visible from Earth with telescopes as small as 10 to 12 inches in diameter.

At more than 20 times larger, the 6.5-meter (21-foot) MMTO telescope "is well-suited to addressing the first LCROSS mission science goal: Confirm the presence or absence of water ice in a permanently shadowed region on the moon," MMTO director and project team leader Faith Vilas said.

Vilas and co-investigators Donald McCarthy Jr., of the UA Steward Observatory, MMTO staff astronomer Morag Hastie, and MMTO principal engineer Shawn Callahan will use state-of-the-art instruments to observe the expanding debris plume concurrently at three different wavelengths.

They'll use an infrared camera and an infrared spectrograph in the "ARIES," an instrument that McCarthy developed, to take images and spectra to follow the shape and growth of the developing plume as well as probe for the presence of "phyllosilicates," or clays formed by the interaction of water with rocks.

"If we get the signature for phyllosilicates, then we've got a pretty firm indication that there's been water there," Vilas said.

ARIES also has a second detector that will take images of the plume at slightly shorter infrared wavelengths.

And the team will use a beamsplitter so they can also use a third camera to image the expanding plume in visible light.

"The cameras will take images at 1/100th of a second, so we'll see the plume as it builds and expands through time at high resolution," Vilas said.

Debris plume size and shape is governed by water vapor in the ejecta, she said.

If NASA launches the Lunar Reconnaissance Orbiter in spring as scheduled, the LCROSS spacecraft will be fired in August to hit the moon's north pole, Vilas said.

August is southern Arizona's monsoon season, so there's some risk of being clouded out.

If launch is delayed, then the LCROSS spacecraft will be fired later to hit the moon's south pole in September or October, Vilas added.

Vilas, McCarthy, Hastie and Callahan will check out their observing instruments and strategy at the MMTO during a night's observing this spring.

The MMTO is located at an altitude of 8,550 feet on the summit of Mount Hopkins, the second highest peak in the Santa Rita Range of the Coronado National Forest, about 30 miles south of Tucson.

Provided by University of Arizona

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1 / 5 (1) Feb 06, 2009
they should have nuked the moon. that would have produced some nice debris. 5600 miles an hour is SLOW in outerspace. ALL of our sattelites orbit faster than that. SLOW
not rated yet Feb 07, 2009
The moon is still just 1/8 the earth's gravity. This should mean a less dense crust which would allow pretty impressive penetration for a 2 ton mass at that velocity. I am not holding out much hope they will find water ice though. Low gravity, no atmosphere, theories most of the moon was molten when it formed, well I am sure the reasons for a lack of water are clear to most people. If they do find water, it will be deep below the surface, and not likely to be an appreciable quantity.
not rated yet Feb 07, 2009
A pity they can't put eg Sodium tracer on the impactor, per the unauthorised C*c*-C*l* advert in AC Clarke's lunar tales...
not rated yet Feb 08, 2009
Is there not another way of doing this ? Like a robotic drilling expedition . Firing a projectile at the moon seems crazy , the moon affects our very being .
not rated yet Feb 09, 2009
watching in ONLY infrared is somewhat limiting. they should cover as many wavelengths as possible. they should bring in hubble, chandra, spitzer, and anything else to expand our visibility of the event across the spectrum.

I bet they'll see more energy being let out than they'd expect, and if there will be a flash of light, they'll see two flashes.

Just like when deep impact hits its asteroid, we wont have enough good eyes looking to clearly determine/investigate any anomalous energy that might (probably) show itself.

But this time, we should be able to get close up and personal with the debris and the crater, see if the impact conforms with impact theory here on earth.

shame they wont do this on OUR side of the moon, and when the moon is eclipsed by Earth. Everyone (well 50% of us) could have then watched from their back gardens.
not rated yet Feb 09, 2009
Is there not another way of doing this ? Like a robotic drilling expedition . Firing a projectile at the moon seems crazy , the moon affects our very being .
A rocket is far easier than a robotic drilling team and 2 tons compared to the mass of the moon is akin to a mosquito hitting your windshield.