Impact from the Lunar Reconnaissance Orbiter's Line of Sight

Scientist and engineers are adjusting LRO’s orbit to have it fly its closest approach to the Cabeus target site just 90 seconds after the Centaur impacts the lunar surface. 

Artist Concept of the Lunar Reconnaissance Orbiter with Apollo mission
imagery in the background. Credit: NASA

The Lunar Reconnaissance Orbiter, better known as LRO, was a sister payload to LCROSS during launch and now the orbiter will pass over the moon at just the right time to capture the Centaur impact to collect key data about the physics of the impact and how volatile materials may have been mobilized.

This image shows the moon’s south pole, as seen by the 1994 Clementine
mission. The possibility of frozen water is one of many reasons NASA is
interested in thisspot as a potential future landing site. However, many of the
craters in this area where frozen water sources are most likely to be found are
in constant shadow, which inhibited Clementine’s ability to see into these craters.
These shadows are the very dark areas at the pole’s center. The upcoming
Lunar Reconnaissance Orbiter mission will study this area and search for
evidence of frozen water sources. Credit: NASA

During and after impact LRO’s LAMP far UV spectrometer will search for evidence of significant water ice or water signatures and how they evolve in the moon’s atmosphere.  LRO’s Diviner radiometer will peer into the impact site to measure the heating effects caused by impact and how the temperature changes over time. LRO will continue to study the impact site using its suite of instruments long after the dust settles.

A Personal Perspective
David A. Paige, principal investigator Diviner
Diviner is one of the seven instruments aboard LRO

We on the LRO Diviner team are looking forward to the LCROSS impact with great anticipation. It’s not every day that we will have an opportunity to excavate a significant volume of material from one of the moon’s permanently shadowed polar cold traps.  We expect that a new lunar impact crater will form, and that dust, rock, and possibly cold-trapped volatile materials such as water ice will be thrown into space.

Everything we learn about the LCROSS impact will come from Earth observations and from observations from nearby spacecraft. Diviner will get excellent views of the impact site as LRO flies by. We intend to make maps of the radiometric temperature of the impact site before and after the impact, as well as observations of the dust plume that will be lofted during the impact event. Diviner’s observations may help confirm the location of the LCROSS impact, and its effects on the impact on the surrounding terrain. Diviner has already mapped the impact site on previous orbits and so any changes that are detected will be of great interest. We have no idea what LCROSS will uncover, but we’re anxious to know the results.

Diviner has acquired the first global daytime and nighttime thermal
maps of the moon. These maps were assembled using Diviner data obtained during
August and the first half of September, 2009. Credit: NASA/GSFC/UCLA

Hopefully, everything will go well for LCROSS and LRO on Friday morning and we’ll learn something new and exciting about the moon!