With the impacts of the Centaur and Shepherding Spacecraft occurring within a permanently-shadowed crater near one of the lunar poles, the impacts themselves will be obscured by the crater rim as seen from Earth and Earth orbit. However, ground-based and orbital observatories will observe the dust and water vapor plume caused by the two impacts into the lunar surface. The impact ejecta cloud should be in view of Earth assets just several seconds after impact and will peak in brightness around 30-100 seconds after impact. The timing of the two impacts will allow simultaneous observations from Hawaii (NASA-IRTF, NASA-Keck, Gemini-N, Subaru, CFHT), the Continental US (Kitt Peak), and from South America (Gemini-S, VLT-ESO in Chile). Compared to the Deep Impact (DI) Mission encounter with comet 9P/Tempel, LCROSS’s Centaur impact plume will have 100 times less mass at 360 times closer range, so the surface brightness will be higher. However, the dust-to-ice ratio for targeted regolith is expected to be 100 in comparison to ~0.5 for Deep Impact. Therefore, ground-based telescopes will observe the thermal evolution of and the properties of the dust in the ejecta plume, and 8-10 m class telescopes, e.g., NASA-Keck+NIRSPEC, will be required to search for water vapor using the non-resonant fluorescent lines at ~3 µm. The longer time scale evolution of the OH exosphere can be followed by telescopes in Spain (Calar Alto), the Canary Islands (Mount Teide), and Australia (Siding Springs, Mt. Stromlo). Orbital assets such as SWAS, HST, NASA’s Galaxy Exploration Explorer, and the Far Ultraviolet Spectroscopic Explorer (FUSE) may be used to observe the impact plume. We will capitalize on the experience gained during the DI observation campaign by members of our science team and other DI participating scientists who are advising the project. The Observation Campaign Manager will be responsible for the coordination of the ground-based observing campaign.

For more information, download the Lunar Crater Observation and Sensing Satellite (LCROSS) Mission: Opportunities for Observations of the Impact Plumes from Ground-based and Space-based Telescopes presentation from the May 2007 AAS conference, the LCROSS Overview for Ground-based Observatories presentation, and the Observation Campaign Summary.

You may download the Astronomer Justification document. This text describes information relevant to the LCROSS mission. Astronomers may use this sample text in support of writing observing proposals to observe the LCROSS impacts and thereby participate in the LCROSS mission. Specific sections of this document include: Introduction, The LCROSS Mission, Mission Relevance and Impact to State of Knowledge, LCROSS Science Goals, LCROSS Shepherding Spacecraft (S/S-C) Measurement Goals, LCROSS Shepherding Spacecraft Payload, Impact Characterization, Lunar Polar Hydrogen - What we Know and Don't Know, The History of Lunar Volatiles: Sources and Sinks, Additional Sample Text: Experimental Design, Description of Experiment.

Additional information and a call for proposals to fund astronomer time and travel in support of LCROSS observations will be available soon. Please check back here and/or contact Jennifer Heldmann (Jennifer.Heldmann@nasa.gov) for additional information.

Amateur Observations

Mission scientists estimate that the Centaur impact plume may be visible through amateur-class telescopes with apertures as small as 10 to 12 inches. As the mission progresses, this site will provide the general public, classrooms, and the amateur astronomy community details on how to observe the impact. The LCROSS mission will actively solicit images of the impact from the public. These images will provide a valuable addition to the archive of data chronicling the impact and its aftermath. This site will include a gallery of images received from both the public and professional communities.