LRO-LAMP observations of the LCROSS impact plume

Area of Science:

• Lunar science
• Planetary geology
• Astrochemistry

Background:

• The Lunar Crater Observation and Sensing Satellite (LCROSS) mission aimed to detect water ice and volatiles in lunar polar regions.
• Cabeus crater was targeted for its potential to harbor trapped subsurface materials due to its location in permanent shadow.

Purpose of the Study:

• To analyze the composition of the plume generated by the LCROSS kinetic impactor.
• To characterize the volatile content of lunar polar soil using remote sensing.

Main Methods:

• The Lyman Alpha Mapping Project (LAMP) ultraviolet spectrograph on the Lunar Reconnaissance Orbiter (LRO) observed the impact plume.
• Analysis of far-ultraviolet emissions, including fluorescence and resonant scattering, to identify atomic and molecular species.

Main Results:

• Detection of far-ultraviolet emissions from molecular hydrogen (H2) and carbon monoxide (CO) due to sunlight fluorescence.
• Observation of resonantly scattered sunlight from atomic mercury (Hg), calcium (Ca), and magnesium (Mg).
• The observed light curve was consistent with a vapor cloud expanding at approximately 1000 Kelvin, containing significant quantities of CO, H2, Ca, Hg, and Mg.

Conclusions:

• The LCROSS impact provided valuable data on the composition of lunar polar regolith.
• The presence of detected volatiles and metals offers insights into the formation and evolution of the Moon.
• LAMP's observations confirmed the utility of UV spectroscopy for remote sensing of lunar impact events.