LCROSS spectroscopy confirms water on the moon

Spectrographic data captured by an Ocean Optics spectrometer has helped NASA confirm the presence of water ice on the moon. The spectrometer, which was custom engineered for space duty by Aurora Design & Technology and dubbed 'Alice', was part of the scientific payload on NASA's Lunar CRater Observation and Sensing Satellite (LCROSS) mission.

The LCROSS shepherding spacecraft (S-S/C) carrying the Alice spectrometer made measurements of the permanently shadowed crater Cabeus, near the lunar south pole, as the spacecraft's Centaur upper rocket stage impacted the crater floor. The instruments on board the S-S/C monitored the emission caused by the Centaur impact, as well as the resulting two-part debris plume it created.

NASA scientists announced in November that the signature of water was seen in both near-infrared and ultraviolet spectroscopic measurements taken during the mission. Ocean Optics’ Alice provided the ultraviolet measurements, confirming the findings of the near-infrared spectroscopic measurements. From the data gathered, NASA scientists were able to estimate that roughly 220 pounds of water were found by the instruments in the material excavated from the 20-30m wide crater formed by the Centaur impact. It is hoped that water on the moon could set the stage for further space exploration by providing drinking water or even rocket fuel derived from its hydrogen and oxygen molecules.

Ocean Optics’ highly-sensitive QE65000 Spectrometer was adapted to withstand the rigours of space – extreme temperature ranges, radiation, shock and vibration. With a wavelength range of 270-650nm and an optical resolution of less than 1.0nm, Alice was designed to identify, with a high degree of accuracy, ionised water (visible at 619nm), OH radicals (visible at 308nm) and other organic molecules containing carbon. Though the measurements were made from the ejecta reflecting sunlight scattered off of the crater walls, the unit’s back-thinned detector was able to make the most of the available light.

Alice was developed in partnership with Aurora Design & Technology, which played a significant role in the mission, developing the optics that collected light from the impact and resulting ejecta plume for the mission. Aurora’s Dr Dave Landis was the only private sector member of the LCROSS Science Team. The company specialises in providing low-cost modifications of COTS instrumentation for use in the aerospace industry as well as other demanding physical environments.

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