Lunar Ice Cube, a science requirements-driven deep space 6U cubesat mission, was selected by the NASA HEOMD NextSTEP program to be deployed in cis-lunar space by NASA’s EM1 mission. We are de-veloping a compact broadband IR instrument for a high priority science application: understanding the nature and role of volatiles in the inner solar system.
The Lunar Ice Cube science team, led by the JPL Science PI, will enable broadband spectral determina-tion of composition and distribution of volatiles in lu-nar regolith as a function of time of day, latitude, rego-lith age and composition, and thus enable understand-ing of current dynamics of lunar volatile sources, sinks, and processes, with implications for evolution-ary origin of volatiles. While Chandrayaan M3 provid-ed a ‘snapshot’ mosaic of the lunar nearside, indicating surface coating of OH/H2O near the poles, Lunar Ice Cube will provide coverage of the same swaths as a function of latitude at several times of day. Lunar Ice Cube measurements will completely encompass the broad 3 micron band resulting from absorption by sev-eral forms of water instead of cutting off at 3 microns as previous Near IR spectrometers have done. Lunar Ice Cube utilizes a versatile GSFC-developed payload: BIRCHES, Broadband InfraRed Compact, High-resolution Exploration Spectrometer, a miniaturized version of OVIRS on OSIRIS-REx. BIRCHES is a low-resource (1.5U, 2 kg, 7W including cryocooler) point spectrometer with a compact cry-ocooled HgCdTe FPA for broadband (1 to 4 micron) measurements. The instrument will achieve sufficient SNR (>100) and spectral resolution (10 nm) through the use of a Linear Variable Filter to characterize and distinguish important water-based and potentially other volatiles and mineral bands. We are also developing compact instrument electronics which can be easily reconfigured to support future instruments with H1RG focal plane arrays in ‘imager’ mode, when the commu-nication downlink bandwidth becomes available. Thermal design is critical for the instrument. The compact and efficient Ricor microcryocooler is de-signed to maintain the detector temperature below 120K. In order to maintain the optical system below 230K, a special radiator is dedicated to optics alone, in addition to a smaller radiator to maintain a nominal environment for spacecraft electronics.
The Lunar Ice Cube team is led by Morehead State University, who will provide build, integrate and test the spacecraft, provide mission operations and ground communication. Propulsion is provided by the Busek Iodine ion propulsion (BIT-3) engine. Attitude Con-trol will be provided by the Blue Canyon Technology XB1, which also includes a C&DH ‘bus’. C&DH will also be supported, redundantly, by the Proton 200k Lite and Honeywell DM microprocessor. Onboard communication will be provided by the X-band JPL Iris Radio and dual X-band patch antennas. Ground communication will be provided by the DSN More-head State University 21-meter substation. Flight Dy-namics support, including trajectory design, is provid-ed by GSFC. The high inclination, equatorial periapsis orbit will allow coverage of overlapping swaths once every lunar cycle at up to six different times of day (from dawn to dusk) as the mission progresses during its nominal six month science mapping period.