An Ultra-Wideband Spectrometer for Lunar Heat-Flow Measurements

The lunar heat-flow ultra-wideband spectrometer operates over an extended frequency band from 300 MHz to 6.0 GHz. It is a direct-acquisition single-chain digital spectrometer measuring 1024 spectral channels over 6 GHz bandwidth with each channel bandwidth about 6 MHz. The LHR instrument is intended to characterize the near surface regolith thermal and dielectric properties in order to determine the local geothermal heat flux. It would also reveal subsurface thermal and dielectric property changes due to buried ice, dielectric materials like ilmenite, and bedrock. The wide spectral bandwidth is expected to provide up to 1 m deep brightness temperature measurements from as close as 5 cm penetration depth at higher frequency end of the spectra. Using information obtained at multiple frequency bands, the subsurface temperatures and dielectric properties can be reconstructed.

 

The instrument is currently being developed at Jet Propulsion Laboratory in Pasadena, CA. The design includes a novel receiver architecture allowing a single chain design for the ultra-wideband channelized spectral operation for enabling the science objectives of the instrument. The lab-bench demonstration of the lunar spectro-radiometer has been performed including the calibration testing. The environmental testing will be further conducted before proceeding with the flight model. The final flight version of the spectro-radiometer instrument is expected to have light weight, low-power and small-size suitable for a deployment into a lunar rover or lander.