The OSIRIS-REx Thermal Emission Spectrometer (OTES) provides mineral and thermal emission spectral maps and local spectral information of candidate sample sites by collecting thermal infrared data. OTES provides full-disk Bennu spectral data, global spectral maps, and local sample site spectral information also.
More Information: Detailed Specifications and Instrument Operations
The OSIRIS-REx Thermal Emission Spectrometer (OTES) provides mineral and thermal emission spectral maps and local spectral information of candidate sample sites from 4 - 50 µm by collecting thermal infrared data. OTES provides full-disk Bennu spectral data, global spectral maps, and local sample site spectral information used to characterize the global, region, and local mineralogic composition and thermal emission from the asteroid surface. The wavelength range, spectral resolution, and radiometric performance are sufficient to resolve and identify the key vibrational absorption features of silicate, carbonate, sulfate, phosphate, oxide, and hydroxide minerals. OTES is also used to measure the total thermal emission from Bennu, which drives the requirement to measure emitted radiation globally. Based on the performance of Mini-TES in the dusty surface environment of Mars, OTES is resilient to extreme dust contamination on the optical elements.
OTES has a single operational mode. It collects one interferogram every 2 seconds while it is on. Commands are used to insert the internal calibration flag into the optical path, and to switch between redundant fringe laser diodes and start-of-scan optical switches. Maps are constructed through the motion of the S/C to scan OTES across the surface of Bennu. No on-board data processing or compression is performed.
OTES uses an uncooled deuterated triglycine sulfate (DTGS) pyroelectric detector with a biased FET to ensure it is poled properly. Identical detectors were used on both MER Mini-TES instruments. OTES command, control, and data flow tasks are controlled by logic in the command and control FPGA. The interface electronics parse out the instrument commands that control the OTES hardware functions. Data flow is controlled by the FPGA.
The sources of absolute error in OTES are:
1) the absolute temperature knowledge of the calibration target thermistors, and
2) the absolute emissivity of the calibration target.
The OTES calibration target thermistors will be calibrated to an absolute accuracy of 0.25 K and the surface emissivity to ±0.0015.
OTES is a copy of the Mars Rover Mini-TES spectrometer (see Christensen et al., 2003) combined with the Mars Global Surveyor (MGS) TES fore-optics.
The OTES team is led by Philip Christensen (IS, ASU), Victoria Hamilton (DIS, SwRI), and Martin Greenfield (IM, ASU).