The OSIRIS-REx Thermal Emission Spectrometer (OTES) Instrument

P. R. Christensen, V. E. Hamilton, G. L. Mehall, D. Pelham, W. O’Donnell, S. Anwar, H. Bowles, S. Chase, J. Fahlgren, Z. Farkas, T. Fisher, O. James, I. Kubik, I. Lazbin, M. Miner, M. Rassas, L. Schulze, K. Shamordola, T. Tourville, G. WestR. Woodward, D. Lauretta

Research output: Contribution to journalReview articlepeer-review

89 Scopus citations


The OSIRIS-REx Thermal Emission Spectrometer (OTES) will provide remote measurements of mineralogy and thermophysical properties of Bennu to map its surface, help select the OSIRIS-REx sampling site, and investigate the Yarkovsky effect. OTES is a Fourier Transform spectrometer covering the spectral range 5.71–100 μm (1750–100cm−1) with a spectral sample interval of 8.66cm−1 and a 6.5-mrad field of view. The OTES telescope is a 15.2-cm diameter Cassegrain telescope that feeds a flat-plate Michelson moving mirror mounted on a linear voice-coil motor assembly. A single uncooled deuterated l-alanine doped triglycine sulfate (DLATGS) pyroelectric detector is used to sample the interferogram every two seconds. Redundant ∼0.855 μm laser diodes are used in a metrology interferometer to provide precise moving mirror control and IR sampling at 772 Hz. The beamsplitter is a 38-mm diameter, 1-mm thick chemical vapor deposited diamond with an antireflection microstructure to minimize surface reflection. An internal calibration cone blackbody target provides radiometric calibration. The radiometric precision in a single spectrum is ≤2.2×10−8Wcm−2sr−1/cm−1 between 300 and 1350cm−1. The absolute integrated radiance error is < 1 % for scene temperatures ranging from 150 to 380 K. The overall OTES envelope size is 37.5×28.9×52.2cm, and the mass is 6.27 kg. The power consumption is 10.8 W average. OTES was developed by Arizona State University with Moog Broad Reach developing the electronics. OTES was integrated, tested, and radiometrically calibrated on the Arizona State University campus in Tempe, AZ.

Original languageEnglish (US)
Article number87
JournalSpace Science Reviews
Issue number5
StatePublished - Aug 1 2018


  • Asteroid
  • Bennu
  • Thermal emission spectrometer

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


Dive into the research topics of 'The OSIRIS-REx Thermal Emission Spectrometer (OTES) Instrument'. Together they form a unique fingerprint.

Cite this