Left: Image of monolithic DASH interferometer; Right: Conceptual Design of a DASH space flight instrument.
Left: Image of monolithic DASH interferometer; Right: Conceptual Design of a DASH space flight instrument.

Objectives
The objective of the DASH development effort is to increase the TRL of the innovative DASH spatial heterodyne spectroscopy (SHS) technique for future space-based thermospheric wind observations. (NRL Patent 7,773,229)

High quality global thermospheric wind observations are currently not available, but are essential for improving orbit determination and comms, geopositioning, via ingest into models such as ISES.

Approach

  • A DASH interferometer passively measures the Doppler shift of atmospheric emissions to derive the wind velocity and temperature
  • The interferometer is similar to conventional SHS, but it has an additional optical path difference built in to optimize the Doppler shift measurement
  • The TRL increase is accomplished via the design and fabrication of a monolithic DASH interferometer, laboratory testing, and a ground based demonstration. For the ground based demonstration, thermospheric winds are measured at night by observing the atomic oxygen airglow (“red line” at 630nm wavelength). Verification and validation is achieved with a co-located Fabry-Perot interferometer
  • On 12 April 2013, NASA selected the Ionospheric Connection Explorer (ICON) to proceed to Phase B. NRL participation in ICON includes providing the thermospheric wind instrument as one of the four Mission science payloads, and also scientific data analysis and interpretation. ICON will study the extreme variability of the ionosphere, to understand the way space weather events grow to envelop regions of Earth with dense ionospheric plasma

Deliverable/Value/Accomplishment

  • Interferometer has been designed, fabricated, tested in the laboratory, and integrated in a ground based breadboard instrument
  • Ground based DASH instrument performed successfully, and validated field measurements of thermospheric winds
  • Launch Plans: A DASH spaceflight instrument, the Michelson Interferometer for Global High-resolution Thermospheric Imaging (MIGHTI), is included in NASA ICON Explorer Mission proposal led by UC Berkeley that is now at the start of Phase B
  • DASH TRL is significantly increased, shortening the time until space-based wind observations will be operationally available for DoD Space Situational Awareness, upper atmospheric analysis