Optical Interferometry Projects

High Resolution Doppler Imager (HRDI)

Visit the HRDI project page.

The High Resolution Doppler Imager (HRDI) was one of the instruments on board the Upper Atmospheric Research Satellite (UARS), launched in 1991 as part of NASA's effort to study the Earth's stratosphere and mesosphere.

The HRDI instrument conducted scientific measurements from November 1991 until April 2005. UARS was deactivated on 14 December 2005, completing 78084 orbits over the course of 5208 mission days. The UARS spacecraft is expected to re-enter the atmosphere sometime in 2009 or 2010.

HRDI observed the emission and absorption lines of molecular oxygen and other atmospheric components in small volumes above the limb of the Earth. From the Doppler shift of the lines, the horizontal winds can be determined to an accuracy of ~5 m s- 1, while the line shapes and strengths yield information about the temperature and atmospheric species, such as mesospheric ozone.

TIMED Doppler Interferometer (TIDI)

Visit the TIDI project page.