TIMED Doppler Interferometer

TIMED Doppler Interferometer

Experiment Overview The TIMED Doppler Interferometer (TIDI) will investigate the dynamics and energetics of the Earth's mesosphere and lower-thermosphere-iono-sphere (MLTI) from an altitude of 60 to 300 km. TIDI measurements will allow us to obtain a global description of the vector wind and tem-perature fields, as well as important information on gravity waves, species densities, airglow and auroral emission rates, noctilucent clouds, and ion drifts. TIDI will provide basic information about global winds and tem-peratures. TIDI will also contribute to the study of MLTI energetics.

Thermosphere-Ionosphere-Mesosphere Energetics and Dynamics (TIMED) Spacecraft

Key Spacecraft Characteristics
Orbital Altitude: 625 km Circular
Orbital Inclination: 74.1o
Total Spacecraft Weight: 660 kg
Spacecraft Size: Mid-Lite class
Launch Vehicle: Delta II 7920

Science Objectives The TIDI interferometer (or Profiler) primarily measures horizontal vector winds and neutral temperatures from 60 to 300 km, with a vertical resolu-tion 2.5 km at the lower altitudes and with an accuracy that approaches ~3 m/sec and ~3 K, respectively, under optimum viewing conditions. The TIDI design allows for 100% duty cycle instrument operation during day-time, nighttime, and in auroral conditions. TIDI views emissions from OI 557.7 nm, OI 630.0 nm, OII 732.0 nm, O2(0-0), O2(0-1), Na D, OI 844.6 nm, and OH to determine Doppler wind and temperature through-out the TIMED altitude range. TIDI also makes spectral ratio observa-tions to determine O2 densities and rotational temperatures.

Description and Specifications
TIDI comprises three major subsystems: four identical telescopes, a Fabry-Perot interferometer with a CCD detector, and an elec-tronics box. Light from the selected regions of the atmosphere is collected by the telescopes and fiber-optically coupled to the de-tection optics. The four fields of view are scrambled along with a calibration field input and converted to an array of five concentric cir-cular wedges. This input then passes through a selected filter, then through a Fabry-Perot etalon, and is finally imaged onto a CCD via a circle to line imaging optic (CLIO) device.

TIDI System
Mass: 41.8 kg
Electrical Power: 19.32 watts (orbit ave.)
Heater Power: 11.0 watts
Data Rate: 2494 bits/sec
Observations: winds, temperatures, and density
Wind accuracy: 3 m/s (line of sight)
Altitude Resolution: 2.5 km
Spectral Range: 550 - 900 nm
Lifetime: >2 years
Electronics System
Hybrid Power supply
80C51 (UTMC) Flight computer
Data acquisition
CCD controller
Filter wheel/ shutters/ PWM heaters
Telescope servo amp

TIDI Layout
(showing two of four telescopes)

Telescope Specifications
Off axis Gregorian
Low scatter optics and baffles
Zenith gimbal
Clear Aperture 7.5 cm
Area 44.2 cm2
Angular FOV 2.5o horiz x 0.05o vert
F/number 2.2

Profiler Specifications
Fixed gap single etalon Fabry-Perot interferometer
2 x 8 position filter wheel
Circle to line image converter (CLIO)
Passively Cooled CCD detector
5 x 32 Channels
Clear Aperture 7.5 cm
Plate Diameter 10.5 cm
Gap 2.2 cm
Interferometer Optics
Finesse 8.1-8.9



	Principal Investigator: Tim Killeen National Center for Atmospheric Research P.O. Box 3000 Boulder, CO 80305 Phone: (303) 497-1111 Fax: (303) 497-1194 Email: killeen@ucar.edu		Project Director: Wib Skinner The University of Michigan 2455 Hayward St. Ann Arbor, MI 48109 Phone: (734)-647-3960 Fax: (734)-763-5567 Email: wskinner@umich.edu

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High Altitude Observatory - National Center for Atmospheric Research
P.O. Box 3000, Foothills Laboratory, Boulder, CO 80307 U.S.A.
303-497-1527

Last updated by S.C. Solomon on 10 January 2004