Gurpreet S. Mand

The Measurements of Pollution in the Troposphere (MOPITT) Instrument: Overall Performance and Calibration Requirements

Abstract The Measurements of Pollution in the Troposphere (MOPITT) instrument will monitor the global concentrations of carbon monoxide and methane. It will be flown on the Earth Observing System Satellite AM-I. This paper briefly describes the scientific objectives, performance requirements, and specifications. It primarily focuses on the pre- and postlaunch calibration requirements. The hardware requirements and methodology for calibration are also discussed as well as cross-calibration and validation of MOPITT with an underflying aircraft MOPITT.

Early mission planning for the MOPITT instrument

The Measurements Of Pollution In The Troposphere (MOPITT) instrument will monitor the global concentrations of carbon monoxide and methane. It will be flown on the Earth Observing Satellite, Terra (EOS-AM1), scheduled for launch late in 1999. This paper describes the proposed early mission operations of MOPITT.

MOPITT On-Orbit Stirling Cycle Cooler Performance

The Measurements of Pollution In The Troposphere (MOPITT) instrument was launched aboard the Terra spacecraft (formerly known as EOS AM-1), from Vandenburg Air Force Base, California on Dec 18th 1999. At present the instrument is in normal operations mode, having undergone its outgas and activation phases.

MOPITT Stirling Cycle Cooler Vibration Performance Results

Both of the Measurements Of Pollution In The Troposphere’s (MOPITT) instrument detector subassemblies require cooling to 90 K with 850 mW head load per subassembly. The stringent spacecraft level mechanical disturbance specification requires compressor forces to be ≤ 200 mNrms and displacer forces to be ≤ 50 mNrms For the first seven (7) harmonics, an acceleration feedback system using two Matra Marconi Space (MMS) 50–80 K Stirling Cycle Coolers (SCCs) and Lockheed-Martin Low Vibration Drive Electronics (LVDE) was used to meet these requirements.

MOPITT airborne validation instrument : MOPITT-A

The Measurements of Pollution in the Troposphere-Aircraft (MOPITT-A) instrument is being constructed at the University of Toronto, as a primary data validation tool for the Terra based MOPITT instrument. MOPITT-A is designed to operate aboard a NASA ER-2 research aircraft and as such must be rugged and field serviceable while maintaining the same characteristics as the satellite instrument. The resulting instrument is a hybrid of flight space components with commercial devices. Calibration data generated by both instruments, at the U of T Instrument Calibration Facility (ICF) will play a key role in data validation.

MOPITT Stirling Cycle Cooler and Cooler Drive Electronics Evaluation

This paper summarizes the vibration compensation results of a Stirling cycle cooler (SCC) for the Measurements Of Pollution In The Troposphere (MOPITT) instrument which will fly on the Earth Observation System AM (EOS-AM) platform. MOPITT is an infrared radiometer that measures global concentrations of CO and CH4 in the lower atmosphere and requires a pair of vibration compensated SCCs to cool the detectors while meeting the NASA EOS platform’s stringent jitter requirements. The Canadian Space Agency (CSA) has contracted COM DEV Atlantic to design and build the instrument which was conceived by a multinational science team. The MOPITT Principal Investigator is Dr. James R. Drummond of the University of Toronto.

Pre-flight testing of the MOPITT instrument

The Measurements Of Pollution In The Troposphere (MOPITT) instrument will monitor the global concentrations of carbon monoxide and methane. It will be flown on the Earth Observing Satellite, EOS-AM1, scheduled for launch late in 1999. This paper primarily describes the pre-flight testing conducted at the University of Toronto, Instrument Characterization Facility (ICF) and will also very briefly describe testing, post integration to the spacecraft at the Lockheed Martin, Valley Force integration and test facility and at the Vandenburg launch site.

Flight electronics for vibration cancellation in cryogenic refrigerators: performance and environmental testing results

Space flight optical instruments and their support hardware must reliably operate in stressing environments for the duration of their mission. They must also survive the mechanical and thermal stresses of transportation, storage and launch. It is necessary to qualify the hardware design through environmental testing and to verify the hardwares ability to perform properly during and/or after some selected environmental tests on the ground. As a rule, flight electronics are subjected to thermal, mechanical and electromagnetic environmental testing. Thermal testing takes the form of temperature cycling over a temperature difference range (Delta) T of up to 100 degrees C for a minimum of six cycles, with additional performance verification testing at the hot and cold extremes. Mechanical testing takes the form of exposure to random vibration, sine sweep vibration, shock spectra and static loading on a centrifuge or by sine burst on a vibration table. A standard series of electromagnetic interference and electromagnetic compatibility testing is also performed.

The radiometric calibration of the MOPITT carbon monoxide length modulated radiometer channels

The MOPITT instrument is measuring atmospheric columns and profiles of carbon monoxide and columns of methane from NASAs Terra satellite. To make these measurements, MOPITT utilises six length modulated radiometers (LMRs). Prior to the integration of MOPITT onto Terra, the radiometric response of the LMRs to simulated atmospheres was measured. Comparison of these measurements to theoretically calculated signals have shown that the response of the carbon monoxide radiometers is within the errors of the calculations. The primary sources of error in these calculations are errors and/or uncertainties in the LMC gas pressure, LMC correlation cell length, and LMR imbalance.

The EOS MOPITT instrument:validation and early results

Launched on the EOS Terra satellite on December 18, 1999, the MOPITT (Measurements of Pollution in the Troposphere) instrument has been observing tropospheric carbon monoxide (CO) and methane (CH/sub 4/) since March, 2000. The instrument is now fully functional, and the retrieval algorithms are now being validated. Because of the pioneering aspect of this instrument, validation is a particularly important phase of operations and is the main emphasis of this paper.