Midcourse Space Experiment: Off-Axis Rejection Performance of the Infrared Sensor

Abstract

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Polar mesospheric clouds: Infrared measurements from the Midcourse Space Experiment

“…Figure 3 indicates a fairly constant radiance level of approximately 1.5 × 10 −8 W cm −2 sr −1 at tangent heights above 97 km due primarily to nonrejected off‐axis radiation from the Earth’s surface. The nonrejected Earth radiance (NRER) is produced by scatter from particulate contamination accumulated on the primary mirror of the SPIRIT III telescope during the period of prelaunch operations and during launch of the MSX satellite [ O'Neil et al , 2006]. The arc‐like features in Figures 2 and 3 are a consequence of maintaining the LOS at an oblique angle from the spacecraft heading and provide information on the location of the cloud along the LOS.…”

“…The PMC components were extracted from the Earth limb radiance profiles measured at 0313:25 UT in a sequence of steps. The radiance component due primarily to NRER together with a small contribution from the zodiacal background was determined by fitting the slowly varying high altitude profiles and extrapolating the profile to lower altitudes using the NRER radiance profiles described by O'Neil et al [2006]. The NRER and zodiacal components of limb radiance were subtracted from a series of limb profiles including those illustrated in Figure 4 to yield limb measurements composed of atmospheric and, if present, polar mesospheric cloud radiance for bands C and E. The dominant source of atmospheric radiance in band C is the long wavelength tail of the 9.6 μ m O 3 vibrational band complex and in band E the atmospheric radiance is due to water vapor rotational state transitions.…”

Modeling and analysis of out-of-field stray radiation of space infrared detection system

“…Taking the SPIRIT III space infrared detection system carried by the MSX satellite with an orbit of 900km as an example, when it observes the tangential height of 80km, the view axis was only 1° different from the tangential height of 40km, but the atmospheric radiance was higher than 1000 times. The measured data shows that in the range of tangential altitude of 0-200km, non-rejected out-of-field atmospheric radiation and Earth radiation are the main components of stray radiation received by the detection system 2,4 .…”