The resulting data will be examined and compared to Martian atmospheric models, much like terrestrial  meteorological data. This will provide an understanding of the atmospheric temperatures and winds as well as the ways in which the solar heating directly and indirectly forces them. It will also provide valuable knowledge of Martian climate changes from season to season.  The original plan also called for routine surface observations. This would have represented a small  portion of the overall science (~10%) from the instrument. They were primarily for studying thermal and  radiative changes of the seasonal polar caps to determine their influence on the weather and climate. The  surface observations are also used for establishing the lowest 10 km of the atmospheric profiles. An  anomaly-imposed operational restriction currently limits the view to only 10° below the limb, which yields  limited, but useful measurements of the surface. Due to the curvature of the surface, this corresponds to an emission angle of 65°, which is useful for some surface science as well as to help constrain the lowest part of the atmospheric profiles.  Detector Configuration For each of the nine channels (8 IR and 1 visible), the instrument has a 21 element detector array on the  focal plane. These are oriented so that they provide a profile of the radiation from the surface to ~80 km when pointed at the limb. Each individual detector is 0.2° by 0.35°, with the narrow dimension providing 5 km vertical resolution on the limb to meet the desired vertical resolution for the profiles.  The radiance profile seen at the limb is a combination of two main factors. The first factor is the amount of  emission/absorption; and whether it is opaque at the wavelength of the channel (in which case the detectors do not see all the way through the atmosphere). The second factor is the temperature of the atmosphere. Both tend to decrease with altitude (ignoring the special case of clouds). Combined, these  changes tend to produce a radiance profile that stays constant until the atmosphere starts to become  transparent, then decreases more or less exponentially (see Fig. 8 for an example profile).  Since the detector signals are not chopped, frequent calibration views of space and the blackbody (or  solar) targets are necessary to provide a good calibration of the observations. On the other hand, time spent on calibration views (and the time spent moving between calibration views) is time when no science data is collected, leading to a desire to minimize the calibration observations.   Individual observations are performed with 2 second integration times, but are usually combined to  improve the signal to noise in the most sensitive cases. When staring at the limb, the signal to noise and  rapid change in signal with altitude allows shifts of as little as 5% of a detector’s width to be noticed. The pointing accuracy requirement for the actuators is not that strict since other sources of pointing errors (in particular, spacecraft orientation) also interfere. However, since the pointing can be determined from the radiance profile, the pointing accuracy requirements on the actuator are looser than this.  Instrument Scanning Patterns MCS slewing is driven by the observations needed to support the science goals of the instrument,  including the calibration views. Both the azimuth and elevation actuators are used to achieve the  necessary orientations, although the elevation actuator performs the majority of the slewing. The scanning is described in detail in [4], but a few locations played a key role in understanding the  anomaly. A graphical representation of the range and frequency of scanning is shown in Fig. 1. The first  position is the stow position. This is with both actuators pointing at 0°. This is a sun safe position that is  used when the instrument is powered off, since even a momentary exposure of the telescopes will  destroy the focal plane. It is also used when the instrument is standing down from normal operations.  When the elevation is at 0°, the telescopes are staring at the built-in black body, one of three calibration  views. The second calibration target, the solar target, is at an elevation of 37°. The standard MCS scan  observes the blackbody about five times per hour and the solar target once an hour. 272