ExoMars Trace Gas Orbiter (EMTGO) Mars Atmospheric Global Imaging Experiment (MAGIE) Instrument Description
MAGIE consists of a dual-lens camera head (upper left in the rendering) and a digital electronics assembly (lower right). The camera head acquires the images, and includes a turntable to keep it properly oriented with respect to the orbital motion of the EMTGO spacecraft. The digital electronics buffer and compress the images for transmission to Earth.
The Mars Atmospheric Global Imaging Experiment (MAGIE) is designed to acquire daily global images of Mars for at least 1 martian year (687 Earth days) at 2 visible wavelengths and 2 ultraviolet wavelengths. MAGIE images will be used to document the weather on Mars by observing the comings and goings of dust storms, dust devils, polar frost, and clouds of water vapor, water ice, and carbon dioxide crystals. MAGIE's ultraviolet observations will map the distribution of water vapor and ozone in the atmosphere.
The EMTGO MAGIE is the third such camera to be sent to Mars. The first was competitively selected by NASA to fly on the Mars Climate Orbiter (MCO) in 1998. That spacecraft was lost during orbit insertion in September 1999. The MCO MARCI had two cameras-- a wide angle system to provide daily global views of the planet, and a medium angle system to provide 40 meters per pixel views of selected areas to be examined for landing site studies. For the 2005 MRO mission, NASA decided only to re-fly the MARCI wide angle system, and replace the 40 meters per pixel medium angle camera with the 6 meters per pixel Context Camera (CTX). For the 2016 EMTGO mission, the MAGIE, consisting of just a wide angle system, was competitively selected by NASA.
On each orbit that EMTGO makes around Mars, MAGIE will simultaneously acquires 4 pictures at 4 different wavelengths. Over the course of a day, EMTGO makes 12 to nearly 13 orbits around Mars. The 12 times 4 pictures per day (48 images) provide a daily record of meteorological events that have occurred on the planet. By building up these images every day for an entire martian year, MAGIE will provide a record that spans through winter, spring, summer, and autumn in both martian hemispheres.
The table below, shows the wavelengths of each MAGIE image. In addition to their utility in observing ozone and discriminating between clouds of dust, water vapor, water ice, and carbon dioxide, these images can also track the changes in brightness of the martian surface, and monitor the growth and retreat of the polar caps.
Looking straight down (nadir orientation) at Mars, MAGIE images are designed to have spatial resolutions in the 0.4 to 20 kilometers per pixel range. The system consists of two separate sets of lenses and detectors--one for the visible light images, and one for the ultraviolet images. The ultraviolet light system will have a 125° field of view lens while the visible light system will have a 140° field of view lens, which permits all of Mars to be viewed. Each MAGIE image is about 2000 pixels wide and can be many thousands of pixels long, depending on the objective of the image.
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