Mars Reconnaissance Orbiter
Context Camera

Earth–Moon Calibration Image

MRO CTX Release No. CTX-2, 12 September 2005


CTX-2a: Earth and Moon

CTX calibration image showing Earth (saturated white, as expected) and Moon.


CTX-2b: Simulated and Actual CTX Views of Moon
Three views of the Moon: from Clementine UVVIS Global Mosaic; a simulated CTX view derived from the UVVIS mosaic; and the actual CTX view (magnified).
NASA/JPL/Malin Space Science Systems

On Thursday, 8 September 2005, the Mars Reconnaissance Orbiter (MRO) Context Camera (CTX) was powered on and the MRO spacecracft pointed the camera at Earth and the Moon. This occurred at the same time that MRO's HiRISE camera was also imaging the Moon (see: PIA08005 and PIA08002 for HiRISE's view). The two objects, Earth and Moon, were about 10 million kilometers (~6 million miles) from the MRO spacecraft at the time the data were obtained.

The purpose of this activity was to acquire calibration images. These images were used to verify that the CTX camera focus and sensitivity remained unchanged following the rigors of the launch environment and upon initial exposure and operation in the cold vacuum of deep space.

The CTX took 5 images of Earth and the Moon and 5 images of stars in the vicinity of Omega Centauri. The first image, above, shows Earth and the Moon. Earth is overexposed because the exposure was set for the brightness of the Moon (which is only about 1/5th as bright as Earth). In other words, the CTX team expected and planned that the image of Earth would be saturated white. The left side of the second image shows a computer graphic representation of the portion of the Moon visible to CTX, using as a base map the Clementine UVVIS mosaic assembled by the U. S. Geologcial Survey. The middle of the second figure shows a simulation of the CTX picture derived from the Clementine mosaic, while the right side of the figure shows the actual CTX image, greatly magnified.

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Malin Space Science Systems built two cameras on the Mars Reconnaissance Orbiter the Context Camera (CTX) and the Mars Color Imager (MARCI). MSSS operates both cameras from its facilities in San Diego, California. The Jet Propulsion Laboratory's operates the MRO spacecraft with its industrial partner, Lockheed Martin Space Systems Company, from facilities in Pasadena, California and Denver, Colorado.

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