Mars Reconnaissance Orbiter
Context Camera

Jewel Box (Open Cluster NGC4755) Star Calibration Image

MRO CTX Release No. CTX-4, 27 December 2005

CTX calibration image showing the Jewel Box.


About three hours after its slews centered images on the bright stars of the Southern Cross (Crux), the Mars Reconnaissance Orbiter (MRO) slewed to point the spacecraft's instruments at the open cluster NGC4755, known to amateur astronomers as the "Jewel Box." The main purpose of this observation was for MRO to take images with its high resolution camera, HiRISE, but the Context Camera (CTX) "rode along" to image the cluster, as well. The HiRISE image of the Jewel Box is shown here:, and the CTX image is shown above.

Compared to a large terrestrial telescope's image of the cluster, for example a picture from the Anglo-Australian Observatory, the CTX image is not very impressive. However, consider that the former is a composite of three 5-minute exposures with the Anglo-Australian Telescope, an instrument with a primary mirror almost 4 meters (~13 ft) in diameter and weighing about 260 tons. CTX has a primary mirror with an effective diameter of about 10 cm (~4 in) and weighs about 3.5 kg; the CTX exposure was 45.9 msec per line. From the MRO mapping orbit altitude of 300 km above the surface of Mars, CTX will image a swath 30 km (~16 mi) wide by up to 300 km (~160 mi) long at a resolution of about 6 meters (~20 ft) per pixel, allowing a large fraction of Mars to be mapped in better detail than ever before.

The Jewel Box image was acquired at about 23:00 UT on 14 December 2005, when MRO was 78 million kilometers (~40 million miles) from Earth and about 22.8 million kilometers (~12 million miles) from Mars. MRO will reach the red planet on 10 March 2006.

Tips for Media Use

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 operates the MRO spacecraft with its industrial partner, Lockheed Martin Space Systems Company, from facilities in Pasadena, California and Denver, Colorado.

To MSSS Home Page