NASA MESSENGER: New Images Reveal Views after Closest Approach, First Mercury Laser Altimeter Results

MESSENGER’s First Image after Closest Approach

Just nine minutes after MESSENGER passed 200 kilometers (124 miles) above the surface of Mercury – its closest distance to the planet during the January 14, 2008, flyby – the probe’s Wide Angle Camera (WAC) on the Mercury Dual Imaging System (MDIS) snapped this image. The WAC is equipped with 11 different narrow-band filters, and this image was taken in filter 7, which is sensitive to light near the red end of the visible spectrum (750 nm). This view, also imaged through the remaining 10 WAC filters, is from the first set of images taken following MESSENGER’s closest approach with Mercury.

The image shows Mercury’s surface as seen from a low viewing angle, looking over the surface and off the limb of the planet on the right side of the image. The cratered terrain in the image is on the side of Mercury unseen by spacecraft prior to this MESSENGER flyby. This scene was imaged at multiple viewing angles as MESSENGER sped away from Mercury, and these multiple views of the same surface features from different perspectives and in different colors will be used to help understand the properties of Mercury’s surface.

First Results from the Mercury Laser Altimeter

On January 14, 2008, MESSENGER’s Mercury Laser Altimeter (MLA) became the first instrument to measure the distance between a spacecraft and the surface of Mercury. MLA operates by first firing a brief laser pulse at the surface. It then measures the time for the pulse to reach the surface and return to the spacecraft, thereby providing a precise distance.

This figure shows the distance, or range, from the MESSENGER spacecraft to the surface of Mercury as measured by MLA during the flyby of Mercury. The instrument acquired the surface at a slant range of about 600 kilometers (about 370 miles) and tracked the surface through closest approach near 200 kilometers (about 125 miles) and out to a distance of about 1,500 kilometers (about 930 miles). During the Mercury encounter the instrument met or exceeded all performance specifications. The MESSENGER team is continuing to process the MLA data, and the final results should enable distances to be measured to better than a meter, allowing the profiles of craters and other features to be measured.

The vertical exaggeration in the figure is about 5:1. The MLA was designed and built at the NASA Goddard Space Flight Center.

Additional information and features from MESSENGER’s first flyby of Mercury will be available online at http://messenger.jhuapl.edu/mer_flyby1.html. Following the flyby, be sure to check for the latest released images and science results!

MESSENGER (MErcury Surface, Space ENvironment, GEochemistry, and Ranging) is a NASA-sponsored scientific investigation of the planet Mercury and the first space mission designed to orbit the planet closest to the Sun. The MESSENGER spacecraft launched on August 3, 2004, and after flybys of Earth, Venus, and Mercury will start a yearlong study of its target planet in March 2011. Dr. Sean C. Solomon, of the Carnegie Institution of Washington, leads the mission as Principal Investigator. The Johns Hopkins University Applied Physics Laboratory built and operates the MESSENGER spacecraft and manages this Discovery-class mission for NASA.