MESSENGER Mission News
July 23, 2007


During its second and final close encounter with Venus on June 5, MESSENGER's wide angle camera captured a sequence of 50 images showing the planet disappearing in the distance. The probe was 60,688 kilometers (37,710 miles) from the planet at the start of the sequence and 89,310 kilometers (55,495 miles) at the end. Initially, images were acquired at a rate of one of every 20 minutes, and then as Mercury shrank the timing interval was increased to 60 minutes. These images represent the last view of Venus by MESSENGER, but they also point toward the spacecraft's first encounter with Mercury on January 14, 2008.

The January flyby will provide the MESSENGER team with its first science observations of its prime target, Mercury. The Venus flyby provided the mission operations team an opportunity to complete successfully a full test of the complicated series of spacecraft motions required to build up high-resolution image mosaics at Mercury. Mariner 10 imaged only one hemisphere of Mercury in 1974-75. During the January flyby the MESSENGER instruments will photograph and make measurements of half of the hemisphere viewed by Mariner 10 and half of the hemisphere never before imaged by spacecraft. MESSENGER will capture the rest of the planet in subsequent flybys in October 2008 and September 2009. In March 2011 MESSENGER will be inserted into orbit about Mercury, allowing detailed observations of the planet for a full Earth year.

During the June 5 flyby, MESSENGER tagged up with the European Venus Express spacecraft-currently orbiting Venus-to make novel observations of the Venus environment. The two spacecraft carry sets of instruments employing different observation techniques which complemented each other, "so we had a unique opportunity to make simultaneous measurements of aspects of Venus from these two platforms-one in a 24-hour orbit and one flying by in a very different trajectory," says APL's Dr. Ralph McNutt, MESSENGER Project Scientist.

On July 19, NASA and the European Space Agency released early results from this coordinated set of observations. Science teams from both missions are collaborating on the interpretation of images and other instrument observations of the Venus cloud deck and surface, atmosphere, and plasma environment. More mature scientific analyses from this joint observation campaign are expected by the end of the year.

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.