[meteorite-list] NASA'S MESSENGER Spacecraft Begins Historic Orbit Around Mercury

[Ron Baalke]

March 17, 2011

Dwayne Brown 
Headquarters, Washington      
202-358-1726 
dwayne.c.brown at nasa.gov 

Paulette Campbell 
Johns Hopkins University Applied Physics Laboratory, Laurel, Md. 
240-228-6792 
paulette.campbell at jhuapl.edu 

RELEASE: 11-079

NASA'S MESSENGER SPACECRAFT BEGINS HISTORIC ORBIT AROUND MERCURY

WASHINGTON -- NASA's MESSENGER spacecraft successfully achieved orbit 
around Mercury at approximately 9 p.m. EDT Thursday. This marks the 
first time a spacecraft has accomplished this engineering and 
scientific milestone at our solar system's innermost planet. 

"This mission will continue to revolutionize our understanding of 
Mercury during the coming year," said NASA Administrator Charles 
Bolden, who was at MESSENGER mission control at the Johns Hopkins 
University Applied Physics Laboratory in Laurel, Md., as engineers 
received telemetry data confirming orbit insertion. "NASA science is 
rewriting text books. MESSENGER is a great example of how our 
scientists are innovating to push the envelope of human knowledge." 

At 9:10 p.m. EDT, engineers Operations Center, received the 
anticipated radiometric signals confirming nominal burn shutdown and 
successful insertion of the MESSENGER probe into orbit around the 
planet Mercury. NASA's MErcury Surface, Space ENvironment, 
Geochemistry, and Ranging, or MESSENGER, rotated back to the Earth by 
9:45 p.m. EDT, and started transmitting data. Upon review of the 
data, the engineering and operations teams confirmed the burn 
executed nominally with all subsystems reporting a clean burn and no 
logged errors. 

MESSENGER's main thruster fired for approximately 15 minutes at 8:45 
p.m., slowing the spacecraft by 1,929 miles per hour and easing it 
into the planned orbit about Mercury. The rendezvous took place about 
96 million miles from Earth. 

"Achieving Mercury orbit was by far the biggest milestone since 
MESSENGER was launched more than six and a half years ago," said 
Peter Bedini, MESSENGER project manager of the Applied Physics 
Laboratory (APL). "This accomplishment is the fruit of a tremendous 
amount of labor on the part of the navigation, guidance-and-control, 
and mission operations teams, who shepherded the spacecraft through 
its 4.9-billion-mile journey." 

For the next several weeks, APL engineers will be focused on ensuring 
the spacecraft's systems are all working well in Mercury's harsh 
thermal environment. Starting on March 23, the instruments will be 
turned on and checked out, and on April 4 the mission's primary 
science phase will begin. 

"Despite its proximity to Earth, the planet Mercury has for decades 
been comparatively unexplored," said Sean Solomon, MESSENGER 
principal investigator of the Carnegie Institution of Washington. 
"For the first time in history, a scientific observatory is in orbit 
about our solar system's innermost planet. Mercury's secrets, and the 
implications they hold for the formation and evolution of Earth-like 
planets, are about to be revealed." 

APL designed and built the spacecraft. The lab manages and operates 
the mission for NASA's Science Mission Directorate in Washington. 

For more information about the mission, visit: 

http://www.nasa.gov/messenger 
	
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