MESSENGER Update - August 3, 2006

MESSENGER Mission News
August 3 , 2006

Happy Anniversary, MESSENGER!

Today marks the second anniversary of MESSENGER's launch. "It's still
more than four and a half years to Mercury Orbit Insertion in March
2011, and there are many milestones between now and then," says Dr.
Sean
C. Solomon, of the Carnegie Institution of Washington, who leads the
mission as principal investigator. "But it's worth pausing for a few
moments today to appreciate how far we've come."

And just how far has the spacecraft traveled since its Aug. 3, 2004,
launch from Cape Canaveral Air Force Station, Fla.? Nearly 1.2 billion
miles. MESSENGER's computers have executed 180,271 commands since
liftoff, a time interval that includes seven major trajectory
correction
maneuvers.

"It's been a busy two years," says MESSENGER Mission Operations Manager
Mark Holdridge, of the Johns Hopkins University Applied Physics
Laboratory (APL) in Laurel, Md. "We've been by Earth and now we are
headed for Venus, another major milestone in this mission."

MESSENGER team members have been running tests all summer to make sure
the spacecraft will operate as intended during the Venus flyby - the
first of two swings past the clouded planet "scheduled for Oct. 24,
2006. There will be a 57-minute solar eclipse during that operation. So
on Aug. 11, engineers will turn the spacecraft solar panels edge-on to
the Sun and discharge the battery, much in the same manner that the
power system will function during the Venus flyby, to verify that the
system will respond appropriately.

Two weeks later, on Aug. 21, engineers will conduct a "star-poor"
region
test, pointing the spacecraft's star tracker in a region of the sky
that
might be utilized during the Venus operations. Holdridge says a similar
test was conducted on July 26, "and we got a positive result from that
test; the preliminary results look good."

All in all, Holdridge says, all systems are functioning very well. "The
spacecraft is very healthy, and the team is working hard to make this
first flyby of Venus a success!"

For encounter details and graphics associated with the October
maneuver,
go online to
http://messenger.jhuapl.edu/the_mission/MESSENGERTimeline/VenusFlyby1.html.

MESSENGER Engineer Named AIAA Engineer of the Year

APL's T. Adrian Hill, the fault protection and autonomy lead for
MESSENGER, was recently named Engineer of the Year by the Baltimore
chapter of the American Institute of Aeronautics and Astronautics
(AIAA). Each year, local AIAA chapters present this award to a member
who has made significant contributions to the field of engineering. For
more information, go online to
http://www.jhuapl.edu/newscenter/pressreleases/2006/060623b.asp.

Where is Mercury?
Mercury's orbit is so close to the Sun that we can only see it from
Earth either just before sunrise or just after sunset. For a diagram of
the orbits of the inner planets, as they appear today, go online to
http://btc.montana.edu/messenger/wheremerc/wheresmerc.php.

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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 Aug. 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 the Discovery-class mission for
NASA.

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