From: baalke{at}familynet-international.net

http://messenger.jhuapl.edu/news_room/details.php?id=98

MESSENGER Mission News
May 30, 2008

The Mastermind behind MESSENGER's Trajectory Honored for Efforts

Jim McAdams, the MESSENGER mission design lead engineer, was named the 2008
Engineer of the Year by the Baltimore Section, American Institute of
Aeronautics and Astronautics (AIAA). Each spring, this chapter of AIAA
honors those in the aerospace community who have made significant
contributions during the previous year.

McAdams of the Johns Hopkins University Applied Physics Laboratory (APL)
in Laurel, Md., "optimized the trajectory and maneuver schedule,
designing one of the most challenging planetary missions in history,"
said APL's Tom Strikwerda, who on May 28 presented the award: a plaque and
a 24-inch-high trophy that McAdams will keep until passing it on to
the next winner a year from now.

Because Mercury lies deep within the Sun's gravity well, travel to the
planet requires an extremely large velocity change. A spacecraft travelling
to Mercury speeds up as it falls toward the Sun; so MESSENGER's trajectory
had to be designed to most effectively utilize the gravitational pull of
Venus and Mercury to achieve most of the required velocity change.

To make the trip possible, the trajectory uses six gravity-assist flybys:
one by Earth, two by Venus, and three by Mercury. These gravity-assists,
along with five large course-correction maneuvers, reduce the energy (and
thus fuel) requirements but greatly prolong the trip. These maneuvers will
also slow the spacecraft's speed just enough
relative to Mercury to enable its thruster to place the probe into orbit
around Mercury.

Upon arrival at Mercury in March of 2011 the spacecraft will enter an
elliptical orbit that passes as close as 200 kilometers to Mercury's far
northern surface every 12 hours. Such an orbit will allow MESSENGER to
measure solar wind and magnetic fields at a variety of distances from the
planet yet still obtain close-up measurements and images of the surface.

"The implementation of this complex mission plan has been a significant
challenge," says McAdams, who also worked on the Near Earth Asteroid
Rendezvous mission. "It's a privilege to join two other MESSENGER team
engineers as recipients of this award," he adds, referring to Robin
Vaughan and Adrian Hill, two other engineers from the team who received
the award in 2004 and 2006, respectively.

McAdams, who holds an M.S. in Aeronautical and Astronautical Engineering
from Purdue University, also created and led the development of MESSENGER
education and outreach products, as well as trajectory data distribution to
the science community. Last summer, he played a critical
role in the creation of the Mercury Flyby Visualization Tool
http://messenger.jhuapl.edu/encounters/>, which provides simulated
views of Mercury from MESSENGER's perspective, during approach, flyby, and
departure, or in real time (as the observations actually occur).

Members of MESSENGER's Geology Discipline Group used the tool both before
and after the probe's first flyby of Mercury in January to gain information
about imaging sites on Mercury. The tool will be updated for
upcoming Mercury encounters.

"Jim McAdams http://messenger.jhuapl.edu/who_we_are/ member_focus.html>
has been a critical member of the MESSENGER team," offers MESSENGER
Principal Investigator Sean Solomon. "Jim is usually several steps
ahead
of the rest of us with respect to planning for mission-critical events,
and we can always count on his results to high precision. The journey to
orbiting Mercury is long and complex, but we have a terrific guide."
------------------------------------------------------------------------

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.
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