The Mastermind behind MESSENGER's Trajectory Honored for Efforts
- From: baalke@xxxxxxxxxxxxx
- Date: Fri, 30 May 2008 15:48:39 -0700 (PDT)
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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