APL's Jim McAdams Named AIAA Engineer of the Year

Jim McAdams of The Johns Hopkins University Applied Physics Laboratory in Laurel, Md., was named the 2008 Engineer of the Year by the Baltimore Section, American Institute of Aeronautics and Astronautics (AIAA). The award is presented to a member of the local chapter who has made a recent, significant contribution in the field of engineering.

McAdams was cited for his work as the mission design lead engineer for the MESSENGER (MErcury Surface, Space ENvironment, GEochemistry, and Ranging) mission — a NASA-sponsored scientific investigation of the planet Mercury that includes the first spacecraft designed to orbit the planet closest to the sun. He was cited for optimizing MESSENGER's trajectory and maneuver schedule, and leading the design of one of NASA's most challenging planetary missions.

Because Mercury lies deep within the sun's gravity well, travel to the planet requires an extremely large velocity change. A spacecraft traveling 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 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-corrections using MESSENGER's main engine, 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 propulsion system to place the probe into orbit around Mercury.

Upon arrival at Mercury in March 2011 the spacecraft will enter an elliptical (egg-shaped) orbit that passes as close as 125 miles to Mercury's surface every 12 hours. Such an orbit will allow MESSENGER to measure solar wind and Mercury's magnetic field 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 to orbit an asteroid. "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 APL staff members who received the award in 2004 and 2006, respectively.

McAdams, who holds a master's degree in aeronautical and astronautical engineering from Purdue University, was also applauded for developing MESSENGER education and outreach products and for distributing trajectory data to the science community. He joined the APL staff in 1994 and is a member of the Laboratory's Principal Professional Staff — the highest professional staff designation.