Washington, April 12 : NASA engineers have adjusted the flight path of the Phoenix Mars Lander, setting the spacecraft on course for its May 25th landing on the Red Planet.
NASA's Mars Reconnaissance Orbiter's High Resolution Imaging Science Experiment camera had taken more than three dozen images of the proposed area for landing - a broad, flat valley informally called "Green Valley."
Analysis of those images prompted the Phoenix team to shift the center of the landing target 8 miles southeastward, away from slightly rockier patches to the northwest. Navigators used that new center for planning the latest maneuver for the spacecraft.
The landing area is an ellipse about 62 miles by 12 miles. Researchers have mapped more than five million rocks in and around that ellipse, each big enough to end the mission if hit by the spacecraft during landing.
Knowing where to avoid the rockier areas, the team has selected a scientifically exciting target that also offers the best chances for the spacecraft to set itself down safely onto the Martian surface.
The trajectory adjustment began by pivoting Phoenix 145 degrees to orient and then fire spacecraft thrusters for about 35 seconds, then pivoting Phoenix back to point its main antenna toward Earth.
According to Brian Portock, chief of the Phoenix navigation team at NASA's Jet Propulsion Laboratory in Pasadena, California, "This is our first trajectory maneuver targeting a specific location in the northern polar region of Mars."
The mission has three more planned opportunities for maneuvers before May 25 to further refine the trajectory for a safe landing at the desired location.
"Our landing area has the largest concentration of ice on Mars outside of the polar caps. If you want to search for a habitable zone in the arctic permafrost, then this is the place to go," said Peter Smith, principal investigator for the mission, at the University of Arizona, Tucson.
"We have never before had so much information about a Mars site prior to landing," said Ray Arvidson of Washington University in St. Louis.
Phoenix will dig to an ice-rich layer expected to lie within arm's reach of the surface. It will analyze the water and soil for evidence about climate cycles and investigate whether the environment there has been favorable for microbial life.