The Mars Reconnaissance Orbiter team is building and testing the spacecraft on a schedule to meet a launch-opportunity period beginning August 10, 2005, and lasting about 3 weeks. An Atlas V two-stage launch vehicle will send the spacecraft on its way to Mars. For the next 7 months, during the cruise and approach phases of the mission, the flight team will put the spacecraft through a series of checkout tests and science calibrations, in addition to conducting several maneuvers required to fine-tune its trajectory.

The spacecraft will begin orbiting Mars in March 2006. A multi-engine burn as the spacecraft first nears the planet will slow the craft enough for Mars’ gravity to capture it. The first orbit will take about 35 hours and have an extremely elliptical shape, with its farthest point about 150 times farther from the planet than its closest point. The mission will use aerobraking for the next 6 months to modify the orbit to a rounder shape optimal for science operations. Aerobraking, used previously at Mars by NASA’s Mars Global Surveyor and Mars Odyssey orbiters, relies on repeated, carefully calculated dips into the upper atmosphere, where friction with the atmosphere slows the spacecraft. This reduces the cost of the mission by reducing by about 450 kilograms (992 pounds) the amount of onboard fuel that must be launched from Earth in order for the spacecraft to enter the desired orbit around Mars.

Mars Reconnaissance Orbiter’s primary science phase will begin in November 2006 and operate for 2 Earth years, encompassing a full Mars year. Every 112 minutes, the spacecraft will make a complete circuit of Mars, flying a nearly circular orbit that will range from about 255 kilometers (160 miles) over the South Pole to 320 kilometers (200 miles) over the North Pole.

In addition to its own science, Mars Reconnaissance Orbiter will serve as a communications relay satellite for missions that land on Mars. The first to use this capability, according to current plans, will be Phoenix, the first mission in NASA’s competitively selected Mars Scout program. Phoenix is a stationary lander for studying Mars’ north polar region in 2008. Data from Mars Reconnaissance Orbiter will also help in selection of landing sites for future missions. Among the first planned for using this capability is a highly sophisticated rover called Mars Science Laboratory, now in development and slated to begin surface operations in 2010.