Optical Navigation Camera
This camera is being tested for improved navigation capability for future missions. If it performs well, similar cameras placed on orbiters of the future would be able to serve as high-precision interplanetary "eyes" to guide incoming spacecraft as they near Mars.
From 30 days to 2 days prior to Mars Orbit Insertion, the spacecraft will collect a series of images of Mars' moons Phobos and Deimos. By comparing the observed position of the moons to their predicted positions, relative to the background stars, the mission team will accurately determine the position of the orbiter in relation to Mars.
While not needed by Mars Reconnaissance Orbiter to navigate to Mars, the data from this experiment will be used to demonstrate that this technique can be used by future spacecraft to ensure their accurate arrival. Accuracy is important to some future landers and rovers that will need extremely precise navigation at Mars arrival to get to their landing sites safely.