This image showing the position of the Martian moon Deimos against a
background of stars is part of a successful technology demonstration
completed by NASA's Mars Reconnaissance Orbiter before arrival at Mars.
The spacecraft's Optical Navigation Camera was used in February and March
2006 to demonstrate the use of pictures from a small camera for
calculating precise location of a Mars-bound spacecraft by comparing the
observed positions of Mars' two moons to their predicted positions
relative to background stars. While this technique was not necessary for
the Mars Reconnaissance Orbiter's own navigation, the demonstration
prepares the way for relying on it for navigating precise arrivals for
future missions that land on Mars.
This example image from the Optical Navigation Camera was taken on March
6, 2006, at a distance of 1.08 million kilometers (671,000 miles) from
Deimos. That moon, the smaller of Mars' two, has a diameter of 15
kilometers (9 miles), and orbits 23,459 kilometers (14,577 miles) above
the planet's surface.