Images from the recent flyby（飞越） of Phobos（火卫一） , on 7 March 2010, are released today. The images show Mars' rocky moon in exquisite（优美的，精致的） detail, with a resolution of just 4.4 metres per pixel. They show the proposed landing sites for the forthcoming Phobos-Grunt mission. ESA's Mars Express spacecraft orbits the Red Planet in a highly elliptical（椭圆的，省略的） , polar orbit that brings it close to Phobos every five months. It is the only spacecraft currently in orbit around Mars whose orbit reaches far enough from the planet to provide a close-up view of Phobos.

Like our Moon, Phobos always shows the same side to the planet, so it is only by flying outside the orbit that it becomes possible to observe the far side. Mars Express did just this on 7, 10 and 13 March 2010. Mars Express also collected data with other instruments.

Phobos is an irregular body measuring some 27 × 22 × 19 km. Its origin is debated. It appears to share many surface characteristics with the class of 'carbonaceous（碳的） C-type' asteroids（小行星） , which suggests it might have been captured from this population. However, it is difficult to explain either the capture mechanism or the subsequent evolution of the orbit into the equatorial plane（赤道平面） of Mars. An alternative hypothesis（假设） is that it formed around Mars, and is therefore a remnant（剩余） from the planetary formation period.

In 2011 Russia will send a mission called Phobos–Grunt (meaning Phobos Soil) to land on the martian（火星的） moon, collect a soil sample and return it to Earth for analysis.

For operational and landing safety reasons, the proposed landing sites were selected on the far side of Phobos within the area 5°S-5°N, 230-235°E. This region was imaged by the HRSC high-resolution camera of Mars Express during the July-August 2008 flybys of Phobos. But new HRSC images showing the vicinity（临近，附近） of the landing area under different conditions, such as better illumination（照明，阐明） from the Sun, remain highly valuable for mission planners.

It is expected that Earth-based ESA stations will take part in controlling Phobos-Grunt, receiving telemetry（遥测技术） and making trajectory（轨道） measurements, including implementation of very long-baseline interferometry (VLBI基长底线干涉量度法). This cooperation is realized on the basis of the agreement on collaboration of the Russian Federal Space Agency and ESA in the framework of the 'Phobos-Grunt' and 'ExoMars' projects.

Mars Express will continue to encounter Phobos until the end of March, when the moon will pass out of range. During the remaining flybys, HRSC and other instruments will continue to collect data.