Fantastic Phobos

Aug 21, 2012
Mars Express HRSC (High Resolution Stereo Camera) image of Phobos taken on 9 January 2011 at a distance of 100 km with a resolution of 8.1 m/pixel. Use red-blue glasses to fully appreciate this image. Phobos is approximately 27 × 22 × 18 km and orbits Mars at a distance of 6000 km above the planet’s surface, or 9400 km from the centre of the planet. Credits: ESA/DLR/FU Berlin (G. Neukum)

(Phys.org) -- Some 135 years after its discovery, Mars’ largest moon Phobos is seen in fantastic detail – and in 3D – in an image taken by ESA’s Mars Express spacecraft as it passed just 100 km by.

This view is much different to the faint object that astronomer Asaph Hall would have just been able to make out as he observed the Red Planet through the United States Naval Observatory’s 66 cm telescope in 1877. Through this telescope he discovered Mars’ smaller, outermost moon Deimos on 12 August and the larger, innermost moon Phobos on 18 August.

More than a century later later, spacecraft in orbit around Mars are studying Phobos in unprecedented detail.

In this image, a bite-sized chunk appears to be missing from the right edge of the irregular shaped moon – this is a side-on view of the rim of large impact crater Stickney, so-called after the maiden name of the discoverer’s wife.

Families of grooves appear to emanate from Stickney, carving channels across the approximately 27 km length of the moon. Initially thought to be associated with the Stickney impact crater, one recent theory suggests that they were instead formed when Phobos passed through debris clouds thrown up from the surface of Mars by asteroid impacts onto the planet’s surface.

Orbiting Mars at just 6000 km from the planet’s surface, it is closer to its parent planet than any other known moon in our Solar System. The moon’s proximity means that it hurtles around Mars faster than the planet rotates: for an observer on the surface of Mars, would appear to rise and set twice a day.

The moon’s orbit is decreasing and in some 50 million years time it will likely break up to form a debris ring around Mars, before colliding with the planet’s surface.

Explore further: Suddenly, the sun is eerily quiet: Where did the sunspots go?

add to favorites email to friend print save as pdf

Related Stories

Mars Express to rendezvous with Martian moon

Jul 16, 2008

(PhysOrg.com) -- Scientists and engineers are preparing ESA’s Mars Express for a pair of close fly-bys of the Martian moon Phobos. Passing within 100 km of the surface, Mars Express will conduct some of ...

Phobos flyby images (w/ Video)

Mar 15, 2010

Images from the recent flyby of Phobos, on 7 March 2010, are released today. The images show Mars' rocky moon in exquisite detail, with a resolution of just 4.4 metres per pixel. They show the proposed landing ...

Phobos flyby season starts again

Feb 16, 2010

(PhysOrg.com) -- Today Mars Express began a series of flybys of Phobos, the largest moon of Mars. The campaign will reach its crescendo on 3 March, when the spacecraft will set a new record for the closest ...

Phobos slips past Jupiter (w/ video)

Jun 17, 2011

(PhysOrg.com) -- Earlier this month, ESA's Mars Express performed a special manoeuvre to observe an unusual alignment of Jupiter and the martian moon Phobos. The impressive images have now been processed into ...

Auspicious orbit marks run-up to Phobos flyby

Jan 29, 2010

(PhysOrg.com) -- On 26 January, Mars Express completed its 7777th orbit around the Red Planet, an auspicious milestone as the satellite is readied for the closest-ever flyby of Phobos, scheduled for just a ...

Recommended for you

Image: Messy peaks of Zucchius

19 hours ago

Even to the naked eye, our Moon looks heavily cratered. The snippet of carved and pitted lunar surface shown in this image lies within a 66 km-wide crater known as Zucchius. From our perspective, Zucchius ...

User comments : 0