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Phobos monolith

The Phobos monolith is a large rock on the surface of Mars' moon Phobos.[1] It is a boulder, about 85 m (279 ft) across and 90 m (300 ft) tall.[2][3] A monolith is a geological feature consisting of a single massive piece of rock. Monoliths also occur naturally on Earth, but it has been suggested that the Phobos monolith may be a piece of impact ejecta. The monolith is a bright object near Stickney crater, described as a "building sized" boulder, which casts a prominent shadow.[4][5] It was discovered by Efrain Palermo, who did extensive surveys of Martian probe imagery, and later confirmed by Lan Fleming, an imaging sub-contractor at NASA Johnson Space Center.[6]

The general vicinity of the monolith is a proposed landing site by Optech and the Mars Institute, for a robotic mission to Phobos known as PRIME (Phobos Reconnaissance and International Mars Exploration).[4] The PRIME mission would be composed of an orbiter and lander, and each would carry four instruments designed to study various aspects of Phobos' geology.[7] At present, PRIME has not been funded and does not have a projected launch date. Former astronaut Buzz Aldrin has spoken about the Phobos monolith and his support for a mission to Phobos.[8]


The object appears in Mars Global Surveyor images SP2-52603[9] and SP2-55103,[10] dated 1998. The object is unrelated to another monolith located on the surface of Mars, which NASA noted as an example of a common surface feature in that region.[11]

In fiction[edit]

The Phobos monolith features in Alastair Reynolds' 2012 science-fiction novel Blue Remembered Earth, wherein its surface has been entirely carved by visiting astronauts into the semblance of a wrecked spaceship.


The debut studio album by The Claypool Lennon Delirium, consisting of American multi-instrumentalists Sean Lennon and Primus's Les Claypool, released on June 3, 2016, is called Monolith of Phobos.[12]

Archived 12 November 2011 at the Wayback Machine Monolith Zoom Archived 1 November 2011 at the Wayback Machine

USGS Mars Global Surveyor MOC Image 55103 - Browse Page

Analysis in year 2000 by Lan Fleming of SPS252603 and SPS255103

Phobos Profile