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  • MIA026: Phobos Subsurface Structure

MIA026: Phobos Subsurface Structure



Mars Report Ref: MIA026

Report date: July-August 2017

Research Status: Open - Possible artificial construction

Description: Phobos Subsurface Structure
Approximate size: 9 km / 5.6 miles

Mission: MRO/HiRISE
Location: Phobos Moon, over 'Stickney Crater'

Observation by: M. J. Craig

Image date: March 2008
Image credit: NASA/JPL/University of Arizona

Graphics/image editing: M. J. Craig

Image source:


The rectilinear grooves on Phobos look remarkably artificial, but may just as well have been caused by natural processes as yet unclear. A partially hollow interior has been confirmed, formed of large cavities.


A prevalent pattern of rectilinear markings cover most of the moon's surface, first observed by R. C. Hoagland from the Mars Express image of 2006. This may indicate that an artificial structure exists beneath the surface dust. Research by Astrophysicist Dr. Iosif S. Shklovskiy suggested that the moon was hollow, a theory supported by the United States Naval Observatory and results from the Phobos flyby mission. A hollow moon may indicate an artificial body with compartments. A vertical monolithic structure on the surface of Phobos found by Efrain Palermo (MIA026.3) and noted by former NASA astronaut Buzz Aldrin, may be an artificial object.


The grooves on the surface of Phobos are "stretch marks" caused by the competing pull of the planet and the moon. Some research also suggests they could be caused by impacts from asteroids. The hollow cavities may be the result of the clumping together of multiple orbiting rocks and debris, that have left voids in between.


MIA026.1 Phobos Subsurface Structure: Geometrical detail over Stickney Crater - MRO/HiRISE 2008

Image credit: NASA/JPL/University of Arizona

Image source:

MIA026.2 Phobos Subsurface Structure: Rectilinear grid pattern - Mars Express 2006

Found by: Richard C. Hoagland

Location size: 5 km / 3 miles

Image pixel width: 9 m

Image credit: ESA/DLR/FU Berlin (G. Neukum)

Image source:

MAI026.3 The Phobos Monolith - MOC/MGS September 1998

(For full report on "The Phobos Monolith", see MR040)

Found by: Efrain Palermo

Object size: 76 m / 250 ft

Image credit: NASA/JPL/MSSS

Original Image source but no longer available from MSSS (image shown above):

New PDS image source:

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