Astronomy Picture of the Day -- Phobos 360

NASA ^ | December 25, 2013 | (see photo credit)

[ETL]

Astronaut Buzz Aldrin says there is a monolith on Phobos.

The Phobos monolith is a large rock on the surface of the moon Phobos,[1] which orbits Mars. It is a boulder about 85 m (279 ft) across.[2] 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.[3][4] It was discovered by Efrain Palermo, who did large surveys of Martian probe imagery, and later confirmed by Lan Fleming, an imaging sub-contractor at NASA Johnson Space Center.

The general vicinity of the monolith is a proposed landing site for a Canadian Space Agency vehicle, funded by Optech and the Mars Institute, for an unmanned mission to Phobos known as PRIME (Phobos Reconnaissance and International Mars Exploration).[3] 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.[5] At present, PRIME has not been funded and does not have a projected launch date.

http://en.wikipedia.org/wiki/Phobos_monolith

[ETL]

Some great photos and interesting info at that site you linked to.

[SunkenCiv]

Porosity would suggest a formation (perhaps from a larger former body) with high heat, resulting in expansion of various materials such as water into vapor, leaving voids as the vapor eventually escaped. On Earth we see pumice, which would be analogous, but which has the gases still in the voids. One of the problems with excavating Herculanaeum is that the stone has billions of pores still containing the poisonous gases belched up by the 79 AD eruption.

[Jack Hydrazine]

The Phobos monolith is impact eject??? LOL!



When you blow up the pic of it you see faceted sides. Now how did THAT happen?

[Jack Hydrazine]

Might look like this.

[SunkenCiv]

Mars has craters, but the distribution of those craters shows that many of them on one side of the planet were formed in a single impact event — either a grapeshot-style with a single bolide breaking up from Mars’ gravity and smashing in many places more or less simultaneously, or more likely, one large impact which threw up ejecta. Could have been an earlier moon of Mars that did it, but Mars has more potential exposure to large asteroids than we do. The two moons probably arrived at the same time, as the odds of capture are much better when three bodies are involved, rather than two.

[SunkenCiv]

My pleasure.

[ETL]

When you blow up the pic of it you see faceted sides. Now how did THAT happen?

"The original HiRISE satellite image supplied to Mail Online by the University of Arizona showing a close up of what appears to be a 'monolith' on Mars..."

"speaking about the satellite picture scientist Alfred McEwen, the principal investigator from the University of Arizona's HiRISE department, said: 'There are lots of rectangular boulders on Earth and Mars and other planets.

'Layering from rock deposition combined with tectonic fractures creates right-angle planes of weakness such that rectangular blocks tend to weather out and separate from the bedrock.'

Fuel was added to the flames after Buzz Aldrin, the second man to walk on the Moon, alluded to a similar monolith detected on Mars' moon Phobos.

Speaking on a U.S. cable television channel last week he said: 'We should visit the moons of Mars.

'There's a monolith there - a very unusual structure on this little potato shaped object that goes around Mars once every seven hours."

http://www.dailymail.co.uk/sciencetech/article-1204254/Has-mystery-Mars-Monolith-solved.html

[ETL]

However, I must say, personally, it IS a very strange feature regardless. I mean, we have perfectly formed natural hexagonal columns here on Earth. But they are easily explained, similarly to hexagonal dried mudcracks. But 4 flat sides is very odd in nature.

_{Adapted from U.S. Geological Survey photo by S. R. Brantley.}

Large eruptions of basalt lava may create deep flows of molten rock. As the rock slowly cools it shrinks slightly. The stresses cause jointing in several different planes, and columns of rock form with a generally hexagonal shape, like pencils. The flow shown here is at Sheepeaters Cliff, in Yellowstone National Park. Note that there is a strongly developed horizontal jointing here, too.

The piece of basalt below displays the six-sided cross section of a column. Some columns may have five or seven sides instead.

http://geology.about.com/library/bl/images/blbasaltcolumns.htm

[ETL]

However, I must say, personally, it IS a very strange feature regardless. I mean, we have perfectly formed natural hexagonal columns here on Earth. But they are easily explained, similarly to hexagonal dried mudcracks. But 4 flat sides is very odd in nature.

_{Adapted from U.S. Geological Survey photo by S. R. Brantley.}

Large eruptions of basalt lava may create deep flows of molten rock. As the rock slowly cools it shrinks slightly. The stresses cause jointing in several different planes, and columns of rock form with a generally hexagonal shape, like pencils. The flow shown here is at Sheepeaters Cliff, in Yellowstone National Park. Note that there is a strongly developed horizontal jointing here, too.

The piece of basalt below displays the six-sided cross section of a column. Some columns may have five or seven sides instead.

http://geology.about.com/library/bl/images/blbasaltcolumns.htm

[ETL]

Everything after “But 4 flat sides is very odd in nature.” was from the website I linked to.

[ETL]

Sorry about the dupe. My finger slipped. :)

[Jack Hydrazine]

Let’s send a lander there to see it up close!

[ETL]

Here from the site you linked is a genuine photo of the surface of Phobos. You can see the parallel lines and layering the piece I posted referred to.

Apparently some are at right angles to each other. That could possibly explain the 4-sided structure of the monolith as impact-ejected rock.

[ETL]

“That could possibly explain the 4-sided structure of the monolith as impact-ejected rock.”-me

But then of course, how could it be that the ‘impact-ejected rock’ came to land perfectly right side up? Unless it perhaps rose straight up from below the surface as a result of an impact.

[ETL]

Let’s send a lander there to see it up close!

Sorry, I can't at this time. Christmas has tapped me out. Maybe sometime afterwards. :)

[ETL]

Jointing

(c) 2001 Andrew Alden, licensed to About.com, Inc.

Rocks are brittle, so they crack, but they crack very carefully. When this body of gneiss was deep underground during the folding and uplift of the southern Sierra Nevada, the stresses made it fracture. The cracks are called joints. You can see that they come in three different sets. The first set is parallel to the surface of this rock exposure, so that it looks like layers. The second set runs up the photo and the third runs diagonally from upper left to lower right. The stream in the picture has plucked out the resulting joint blocks to form its rugged streambed.

Joints are like faults, except that there is no movement along them. Joint patterns can be mapped to yield insights into the stresses that have affected the region during its geologic history. Sometimes jointing can occur as a body of rock is uncovered by erosion. As the overlying weight is removed, internal stresses may create jointing that results in the erosional process of exfoliation. That is common elsewhere in the Sierra, and perhaps it's an element at this locality too.

http://geology.about.com/library/bl/images/bljointing.htm

[Jack Hydrazine]

How about these photos of Phobos taken by the Russian's Phobos 2 probe taken with its infrared camera way back in 1989?



Is it natural? Is it caused by weathering?

How about the photo of Mars below taken by the Mars Odyssey by its infrared camera in 2002? NASA tried to pass it off as typical Martian mesas.

[trebb]

Seriously, what could possibly be at the core besides solid rock. Can't be molten magma for something so tiny. Perhaps it's fragmented rock.

Sugar plums - everyone knows that...

[ETL]

Those pics you just posted very well support the idea that the 4-sided feature (”monolith”) is natural, as at least some of the linear features on Phobos (joints, bedding, whatever) ARE at right angles to each other.