The Marius Hills are a set of

volcanic A volcano is commonly defined as a vent or fissure in the crust of a planetary-mass object, such as Earth, that allows hot lava, volcanic ash, and gases to escape from a magma chamber below the surface. On Earth, volcanoes are most often fo ...

domes A dome () is an architectural element similar to the hollow upper half of a sphere. There is significant overlap with the term cupola, which may also refer to a dome or a structure on top of a dome. The precise definition of a dome has been a m ...

located in

Oceanus Procellarum Oceanus Procellarum ( ; from ) is a vast lunar mare on the western edge of the near side of the Moon. It is the only one of the lunar maria to be called an "Oceanus" (ocean), due to its size: Oceanus Procellarum is the largest of the maria ("s ...

Earth Earth is the third planet from the Sun and the only astronomical object known to Planetary habitability, harbor life. This is enabled by Earth being an ocean world, the only one in the Solar System sustaining liquid surface water. Almost all ...

Moon The Moon is Earth's only natural satellite. It Orbit of the Moon, orbits around Earth at Lunar distance, an average distance of (; about 30 times Earth diameter, Earth's diameter). The Moon rotation, rotates, with a rotation period (lunar ...

. The domes are thought to have formed from lavas more

viscous Viscosity is a measure of a fluid's rate-dependent resistance to a change in shape or to movement of its neighboring portions relative to one another. For liquids, it corresponds to the informal concept of ''thickness''; for example, syrup h ...

than those that formed

lunar mare The lunar maria ( ; mare ) are large, dark, basaltic plains on Earth's Moon, formed by lava flowing into ancient impact basins. They are less reflective than the "highlands" as a result of their iron-rich composition, and hence appear dark to ...

s. These domes average approximately in height. The Marius Hills take their name from the nearby diameter crater Marius. These hills represent the highest concentration of volcanic features on the Moon.

Geography and geology

An abundance of domes, cones, and volcanic

rille Rille (German for 'groove') is typically used to describe any of the long, narrow depressions in the surface of the Moon that resemble channels. The Latin term is ''rima'', plural ''rimae''. Typically, a rille can be several kilometers w ...

s and channels is characteristic of the Marius Hills. The

Lunar Reconnaissance Orbiter The Lunar Reconnaissance Orbiter (LRO) is a NASA robotic spacecraft currently orbiting the Moon in an eccentric Polar orbit, polar mapping orbit. Data collected by LRO have been described as essential for planning NASA's future human and robotic ...

photographed a pit that could be a skylight in a

lava tube A lava tube, more rarely called a pyroduct, is a 'roofed conduit through which molten lava travels away from its vent'. If lava in the tube drains out, it will leave an empty cave. Lava tubes are common in low-viscosity volcanic systems. La ...

, indicating that part of its roof has collapsed, as often happens after lava tubes cease to be active.

Domes

Data from the Lunar Reconnaissance Orbiter has been used to identify two different varieties of domes among the Marius Hills: (1) large, irregularly shaped domes and (2) smaller domes with steep sides and diameters of about . Another feature, possibly

pyroclastic Pyroclast, Pyroclastic or Pyroclastics may refer to: Geology * Pyroclast, or airborne volcanic tephra fragments * Pyroclastic rock, rock fragments produced and ejected by explosive volcanic eruptions * Pyroclastic cone, landform of ejecta fro ...

, or primarily volcanic in composition, has a roughly circular shape and steep sides. Bright, high

albedo Albedo ( ; ) is the fraction of sunlight that is Diffuse reflection, diffusely reflected by a body. It is measured on a scale from 0 (corresponding to a black body that absorbs all incident radiation) to 1 (corresponding to a body that reflects ...

boulders have been shown to be characteristic of lava flows in the Marius Hills. This suggests blocky lava with a high

silica Silicon dioxide, also known as silica, is an oxide of silicon with the chemical formula , commonly found in nature as quartz. In many parts of the world, silica is the major constituent of sand. Silica is one of the most complex and abundant f ...

content formed these features. This hypothesis, however, is not supported by data obtained from the Clementine lunar orbiter. Analysis of lower albedo, or less reflective boulders suggest that many domes in the area may contain two layers of material: (1) an upper layer of thin, dark material covering (2) a layer of thick, bright material.

Marius Hills "Hole"

The hole, first discovered by the Japanese SELenological and ENgineering Explorer (

SELENE In ancient Greek mythology and Ancient Greek religion, religion, Selene (; , meaning "Moon")''A Greek–English Lexicon's.v. σελήνη is the goddess and personification of the Moon. Also known as Mene (), she is traditionally the daughter ...

) and then later imaged by the

has been the subject of much research and speculation. There is a possibility that this feature could be a skylight in a

. The depth of this hole is estimated to be between and its width is estimated to be several hundreds of meters. Additional radar echo patterns suggesting intact lava tubes have been found at several other locations around the Marius Hills, which correspond to areas of mass deficit in the

GRAIL The Holy Grail (, , , ) is a treasure that serves as an important motif in Arthurian literature. Various traditions describe the Holy Grail as a cup, dish, or stone with miraculous healing powers, sometimes providing eternal youth or sustenanc ...

data.

Exploration

Apollo program

The Marius Hills region was at one time considered a possible landing site for a lunar landing mission during the

American American(s) may refer to: * American, something of, from, or related to the United States of America, commonly known as the "United States" or "America" ** Americans, citizens and nationals of the United States of America ** American ancestry, p ...

Apollo program The Apollo program, also known as Project Apollo, was the United States human spaceflight program led by NASA, which Moon landing, landed the first humans on the Moon in 1969. Apollo followed Project Mercury that put the first Americans in sp ...

(eventually becoming the alternative site for

Apollo 15 Apollo 15 (July 26August 7, 1971) was the ninth crewed mission in the Apollo program and the fourth Moon landing. It was the first List of Apollo missions#Alphabetical mission types, J mission, with a longer stay on the Moon and a greate ...

), with the possibility of gaining insight about the volcanic history of the Moon from domes in the area. A site in the northern Marius Hills, located in the center of a five-kilometer circle in a shallow valley between four domes near a small sinuous depression, was one of nine potential Apollo landing sites studied in-depth as part of a 1968 Bellcom report describing the geology of those nine locations and potential mission plans. This site in particular, the Bellcom study suggested, could have offered the opportunity for up-close examination of planetary ridges similar to those located at the bottoms of Earth's oceans and sampling of a variety of material from the Moon's interior churned up during the area's highly active volcanic past. The Bellcom study referenced an earlier 1968 study, prepared by the

United States Geological Survey The United States Geological Survey (USGS), founded as the Geological Survey, is an agency of the U.S. Department of the Interior whose work spans the disciplines of biology, geography, geology, and hydrology. The agency was founded on Mar ...

, that outlined a detailed mission plan for the proposed site. This plan included four EVAs using a

Lunar Roving Vehicle The Lunar Roving Vehicle (LRV) is a Battery electric vehicle, battery-powered four-wheeled Rover (space exploration), rover used on the Moon in the last three missions of the American Apollo program (Apollo 15, 15, Apollo 16, 16, and Apollo 17 ...

and Lunar Flying Units for increased mobility in sampling the various features in the site radius.

Potential human settlement

The probable lava tube could provide radiation shielding for a future underground lunar colony. However, it is unclear whether the tube is open or accessible. Two other lunar sites have been found by remote sensing, including on the far side's

Mare Ingenii Mare Ingenii (Latin ''ingeniī'', the "Sea of Cleverness") is one of the few lunar mare features on the far side of the Moon. The mare sits in the Ingenii basin, which is of the Pre-Nectarian epoch, which lies in turn in the outer part of the o ...

. An even larger, intact but buried lava tube estimated to be 1.7 km in length and 120m wide was detected by the

Chandrayaan-1 Chandrayaan-1 (; from Sanskrit: , "Moon" and , "craft, vehicle") was the first Indian lunar probe under the Chandrayaan programme. It was launched by the Indian Space Research Organisation (ISRO) in October 2008, and operated until August 200 ...

orbiter.A. S. Arya, R. P. Rajasekhar, Guneshwar Thangjam, Ajai and A. S. Kiran Kumar
"Detection of potential site for future human habitability on the Moon using Chandrayaan-1 data"''Current Science, Vol. 100'', NO. 4
25 February 2011 (accessed 24 January 2015)

References

External links

*{{Cite APOD , date=October 25, 2017, title=Marius Hills: Holes in the Moon Volcanoes on the Moon LQ10 quadrangle