Chao Meng-Fu is a diameter

crater A crater is a landform consisting of a hole or depression (geology), depression on a planetary surface, usually caused either by an object hitting the surface, or by geological activity on the planet. A crater has classically been described ...

on Mercury named after the Chinese painter and calligrapher

Zhao Mengfu Zhao Mengfu (; courtesy name Zi'ang (子昂); pseudonyms Songxue (松雪, "Pine Snow"), Oubo (鷗波, "Gull Waves"), and Shuijing-gong Dao-ren (水精宮道人, "Master of the Water Spirits Palace"); 1254–1322), was a Chinese calligrapher, p ...

(1254–1322). Due to its location near Mercury's south pole (132.4° west, 87.3° south) and the planet's small

axial tilt In astronomy, axial tilt, also known as obliquity, is the angle between an object's rotational axis and its orbital axis, which is the line perpendicular to its orbital plane; equivalently, it is the angle between its equatorial plane and orbita ...

, an estimated 40% of the crater lies in permanent shadow. This combined with bright radar echoes from the location of the crater leads scientists to suspect that it may shelter large quantities of

ice Ice is water that is frozen into a solid state, typically forming at or below temperatures of 0 ° C, 32 ° F, or 273.15 K. It occurs naturally on Earth, on other planets, in Oort cloud objects, and as interstellar ice. As a naturally oc ...

protected against sublimation into the near-vacuum by the constant temperatures.

Radar evidence for ice

Radar Radar is a system that uses radio waves to determine the distance ('' ranging''), direction ( azimuth and elevation angles), and radial velocity of objects relative to the site. It is a radiodetermination method used to detect and track ...

studies involving

Arecibo Arecibo (; ) is a Arecibo barrio-pueblo, city and Municipalities of Puerto Rico, municipality on the northern coast of Puerto Rico, on the shores of the Atlantic Ocean, located north of Utuado, Puerto Rico, Utuado and Ciales, Puerto Rico, Ciale ...

(

Puerto Rico ; abbreviated PR), officially the Commonwealth of Puerto Rico, is a Government of Puerto Rico, self-governing Caribbean Geography of Puerto Rico, archipelago and island organized as an Territories of the United States, unincorporated territo ...

), Goldstone (

California California () is a U.S. state, state in the Western United States that lies on the West Coast of the United States, Pacific Coast. It borders Oregon to the north, Nevada and Arizona to the east, and shares Mexico–United States border, an ...

United States The United States of America (USA), also known as the United States (U.S.) or America, is a country primarily located in North America. It is a federal republic of 50 U.S. state, states and a federal capital district, Washington, D.C. The 48 ...

), and the

Very Large Array The Karl G. Jansky Very Large Array (VLA) is a centimeter-wavelength radio astronomy observatory in the southwestern United States built in the 1970s. It lies in central New Mexico on the Plains of San Agustin, between the towns of Magdalena, Ne ...

(

New Mexico New Mexico is a state in the Southwestern United States, Southwestern region of the United States. It is one of the Mountain States of the southern Rocky Mountains, sharing the Four Corners region with Utah, Colorado, and Arizona. It also ...

) detected a number of highly-radar-reflective depolarized areas on Mercury, including several locations at the planet's

poles Pole or poles may refer to: People *Poles (people), another term for Polish people, from the country of Poland * Pole (surname), including a list of people with the name * Pole (musician) (Stefan Betke, born 1967), German electronic music artist ...

. Many of these reflective features appear to coincide with craters imaged by ''

Mariner 10 ''Mariner 10'' was an American Robotic spacecraft, robotic space probe launched by NASA on 3 November 1973, to fly by the planets Mercury (planet), Mercury and Venus. It was the first spacecraft to perform flybys of multiple planets. ''Marin ...

'', with the largest feature at the south pole corresponding to Chao Meng-Fu crater. The luminosity and depolarization of the radar reflections are much more characteristic of ice than of the

silicate A silicate is any member of a family of polyatomic anions consisting of silicon and oxygen, usually with the general formula , where . The family includes orthosilicate (), metasilicate (), and pyrosilicate (, ). The name is also used ...

rocks making up Mercury's crust. Still, these reflections are too dim to be pure ice; it has been hypothesized that this is due to a thin or partial layer of powder over the underlying ice. However, with no direct confirmation, it is always possible that the observed radar reflectivity from Chao Meng-Fu and similar craters is due to depositions of

metal A metal () is a material that, when polished or fractured, shows a lustrous appearance, and conducts electrical resistivity and conductivity, electricity and thermal conductivity, heat relatively well. These properties are all associated wit ...

-rich minerals and compounds.

NASA The National Aeronautics and Space Administration (NASA ) is an independent agencies of the United States government, independent agency of the federal government of the United States, US federal government responsible for the United States ...

's ''

MESSENGER Messenger, Messengers, The Messenger or The Messengers may refer to: People * Courier, a person or company that delivers messages, packages, or mail * Messenger (surname) * Bicycle messenger, a bicyclist who transports packages through cities * M ...

'' mission confirmed the strong correlation of radar reflectivity with permanently shadowed craters, as shown on the maps to the right.

Ice origins

Chao Meng-Fu's ice may have originated from impacts of water-rich

meteorites A meteorite is a rock that originated in outer space and has fallen to the surface of a planet or moon. When the original object enters the atmosphere, various factors such as friction, pressure, and chemical interactions with the atmospheri ...

and

comets A comet is an icy, small Solar System body that warms and begins to release gases when passing close to the Sun, a process called outgassing. This produces an extended, gravitationally unbound atmosphere or coma surrounding the nucleus, an ...

or from internal

outgassing Outgassing (sometimes called offgassing, particularly when in reference to indoor air quality) is the release of a gas that was dissolved, trapped, frozen, or absorbed in some material. Outgassing can include sublimation and evaporation (whic ...

. Due to bombardment by the

solar wind The solar wind is a stream of charged particles released from the Sun's outermost atmospheric layer, the Stellar corona, corona. This Plasma (physics), plasma mostly consists of electrons, protons and alpha particles with kinetic energy betwee ...

and intense light from the Sun, ice deposits on most of Mercury would be rapidly lost to space; in the permanently shadowed portions of Chao Meng-Fu, though, temperatures are too low to permit appreciable sublimation and ice may well have accumulated over billions of years.

Chao Meng-Fu crater in fiction

A geothermally heated ocean beneath Chao Meng-Fu crater serves as the home of an alien species in Stephen Baxter's story ''Cilia-of-Gold,'' first published in the August 1994 issue of

Asimov's ''Asimov's Science Fiction'' is an American science fiction magazine edited by Sheila Williams and published by Dell Magazines, which is owned by Penny Press. It was launched as a quarterly by Davis Publications in 1977, after obtaining Isaac A ...

and reprinted in his collection Vacuum Diagrams. Gerald Nordley's novelette ''Crossing Chao Meng-Fu,'' originally published in the December 1997 issue of ''

Analog Analog or analogue may refer to: Computing and electronics * Analog signal, in which information is encoded in a continuous variable ** Analog device, an apparatus that operates on analog signals *** Analog electronics, circuits which use analog ...

'', depicts rock-climbers struggling to traverse the crater. Mark Anson's novel ''Below Mercury''Anson, Mark. ''Below Mercury''. Glenn Field Publishing, 2011. is set in an abandoned ice mine below Chao Meng-fu crater.

References

External links

Radar Imaging of Mercury's North and South Poles at 3.5 cm Wavelength
contains radar images, including one showing the bright reflection from Chao Meng-Fu crater. {{Mercury (planet) Impact craters on Mercury

Radar evidence for ice

Ice origins

Chao Meng-Fu crater in fiction

See also

References

External links