 MESSENGER NAC image centered on Chao Meng-Fu. Located near Mercury's south pole, a large portion of the crater is permanently shadowed | |
| Feature type | Impact crater |
|---|---|
| Location | Bach quadrangle,Mercury |
| Coordinates | 87°18′S132°24′W / 87.3°S 132.4°W /-87.3; -132.4 |
| Diameter | 167 km (104 mi) |
| Eponym | Zhao Mengfu |
Chao Meng-Fu is a 167 km (104 mi) diametercrater onMercury named after theChinese painter and calligrapherZhao Mengfu (1254–1322). Due to its location near Mercury's south pole (132.4° west, 87.3° south) and the planet's smallaxial tilt, an estimated 40%[1] 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 ofice protected againstsublimation into the near-vacuum by the constant −171 °C (−276 °F) temperatures.
Radar studies involvingArecibo (Puerto Rico),Goldstone (California,United States), and theVery Large Array (New Mexico,United States) detected a number of highly-radar-reflective depolarized areas on Mercury, including several locations at the planet'spoles. Many of these reflective features appear to coincide with craters imaged byMariner 10, with the largest feature at the south pole corresponding to Chao Meng-Fu crater.[2][3]
The luminosity and depolarization of the radar reflections are much more characteristic of ice than of thesilicate rocks making up Mercury'scrust. 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 ofmetal-rich minerals and compounds.NASA'sMESSENGER mission confirmed the strong correlation of radar reflectivity with permanently shadowed craters, as shown on the maps to the right.
Chao Meng-Fu's ice may have originated from impacts of water-richmeteorites andcomets or from internaloutgassing. Due to bombardment by thesolar wind 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 appreciablesublimation and ice may well have accumulated over billions of years.[citation needed]
A geothermally heated ocean beneath Chao Meng-Fu crater serves as the home of an alien species inStephen Baxter's storyCilia-of-Gold, first published in the August 1994 issue ofAsimov's and reprinted in his collectionVacuum Diagrams.
Gerald Nordley's noveletteCrossing Chao Meng-Fu, originally published in the December 1997 issue ofAnalog, depicts rock-climbers struggling to traverse the crater.
Mark Anson's novelBelow Mercury[4] is set in an abandoned ice mine below Chao Meng-fu crater.
