Descartes Highlands
Encyclopedia
The Descartes Highlands is an area of lunar
highlands located on the near side
that served as the landing site of the American
Apollo 16
mission in early 1972. The Descartes Highlands is located in the area surrounding Descartes
crater, after which the feature received its name.
material, perhaps debris from large impact events. North and South Ray craters, the former sampled directly by the Apollo 16 crew, revealed a layering sequence, possibly an overlap of the Cayley and Descartes formations.
The area of the Descartes Highlands is characterized by an undulating landscape covered with old and some new, sharp rimmed craters. Based upon findings during the Apollo 16 mission, some of the floors of these craters were covered with glass similar to that found at the Taurus-Littrow landing site on Apollo 17
. According to Apollo 16 commander John Young, the arrangement of the glass gave it the appearance of dried mud.
Before Apollo 16 sampled the Descartes Highlands, it was believed that volcanic
material would be abundant in the area after visual analysis of the features there. It was thought that the formations in the area were formed by lava
s more viscous
than the lavas that formed the Lunar mare. This was later disproved after the analysis of samples from the area. It was revealed that many of the rocks in the area are not volcanic in origin, but breccia
s composed of fragments from several lunar impacts.
material, either directly or indirectly. A landing site in the Lunar highlands was to be selected with the goal of investigating the material located there. Two landing sites were given consideration to achieve this goal: the Descartes site and the crater Alphonsus
.
The Descartes Highlands was selected for the Apollo 16 mission in order to enable astronauts John Young and Charles Duke to sample the prominent Descartes and Cayley formations concentrated in the area. Sampling these formations was a priority, as the two cover much of the near side of the Moon. Priority was also given to locating and obtaining samples of old highland material that was older than the Imbrium impact
in order to give insight to the geologic
timeline and composition of the Moon. North and South Ray craters, both prominent features in the immediate landing area, were also prioritized because material from the prominent formations in the area had been naturally excavated there by the impacts that formed them.
Moon
The Moon is Earth's only known natural satellite,There are a number of near-Earth asteroids including 3753 Cruithne that are co-orbital with Earth: their orbits bring them close to Earth for periods of time but then alter in the long term . These are quasi-satellites and not true moons. For more...
highlands located on the near side
Near side of the Moon
The near side of the Moon is the lunar hemisphere that is permanently turned towards the Earth, whereas the opposite side is the far side of the Moon. Only one side of the Moon is visible from Earth because the Moon rotates about its spin axis at the same rate that the Moon orbits the Earth, a...
that served as the landing site of the American
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...
Apollo 16
Apollo 16
Young and Duke served as the backup crew for Apollo 13; Mattingly was slated to be the Apollo 13 command module pilot until being pulled from the mission due to his exposure to rubella through Duke.-Backup crew:...
mission in early 1972. The Descartes Highlands is located in the area surrounding Descartes
Descartes (crater)
Descartes is a heavily worn lunar crater that is located in the rugged south-central highlands of the Moon. To the southwest is the crater Abulfeda. It is named after the French philosopher, mathematician and physicist René Descartes....
crater, after which the feature received its name.
Geology
Two major formations dominate the Descartes Highlands area: the Cayley plains and the Descartes formation. The latter is composed primarily of highland plateauPlateau
In geology and earth science, a plateau , also called a high plain or tableland, is an area of highland, usually consisting of relatively flat terrain. A highly eroded plateau is called a dissected plateau...
material, perhaps debris from large impact events. North and South Ray craters, the former sampled directly by the Apollo 16 crew, revealed a layering sequence, possibly an overlap of the Cayley and Descartes formations.
The area of the Descartes Highlands is characterized by an undulating landscape covered with old and some new, sharp rimmed craters. Based upon findings during the Apollo 16 mission, some of the floors of these craters were covered with glass similar to that found at the Taurus-Littrow landing site on Apollo 17
Apollo 17
Apollo 17 was the eleventh and final manned mission in the American Apollo space program. Launched at 12:33 a.m. EST on December 7, 1972, with a three-member crew consisting of Commander Eugene Cernan, Command Module Pilot Ronald Evans, and Lunar Module Pilot Harrison Schmitt, Apollo 17 remains the...
. According to Apollo 16 commander John Young, the arrangement of the glass gave it the appearance of dried mud.
Before Apollo 16 sampled the Descartes Highlands, it was believed that volcanic
Volcano
2. Bedrock3. Conduit 4. Base5. Sill6. Dike7. Layers of ash emitted by the volcano8. Flank| 9. Layers of lava emitted by the volcano10. Throat11. Parasitic cone12. Lava flow13. Vent14. Crater15...
material would be abundant in the area after visual analysis of the features there. It was thought that the formations in the area were formed by lava
Lava
Lava refers both to molten rock expelled by a volcano during an eruption and the resulting rock after solidification and cooling. This molten rock is formed in the interior of some planets, including Earth, and some of their satellites. When first erupted from a volcanic vent, lava is a liquid at...
s more viscous
Viscosity
Viscosity is a measure of the resistance of a fluid which is being deformed by either shear or tensile stress. In everyday terms , viscosity is "thickness" or "internal friction". Thus, water is "thin", having a lower viscosity, while honey is "thick", having a higher viscosity...
than the lavas that formed the Lunar mare. This was later disproved after the analysis of samples from the area. It was revealed that many of the rocks in the area are not volcanic in origin, but breccia
Breccia
Breccia is a rock composed of broken fragments of minerals or rock cemented together by a fine-grained matrix, that can be either similar to or different from the composition of the fragments....
s composed of fragments from several lunar impacts.
Landing site selection
All of the preceding Apollo landing missions sampled Lunar mareLunar mare
The lunar maria are large, dark, basaltic plains on Earth's Moon, formed by ancient volcanic eruptions. They were dubbed maria, Latin for "seas", by early astronomers who mistook them for actual seas. They are less reflective than the "highlands" as a result of their iron-rich compositions, and...
material, either directly or indirectly. A landing site in the Lunar highlands was to be selected with the goal of investigating the material located there. Two landing sites were given consideration to achieve this goal: the Descartes site and the crater Alphonsus
Alphonsus (crater)
Alphonsus is an ancient impact crater on the Moon that dates from the immediate post-Nectarian era. It is located on the lunar highlands on the eastern end of Mare Nubium, west of the Imbrian Highlands, and slightly overlaps the crater Ptolemaeus to the north. The surface is broken and irregular...
.
The Descartes Highlands was selected for the Apollo 16 mission in order to enable astronauts John Young and Charles Duke to sample the prominent Descartes and Cayley formations concentrated in the area. Sampling these formations was a priority, as the two cover much of the near side of the Moon. Priority was also given to locating and obtaining samples of old highland material that was older than the Imbrium impact
Mare Imbrium
Mare Imbrium, Latin for "Sea of Showers" or "Sea of Rains", is a vast lunar mare filling a basin on Earth's Moon and one of the larger craters in the Solar System. Mare Imbrium was created when lava flooded the giant crater formed when a very large object hit the Moon long ago...
in order to give insight to the geologic
Geology
Geology is the science comprising the study of solid Earth, the rocks of which it is composed, and the processes by which it evolves. Geology gives insight into the history of the Earth, as it provides the primary evidence for plate tectonics, the evolutionary history of life, and past climates...
timeline and composition of the Moon. North and South Ray craters, both prominent features in the immediate landing area, were also prioritized because material from the prominent formations in the area had been naturally excavated there by the impacts that formed them.