Ryder Crater on Moon's Far Side | NASA's Lunar Reconnaissance Orbiter
Color shaded relief map centered on the South Pole–Aitken (SPA) Basin. Lunar Reconnaissance Orbiter Camera (LROC) Wide Angle Camera (WAC) stereo model combined with Lunar Orbiter Laser Altimeter data
Ryder Crater is oblong (13 x 17 km) with a distinctive slump on its eastern side and is located in the South Pole–Aitken (SPA) Basin on the far side of the Moon. The basin is the largest at roughly 2,500 km in diameter (1,600 miles), and possibly oldest (estimated age of 4.3 billion years) basin on the Moon. The SPA basin is also the deepest one recognized on the Moon, between 6.2 and 8.2 km (3.9–5.1 mi) deep. It is estimated that it was formed approximately 4.2 to 4.3 billion years ago during the Pre-Nectarian epoch. It is among the largest known impact craters in the Solar System.
Because of its odd shape, scientists question whether Ryder is two craters or one. This distinctive landform could have formed when an impactor struck the surface at a grazing angle (<15° from the horizon), or when an asteroid split in two just before impact. However, there is another factor at play here. Ryder Crater formed on a steep ridge, and this kind of uneven terrain is often responsible for asymmetric craters.
The steep ridge Ryder formed upon is the degraded rim of an older crater that is ~70 km across with a vertical drop of over 3000 meters (approximately 10,000 feet) from its rim to its floor. Even this older crater may have been affected by the uneven terrain it was formed from. Its eastern rim appears to have formed on a topographic high perhaps related to the SPA basin, leaving it well above its western rim. The impactor that formed Ryder crater struck the very highest point of the older crater's rim, and in this case it is not hard to imagine that the final shape of Ryder crater was strongly affected by its encounter with the extra steep slope. The high point of Ryder's rim is approximately 1500 meters (5000 feet) higher than the low point of its rim.
Ryder Crater was named after Graham Ryder, a lunar scientist that worked at the Lunar and Planetary Institute and the NASA Johnson Space Center, studying lunar geology through detailed analyses of Apollo samples. Given his unique and important contributions to lunar science, it is fitting that such a striking crater bears his name.
These images were captured by NASA's Lunar Reconnaissance Orbiter (LRO) spacecraft (2009-2026).
LRO has made a 3-D map of the Moon's surface at 100-meter resolution and 98.2% coverage (excluding polar areas in deep shadow), including 0.5-meter resolution images of Apollo landing sites.
LRO has been studying the Moon from up close since 2009, making it the longest-lived lunar orbiting mission ever. The orbiter has mapped the Moon’s surface and measured its temperature, composition, and radiation environment in unprecedented detail. Data from LRO enables NASA, and our international and commercial partners, to select locations on the lunar surface where spacecraft and astronauts can safely land. The orbiter is also helping NASA identify areas near the Moon’s South Pole with crucial resources like water and extended sunlight that provides power for equipment and supports exploration activities.
https://science.nasa.gov/mission/lro/
Release Date: Oct. 19, 2020
No comments:
Post a Comment