The floor of Aristarchus crater provides explorers a unique opportunity to study a wide variety of lunar rocks and geologic processes, possibly including how lunar granite forms. Diverse materials such as dark, multilayered mare basalts in the walls, bright crustal rocks in the central peak, impact melt, and even regional pyroclastic materials blanketing the crater are brought to the floor and accummulated through mass wasting. All these features creates a bountiful trove of geologic materials.
A close up view of the Aristarchus Central Peak. Image is 700 m wide, NAC M122523410. Credit: NASA/GSFC/Arizona State University.
Aristarchus crater floor
Future astronauts exploring Aristarchus crater could easily sample materials from the highest point of the Central Peak without having to climb to the summit. They will simply browse the samples delivered at the base!
THE ARISTARCHUS PLATEAU - 50°W, 25°N
The Aristarchus crater is located on the edge of the Aristarchus Plateau, one of the most geologically interesting regions of the Moon. This complex impact crater of 40 km wide and 3.5 km deep has been probably formed 175 million years ago.
From LROC WAC color images you can see that the gray streaks show up as distinct color anomalies, color due to variations in rock type. The area has long been known to be among the reddest spots on the Moon - meaning its reflectance strongly increases from short to long wavelengths. In the WAC color image below, you can see the distinct red-hued region, which is largely blanketed by the glass-rich products of explosive volcanic eruptions. This area is surrounded by bluer terrain, which formed when titanium-rich (at least it is thought that titanium is in these rocks) lava flowed across the surface and flooded the area, forming a portion of Oceanus Procellarum. In both of the WAC context images, you can see Vallis Schröteri, a canyon-like feature known as a sinuous rille, through which the lava once flowed.
Aristarchus central peak
The impact straddled the boundary of the plateau and the surrounding mare, thus excavating both very different rock types, as well as underlying crustal rocks.
The Aristarchus Central Peak show a diversity of features
The high albedo material is most likely a common lunar rock type, anorthosite, while the dark areas is basaltic. What is the dark material exposed in the Aristarchus central peak? Scientists are not sure, however we know the adjacent Aristarchus plateau is blanketed in dark pyroclastic deposits.
West wall of Aristarchus crater seen obliquely by the LROC NACs from an altitude of only 26 km. Scene is about 12 km wide at the base. Image NAC M175569775. Credit: NASA/GSFC/Arizona State University.
Just above, an oblique (-67.03° off nadir) view of sunrise within the deep interior of the famous Cobra Head of Schröter Valley on the Aristarchus Plateau. Check at the right for a global view.
Credit: lroc.sese.asu.edu / The LROC NAC right-video has been taken the 2010-03-06 at 14:02:24.346 UTC. The video features high definition flyover of the central peak of Aristarchus crater, near a Constellation region of interest.
MOSCOVIENSE - 147°E, 26°N
Moscoviense basin on the far side of the Moon is a Nectarian-aged multi-ring impact basin that formed 3.85-2.92 Ga. The basin contains an elongated floor with non-concentric basin rings. The basin contains some of the thinnest crust on the Moon, although it is located in the relatively thicker crust of the lunar highlands.
The basin contains a deposit of mare, a pyroclastic deposit, and several lunar swirls. Within, we have orthopyroxene, olivine, and Mg-Al Spinel in an anorthosite-rich peak ring. This latter, may originated from differentiated magmatic intrusions into the lower crust, potentially near the crust/mantle boundary. The mare in the basin is also diverse, including low and high FeO, low and high TiO2, and possibly high alumina.
The diversity of crustal materials present in the basin will allow the possibility to constrain the bulk composition of the Moon.
The Moscoviense Basin. On the left, LROC WAC base map with LOLA shaded topography. On the right, LOLA-derived slopes.