Secrets of Schröteri

Vallis Schröteri is a magnificent sinuous rille and of particular interest is its inner rille, which diverges from the primary rille near the arrow. This nested form indicates that multiple eruptive events occurred or there was a large change in the volume of a single eruption over time. LROC WAC mosaic, 100 m/pixel.

LROC NAC close-up of a bend in the inner rille of Vallis Schröteri; the rille walls are visible in the upper left and lower right corners of this image. The arrow in the LROC WAC mosaic above denotes the location of this image; image width is 600 m.

Photo credit: NASA/GSFC/Arizona State University

Note: The large crater in the top image is Herodotus Crater.

Impact Melt Features on Tycho Crater's Floor

Depressions and positive relief features in Tycho crater were caused by a complex mixture of granular material and impact melt settling to the floor. Image width is 370 m, LROC NAC M119923147L.

LROC WAC mosaic with arrow noting the location of the melt features within Tycho crater seen in the NAC image above. Image width is 150 km.

Impact melt creates a wide variety of features on the Moon. These include melt ponds, draped ejecta, viscous flows, linear and nonlinear depressions, and positive relief features. As impact melts mix with loose rock during crater formation, solid pieces of rock stick above the surface of the ponding melt to form little peaks (positive relief features). The depressions are possibly cooling fractures in the melt that result as the melt slowly solidifies and contracts (the opposite of how water behaves when it freezes), however they could also be part of an impact melt drainage network. We don't know for certain know the origin of all of these features, the best way to find out is to have astronauts traverse this terrain while exploring the Moon.

Photo credit: NASA/GSFC/Arizona State University

Block of Ejecta in Tycho Crater

320 meter (1,050 feet) block of ejecta in Tycho crater covered by a veneer of impact melt. Image width is 370 meters (1214 feet), LROC NAC 142334392RE.

LROC WAC context mosaic of Tycho, arrow points to the ejecta block within Tycho. Image width is 150 km.

Tycho crater is a Copernican age crater (85 kilometers, or 53 miles, diameter) located at 43.3° South, 11.2° West. It is named for the 16th century Danish astronomer Tycho Brahe and is one of the most visible features on the near side of the Moon. Its ray system is so obvious and widespread that Apollo 17 astronauts sampled its ejecta, over 2,000 kilometers (1,243 miles) away from the crater. Scientists dated the Tycho samples at about 110 Ma. We also have surface views of Tycho's ejecta blanket taken by the Surveyor 7 soft lander.

Notice the smooth areas on the top of the ejecta block in this NAC frame. Most likely the smooth area is a thin sheet of impact melt. The large block was probably flung up during the impact event, fell back down into the crater, and subsequently covered by impact melt. This series of events must have occurred quickly after the impact, as the melt would solidify soon after forming.

Photo credit: NASA/GSFC/Arizona State University

Rilles As Far As The Eye Can See

LROC WAC mosaic of the rille-rich Prinz crater region. Bench-like features are visible in the Prinz B depression and two flows originating in Prinz B converge just west of the arrow.

The bouldery, higher-reflectance mound in the central portion of this image is an island near the source region, Prinz B, for a short sinuous rille. The two rilles join at the triangular tip of this kipuka-like structure and flow northwestward for ~10 km. Image width is 500 m.

Photo credit: NASA/GSFC/Arizona State University

Smooth Floor in Copernicus Crater

With the exception of recent impacts (such as this one) into the floor material of Copernicus, much of the northwestern floor of Copernicus appears smooth and relatively featureless (upper right corner). This region on the crater floor appears similar to mare basalt flows, but studies show that volcanism has not shaped the landscape of Copernicus' interior. Instead, it is possible that a vast volume of impact melt was created during impact and cooled differentially across the crater floor such that some areas appear smooth while others are hummocky. LROC NAC M135317661L, image width is 520 meters (1706 feet).

Photo credit: NASA/GSFC/Arizona State University

Apollo 11 Landing Site by SMART-1

This lunar map is a mosaic of images taken by the Advanced Moon Imaging Experiment (AMIE) on board ESA's SMART-1 spacecraft. The image shows the landing site of Apollo 11 and three prominent craters in the vicinity which have been named in honor of the astronauts on board the first mission to land humans on the Moon.

Note that the images were acquired during different orbits and therefore at different lunar times with varying lighting conditions. This is particularly noticeable in the shadows that are cast: in the images that make up the top left of the map, the shadows fall to the right, whereas the shadows in the images making up the bottom of the map, fall to the left.

Image Details:

Source Image Orbit Numbers
92, 93, 1752, 1882, 1885, 1888 and 2086

Source Image Resolution
125-127 meters per pixel

Map Coverage:
22 -26 degrees East longitude
0 – 3 degrees North latitude

Apollo 11 Landing Site:
23.47297 degrees East longitude
0.67408 degrees North latitude

Photo credit: ESA/SMART-1/Space-X (Space Exploration Institute)

South Pole Mosaic

This mosaic is composed of images of the lunar south pole, taken between May 2005 and February 2006, during different phases of the mission and from a distance of about 400 km, allowing medium-field snapshots (about 40 km across) and high-resolution views (40 m/pixel) of the region. From 109 of 113 SMART-1 images of the Shackleton area taken during the season, an illuminated peak - located 7 km from the Shackleton rim - was identified. This "Peak of (almost) Eternal Light" could be used to supply electricity - via solar panels - for a future international lunar base.

Photo credit: ESA/SMART-1/AMIE

Hadley Rille by SMART-1

Sinuous rilles are probably the most recognizable of small volcanic features on the Moon. Many partially resemble river valleys on Earth. The rilles mark lava channels or collapsed lava tubes that formed during mare volcanism. Lunar samples indicate that the Moon has always been dry, thus confirming the volcanic origin of the rilles.

This image shows Hadley Rille, the sinuous depression running across the top half of this image. Below it are the Apennine mountains (1-2-km in height). The large crater in the center of the image is the 5.5 km diameter Hadley C crater.

SMART-1 measurements were used for cross-calibration with in-situ data from the Apollo 15 landing site, near the upper right bend of the rille in this image.

Location: The feature is centered at: 25.0° N 3.0° E.

Photo credit: ESA/SMART-1/AMIE