When we look up at the moon we can see the very large Tycho crater as above (image above wiki commons).
I’ve talked some about central peaks in recent posts and the Lunar Reconnaissance Orbiter has taken some spectacular images of Tycho at very close range. Click the image to see the central peak of Tycho from the LRO, that central peak is more than 2 km / 6562 ft high.
Not all craters have central peaks, it depends on the gravitational field of the body and the material being impacted and of course how large the impact is. Here is a very short video of the concept in a fluid. In rocky moons and planets the central peaks can be formed by the rock being pushed back up by the underlying substrate (rock) instead of the fluid in the video. It is very much like a rebound event.
There are lots of variables that play into the formation of central peaks. You can imagine if the impacted surface was say sandy regolith the peak would just fall down on itself and if the impacting body was not large enough material would be just swept away. Likewise an air burst meteor may not leave a central peak becuase the blast might not be concentrated enough. Even the angle of impact makes a difference.
The bright flash of a meteor impact was seen on the moon a couple of years ago on 17 March 2013. The flash was some 10 times any flash recorded before. NASA recorded the flash at lunar coordinates 20.6°N, 336.1°E.
The Lunar Reconnaissance Orbiter was able to image the location before and after and it turns out it has found a few more.
The video and a really cool before/after image is located at the NASA site.`
Todays moon post is from close to home, our own moon. The image above is the central peaks in the crater Tycho as seen by the Lunar Reconnaissance Orbiter. The central peak complex above is about 15 km / 9.3 miles wide, left to right (southeast to northwest in this view). A very popular target with amateur astronomers, Tycho is about 82 km / 51 miles in diameter. The central peak’s summit is 2 km / 1.24 miles above the crater floor.
Central craters generally form from an impact of a large body onto in this case the lunar surface. The heat generates surface melt and the “liquid” is pushed from the point of impact and then rebounds from the edges back to the center and freezes in place. Rock freezes at a much higher temperature than water as you well know.
Impact craters are a whole study on their own and there are many different types. The University of Wisconsin at Green Bay has a nice web page looking at the different types of craters and central peak formation. Depending on what body the craters are on they may appear a little different than lunar craters, for example: craters on Mercury generally are a little more muted the walls and central peaks don’t seem to reach out as much as lunar craters, this is because in part, Mercury has more gravity than the moon.
Click here to visit the source page for the image and more information about Tycho.
This image from the LRO shows the Apollo 15 landing area and the EVA routes drawn in. The great thing about this is you can go to The Project Apollo Image Gallery and see images of the area taken from the mission, including photos taken from the surface along the route marked above. note: you may have to click the Apollo 15 link once the page opens.
See that small bright crater on the St. George crater rim? it was there in July 1971 when Commander David Scott and Lunar Module Pilot James Irwin landed. Alfred Worden remained in orbit in the Command Module and was no doubt the source of many of these great shots. Do check the archive photos out – there are a lot of them.
The NASA caption puts it all in perspective nicely I think. You can read it below or at the NASA site where you can get a larger version of the image too.
This image from NASA’s Lunar Reconnaissance Orbiter shows the area surrounding Apollo 15’s landing site, annotated with the traverse plots of the mission’s first two moonwalks, abbreviated as EVAs (extra-vehicular activities). Numbers indicate elevations in meters above the landing site (indicated by the arrow labeled “LM” — lunar module). Astronauts David Scott and James Irwin ventured to the lower slopes of Mons Hadley Delta (center left). The distance they travelled from the lunar module to Elbow crater along the edge of Hadley Rille (EVA 1) is about 2.8 miles. Apollo 15 was the first mission on which the “lunar rover” was used.
This looks like flowing water, but no this is the moon. Most of what we are looking at is material disturbed by the impact that created Dionysius, some if it is from other geologic processes. This flow is on the eastern side of the crater (see the link above)
There is a large image and a detailed description of the scene at the LROC site.
Scientists at NASA used the Lunar Reconnaissance Orbiter has released the first high resolution interactive mosaic of the lunar north pole. What a bit of work, some 10,581 images went into the making of the image. You can pan and zoom down to an image resolution of two meters (six-and-a-half feet) per pixel.
The Lunar Reconnaissance Orbiter took a before and after image of the area where China set down the rover Yutu (Jade Rabbit). The before and after shots are what you see above.
The distance from camera to rover is about 150 km / 93 miles. The rover itself is only 150 cm / 5 feet. Apparently the reason it shows up, because the pixel size in the image is also 150 cm, is the solar panels reflect light efficiently and the shadow is evident. NASA tells all about the image below.
Hopefully we will get to see if the rover moves about in the future.
Chang’e 3 landed on Mare Imbrium (Sea of Rains) just east of a 450 m diameter impact crater on 14 December 2013. Soon after landing, a small rover named Yutu (or Jade Rabbit in English) was deployed and took its first tentative drive onto the airless regolith. At the time of the landing LRO’s orbit was far from the landing site so images of the landing were not possible. Ten days later on 24 December, LRO approached the landing site, and LROC was able to acquire a series of six LROC Narrow Angle Camera ( NAC ) image pairs during the next 36 hours (19 orbits). The highest resolution image was possible when LRO was nearly overhead on 25 December 03:52:49 UT (24 December 22:52:49 EST). At this time LRO was at an altitude of ~150 km above the site, and the pixel size was 150 cm. Continue reading →
LROC gives us this view of the Sinus Iridum and the general area. China is planning on putting a lander in this region and have just successfully put the spacecraft carrying their rover in lunar orbit to do just that.
The Chang’e-3 entered a 100 km high circular orbit on Friday after a braking by a variable thrust engine of 361 seconds.
Speculation is the Chang’e 3 will be in the area of the crater Laplace A in the center of the picture. The area has been visitied by a rover before, the arrow in the lower left shows where the Soviet Lunokhod 1 landed. The Lunokhod 1 landed on 17 November 1970 and operated until contact was lost on 14 September 1971.
I mentioned the other day some of my favorite LROC images featured boulder tracks and as luck would have it I found another one on the LROC site. I say YAY! There is activity up there every now and then – mostly then. These probably created from the crater making impact?
This one is pretty cool not just because of the curved tracks, these tracks are located on the far side of the moon. The associated crater is called Van Gent U.
Have a look at the LROC site for a full description and a link to a zoomable version of the image.