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New views of the Moon

Two significant announcements happened lately, within a week: China released the complete lunar views of Chang'e-2, the highest-resolution map ever that covers the entire globe, in preparation for their upcoming landing attempts. Meanwhile NASA released the first views of the Moon of the MoonKAM educational cameras aboard the GRAIL space probes.



Preparing to land

China is working steadily to have their Chang'e-3 rover land on the surface in the next few years, followed eventually by actual taikonauts. A key ingredient is high-resolution imagery of the surface to select the landing sites. Chang'e-2 mapped the entire globe of the Moon between October 2010 and May 2011 and later departed to the Sun-Earth L2 Lagrange point. The map has a resolution of 7 meters per pixel, and represent the best global map currently available. Pay attention to the attribute “global” though: several missions, ranging from the Lunar Orbiters in the sixties to the Lunar Reconnaissance Orbiter right now, achieved far superior imagery, but were (or in the case of LRO, are) limited to certain areas of the Moon. The American Clementine spacecraft also carried out a global mapping with resolution ranging between 7-20 meters per pixel in the nineties.


Chang'e-2 itself captured better images from a few selected regions like Sinus Iridium for example, which is one of the possible landing sites of Chang'e-3. But the general 7-meter resolution is sufficient to detect the presence of artifacts on the Moon, the Apollo landing sites can be identified on the images.

The Chang'e-2 map has a Google Maps-style application too. The above picture shows the landing site of Apollo-15, next to the scenic Hadley rille. The yellow markings (not the pins, the lines) show the spot where the Lunar Module kicked up the dust. According to estimates based on comparison with the LRO images, the resolution here is only 50 m/px.


Chang'e-3 is currently slated to land on the Moon some time in 2013. It's basically the only competitor to the GLXP landings, as the Russian-Indian Luna-Resurs and Russian-only Luna-Glob programs will most likely face delays after the failure of the Phobos-Grunt mission.


Preparing to educate

The two GRAIL orbiters, Ebb and Flow are currently slowly lowering their orbits around the Moon, but NASA has already put the small educational cameras, the MoonKAMs to the test. In the short movie below, the north pole of the Moon rises from the bottom and we fly over the far side, reaching the terminator (the day-night boundary) just short of the south pole.


Now, I'd like to add a few remarks here. First, taking pictures in space can be tricky: the contrast is very strong between the pitch black of space and the shining surface of the Moon, and the camera can't really handle it before the Moon fills about a quarter of the view. Second, we are looking at the far side of the Moon, but not at the dark side (that's, frankly, quite obvious) – the dark side actually faces the Earth at the time of shooting. The two phrases, far side and dark side mean different things and only coincide at full moon! So please, use them wisely, they are not interchangeable.




László Molnár

Image sources:

1.) 2.) Chinese Lunar Exploration Program / China Ministry of National Defense

3.) National Astronomical Observatories, Chinese Academy of Sciences

4.) NASA / JPL- Caltech

Last Updated (Tuesday, 14 February 2012 08:55)

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