U.S. Orbiter Spots Chinese Lander on the Moon

Bad Astronomy
The entire universe in blog form
Jan. 13 2014 11:00 AM

You Too Can See Yutu

On Dec. 14, 2013, China successfully put a lander and rover on the Moon. I was hoping that at some point NASA’s Lunar Reconnaissance Orbiter would be able to spot it, and it actually happened faster than I expected:

Photo by NASA/GSFC/Arizona State University


The animated image shows before-and-after shots of the area. You can clearly see both the lander (big blob) and the rover (smaller blob) in the “after” picture, which was taken on Dec. 24, 2013, when LRO was almost directly overhead the pair. Each pixel in the image is about 1.5 meters in size, and the whole image is about 600 meters (roughly 2,000 feet) across. The “before” image was taken in June 2013 and is almost exactly the same except for the presence of the two human-made objects (the lighting is also a bit different, but not starkly so).

spectrum of lunar surface
Spectra are like the DNA tests of the cosmos.

Graph by Institute of High Energy Physics, CAS

The rover, named Yutu, is already sending science data back to Earth and in fact took a pretty nifty X-ray spectrum of the lunar surface:

Phil Plait Phil Plait

Phil Plait writes Slate’s Bad Astronomy blog and is an astronomer, public speaker, science evangelizer, and author of Death From the Skies!  

The rover has a device with a small radioactive source in it. This bombards the lunar surface below it with subatomic particles and X-rays, which responds by emitting X-rays itself. Each element in the regolith (what scientists call the crushed up rock and dust on the surface) emits an X-ray with a very specific energy that’s like a fingerprint, identifying the material. This can then be plotted to determine what’s in the regolith, as well as how much of each element there is. You can see the signals from silicon, aluminum, calcium, potassium, iron, and more (the “Ka” and “Kb” refer to the way the material emits X-rays, much like oxygen in our own atmosphere can emit green or red light in an aurora).

So Yutu, like Curiosity on Mars, is a moving chemistry lab, able to determine the composition of the surface over which it travels. If and when humans go back to the Moon (and it’ll be “when,” folks), they’ll want to know this information. The regolith is rich in materials that can be used to create shelter, air, water, and even rocket fuel. At some point, this chemical bounty will be used to sustain a human population on the Moon and allow them to further explore space itself.

I don’t know when that will be, but I suspect it’ll be sooner than most people think. China is clearly serious about this, and I hope the American government will start to take it seriously as well. Right now, the White House is still sticking by devastating cuts to NASA’s planetary exploration program. Both the Cassini Saturn probe and the Mars Curiosity rover are under the threat of a budget ax.

Our technology is getting better, our knowledge is growing, and support by the public is substantial. Now is not the time to be turning our backs on the solar system. It never is.


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