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China's Chang'e-4 Launches On Mission To the Moon's Far Side (nytimes.com)
An anonymous reader quotes a report from The New York Times: China is aiming to go where no one has gone before: the far side of the moon. A rocket carrying the Chang'e-4 lunar lander blasted off at about 2:23 a.m. local time on Saturday from Xichang Satellite Launch Center in southern China. (In the United States, it was still midday Friday). Chinese authorities did not broadcast the launch, but an unofficial live stream recorded near the site showed the rocket rise from the launch pad until its flames looked like a bright star in the area's dark skies. Nearly one hour later, Xinhua, China's state-run news agency reported that Chang'e-4 had successfully launched. Exactly when it will set down at its destination has not yet been announced -- possibly in early January -- but Chang'e-4 will provide the first close-up look at a part of the moon that is eternally out of view from Earth. The rover will attempt to land in the 110-mile-wide Von Karman crater. The crater is within an area known as the South Pole-Aitken basin, a gigantic, 1,600-mile wide crater at the bottom of the moon, which has a mineralogy distinct from other locations. "That may reflect materials from the inside of the moon that were brought up by the impact that created the basin," reports The New York Times.
The suite of instruments on the rover and the lander -- cameras, ground-penetrating radar and spectrometers -- "will probe the structure of the rocks beneath the spacecraft, study the effects of the solar wind striking the lunar surface," the report says. "Chang'e-4 will also test the ability of making radio astronomy observations from the far side of the moon, without the effects of noise and interference from Earth." It will also see if plant seeds will germinate and silkworm eggs will hatch in the moon's low gravity.
The suite of instruments on the rover and the lander -- cameras, ground-penetrating radar and spectrometers -- "will probe the structure of the rocks beneath the spacecraft, study the effects of the solar wind striking the lunar surface," the report says. "Chang'e-4 will also test the ability of making radio astronomy observations from the far side of the moon, without the effects of noise and interference from Earth." It will also see if plant seeds will germinate and silkworm eggs will hatch in the moon's low gravity.
They do have a satellite in orbit around the moon to relay the signals. And they are not mapping the moon but exploring the surface.
I don't know that it's actually in orbit. The comms satellite is beyond the Moon in the L2 point of gravitational balance with the Moon and the Earth. Because the Moon is smaller than the Earth, apparently there's enough room to 'peek around the side" and relay signals to Earth.
Do they have another satellite? Because how are they going to get the signals back?
It's communicating via the previously launched Queqiao "Magpie Bridge" relay satellite which is in a halo orbit around the second Earth-Moon Lagrange point (E-M L2). REFs:
There is a legitimate concern with using solar panels somewhere that has 2 week long nights. But you're correct that they're combining nuclear with solar to address that, having the lander power down and not do any work at night with the nuclear being just enough to keep it warm:
"The rover and the lander feature solar panels for daytime power and operation, along with nuclear plutonium-238 heaters to keep their electronic components warm during the two-week-long lunar night." (source)
Apparently solar is enough cheaper or longer lasting than other options that it's worth being limited to half time operation.
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