Under The Radar: China has been operating a Robotic Telescope On the Moon – for 18 months!

It’s not very often that I’m utterly gobsmacked when I read the day’s latest physics and astronomy’s preprint journal articles on the arXiv server. But today I was, thanks to one rather unassuming paper, which hasn’t quite made a splash on the news networks yet.

But it should! The first sentence of this remarkable submission states:

“As the first robotic astronomical telescope working on the lunar surface in the history of mankind, Lunar-based Ultraviolet Telescope (LUT) on board the Chinese first lunar lander … has smoothly worked for 18 months on the Moon up to the time when this paper is prepared.”

That’s right, the Chinese lunar lander Chang’e 3, contained a robotic telescope, which has been working away quietly since it landed on the Mare Imbrium (Sea of Rains) in December 2013. The Moon is a wonderful place to do astronomy, for several reasons.

Firstly, the Moon doesn’t have an atmosphere, which can absorb and scatter light on its way to the telescope. In fact, some types of telescope simply don’t work on the ground, and have to be above the atmosphere, such as ultraviolet (UV) telescopes, like the LUT that China is now operating on the Moon.

Secondly, the Moon’s slow rotation means that the telescope can observe the same patch of sky for much longer before it moves out of view. Thirdly, the Moon can be very cold (when the Sun isn’t shining on it), which keeps the noise levels in the telescope low and its images nice and crisp. The flip side is that when the Sun is shining, it gets very hot, and some nifty cooling techniques are required, which the LUT has.

Doing astronomy on the lunar far side, especially radio astronomy, has been a pipe dream of astronomers ever since Apollo 8 looped around the Moon in Christmas 1968. Being able to observe the Universe with the yammering Earth and the booming Sun safely tucked away behind the Moon’s surface would make this one of the best places in the Solar System to do astronomy.

And now, the Chinese are doing astronomy on the Moon. Not the far side, but that’s next on China’s wish list. Personally, I don’t think there’s enough credit given to the team responsible for this brilliant achievement. With 180,000 images taken in the last 18 months, and many more to come in the future, I look forward to seeing the fruits of their labours.

Wang, J. et al. (2015). 18-Months Operation of Lunar-based Ultraviolet Telescope: A Highly Stable Photometric Performance. to be published in Astrophysics and Space Science, currently available as a preprint on the arXiv.