Chang'e I will experience a lunar eclipse around February 21. This may lead to a power shortage because of the lack of sunlight on its solar panels that generate electricity, experts have said.

The lunar eclipse will be the first of two that are expected, with the second likely to occur in August, Ye Peijian, lead designer of Chang'e I, said.

"The orbiter will be operating without a solar power supply for five-and-a-half hours," he said yesterday in an online interview.

The temperature on the lunar orbiter will subsequently drop to nearly minus 130 C.

"The eclipses will be a real challenge for the proper function of various pieces of equipment on Chang'e I," he said.

Rao Wei, a designer at the Academy for Space Technology Research, said repeated testing and preparation beforehand should be able to solve the "blackout" problem.

The storage battery will be put to use during the blackout to power the normal operation of the lunar probe, he said.

Non-essential equipment on the orbiter is also designed to pause, allowing the limited power of the battery to work key parts during the blackout, Rao told the Xinhua News Agency.

Enhancing the performance of the storage battery and cold-resistant devices on the satellite will keep warming the probe, he said. In normal conditions the solar battery is recharged every 127 minutes.

Eclipses occur when the Earth is positioned on a straight line with the Sun and the moon. In a lunar eclipse, the Earth's shadow falls on the moon, darkening it, and can be seen from wherever on Earth the moon is above the horizon.

(China Daily November 30, 2007)