麻豆传媒

China鈥檚 lunar orbiter is set to begin switching on its science instruments. The spacecraft should help determine the thickness of the lunar soil and shed new light on the Moon鈥檚 internal composition, which could help in understanding its origins.

The China National Space Administration launched the Chang鈥檈 1 spacecraft on 24 October and it settled into orbit around the Moon on 7 November.

Chang鈥檈 1 is named after a goddess who flew to the Moon in a Chinese legend.

The spacecraft鈥檚 capabilities are similar in many respects to those of the other three spacecraft that are either at the Moon already or heading there soon: Japan鈥檚 Kaguya spacecraft, which is already in orbit, India鈥檚 Chandrayaan-1, due to launch in early to mid 2008, and NASA鈥檚 Lunar Reconnaissance Orbiter (LRO), slated for launch in late 2008.

Unique instrument

China鈥檚 spacecraft is now set to begin the science phase of its mission by starting to gradually turn on its science instruments.

Like the other missions, Chang鈥檈 1 has spectrometers to map the chemical composition of the Moon鈥檚 surface, a laser altimeter to map the Moon鈥檚 topography, and a camera to photograph the surface.

However it does have one unique instrument 鈥� a radiometer that operates at microwave frequencies. The microwave radiometer will measure heat radiation coming from the Moon. This will allow it to map the depth of the lunar soil across the Moon鈥檚 surface because the layer鈥檚 thickness affects the flow of heat.

These measurements may also shed light on the proportion of radioactive elements like uranium and thorium inside the Moon, since their decay produces heat and should increase the amount of heat radiated by the Moon, says Paul Spudis of the Johns Hopkins University Applied Physics Laboratory in Laurel, Maryland, US, who is developing radar instruments to fly on LRO and Chandrayaan-1.

The amount of these elements would give clues to the Moon鈥檚 origins, he says, since different formation scenarios lead to different compositions.

鈥楻ace to the Moon鈥�

In addition to returning science results on the Moon, Chang鈥檈 1 will serve as a stepping stone for China鈥檚 space programme, Spudis says.

鈥淚f you can send a spacecraft to the Moon, operate it, map the planet, and do science, you鈥檝e basically proven the concept,鈥� he told 麻豆传媒. 鈥淵ou can do that in other missions, like to Mars and Venus. You鈥檙e getting your feet wet in the planetary exploration game.鈥�

The Moon missions of the various countries aim to cooperate with one another going forward, even if the design of the missions was not coordinated to avoid duplication, Spudis says. 鈥淭here鈥檚 a broad agreement, at least at the science meetings I have been to, that we鈥檙e all going to share this data, ultimately,鈥� he says.

In the longer term, he sees a more competitive 鈥渞ace to the Moon鈥� developing. 鈥淚 look at a race to the Moon, or into the solar system if you will, less as a race between countries as between competing philosophies.鈥�

He says the settlement of the Moon and the development of its resources will raise issues that will need to be confronted. 鈥淭here is a question of what kind of politico-economic paradigm you will do that under,鈥� he says, adding that he thinks these issues are still 20 to 40 years away from coming to a head.