The China National Space Administration (CNSA) formally announced in March 2003 that it had begun working on its lunar probe project. The program is known as the Chang'e Project, named after the woman who flew to the moon in an ancient Chinese fairy tale. While the dream of landing the moon has inspired many Chinese, others have serious doubts about the value of the lunar probe.
A waste of time, effort & money?
Hu Wenrui, a leading scientist in fluid mechanics, says that it will be difficult for China to make significant breakthroughs with its lunar probe. Hu, an academician with the prestigious Chinese Academy of Sciences (CAS) and concurrently with the International Academy of Astronautics, is deeply concerned about the domestic media's lunar probe craze.
But chief project scientist Ouyang Ziyuan disagrees. "The lunar probe will definitely be rewarding," he said during a lecture series entitled "Science and China," held by the Beijing University of Aeronautics and Astronautics on June 5.
"Premier Wen has said that the full construction of a prosperous society depends on the promotion of science. The lunar probe is an important stimulus to China's scientific development," says Ouyang.
The first stage of the lunar probe project, Chang'e I, will entail the launch of China's first lunar explorer and lunar satellite. The total budget for this phase is 1.4 billion yuan (US$169 million). So far, 1.3 billion yuan (US$162 million) has been allocated.
In Ouyang's view, this budget hardly large. "It is only equal to the money used to build two kilometers of subway in Beijing. It will affect neither China's construction of a prosperous society nor poverty relief."
Ouyang goes on to describe the spin-off benefits that many people overlook. "The lunar probe has extremely high technological requirements in such areas as rocketry, communication, monitoring and control, remote sensing, apparatus research and development. These will give impetus to rapid advances in science and technology. The Apollo program of the United States is an example of that."
The US invested more than US$20 billion in the Apollo moon landing project. According to later estimates, the return ratio was 1 to 4 or 5: every dollar invested brought a return of four or five.
The infrared thermometers that everyone in Beijing saw during the SARS epidemic provide an example of how technology developed for government projects such as defense can be used in civil and commercial applications.
Hu Wenrui says that many fellow scientists have good reasons for their doubts about -- or even opposition to -- the moon project. China's explorer is set to orbit 200 kilometers above the surface. The US orbiter in 1998 was just 100 kilometers from the surface, as will be Japan's, set to launch in 2005.
But Hu points out that even if the orbit were at the same altitude as those of the US and Japan, China's probe would not "see" any better or more clearly than theirs. "The repeated observation, lacking innovation or any kind of breakthrough, is a kind of waste in science," says Hu Wenrui.
Ouyang Ziyuan sees things differently. He believes that are many opportunities for China to make a contribution.
"Taking a three-dimensional image of the moon is one example: there are none available in the world now. And there are gaps in what is available in other countries. The South and North Pole parts were not well done. We will complete it. This graph can help us to better understand the structure of the moon."
"Besides, we will explore 14 group elements of great importance on the moon's surface. The US only made five groups. Things like this differentiate our probe."
Ouyang admits that China got a late start with its moon project. The country was still crawling and had not yet learned to walk, he says, while the other nations had already started to dance ballet. But, he points out, China's technology need not be better than theirs in order to make a contribution by doing something in a new and improved way. "If we are never to do anything that anyone else has done, then we need not build railways, cars or airplanes," he says.
How much do we need helium 3?
Another point of debate is the moon's abundant store of helium 3. This element is considered by many scientists to be the perfect fusion energy source: non-polluting, potent and with almost no radioactive by-products. Although it is extremely rare on Earth, scientists estimate there are at least a million tons of helium 3 on the moon, enough to power the world for thousands of years.
China currently burns billions of tons of coal and petroleum every year to meet its energy needs. If it replaced these fossil fuels with helium 3, China would need only 10 tons, while 100 tons would provide power to the whole world. Exploring the depth of the moon's soil and the quantity and distribution of helium 3 are important goals of Chang'e I.
But Hu Wenrui points out that the current international quoted price for sending items into Earth orbit is about US$20,000 per kilogram. A round trip to the moon would easily double the cost.
Hu says that seawater contains such fusion energy sources as deuterium and tritium, isotopes of hydrogen. The energy released by fusing the deuterium in just one cubic kilometer of seawater would be nearly equal, by some estimates, to that contained in the entire planet's fossil fuel reserves. Hu asserts that it is not necessary to go to the moon when there are such easily accessible and relatively inexpensive energy sources here.
Ouyang argues that the power-generating capacity of deuterium and tritium is low in comparison with helium 3, and 80 percent of its energy is released in radioactive neutrons, which adds risk. Because radioactive by-products from fusing helium 3 and deuterium are negligible, a nuclear power station using these materials could be built downtown in a big city without concerns about safety, says Ouyang. Radiation-free helium 3 is also the perfect fuel for spacecraft, he said. Elimination of the heavy radioactivity shield would allow for a larger payload.
"I don't mean that we can start using it right now. But we should explore the prospects. After all, the Earth's resources are not inexhaustible," explains Ouyang. "Existing petroleum can provide power for another 60 years; natural gas for around 60 years; coal for 100 years. But we'll still need energy after that. As scientists, we have to look toward the future."
When will Chang'e fly to the moon?
The Chang'e lunar probe project comprises three phases: orbiting, landing and a round trip including a landing. China plans to launch Chang'e I, the moon-orbiting satellite, before 2007. Phase two, the landing of an unmanned vehicle on the moon's surface, is projected to take place by 2010. Phase three will entail collecting samples of lunar soil with an unmanned vehicle that will then return to Earth, and should be completed by 2020.
"Our Chinese dream of landing the moon is sure to be realized," says Ouyang Ziyuan.
Hu Wenrui, a native of Wuhan City in Hubei Province, is a leading scientist in the field of fluid mechanics. He graduated from Peking University in 1958. A research professor with the Chinese Academy of Sciences' Institute of Mechanics, he was elected academician of the CAS in 1995 and elected academician of the International Academy of Astronautics' Basic Science Division in 2001.
Ouyang Ziyuan, a native of Shangrao County, Jiangxi Province, was born in October 1935. An academician of the Chinese Academy of Sciences, he is an expert in resources and environment, geochemistry, comparative planetology and cosmochemistry. Since completing postgraduate studies at the Chinese Academy of Sciences' Geological Institute in 1961, he has been engaged in research on extraterrestrial materials including meteorites, cosmic dust and lunar rocks. He has served as head of the Geochemistry Institute of CAS and director of the Resources and Environment Sciences Bureau of CAS. His appointment as chief scientist of the lunar probe project was announced in February 2004.
(Beijing Sci-tech Report, translated by Wang Qian for china.org.cn, June 24, 2004)