|Analysts believe Bolden may hold talks on possible co-operation in space with China during his six-day visit [AP]
Charles Bolden, the head of Nasa, has arrived in China for a six-day official visit during which analysts believe he may holds talks on possible co-operation with the emerging space power.
Bolden's trip comes just two weeks after the successful launch of a second Chinese lunar probe, Chang'e-2, part of a programme that seeks to send men to the Moon by 2020.
Faced with serious budgetary constraints, the US earlier this year abandoned its Constellation programme to return Americans to the Moon as a prelude to the conquest of Mars.
In contrast, China, whose economy is booming, has invested heavily in its space programme.
India and Russia are already developing a joint robotic space probe to be launched in 2013 - the same year that China hopes to conduct its third lunar landing.
Bolden's tour was first announced in November 2009 during a visit to China by Barack Obama, the US president.
During a visit to Japan at the end of 2009, Bolden said Washington was ready to discuss partnerships in space projects with China.
Beijing has sent six astronauts to space, which, among other factors, means that China now has the world's third most advanced space programme, after the US and Russia.
China has co-operated previously with the European Space Agency to explore the earth's magnetic field.
"In a sense, [space exloration] already is a global initiative ... from launching communications satellites to sending probes - and in some cases people into space," Robert Massey, of Britain's Royal Astronomical Society, told Al Jazeera.
"Bolden is there basically just to shake a few hands. It's the first step in very long process to get co-operation between the US and China in space flight."
Morris Jones, space analyst
Massey said it is still dangerous and inconvenient to explore space, but societies have become increasingly dependent on weather satellites and navigation systems.
Beyond establishing a human presence on the moon, extracting mineral resources is another, if less glamorous, goal of lunar exploration.
While humankind has already sent probes to all the planets - and to asteroids and comets - Massey said the scientific yield from space exploration is still quite high.
"If you're a responsible head of Nasa, and you want to find out what other people are doing, see if there are ways you can co-operate," Massey said.
Space programmes require a lot of technology, industry, and money but remain an international status symbol, Morris Jones, a space analyst, told Al Jazeera.
But Morris said he did not think Bolden would be given much in the way of useful technical data during his visit.
"Bolden is there basically just to shake a few hands. It's the first step in a very long process to get co-operation between the US and China in space flight," Morris said.
"Relations between the US and China are very bad at the moment for all sorts of political and economic reasons.
"Relations on earth have a direct bearing on what they will do in outer space."
Bolden's trip has been criticised by some US politicians, who see Beijing as a competitor rather than a potential partner in the space race.
Representative John Culberson, a Republican from Texas, recently raised objections to the trip in a letter to Obama, saying the US Congress should have been consulted first.
"I have grave concerns about the nature and goals of China's space programme and strongly oppose any co-operation between Nasa and CNSA's (China National Space Administration's) human space flight programmes without congressional authorisation," he wrote.
"Considering that Congress has raised concerns about and set limitations on cooperation with China, I do not believe it is appropriate for the administrator to meet with any Chinese officials until Congress is fully briefed on the nature and scope of Mr. Bolden's trip and planned discussions on co-operation," the letter said.