As milestones go, this could be seen as a small one. After all, China merely performed a feat that Americans achieved more than 45 years earlier (and its space station is about the size of the Salyut 1 Russia flew about 40 years ago). There was a key difference, though: While the first American docking was with a manned Gemini capsule and an unmanned Agena upper stage, the Chinese performed the entire operation with unmanned spacecraft?a feat that the U.S. had never actually performed until recently, and a tribute to the intervening decades of technological development. The question now is: What does China?s recent success say about its goals in space?
When NASA achieved its first orbital docking in 1966, it was a key demonstration needed to develop the confidence to later go to the moon. That?s because the Apollo mission required a similar rendezvous and docking in lunar orbit between the ascending lunar module and the orbiting command module in order to get the astronauts back home to earth.
Chinese leaders openly want to have a manned space station by the end of the decade, and this demonstration is crucial to that goal for two reasons. First, assembling a space station during multiple missions (as the U.S. and other nations did with the International Space Station) requires the capability to mate two pieces in orbit. And even if the station could be launched in a single piece (as Skylab was in the 1970s), every visit to a space station requires a rendezvous and docking. With this mission a success, expect manned flights on Shenzhou missions in the next couple years.
But how about beyond low Earth orbit (LEO)? Former NASA administrator Mike Griffin, who for years has warned that China could go to the moon before the U.S. could break out its holding pattern in LEO, testified before Congress on this subject just a few weeks ago. In this telling exchange, he outlines how China?taking advantage of the docking sophistication it displayed this week?could mount a mission to the moon without even building a heavy-lift rocket:
I know the Chinese Long March 5 rocket is in development. I wondered if you could compare that to anything we have in the American inventory. When it?s built will it really be larger than anything we have? And why do you think that the Chinese are building such a large rocket?
Griffin: Well, the Long March 5 is comparable in scale to today?s Delta IV Heavy or to the Ares I crew vehicle?which we were going to build and which was cancelled. So it?s on the order of, and of course until it flies regularly we won?t actually know, but it?s on the order of 25 tons of payload to LEO. So it?s not in the class of, say, the Saturn V or the new SLS [Space Launch System].But it?s a very significant capability and in fact by launching and rendezvousing four of those in LEO it would be possible for the Chinese to construct a manned lunar mission with no more than that rocket and no more than Apollo technology. And I have in the past written up on how that mission would work from an engineering perspective. So with the Long March 5 the Chinese inherently possess the capability to return to the moon should they wish to do so.
And you are saying that we do not have anything comparable to that other than what had been talked about?
We do not. Well, we have nice view graphs (laughter in the background).Actually, contrary to Griffin?s implication, the Delta IV Heavy has flown, so it?s more than "view graphs." And the Long March 5 isn?t scheduled to fly until 2014. But even in that timeline, China could be thinking about a moon visit relatively soon. In the U.S., by comparison, the Space Launch System NASA is now mandated to build couldn?t return Americans to the moon until at least the late 2020s (and would add tens of billions to the cost), according to a recently leaked NASA internal document.
China has yet to make any specific commitments to manned lunar missions, though the Chang?e series of unmanned lander missions, which are planned to culminate in a sample return rocket in 2020, could be a precursor to such missions. The nation?s nonmilitary space program (though it?s somewhat hard to separate military from nonmilitary, as China doesn?t have a civil space agency like NASA and its "taikonauts" are military personnel) seems aimed primarily at national prestige and cementing relations with the developing world through cooperative activities. It?s not clear how a lunar program will fit into that.
However, some aerospace bigwigs see aggressive lunar goals in China?s future. A couple weeks ago, at a space conference in Las Cruces, N.M., space real-estate developer and Bigelow aerospace founder Bob Bigelow made a second major speech in 2011, warning that, in his view, the Chinese plan not only to visit, but also to claim the moon, casting aside the 1967 Outer Space Treaty that forbids nations from claiming sovereignty of off-planet property. "China already has a grand national vision," he said then. "Their vision is that China wants to be indisputably No. 1 in the world, measured any way you want to measure."
And Washington certainly isn?t doing anything to diminish the idea of a second space race based on national pride. The same day China achieved its space docking, Virginia Congressman Frank Wolfe, chairman of the appropriations committee for NASA, called a hearing to find out why administrator Charles Bolden and presidential science adviser John Holdren had been meeting with Chinese space officials, when the NASA budget expressly forbids any cooperation with China. (The dispute is over $3,500 spent to host the meeting, so this is simply a symbolic squabble.)
But Congress should perhaps be careful what they wish for in excluding China from cooperative space activities. In the 1970s, the French were upset by what they considered unreasonable demands for American control over the use of satellites that they were going to launch in the Space Shuttle, then in development. The result was the European Ariane rocket, which has taken a lot of launch business not just from the Shuttle, but also from American commercial launch providers over the past decades.
Besides, there?s one other point to consider in how much of a threat the Chinese are. China?s space industry has expressed concerns that it won?t be able to compete with the SpaceX Falcon on cost, even with Chinese government subsidies. So as long as we don?t regulate our own competitive private industry out of business, we may not need to be so restrictive.
Source: http://www.popularmechanics.com/science/space/news/chinas-space-docking-what-does-it-mean?src=rss
fall back time change when does daylight savings start when does daylight savings start earthquake in texas earthquake in texas official time
No comments:
Post a Comment
Note: Only a member of this blog may post a comment.