Saturday, March 13, 2010

Aviation Week: Longer Marches



China launches the Chang'e 1 on October 24, 2007. It mapped the Moon's surface from lunar orbit.

Aviation Week has an excellent lengthy article on the current state of the Chinese space program. Click here to read the article.

As I wrote on March 7, China is studying a human lunar mission but does not currently have the technology to launch such a mission.

This new article suggests that, if China goes ahead with a Moon mission, it will be similar to what NASA Administrator Charlie Bolden recently suggested. Instead of one big Apollo-like rocket that carries the entire payload, the approach would be to launch multiple craft into Low Earth Orbit, assemble them there, and then fly the completed vehicle to the Moon.

The advantage of doing it this way is to keep down the cost of building a huge heavy lifter to get the entire mission off the ground in one launch.

The article states:

Since the lift-off thrust of the [Chinese] launcher will be lower than that of the Saturn V, it will be unable to deliver as great a mass to lunar orbit—probably about 35 tons, compared with the U.S. launcher’s 45 tons, estimates one U.S. rocket engineer. But NASA needed that 45 tons for missions that were close to the minimum conceivable—brief stays on the Moon by two astronauts. Moreover, the Apollo equipment was built so lightly that even now the Chinese would probably struggle to do that minimum mission with much less mass.

So the thrust of the proposed Moon rocket strongly suggests that Chinese engineers plan to launch their lunar craft in at least two parts and assemble it in low Earth orbit, as NASA planned in the Constellation Program by launching the crew capsule separately. In proposing a Moon launch vehicle, the Chinese engineers are avoiding the risky alternative of a longer succession of Long March 5 launches.

Getting 3,000 tons of thrust under a single rocket presents a formidable technological challenge for China, whose largest engine so far, the YF-100, generates thrust of just 120 tons. The Soviet Union’s disastrous experience with the 30-engine first stage of its N-1 lunar launcher argues against attempting such an arrangement with the YF-100.

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