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Insight-China (15) Chang'e 5 Mission & Hypersonic-Missile test

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Chang'e 5 Test Mission completes Demo

photo source: pic.miercn.com and http://i.guancha.cn

Chang'e 5-T1 is an experimental unmanned lunar mission that was launched on 23 October 2014 by the China National Space Administration (CNSA) to conduct atmospheric re-entry tests on the capsule design planned to be used in the future Chang'e 5 missions.

During this mission, Chang'e 5-T1 achieved a few technical break through that has not been previously made by any nations.

Mission (1)(2)
The test mission launched on Oct. 23 from the Xichang space center in southwestern China, traveled 840,000 kilometers around the far side of the moon, and deployed a compact landing capsule for a high-speed re-entry into Earth’s atmosphere.

CNSA Chang'e 5 control center http://i.guancha.cn/News/big/2014/10/24/635497294343782225.jpg

(1) lunar flyby - Lunar Orbit Rendezvous
- Service Module entered lunar orbit by January 13th, 2015 with period of 8 hours.

After dropping off the Return Vehicle , the Service Module entered a highly elliptical orbit from where it maneuvered to a Lissajous orbit around the Earth-Moon Lagrange Point 2 to eventually reach a lunar orbit by mid January. This complex maneuver can save energy so that the whole system weight can be reduced.

Lissajous orbit: http://en.wikipedia.org/wiki/Lissajous_orbit
named after Jules Antoine Lissajous, is a quasi-periodic orbital trajectory that an object can follow around a Lagrangian point of a three-body system without requiring any propulsion.

Lagrange Points: http://en.wikipedia.org/wiki/Lagrangian_point#L2
the Lagrangian points are positions in an orbital configuration of two large bodies where a small object affected only by gravity can maintain a stable position relative to the two large bodies.
Lagrange Point 2 in this chart

(2) Earth reentry - skip re-entry technique
The spacecraft ferried a Re-Entry Vehicle around the Moon for a high-speed re-entry demonstration that was the core objective of the mission. The Return Vehicle landed in Inner Mongolia on 31 October 2014.

Xiaofei Return Capsule

skip re-entry technique:

skip re-entry illustration chart:
http://www.spaceflight101.com/uploads/6/4/0/6/6406961/7619760_orig.jpg

Plain English description
Traveling at approximately 25,000 mph, the entry vehicle lowered into the atmosphere twice, bouncing back into space and skipping like a rock across water before parachuting to a touchdown in China’s Inner Mongolia. Such skip re-entry maneuvers can diminish the speed and reduce the heat encountered by a spacecraft streaking back to Earth.

the skip re-entry technique that was used with mixed success by the Russian Zond missions in the 60s & 70s and was also conceptualized for the Apollo missions that ended up using a modified entry scheme.

Text in full: http://spaceflightnow.com/2015/01/21/chinese-pathfinder-probe-arrives-in-lunar-orbit/

WU-14 hypersonic missile
http://en.wikipedia.org/wiki/WU-14

compare with skip re-entry trajectory, hypersonic missile trajectory has not much difference.
chart

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