Friday, October 1, 2010

Chang'E-2 takes direct approach

Updated 2 October 2010 - 1708 UT

Chang'E-2, second of China's four planned unmanned missions to the Moon through 2017, begin it's mission successfully Friday, October 1, 2010. [CCTV-4].

The Chinese National Space Agency's Lunar Exploration Program (CLEP) successfully began a second unmanned lunar mission, Friday October 1, 2010, with high confidence in their spacecraft and high hopes for what is billed as a technical mission. A modified Long March 3C booster lifted off on-time, at the opening of its launch window, and soon accelerated Chang'E-2 toward it's planned rendezvous with the Moon 120 hours later.

It's a faster, direct trajectory than was used in 2007 to increase an Earth-orbit apogee for Chang'E-1 probe to encounter the Moon at the height reached in a third eccentric orbit, and reflects China's earned confidence in their Lunar Exploration Program.

"It is estimated Chang'E-2 can reach lunar orbit within five days, compared to 13 days, 14 hours and 19 minutes for Chang'E-1," Ouyang Ziyuan, chief scientist at the China Lunar Exploration Project (CLEP) told Xinhua.

"China had not been to the Moon before Chang'E-1 so we were very prudent and adjusted its transfer orbit in a very slow manner. It traveled 2.06 million kilometers before lunar orbit insertion," Ouyang said. "It's different now. We can send Chang'E-2 directly to the moon, and we have also planned to reach the Moon within five days."

The Chang'E-2 mission profile calls for a lower lunar orbit, and hints at China's intention to eventually maneuver the probe into one or more rehearsal transfer orbits with a 9 km perilune over future landing targets. Equipped with an improved digital camera, mission planners hope to use these low passes to gather images of selected landing targets at higher than an advertised 1 meter resolution.

Chang'E-3, a future stationary lander with robotic rover is under development for 2013 along with Chang'E-4, a lunar sample return mission in 2017.

China's State-run media pulled out all the more obvious stops, Friday evening, devoting well over an hour of full televised coverage of the successful launch of Chang'E-2 from Xichang Satellite Launch Center in Sichuan Province [CCTV-4].

Mainland sources report specifics on the Chang'E-2 payload are "necessarily similar to that of it's predecessor," with a few significant differences:

1. Optical Imaging System: (pdf) A.) Charge Coupled Device (CCD) improved stereo camera (improved) for global lunar surface imagining - resolution improved from 120 meter to 10m. In lower passes (e.g. rehearsal of landing logistics, short of Terminal Descent) resolution can approach 1 meter. More specification of CCD: LPSC 2010 #2570 (pdf). B.) Interferometer spectrometer imager (same as Chang'E-1): Specs: LPSC 2010, #2061 (pdf).

2. Laser Altimeter (improved): Focused on several candidate soft landing Regions of Interest, 5 laser points per second (1 point of chang'e-1) to the lunar surface. More information, HERE.

3. Gamma/X-ray Spectrometers (same as Chang'E-1): LPSC 2010, #1046 (pdf).

4. Microwave Detector (same as Chang'E-1): LPSC 2010, #1125 (pdf).

5. Space Environment Monitor System (Same as Chang'E-1, i.e., "measure the contents of heavy ions, energy spectra of protons and contents and spatial distribution of low-energy ions in solar wind. A.) High-Energy solar particle detector, B.) Low-Energy Ion Detector.)

Public mock-up of the China Lunar Exploration Program (CLEP) Chang'E-3 stationary lander component, now under development, for a planned soft landing on the Moon in 2013. China's methodical dual-track developmental plans, its manned and unmanned (lunar), space programs are devoted more to improving engineering design capability over science [Xinhua].

Prior to launch, Yong-Chun Zheng. of the National Astronomical Observatories at the Chinese Academy of Science in Beijing outlined more specifics of the CLEP program's legacy and future.

The Chang'E-1 orbiter was the first lunar probe of China. The lunar orbiting project is the first step of China's "orbiting, landing, returning" strategy of lunar exploration. Chang'E-1 was successfully launched October 24, 2007 at Xichang Satellite Launch Center and was guided to a sucessful targeted impact March 1, 2009.

The total mission length was 495 days with a total raw data count of approximately 1.37TB, with 4TB of scientific data product produced. By the analysis and application of these data, a series of science results have been achieved, especially "the global image of the Moon." Chang'E-1 completed its four scientific objectives and provides the foundation for the promotion of lunar and planetary sciences in China and for succeeding lunar exploration missions.

Chang’E-2 had been designed and produced as a backup of Chang'E-1. After the success of Chang'E-1, technical modifications for new mission goals for Chang'E-2 were developed as technical test vehicle for the second stage of China’s Lunar Exploration Program (CLEP). Following launch, Friday:

Time from launch to be LOI was shortened from CE-1's 12 to CE-2's 5 days.

The orbit altitude was lowered down from CE-1's 200 km to CE-2's 100 km.

The spatial resolution of CCD stereo camera will be improved from CE-1's 120 m to CE-2's 10 m.

The frequency of laser pulse of laser altimeter will be improved from CE-1's 1 Hz to CE-2's 5 Hz. The mission goals of CE-2 will focus on high resolution imagery of the planned landing site of the CE-3 lunar lander and rover.

Key technology involving soft landing a on the Moon will be tested during the CE-2 mission, and the success of CE-2 will provide an important technical basis for the successful implementation of China's future lunar exploration.

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