Chang'e I / II - Orbiter
A lunar probe project was officially started in January 2004, and as of the end of 2004 a lunar orbiting exploration was scheduled to be carried out by the end of 2007. This project also foresaw landing a remote control vehicle on the Moon by the end of 2010, and taking lunar mineral samples by 2020.
The first phase of the project would see China send a 2,350 kilogram lunar orbiter spacecraft to circle the moon and map its surface to get three-dimensional images of it. This part of mission would also deal with analyzing the content and distribution of useful elements on the moon surface, measure the density of lunar soil and exploring the lunar space environment. The scientists have done advances in the design of the orbit of the sounding Chang'e - I that would examine its surface and geography, making the first stage of the project.
China launched Chang'e-1 in 2007 and Chang'e-2 in 2010. The first probe collected a large body of data and a completed map of the moon. The second mission greatly enhanced the resolution of the previous map and generated a high-definition image of Sinus Iridium, a plain of basaltic lava, considered by lunar observers to be one of the satellite's most beautiful features.
The platform is based on the one used for the DFH-3 communications satellite. Mature technologies and experiences from related satellite missions have been fully inherited and utilized. In terms of technical configuration, Chang’e-1 is actually a new spacecraft. Project engineers had a stronger sense of this along with the progress of the development work.
The CCD optical system used a series of three 2-dimensional original images of a target area, taken before, during and after flyover of the spacecraft, to reconfigure a 3-dimensional image of the lunar surface. This demanded a higher accuracy in attitude control and orbital determination. The Interferometer Spectrometer Imager is a camera that obtains images based on the fact that different objects have different spectrum properties. It was used to perform multi-spectral remote sensing of the lunar surface. By filling spectral information into the digital lunar terrains obtained through stereo imaging, scientists would be able conduct researches on the properties of regional resources and materials.
The Laser Altimeter was used to provide complementary data to the elevation data of lunar surface and to refine the lunar surface digital model. The Gamma/X-ray spectrometers can obtain the distribution of different elements according to the differences of energy spectra of gamma and X rays emitted by various elements due to cosmic ray excitation, such as the gamma-ray spectra for elements of Th, U and K, and X-ray spectra for elements of Na, S and Ni. The data concerning elements of Fe, Ti, Al and Mg can be obtained through both gamma- and X-ray spectra.
Microwave/millimeter-wave radiometer was used on the satellite. According to the different depths penetrating into lunar soil of microwaves in different bands, lunar soil depth data can be obtained by measuring the microwave radiation brightness of the regolith in given bands. This is a kind of passive measurement. The microwave detector on Chang’e-1 will operate in four different frequency bands. Space Environment Monitor System was mainly to measure the contents of heavy ions, energy spectra of protons and contents and spatial distribution of low-energy ions in solar wind.
The LM-3A launch vehicle, which is primarily designed to launch satellites based on the DFH-3 platform, was selected to launch Chang’e-1. LM-3A had succeeded in all of its nine flights, seven of which were made for satellites based on the DFH-3 platform. For the Chang’e-1 mission, the launch vehicle was adapted in many areas. Particularly, major efforts have been made to improve its reliability, with redundant designs used on a number of critical links. Chang’e-1 would be launched at Xichang Satellite Launch Center, a launch site for China’s geosynchronous satellites. The launch center was modified in many areas to adapt it to the requirements of a lunar mission, especially in safety and reliability.
The TT&C System was formed based on China’s existing TT&C bases and instrumentation ships for space missions. To improve orbital measurement accuracy and provide redundant means for TT&C, astronomical Very Long Baseline Interferometry (VLBI) would be used for the first time in China to provide right ascension and declination needed for orbital measurement and determination of Chang’e-1. The so-called Ground Application System refers to the system responsible for Chang’e-1 downlink data reception, science data processing and study and in-orbit operation of the spacecraft.
Chang'e-1 was launched into space on 24 October2007, and sent the first full map of the moon's surface back to China one month later. A dozen performance tests were carried out while Chang'e-1 was in orbit to find out its orbit adjustment capability.
Chang'e-1 finished it 16 month mission when it was deliberately crashed onto the Moon on March 1, 2009 . Chang'e-1, China's first lunar probe, impacted the moon at 4:13 p.m. Beijing Time (0813 GMT) Sunday, said sources with the State Administration of Science, Technology and Industry for National Defense. The satellite ended its 16-month mission Sunday when it hit the lunar surface at 1.50 degrees south latitude and 52.36 degrees east longitude. Chang'e-1 began to reduce its speed at 3:36 p.m. Beijing Time (0736 GMT) under remote control by two observation and control stations in east China's Qingdao and northwest China's Kashi.
Chang’e-2 was the lunar orbiting satellite that also carried both a high-resolution camera and a small lunar impactor probe. The follow on Chang'e-2 based on the back-up Chang’e-1 updated spacecraft was expected to be launched as early October or end of 2010 but not later than early 2011 according to the Chinese State Administration of Science Technology and Industry for National Defense. It was expected to continue the Chang'e-1 mission in addition to testing un-crewed lunar soft landing technologies in preparation for the Chang'e-3 landing. Additionally it would carry a higher resolution imaging CCD camera system better than the imaging system used on Chang'e-1 for imaging the landing area.
The delays in receiving foreign supplied equipment for the Chang'e-2 spacecraft caused several rescheduling issues in addition to emphasizing the need for Chine to become self reliant on the " core technologies and basic advanced components" production. The highest impact appeared to be in high technology electronic components for systems operations. Chang'e-2 planned to orbit approximately 100 km close to the lunar surface than that demonstrated by Chang'e-1. Chang'e-2 was based on the Chang'e-1 spacecraft back up with considerable upgrades but is considered as a part of the second phase of China's uncrewed lunar exploration program. It would be launched by the end of 2010 on a Long March- 3C booster according to the Party chief of the Chinese Academy of Launch Vehicle Technology, Liang Xiaohong.
Developed with indigenous technology, the 900-million-yuan ($134 million) Chang'e-2 mission was to test key components for a soft-landing on the moon. The aim of launching the Chang'e-2 experimental mission was to test the key techniques of Chang'e-3 and Chang'e-4, as a preparation for a soft lunar landing in the future. Wu Weiren, Chief Engineer, China's Lunar Exploration Program, said, Chang'e-2 mainly serves as a pioneer satellite for its successors. It will detect the surroundings on the lunar surface and make sure the current orbit is suitable for a soft-landing operation in the future. Compared to Chang'e-1, the technique of Chang'e 2 is more renewed, advanced and complicated. A rocket with a stronger impulse sent Chang'e 2 directly into the earth-moon transfer orbit. This cuts the total travel time to lunar orbit by half. The Chang'e-2 could reach lunar orbit within five days, compared to Chang'e-1, which required nearly 14 days.
China's second unmanned lunar probe, Chang'e II, blasted off from the Xichang Satellite Launch Center (XSLC) in southwest China's Sichuan Province on 01 October 2010. When Chang'e-2 reaches its circling orbit around the moon, the CCD camera it carries will capture the 3D image of the lunar surface with a high resolution of 10 meters. When it lowers to 15 kilometers from the moon, the camera will be able to take clearer pictures of the selected soft-landing area with a higher resolution of 1 meter. The scientific objectives of the project include investigating the lunar landscape and exploring the geological structure of the moon. The mission would also help China study the material composition of the moon and search for usable resources.
Chang'e-2 left its lunar orbit for an extended mission to the Earth-Sun L2 Lagrangian point on June 9, 2011, after finishing its lunar objectives, which collected data for a complete lunar map. The Chang'e-2 entered the L2 orbit, where gravity from the sun and Earth balances the orbital motion of a satellite, in late August 2011. On 21 September 2011, the Chang'e-2 sent back its first batch of data while orbiting the second Lagrange Point (L2) about 1.7 million kilometers away from Earth. The orbiter was scheduled to travel around the L2 orbit until the end of 2012, according to the State Administration of Science, Technology and Industry for National Defence (SASTIND). The data it sent back was obtained by the orbiter's gamma-ray spectrometer, high-energy solar particle detector and solar wind ion detector while it travelling from the moon's orbit to L@. The probe departed from L2 in 2012 and began a mission to Toutatis.
Chang’e 2 carried out the world’s first close-range probe of Mars at 16:30:09, on Dec. 13, 2012, the State Administration of Science, Technology and Industry for National Defense (SASTIND) announced. But this seems to have been in error. Chang'e-2 has successfully conducted a maneuver in which it flew by the asteroid Toutatis, about seven million km away from the Earth. The flyby was the first time an unmanned spacecraft launched from Earth had taken such a close viewing of the asteroid, named after a Celtic god. It also made China the fourth country after the United States, the European Union and Japan to be able to examine an asteroid by spacecraft. Chang'e-2 came as close as 3.2 km from Toutatis and took pictures of the asteroid at a relative velocity of 10.73 km per second, the SASTIND said in a statement. Data from Beijing Aerospace Command and Control Center showed that Chang’e 3 is capable of flying 300 million km away from the earth, the longest range of any Chinese spacecraft.
Chang'e 2 scored several records: being the first to capture full coverage map of the moon with a resolution of seven meters; being the first object ever to reach the L2 point directly from lunar orbit; and being the first to closely observe the asteroid Toutatis. Chang'e-2's extended missions, which were conducted millions of km away from Earth, have tested China's spacecraft tracking and control network, including two newly built measuring and control stations in the northwest Xinjiang Uygur Autonomous Region and northeast Heilongjiang province, according to the SASTIND.
|
NEWSLETTER
|
| Join the GlobalSecurity.org mailing list |
|
|
|
