Chang'e 1 Lunar Orbiter Probe

Chang'e 1 Lunar Orbiter Probe Mission

Chang’e 1 is the first orbiting mission in the Chinese Lunar Exploration Programme (CLEP). The first phase of the lunar exploration programme aims to send unmanned spacecraft to orbit the Moon. A total of two spacecraft were built for the mission, with the first spacecraft launched in October 2007. A second spacecraft, possibly named Chang’e 2, is scheduled to be launched in 2009.

The Chang’e 1 spacecraft was designed and developed by the China Academy of Space Technology (CAST). The onboard mission equipment was developed by the Centre for Space Science and Applied Research (CSSAR) of the China Academy of Sciences (CAS). The engineering development phase of the project began in April 2004 and the research and development of a prototype was completed by November 2005. Design, manufacturing, assembly, testing and ground experiment of the spacecraft was completed by late 2006.

Chang’e 1 Launch

Chang'e 1 launch from the Xichang Satellite Launch Centre (Chinese Internet)

The Chang’e 1 spacecraft was launched from the Xichang Satellite Launch Centre (XLSC) by a CZ-3A three-stage space launch vehicle (SLV) at 10:05 GMT (18:05 Beijing Time) on 24 October 2007. The spacecraft entered the Super-Synchronous Transfer Orbit (SSTO) at 10:29 GMT and its solar panel was expanded successfully at 10:59 GMT.

After circling in the SSTO around the Earth for 1.5 times, the spacecraft fired its solid rocket for the first orbit changing manoeuvre at 09:55 GMT on 25 October. This was followed by another three orbit changing manoeuvres, which eventually place the spacecraft on the lunar transfer orbit at 09:28 GMT on 31 October 2008. The Chang’e 1 left the lunar transfer orbit and entered the lunar orbit on 5 November.

On arrive to the lunar orbit, thrusters of the Chang’e 1 fired to slow the spacecraft down. After three slowing down fires, the spacecraft’s velocity was finally reduced to 5,724km/hour. This settled it into its final orbiting pattern, circling at 200km above the Moon’s surface once every 127 minutes.

Spacecraft Design

The Chang’e 1 was based on the DongFangHong 3 (DFH-3) satellite bus developed by the CAST. The spacecraft is in a cube-shape (2m X 1.72m X 2.2m), and weights 2,350kg. The satellite is fitted with a pair of solar panels, with a span of 18.1m when fully expanded.

The Chang’e 1 consists of two main sections: satellite bus and mission payload. The satellite bus comprises nine sub-systems including navigation, guidance, propulsion, data management, data transmission, etc. The mission payload consists of 24 pieces of equipment, including a CCD camera, microprobe instruments and a high-energy sun particle detector, with a total mass of 130kg.

Objectives

The Chang’e 1 was tasked with a number of missions, include to obtain three-dimensional images of Moon surface and making outline graphs of lunar geology and structures; probing useful elements on the Moon surface and analysing the elements and materials; probing the features and depth of the lunar soil; and probing the space environment between 40,000km and 400,000km from the Earth.

The China National Space Administration (CNSA) revealed the first image of the Moon surface captured by the camera onboard the Chang’e 1 on 26 November 2007. On 11 December, the CNSA published more images from the Chang’e 1, showing the far side of the Moon.

Mission End

Chang’e 1 carried out a controlled crash into the Moon surface at GMT 08:13:10 on 1 March 2009 under the command of the Beijing Aerospace Command & Control Centre (BACC), ending its 16-month flight mission. The impact spot is located at 1.5°S 52.36°E.