SCIENTIFIC EQUIPMENT ON APPLICATIONS MISSIONS

As had been the practice in the Russian space program, Chinese scientists used applications satellites to carry scientific instruments (equivalent Russian add-on packages were called пайка modules, “nauk” being the Russian word for “science”). These were flown on the first communications satellites in 1984 and 1986. Both the first, Shiyan Tongbu Tongxin Weixing, and the second, Shiyong Tongbu Tongxing Weixing 1, carried particle detectors (semi-conductor and electron detector, semi­conductor proton detector) and a broadband soft x-ray detector to measure solar bursts and resultant x-ray storms. Their purpose was to measure changes in the intensity of electrons and protons in 24-hr orbit, as well as static electricity on the spacecraft. A small telescope studied proton fluxes in the 10-30-MeV range and electrons from 0.5 MeV to 1 MeV. Solar bursts were detected and measured on 21st April 1984 and 4th February 1986. Solar x-rays were surveyed in the 1-8-A range.

Scientific instruments were then fitted to weather satellites. Feng Yun 1-1 carried equipment to detect cosmic rays, protons, and alpha particles, as well as carbon, nitrogen, oxygen, and ion particles in the Earth’s radiation belts. Feng Yun 1-2 carried a cosmic ray composition monitor in the range of 4-23 MeV to detect and measure both solar proton events and galactic cosmic rays, and these were matched against readings at the Zhongshan Antarctic base. It detected helium, nitrogen, oxygen, heavy ion, and anomalous iron particles in the inner radiation belt and five solar proton events over September 1990 to February 1991. It flew through the inner radiation belt South Atlantic Anomaly and measured the changing intensities of protons, alpha particles, and carbon ion and iron atoms. Doing so at a time of solar maximum proved to be harmful to the satellite, for the radiation levels disrupted its logic board, causing a complete breakdown at one stage. Energetic particle detectors were designed to measure how heavy ions, protons, and electrons affect weather, one outcome being a mapping of the South Atlantic Magnetic Anomaly.

Feng Yun 1-2 carried two additional experiments – two balloons called Qi Qi 1 and 2 (the name Da Qi has also been used). Their purpose was to measure the density of the upper atmosphere between 400 km and 900 km, and they were tracked by seven ground stations. Made out of polyester film and measuring 2.5 m and 3 m in diameter, deployed in similar orbits, they decayed from orbit the following year, one in March, the other in July. Diagrams were duly published of fluctuations in atmospheric density over the first 90 days of the mission. They were the first scientific satellites to benefit from project 863. Combined with accurate ground observations, they proved to be a cheap but effective way of measuring atmospheric density during solar maximum.

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The geosynchronous Feng Yun 2-1 carried a high-energy particle detector and solar x-ray detector to measure solar proton and high-energy particle events, while later 2-3 carried a solar x-ray detector to measure x-rays from the Sun above 4 keY in 10 channels and the results were compared to the American Geostationary Operational Environmental Satellite (GOES). The spacecraft also carried two scientific detectors, one to measure 3-300-MeV protons and the other to measure

0. 15-5.70-MeV electrons. For 2008-09, they measured little, due to the solar

minimum, only finding electrons in the South Atlantic Magnetic Anomaly and around the North and South Poles. The problem of radiation damage to satellites operating in 24-hr orbit continued to bother the Chinese, for they fitted high-energy electron detectors to Feng Yun 2-3. They supplied three years of data, from 2005 to 2008, giving more accurate predictions of the frequency of upset events. Later FY-3s will be fitted with instruments to measure the ionosphere and auroras [10].

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