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Mitsubishi altitude control system packs single sensor

Posted: 12 Feb 2002 ?? ?Print Version ?Bookmark and Share

Keywords:mitsubishi electric? mistubishi? altitude control system? advanced star sensor system? satellite altitude control?

The Advanced Star Sensor System altitude control system incorporates a single sensor that determines a satellite's exact altitude from the images of bright-fixed stars with a magnitude of up to 5.

The system is aimed in facilitating communication, observation, navigation, and other valuable services for satellites. It will be included in the payload of the Unmanned Space Experiment Recovery System (USERS) satellite scheduled for launch in the summer of 2002 for inflight testing.

In a project commissioned by the Institute of Unmanned Space Experiment Free Flyer (USEF) and the New Energy and Industrial Technology Development Organization (NEDO), ground tests using a flight model demonstrated the system's ability to determine attitude and verified that the system met all requirements of satellite deployment.

The Advanced Star Sensor System determines satellite altitude from bright fixed star patterns by using the equivalent field of view of a combination of sequential, multiple images the spacecraft gets as it rotates in 10min to 20min.

The star sensor can detect enough fixed stars with a magnitude of up to 5 in the virtual image, enabling the altitude to be determined with >99 percent probability. The system has a 1 arc-min altitude determining accuracy and a 3 arc-min/s angular-rate determining accuracy.

The system has also integrated sensor data processing and altitude-control electronics, enabling the company to implement the system at a compact weight of 6.2kgabout 1/2 to 1/3 the weight of functional, equivalent systems. It also used commercial components for the CPUs, CCDs, and memory to drive the cost of the system down.

In addition, the system has three separate CPUs to calculate the satellite altitude. The calculation results are harmonized by a majority-processing scheme, eliminating CPU malfunctions due to radiation-induced memory upsets.

The company also plans to integrate the data recorder and the data handling system into the system's future version. These devices are currently separate from the altitude control system.





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