KYODO NEWS - Dec 30, 2019 - 13:18 | All, Japan

Japan's super low altitude satellite "Tsubame" has been registered by the Guinness World Records as having achieved the "lowest altitude by an Earth observation satellite in orbit," the nation's space agency has announced.

The satellite flew at an orbital altitude of 167.4 kilometers from Sept. 23 to 30 as part of its test mission from Dec. 23, 2017, to Oct. 1, 2019, compared with the 600 to 800 km zone where most Earth observation satellites operate.



[Photo courtesy of JAXA]

Tsubame maintained the record-low altitude for a period of seven days by using its ion engine system -- cultivated by the Japan Aerospace Exploration Agency or JAXA -- and gas-jet thrusters, successfully taking high resolution images and acquiring data on atmospheric and atomic-oxygen density.

Since this type of satellite requires a greater amount of propellant than conventional ones, JAXA adopted an ion engine, which utilizes propellant 10 times more efficiently than gas jets, to counter the atmospheric drag.

While placing a satellite in the super low orbit can yield more detailed observations of activities on the Earth's surface, operation at an altitude below 300 km is difficult.

JAXA said at such altitude the satellite will be exposed to "1,000 times more atmospheric resistance than those at usual altitudes and concentrated atomic oxygen" that would accelerate the deterioration of satellite parts.

According to JAXA, the 2017 to 2019 test mission also showed that material it developed is capable of withstanding exposure to atomic oxygen for a lengthy period of time.

"I'd like to make use of this achievement toward future science, technology and satellite utilization, and contribute to helping solve as many social issues as possible," said Masanori Sasaki, the Super Low Altitude Test Satellite project manager at JAXA.

Tsubame first reached an orbital altitude of 271.5 km last April and gradually descended to the record-low altitude before completing its mission on Oct. 1 and burning up in the atmosphere.

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