Japan’s superlow altitude satellite Tsubame has been registered by 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.
Tsubame maintained the record-low altitude for a period of seven days by using its ion engine system — developed by the Japan Aerospace Exploration Agency or JAXA — and gas-jet thrusters, successfully capturing high resolution images despite atmospheric drag and the density of atomic-oxygen present in superlow altitudes.
Since this type of satellite requires a greater amount of propellant than its conventional peers, JAXA adopted an ion engine, which utilizes propellant 10 times more efficiently than gas jets, to counter the atmospheric drag.
The Tsubame satellite | JAXA / VIA KYODO
While placing a satellite in superlow orbit can yield more detailed observations of activity on the Earth’s surface, operations at altitudes below 300 km is difficult.
JAXA said that at such an 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 the satellite parts.
According to JAXA, the 2017 to 2019 test mission also showed that the 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 to develop 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.