Super Low Altitude Test Satellite
Mission typeTechnology demonstration
COSPAR ID2017-082B Edit this at Wikidata
SATCAT no.43066
Mission duration1 year, 9 months and 8 days
Spacecraft properties
ManufacturerMitsubishi Electric Corp.
Launch mass400 kilograms (880 lb)
PowerSolar panel, 1140 W
Start of mission
Launch dateDecember 23, 2017 (2017-12-23)  UTC
Launch siteTanegashima Yoshinobu 1
End of mission
Deactivated1 October 2019
Decay date1 October 2019
Orbital parameters
RegimeLow Earth orbit
Altitude180 kilometres (110 mi)-268 kilometres (167 mi)
Lowest record - 167.4 kilometres (104.0 mi)

Super Low Altitude Test Satellite (SLATS) or Tsubame was a JAXA satellite intended to demonstrate operations in very low Earth orbit (VLEO, below 200 km), using ion engines to counteract aerodynamic drag from the Earth's atmosphere which is substantial at such lower orbital altitudes. It was launched on 23 December 2017, and decommissioned on 1 October 2019.[1]

The spacecraft was equipped with sensors to determine atomic oxygen density, an exposure facility to measure material degradation in the 200 km orbit, and a small camera.[2] Initial designs had conventional, though slightly canted, solar panels (compare to the aerodynamic shape and on-body solar panels of GOCE, which flew in a 255 km orbit). SLATS received the nickname Tsubame (Japanese for barn swallow) on 14 July 2017.[3] According to JAXA, this name was chosen as the thin, elongated satellite in super low orbit with a set of solar array wings was reminiscent of a small swallow flying low.

SLATS was launched 23 December 2017 on a H-IIA rocket alongside the GCOM-C (Shikisai) satellite to a 630 km orbit, followed by orbit-lowering manoeuvres by a combination of chemical propulsion and aerobraking, with final operation at an altitude below 180 km.[4]

SLATS was operated at 7 altitudes: 271.5 and 216.8 km each for 38 days, and 250, 240, 230, 181.1 and 167.4 km each for 7 days.[5] At 167.4 km the RCS thrusters were used in addition to the ion thruster to maintain altitude.[5]

The operation of the satellite was finished on 30 September 2019, and it was decommissioned in orbit on 1 October 2019 by terminating the communication radio and power.[1] The satellite deorbited 1 October 2019.[6]

On 30 December 2019, Guinness World Records recognized Tsubame's achievement, which reached the lowest altitude ever among Earth observation satellites.[7]


  1. ^ a b 超低高度衛星技術試験機「つばめ」(SLATS)の運用終了について (in Japanese). JAXA. 2 October 2019. Retrieved 3 October 2019.
  2. ^ "SLATS". eoPortal. Retrieved 19 December 2015.
  3. ^ "気候変動観測衛星(GCOM-C)と超低高度衛星技術試験機(SLATS)の愛称決定について" (Press release) (in Japanese). JAXA. July 14, 2017. Retrieved August 24, 2019.
  4. ^ "超低高度衛星技術試験機(SLATS)の検討状況について" (PDF) (in Japanese). JAXA. 4 September 2013. Retrieved 2016-06-06.
  5. ^ a b "About Super Low Altitude Test Satellite "TSUBAME" (SLATS)". Archived from the original on 2018-03-28. Retrieved 2020-12-21.
  6. ^ "SLATS". 26 January 2023. Retrieved 26 January 2023.
  7. ^ The Japan Times, Japan's low altitude satellite Tsubame registered in Guinness World Records, 30 December 2019