Mission typeTechnology demonstrator
COSPAR ID2014-029C Edit this at Wikidata
SATCAT no.39768
WebsiteOfficial page (Japanese)
Spacecraft properties
ManufacturerAdvanced Engineering Services Co., Ltd.[1]
Launch mass48 kg (106 lb)
Dimensions496 mm × 495 mm × 485 mm (19.5 in × 19.5 in × 19.1 in)
Start of mission
Launch date24 May 2014; 8 years ago (2014-05-24)
RocketH-IIA 202
Launch siteTanegashima, LA-Y
Orbital parameters
Reference systemGeocentric
RegimeSun Synchronous
Perigee altitude629.8 km
Apogee altitude647.4 km
Period97.5 min

SOCRATES or Space Optical Communications Research Advanced Technology Satellite is a Japanese micro-satellite launched in 2014. The satellite is purely a technology demonstrator designed by NICT intended to help AES company to gain experience in basic mission control, attitude control and spacecraft communications. Its main experiment is SOTA (Small Optical TrAnsponder), an optical small satellite communications demonstrator.[2] All subsystems of spacecraft are powered by solar cells mounted on spacecraft body and stub wings, with estimated electrical power of 120W BOL degrading to 100W EOL.[2][3][4]

SOTA was the first lasercom on board a microsatellite, performing a variety of experiments in a less-than-6 kg compact package, being the main one the 10 Mbit/s links at 1549 nm using coarse and fine-pointing to accurately transmit the 35-mW laser through a 5-cm Cassegrain telescope.[5] SOTA had other additional capabilities, i.e. B92-like QKD protocol at 800-nm band to perform the first-time quantum-limited demonstration from space.[6]


SOCRATES was launched from Tanegashima, Japan, on 24 May 2014 at 03:05:00 UTC by an H-IIA 202.[7]

See also


  1. ^ a b "SOCRATES (Space Optical Communications Research Advanced Technology Satellite)".
  2. ^ a b "SOCRATES". eoPortal Directory. Retrieved 2016-08-24.
  3. ^ Krebs, Gunter Dirk (2016-04-21). "SOCRATES". Gunter's Space Page. Retrieved 2016-08-24.
  4. ^ "SOCRATES". NASA Space Science Data Coordinated Archive. 27 April 2016. Retrieved 2016-08-04.
  5. ^ "Acta Astronautica "LEO-to-ground optical communications using SOTA (Small Optical TrAnsponder) – Payload verification results and experiments on space quantum communications"". Acta Astronautica. Retrieved 2020-02-18.
  6. ^ "Satellite-to-ground quantum-limited communication using a 50-kg-class microsatellite". Nature. Retrieved 2020-02-18.
  7. ^ "SOCRATES". NASA Space Science Data Coordinated Archive. 27 April 2016. Retrieved 2016-08-04.