SDS-4 (Small Demonstration Satellite 4) is a small satellite (50 cm cube with mass of 50 kg) developed byJAXA. It was launched as a secondary payload on theShizuku mission on 17 May 2012 UTC.[4]
In 2019, its ownership was transferred to theSKY Perfect JSAT Corporation (JSAT).[5] Operation was terminated by the end of June 2021.[6]
There are four rather specialised systems on the satellite:
SPAISE (SPace-based Automatic Identification SystEm) - test on-orbit a receiver for picking up signals fromAutomatic Identification System transmitters on ships well out to sea, and determine how space-based reception is affected by interference between nearby transmitters and by environmental conditions.
FOX (Flat heat-pipe on-orbit experiment) - to test whether flat heat pipes work in space in accordance with theoretical models and with tests on Earth
IST (In-flight experiment of Solar absorption rate with THERME) - to acquire information about the effect of sunlight in space on thermal coatings, re-flying the THERME instrument developed by CNES for testing different thermal coatings[7]
QCM (Quartz Crystal Microbalance) - to test whether a Japanese-manufactured quartz microbalance works well in monitoring contamination of the satellite from assembly to on-orbit operation.
Launches are separated by dots ( • ), payloads by commas ( , ), multiple names for the same satellite by slashes ( / ). Crewed flights are underlined. Launch failures are marked with the † sign. Payloads deployed from other spacecraft are (enclosed in parentheses).
