Mission OverviewSFXTI logo showing a snowflake over top the sun

The Solar Flare X-ray Timing Investigation (SFXTI) is an external International Space Station (ISS) payload that wasdeveloped and designed by SSEL for the purpose of studying hard X-ray radiation during solar flares. The instrument was developed in conjunction with the Montana Space Grant Consortium (MSGC) for the EPSCoR program, which is where the secondary name EISSFLAIX (EPSCoR ISS Solar Flare Acceleration Investigation through X-rays) comes from.

The instrument contains four scintilator crystals paired with silicon photomultipliers (SiPM). The crystals interact with the hard x-rays and produce violet and ultraviolet light. This light is then measured and recorded by the electronics within the instrument and the data is sent back to earth via data streams from the ISS.

SFXTI records data at a much faster temporal rate then ever before. SFXTI will measure data 32 times a second which will help uncover sloar flare acceleration at unprecedented spatiotemporal scales.

The instument will be hosted on a platform developed by Aegis Aerospace called "Space Test Program - Houston 10" (STP-H10). This spacecraft contains other expirements and will be mounted on the outside of the ISS on the Columbus Module.


The SFXTI payload has successfully completed thermal and vibrational environmental testing. The instrument has been delivered to Aegis Aerospace at Johnson Space Center and is awaiting integration onto STP-H10.  The current best estimate for launch and on-orbit opperation is December 2024.

SFXTI on the vibration table for testingThe completed SFXTI instrument installed on a vibration table at JSC