SASSI²

SASSI² [University Of Illinois, Urbana-Champaign]

The SASSI² (Student Aerothermal Spectrometer Satellite of Illinois and Indiana) is a 3U CubeSat scientific investigation mission by the University Of Illinois, Urbana-Champaign, and, which will utilize optical instrumentation in conjunction with temperature and pressure measurements to improve models of thermochemical non-equilibrium and electronic excitation occurring in high enthalpy flows.

This mission will characterize the flow and radiation generated by the diffuse bow shock formed during high-speed flight through the upper atmosphere. Optical spectrographic measurements of the radiation will provide benchmark data for flow, radiation, and materials modeling, improving aerothermal reentry models. Improved modeling will enable reduction of current thermal protection system design margins, ultimately resulting in lower-mass, higher-reliability thermal protection systems.

The satellites payload consists of an optical spectrometer Payload (UIUC) and the Purdue Sensor Payload. It consists of following instruments:

• Static and dynamic pressure measured by Patterson probe with a pirani gauge.
• External temperatures measure using armored thermocouple.
• Internal temperatures measured using silicon bandgap sensors.
• Spectrographic intensity measure by Ocean Optics HR4000 using fiber cables.

The satellite was built for a deployment from the ISS. Magnetic rotors provide attitude control during gradual orbital decay and orient the CubeSat perpendicular to freestream near apogee. It retains orbital energy by maintaining orbital eccentricity. SASSI² will record atmospheric data below 200 km.

It was selected in 2017 by NASA's CubeSat Launch Initiative (CSLI) to be launched as part of the ELaNa program. SASSI² was launched with the Cygnus CRS-11 mission on an Antares-230 rocket, which deployed it directly from the launch vehicles stage 2 in a very low orbit.