The SIDAR (Solar Irradiance, Data and Rescue), formerly known as JPSS Free Flyer 1, will be a complementary mission to the JPSS 1 satellite. It will fly the instruments, which were originally planned for the NPOESS satellites, but could not accomodated on the JPSS 1 satellite due to the size limitation of the cloned NPP satellite.

SIDAR will carry:

1. Total Solar Irradiance Sensor (TSIS), a NASA instrument meant to continue the agency’s 33-year record of monitoring the sun’s energy that reaches Earth. It will replace similar sensors on NASA’s SORCE satellite launched in 2003 and on the failed Glory satellite. TSIS was already purchased and built for the cancelled NPOESS program.
2. Advanced Data Collection System (A-DCS), a payload provided by the French space agency CNES to continue the monitoring of data gathered by sensors attached to ocean buoys, other maritime platforms and marine animals.
3. Search and Rescue (SARSAT) instruments.