Mission

The two 6U CubeSat spacecraft were launched into two different 531 km altitude, near-polar sun-synchronous (97.5° inclination) orbits in late spring 2024 (May 25 and June 5). Each satellite has a heritage miniaturized IR spectrometer, covering the 3-54 μm wavelength region at approximately 0.84 μm spectral sampling. Mission science operations (after in-orbit checkout was complete) began in early summer 2024. PREFIRE-SAT1 crosses the equator going toward the north at about 03:35 local time, and crosses the equator going southward at about 15:35 local time (PREFIRE-SAT2 does these at about 08:00 and 20:00 local time). Radiance measurements are collected across the globe, although other science products derived from those are currently produced only for the polar regions (poleward of 60° latitude).

Measurement Data: Two spacecraft in near-polar orbits view Arctic and Antarctic surfaces and clouds, providing multiple observations of those regions each day. PREFIRE measures variations in FIR emissivity and the amount of outgoing infrared energy that remains within the atmosphere via thermal radiometric sampling at the top of the polar atmosphere. These measurements are integrated with models to understand the role of FIR radiation in the Arctic and Antarctic.

Ongoing Mission: The two PREFIRE CubeSats are continuing to gather information about seasonal cycles, with diurnal subsampling where the two orbits cross at different times of day. They are withstanding a lot of “space weather” (geomagnetic storms, solar outbursts, and high-energy particles) in order to do this. Since the CubeSats are tiny (the size of a large shoebox), they have no space for an active propulsion system, and so their orbit altitudes are very slowly decreasing with time. However, this also means that they have a more close-up view of Earth as time goes on.