PREFIRE (Polar Radiant Energy in the Far-InfraRed Experiment)

NASA’s first dedicated far-infrared mission — a pair of CubeSats measuring the 5-54 µm thermal-IR spectrum from polar regions. The far-IR (>15 µm) carries ~60% of Earth’s outgoing longwave radiation in cold polar regions but has been essentially unmeasured from space. PREFIRE closes that gap. Operational data released August 2025.

What it sees

• 5-54 µm spectrometer at 0.84 µm resolution — extends well beyond the standard 3-15 µm IR window into the rotational water-vapor + ice-emission regime that’s been dark to satellites
• Two CubeSats in near-polar orbits; each ~3 kg, ~6U form factor
• Designed for polar science specifically — primary observation domain ±60° latitude poleward
• No imaging — point-FOV spectrometer (not an imager)

Why it matters

• The far-infrared has been a 50-year blind spot. ~60% of polar outgoing longwave radiation lives at wavelengths longer than 15 µm; current climate models simulate this regime largely without observational constraint.
• First-of-its-kind direct measurement of polar surface + atmospheric emissivity in the far-IR. Climate models will be re-validated against PREFIRE data.
• Demonstrator for low-cost CubeSat science. Two CubeSats at fraction of free-flyer cost answering a fundamental climate science question. Template for future NASA mission architecture.
• Baynes cited PREFIRE specifically in 2024-25 program highlights → leadership visibility.

Where to get the data

• earthaccess Python: short names beginning PREFIRE_* (verify via CMR — naming was finalizing post-launch)
• ASDC DAAC portal: asdc.larc.nasa.gov
• PREFIRE mission portal: prefire.ssec.wisc.edu — also has tutorials + initial science papers
• Recent release announcement: First PREFIRE datasets released (earthdata.nasa.gov/news/first-prefire-datasets-released)

What it enables (largely new science)

• Polar surface emissivity in the far-IR (Arctic + Antarctic surface types: snow, sea ice, melt ponds, glacier ice — each has a distinct far-IR signature)
• Polar atmospheric water vapor profiling at high spectral resolution
• Polar cloud + ice-cloud microphysics
• Climate-model evaluation in the polar far-IR regime
• Radiation-budget closure in the polar regions
• Cross-validation with CERES (broadband radiation) — far-IR component now observed directly

Gotchas

• Brand new. Operational data only since August 2025. Documentation evolving. Tutorial ecosystem nearly non-existent.
• Point-FOV, not imaging. Don’t expect spatial maps in the traditional sense; you get along-track samples.
• CubeSat power limits mean duty cycle is finite — not continuous observation.
• ±60° polar focus. PREFIRE is intentionally polar-focused; tropical + mid-latitude observations are sparse.
• 10-month baseline mission length. Extension possible but not guaranteed. Plan analyses for the short available record.
• Two CubeSats; one had early commissioning issues (PREFIRE-2 had initial pointing anomalies, now resolved). Always check QA flags.

Related missions

• CERES on Terra + Aqua + Suomi NPP + NOAA-20: broadband radiation; PREFIRE is the spectral complement.
• AIRS (s19 →): hyperspectral IR up to 15 µm; PREFIRE extends this beyond.
• CrIS / IASI: operational hyperspectral IR; complementary in the 3-15 µm window.
• PREFIRE-2 / FORUM (ESA): planned ESA far-IR Earth-explorer mission ~2027, complementary global coverage.

Related datasets