Quick Facts: Climate Absolute Radiance and Refractivity Observatory (CLARREO) Pathfinder

From its home on the International Space Station, the CLARREO Pathfinder reflected solar spectrometer will calibrate by pointing to the Sun and Moon. (Courtesy NASA)


In 2016, the CLARREO project received authorization to conduct a pathfinder mission called CLARREO Pathfinder (CPF). The foundation for CPF is the ability to produce highly accurate and trusted climate records. These tested climate records can be used to lay the groundwork for informed decisions on mitigation and adaptation policies that address the effects of climate change on society.

The urgency for CPF results from the growing need for higher accuracy, long-term climate change observations than current instruments are capable of providing. CPF data will dramatically increase how accurately we define the real climate future that society faces and assist policy makers in formulating more informed decisions about how to respond.

The timing of CPF is a result of recent advances in a wide range of scientific, measurement, and technological areas. These advances combine to enable CPF to be focused on unprecedented accuracy at decade time scales. CPF will assess the relative contributions of climate variables to climate change, greatly expanding the uses of existing space-based data sets for societal benefit.

LASP is playing a major role in CPF by providing the Reflected Solar (RS) instrument, which will measure solar radiation reflected from Earth in wavelength bands covering most of the solar spectrum (between 350-2300 nm). CPF will demonstrate improved measurement accuracy by factors of 5-10 over existing on-orbit instruments, which will enable the calibration of other climate sensors, and set the stage to monitor climate change from space, identify its underlying causes, and improve models to enable sound policy decisions.

CPF is scheduled to launch to the International Space Station (ISS) in 2023.

LASP Roles

LASP will provide:

  • The Reflected Solar (RS) instrument
  • The Pointing system for Earth, Sun, and Moon viewing
  • LASP science Principal Investigator, Peter Pilewskie, and Instrument Principal Investigator, Greg Kopp
  • Instrument integration and operations for RS

LASP Instruments

The CLARREO RS instrument design represents an advance in absolute calibration over existing approaches. The RS benchmark measurement is spectrally resolved reflectance of solar radiation from Earth with an uncertainty of 0.3% or less. One of the critical differences of this instrument relative to others in orbit is its ability to point the entire instrument at the Earth, the Sun, the Moon, and deep space.

Views of the Sun are used to provide absolute calibration of the RS instrument, in units of reflectance or reflected radiance. Scanning the instrument view across solar and lunar disks also provides images suitable for flat-fielding the instrument’s detector array.

Quick Facts

Launch date: Delivery to ISS in 2023
Launch location: Cape Canaveral Air Force Station
Launch vehicle: TBD
Mission target: Low Earth orbit onboard the ISS
Mission duration: 1 year
Other organizations involved:

  • NASA’s Langley Research Center (LaRC)
  • NASA’s Goddard Space Flight Center (GSFC)