**Enabling climate-quality calibration of satellite remote sensing
instruments using the Moon**

# Statement of Problem and Objective

A unique effort to utilize the Moon as a standard light source for
radiometric calibration of Earth-imaging instruments in orbit has been
developed under the USGS Astrogeology Team at Flagstaff, AZ. Because
this is a NASA-funded project, contractual obligations effectively limit
the application of lunar calibration to NASA Earth Observing System
(EOS) instruments, although the technique can be applied to almost any
sensor system within the operational wavelength range of 350 nm to 2500
nm. If the USGS were to directly support maintaining and further
development of lunar calibration as an enabling technology, the
calibration needs of the larger remote sensing and climate monitoring
communities would be better served.

# Relevance and Impact

The USGS has taken a leading role in US land imaging programs, and
climate change is one of the most important issues facing society today.
The lunar calibration technique has demonstrated capabilities for sensor
stability monitoring with the precision needed to detect climate change,
and for cross-calibration of instruments having similar wavelength
channels on different spacecraft platforms. Direct benefits to USGS land
imaging programs from lunar calibration include, among others: 1) the
Moon provides a stable reference that can establish a common radiometric
scale for instruments whose mission lifetimes do not overlap, such as
the anticipated gap between Landsat-7 and the Landsat Data Continuity
Mission; 2) the Moon provides a common source for cross-calibration of
sensor systems whose data products are being used to develop the
contiguous, long-term monitoring records of Earth observations that are
essential for detecting the effects of climate change; 3) the USGS could
provide lunar calibration as a service to other US agencies involved in
environmental remote sensing (e.g. NOAA), as well as to the foreign
satellite programs that are being relied upon to supplement US
Earth-observing capabilities as these capabilities diminish.

# Work Strategy

Ongoing project efforts are focused on refinement of the lunar
photometric models that underpin the lunar calibration technique.
Because these models are developed from a dataset of ground-based
observations, accurate characterization and removal of atmospheric
artifacts is required. Reduction of uncertainties in this process and in
the absolute radiometric scale of the dataset and models are continuing
activities that are necessary to "smooth the bumps" in the modeled lunar
reflectance and validate the Moon as an absolute calibration reference.
Servicing the spacecraft instrument teams that utilize lunar calibration
is a fundamental aspect of the program.

# Partnerships

All development work on lunar calibration since the project's inception
has been done at the USGS Flagstaff Science Center, where the
observational database is housed and where the radiometric measurements
of the Moon were acquired from a dedicated observatory on campus.
Continuing project needs could benefit from collaboration with the
Landsat Calibration/Validation group at the EROS Data Center.