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High Accuracy. In-Orbit Calibration Reference.
Lunar Reflectance.

One of the most challenging tasks in remote sensing from space is achieving instrument calibration accuracy on-orbit. The Moon is considered to be an excellent exoatmospheric calibration source. In fact, SeaWiFS, launched in the late 1990’s, was the first spaceborne sensor to make full use of Moon imaging for on-orbit radiometric performance.

Unfortunately, the current accuracy of the Moon as an absolute reference is limited to 5 – 10%, meaning that the inadequate accuracy of absolute lunar irradiance values causes mission operators to cite the risk of lunar maneuvers as exceeding the benefits of using the Moon as a reference.

ARCSTONE is a mission concept that provides a solution to this challenge. An orbiting spectrometer flying on a small satellite in low Earth orbit (LEO) will provide lunar spectral reflectance with accuracy sufficient to establish an SI-traceable absolute lunar calibration standard for past, current, and future Earth weather and climate sensors.

After launch, ARCSTONE will leverage existing NASA assets by using the Total and Spectral Irradiance Sensor (TSIS) observations – accurate Spectral Solar Irradiance (SSI) – for SI-traceable and spectral calibration of the ARCSTONE instrument on orbit.

“Detecting trends in environmental parameters measured at solar reflectance wavelengths requires on-orbit instrument stability at a level of 1% over a decade. This benchmark can be attained using the Moon as a radiometric reference.”

Required Observations

Spectral measurements of lunar and solar irradiance are required to retrieve reflectance of the Moon with a spectral range of 350 nm to 2300 nm and a spectral sampling of 4 nm.
The ARCSTONE mission’s goal is to achieve < 1.0%(k = 2) absolute accuracy for spectral lunar reflectance. Daily observations over 3 years are needed to cover minimum required libration space.

The tilt of the Moon’s orbit means that it’s seen from slightly different angles throughout the course of a month.
This animation shows what the changing view of the Moon looks like when a month is compressed into 24 seconds. The wobble is called libration.
Animation credit: Scientific Visualization Studio.

Mission Impacts
  1. Collaborating with the Global Space-based Inter-Calibration System (GSICS) community, the ARCSTONE mission will provide the data necessary to establish the international standard for absolute lunar calibration.
  2. Establishing highly accurate Earth climate observations is estimated to have an economic impact at ~ $12T over 40 to 60 years1. The use of ARCSTONE’s highly accurate spectral measurements on Earth observations will contribute to this economic impact.
  3. Improving the performance and impact of past (SeaWiFS), current (Moderate Resolution Imaging Spectroradiometer (MODIS), Visible Infrared Imaging Radiometer Suite (VIIRS)),
    and future Decadal Survey missions – Plankton, Aerosol, Cloud, ocean Ecosystem (PACE), Climate Absolute Radiance and Refractivity Earth Observatory (CLARREO), and the Advanced Composition Explorer (ACE).
    Here you can find a list of instruments with lunar observation capabilities from the 2014 GSICS Lunar Calibration Workshop.
  4. 1Cooke et al., “Value of Information for Climate Observing Systems,” Environ. Syst. Decis., 12 pp., 2014.
Technical Readiness

Currently, the ARCSTONE instrument is at TRL 3. The instrument breadboard was assembled, tested, and characterized at NIST in April 2016.
Initial flight instrument design is complete. The mission will be ready for launch three years from its start date.

Team Satellite Sensor G/L Dates Number of obs Phase angle range (°)
CMA FY-3C MERSI LEO 2013-2014 9 [43 57]
CMA FY-2D VISSR GEO 2007-2014    
CMA FY-2E VISSR GEO 2010-2014    
CMA FY-2F VISSR GEO 2012-2014    
JMA MTSAT-2 IMAGER GEO 2010-2013 62 [-138,147]
JMA GMS5 VISSR GEO 1995-2003 50 [-94,96]
JMA Himawari-8 AHI GEO 2014- -  
EUMETSAT MSG1 SEVIRI GEO 2003-2014 380/43 [-150,152]
EUMETSAT MSG2 SEVIRI GEO 2006-2014 312/54 [-147,150]
EUMETSAT MSG3 SEVIRI GEO 2013-2014 45/7 [-144,143]
EUMETSAT MET7 MVIRI GEO 1998-2014 128 [-147,144]
CNES Pleiades-1A PHR LEO 2012 10 [+/-40]
CNES Pleiades-1B PHR LEO 2013-2014 10 [+/-40]
NASA-MODIS Terra MODIS LEO 2000-2014 136 [54,56]
NASA-MODIS Aqua MODIS LEO 2002-2014 117 [-54,-56]
NASA-VIIRS NPP VIIRS LEO 2012-2014 20 [50,52]
NASA-OBPG SeaStar SeaWiFS LEO 1997-2010 204 (<10, [27-66])
NASA/USGS Landsat-8 OLI LEO 2013-2014 3 [-7]
NASA OCO-2 OCO LEO 2014    
NOAA-STAR NPP VIIRS LEO 2011-2014 19 [-52,-50]
NOAA GOES-10 IMAGER GEO 1998-2006 33 [-66, 81]
NOAA GOES-11 IMAGER GEO 2006-2007 10 [-62, 57]
NOAA GOES-12 IMAGER GEO 2003-2010 49 [-83, 66]
NOAA GOES-15 IMAGER GEO 2012-2013 28 [-52, 69]
VITO Proba-V VGT-P LEO 2013-2014 25 [-7]
KMA COMS MI GEO 2010-2014 60  
AIST Terra ASTER LEO 1999-2014 1 -27.7
ISRO OceanSat2 OCM-2 LEO 2009-2014 2