Achieving Instrument High Accuracy In-Orbit
One of the most challenging tasks in remote sensing from space is achieving required instrument calibration accuracy on-orbit. The Moon is considered to be an excellent exoatmospheric calibration source. However, the current accuracy of the Moon as an absolute reference is limited to 5 - 10%, and this level of accuracy is inadequate to meet the challenging objective of Earth Science observations. ARCSTONE is a mission concept that provides a solution to this challenge. An orbiting spectrometer flying on a small satellite in low Earth orbit 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.

A depiction of the ARCSTONE observatory using engineering instrument designs and actual CubeSat images
The ARCSTONE observatory is shown in low Earth orbit with the spectrometer viewing the Sun and Moon. The spacecraft rotates in order to view the Moon or the Sun.

“The Moon is available to all Earth-orbiting spacecraft at least once per month, and can be used to tie together the sensor radiance scales of all instruments participating in lunar calibration without requiring near-simultaneous observations.”