High precision atmospheric CO2 measurements from space: The design and implementation of OCO-2

The OCO-2 mission is designed to make high-precision, high-spatial resolution measurements of carbon dioxide, globally. OCO-2 will carry a single instrument that incorporates 3 high resolution grating spectrometers that will make co-boresighted measurements of reflected sunlight in near-infrared CO
₂
and molecular oxygen (O
₂
) absorption bands. These measurements will be used to retrieve spatially-resolved estimates of the column-averaged CO
₂
dry air mole fraction, X
_CO2
. The OCO-2 mission is a `carbon copy' of the OCO mission that was constructed and launched in February 2009. Unfortunately, because of a failure of the launch vehicle, the OCO observatory never reached orbit. In March 2010, JPL was given direction to build a replacement for the OCO instrument mission, to be called OCO-2. In order to minimize risk, and reduce cost, the mission was directed to duplicate the design of the OCO observatory. In this paper, we discuss some of the unique features of the OCO design, as well as the challenges presented by trying to implement a design that is more than a decade old.