OCO-2 Observatory
OCO-2 operates in a near-polar, approximately 705 km altitude, sun-synchronous orbit, enabling it to observe most of Earth's surface at least once every sixteen days.
To maximize science return the Observatory collects data in three modes. In nadir mode, the instrument looks straight down at the surface below the observatory. In glint mode, it tracks the point close to where sunlight reflects from Earth's surface, a geometry that is required to measure over the ocean because in nadir the ocean does not reflect sufficient light. In target mode, the instrument scans repeatedly across a fixed surface site as the observatory passes overhead, enabling a large number of observations that can be directly compared with ground-based instruments such as those of the Total Carbon Column Observing Network (TCCON) and airborne campaigns used to calibrate and validate OCO-2 data.