CHRONOS Threshold Science Mission

The Threshold Mission is characterized by a reduction of investigation duration to a single year, while observing a continental domain 24 times per day, with a ground sample distance (GSA) at the center of the domain of 8 km × 8 km GSA, better than existing CO and CH4 capabilities (MOPITT CO: 22 km × 22 km, GOSAT CH4, 10 km × 10 km). Reduction to one year removes the opportunity to assess inter-annual variability, but delivers sufficient data to assess emissions and transport across seasons. Such a Threshold Investigation preserves the frequent sampling and dense data that are unavailable from any other source to address the Science Objectives.

CHRONOS offers a significant hardware descope, available in Phase B, to integrate and fly a focal plane array with lower pixel operability than the baseline specification, saving the investigation approximately 10% of reserves (see §G.X ).  The inoperable pixels will provide no data for the locations imaged to them for the life of the mission, and create discontinuity in the tracking of transport, thus degrading the scientific discovery of the mission. The impact on CHRONOS science is minimized through selective orientation of the 2-D array with respect to ground targets and the inoperable pixels.

CHRONOS data products derive heritage from those of MOPITT and SCIAMACHY, which are validated, published in the peer-reviewed literature, archived, and in broad scientific use. CHRONOS’ powerful hourly science data derived from the carefully selected instrument concept informs high priority air and climate pollution decisions.