THE COMPACT INFRARED RADIOMETER IN SPACE (CIRIS) IS AN UNCOOLED IMAGING INFRARED (7.5 UM TO 13 UM) RADIOMETER DESIGNED FOR HIGH RADIOMETRIC PERFORMANCE FROM LEO ON A CUBESAT SPACECRAFT. THE CIRIS DESIGN IS BASED ON A BALL AIRCRAFT-MOUNTED INSTRUMENT WITH MODIFICATIONS TO IMPROVE RADIOMETRIC UNCERTAINTY IN THE SPACE ENVIRONMENT. A HIGH EMISSIVITY BLACKBODY SOURCE COATED WITH CARBON NANOTUBES REDUCES ERROR IN ON-BOARD CALIBRATION. ALGORITHMS COMPENSATE THE DETECTOR SIGNAL FOR CHANGING EXTERNAL TEMPERATURES ADDRESSING ANOTHER SOURCE OF UNCERTAINTY. THE CIRIS MISSION WILL ENABLE CONSTELLATIONS OF SIMPLE INEXPENSIVE CUBESATS TO REPLACE LARGER MORE COMPLEX INSTRUMENTS FOR MULTIPLE APPLICATIONS IN SCIENTIFIC RESEARCH AND LAND USE MANAGEMENT.