Ultra-Fine-Grained Atmospheric Aerosol and Trace Gas Measurements with Future Space- based Tunable Laser LIDAR: The STARCaL Project

We propose a tunable laser-based satellite-mounted LIDAR system for a very wide variety of applications in atmospheric and climate studies, ground- and space-based astronomical telescope calibration, as well as national defense and security. This broad range of applications is joined by a common need for beam pointability, wavelength tunability from visible through the near-infrared, and precision radiometry, and thus could be accomodated via a single satellite platform. Wavelength tunability from 300 to 2400 um is provided via well-tested optical parametric oscillator technology, and the beam is precisely sampled using an electrical substitution radiometer. Upcoming astrophysical projects investigating the recently- discovered accelerated expansion of the universe (from the so-named "dark energy") require significant improvements in both spectrophotometric and absolute flux calibration of telescopes, which this project provides. Simultaneously, STARCaL provides wavelength-tunable, pointable LIDAR data analogous to CALIPSO, with ultra- precise beam radiometry, for precision measurements of aerosols and trace gases in all parts of the atmosphere. The technology for this project is now well-tested in space and on the ground.