Program: GS-2009B-Q-46

Title:First Thermal Maps of the Stratosphere of Uranus: Follow-up to Detection of Rotational Variability by the Spitzer IRS
PI:Glenn Orton
Co-I(s): Leigh Fletcher, Therese Encrenaz, Heidi Hammel, Thomas Geballe, Amanda Mainzer


We propose to make the first maps of the thermal structure of the stratosphere of Uranus. Such maps will determine the extent of radiative heating in an environment of extreme seasonal variability, with the 98-degree inclination of the rotation axis of Uranus to the ecliptic. Regularly spaced observations during a single rotation of Uranus will allow us to examine the extent of longitudinal variability in its stratosphere. These observations will follow up the detection of strong rotational variability in our Spitzer IRS disk-averaged spectra in emission features of methane, ethane and acetylene. This detection implies the presence of a thermal feature or features of high amplitude which have never been imaged before. Because Uranus is a faint thermal object, we propose to image it at 13.1 microns, the brightest possible radiance, arising from stratospheric acetylene and ethane.