The (new) Mid-Infrared Spectrometer and Imager (MIRSI) for the NASA Infrared Telescope Facility

The Mid-Infrared Spectrometer and Imager (MIRSI) was developed at Boston University and has been in use since 2002 on the Infrared Telescope Facility (IRTF), making observations of asteroids, planets, and comets in the 2 - 25 μm wavelength range. Recently the instrument has been unavailable due to electronics issues and the high cost of supplying liquid helium on Maunakea. We have begun a project to upgrade MIRSI to a cryocooler-based system with new array readout electronics and a dichroic and optical camera to simultaneously image the science field for image acquisition and optical photometry. The mechanical cryocooler will enable MIRSI to be continuously mounted on the IRTF multiple instrument mount (MIM) along with the other facility instruments, making it available to the entire community for multi-wavelength imaging and spectral observations. We will propose to use the refurbished MIRSI to measure the 10 μm flux from Near Earth Objects (NEOs) and determine their diameters and albedos through the use of a thermal model. We plan to observe up to 750 NEOs over the course of a three year survey, most of whose diameters will be under 300 meters. Here we present an overview of the MIRSI upgrade and give the current status of the project.This work is funded by the NASA Solar System Observations/NEOO program.