HaloSat

HaloSat was designed to survey the distribution of hot gas in the Milky Way and constrain the mass and geometry of the Galactic halo.

The mission, led by the University of Iowa (UIowa, PI P.Kaaret) as a rapid-development CubeSat mission, was selected by NASA with funding started in 2016. Launched on May 21, 2018 from the Wallops Space Flight Facility, as part of the payload of the Cygnus OA-9 International Space Station (ISS) resupply mission, HaloSat was placed in the airlock of the Japanese Experiment Module (JEM) and deployed into circular low Earth orbit on July 13, 2018 using a Nanoracks CubeSat Deployer. The science operations started in October 2018.

To trace the Galactic halo, HaloSat is equipped with a non-focusing instrument, comprised of three independent silicon drift detectors with the following characteristics:

• Energy range : 0.4 -7.0 keV
• Field of view : 10 deg diameter full response, tapering to 14 deg zero response
• Energy Resolution : ~85 eV at 677 eV and ~137 eV at 5895 eV.

The observing strategy was to divide the sky into 334 positions and acquire a minimum of 8000 detector-seconds for each position. Originally approved for 12 months of science operations, HaloSat successfully collected science data from October 15, 2018, up to September 29, 2020, effectively doubling the mission life time. HaloSat was the first mission dedicated to Astrophysical Science using a Cubesat platform.

The science data center is located at UIowa where the data are processed and the outputs provided to the HEASARC archive for public distribution. Mission operations are handled by Blue Canyon Technologies.