  The Space Industry Responsive Intelligent Thermal (SpIRIT) 6U CubeSat is a
mission led by The University of Melbourne in cooperation with the Italian
Space Agency. Launched in a 510 km Polar Sun Synchronous Orbit in December
2023, SpIRIT carries multiple subsystems for scientific and technology
demonstration. The main payload is the HERMES instrument for detection of
high-energy astrophysics transients (Gamma Ray Bursts), and for studies of
their variability at scales below 1 ms. The satellite includes a novel thermal
management system for its class, based on a Stirling-cycle cooler and
deployable thermal radiator, designed to cool HERMES to reduce instrumental
background noise. A low-latency communication subsystem based on a sat-phone
network is supporting rapid transmission of time-critical data and
telecommands. SpIRIT is also equipped with a set of RGB and thermal IR cameras,
connected to an on-board image processing unit with artificial intelligence
capabilities for autonomous feature recognition. To effectively manage all
interfaces between different subsystems and mission stakeholders, the
University of Melbourne developed an instrument control unit (PMS) which
operates all payloads. PMS also provides backup uninterruptible power to the
HERMES instrument through a supercapacitor-based UPS for safe instrument
shutdown in case of platform power interruptions. This paper first presents a
mission and payload overview, and early in-orbit results, along with lessons
learned throughout the mission. This work not only sheds light on the novelty
of some of the on-board technologies onboard and on their potential impact to
enable greater utilization of CubeSats for scientific missions, but also offers
insights into the practical challenges and accomplishments related to
developing and operating a multi-organization CubeSat with a complex array of
instruments and systems.
