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HOTSAT 1 is a pathfinder mission built by SSTL for Satellite Vu, flying a low-cost high resolution mid-wave infrared (MWIR) detector. It is a pathfinder for Satellite Vu's seven satellite constellation.

HOTSAT 1 is based on the DarkCarb version of the SSTL Carbonite platform and makes use of a 0.32 m diameter telescope and a Mercury Cadmium Telluride (MCT) cooled detector. One of the main benefits of this design is the ability to image throughout both the day and the night with no sensitivity to lighting conditions. The imager has a ground resolution of 3.5 m and a swath width of 4 km. As the imaging capability is not dependent on illumination conditions, non-SSO orbits can also be considered.

Applications for the DarkCarb satellites are:

  • Change detection and human activity
  • Pattern of life assessments
  • Humanitarian and disaster management
  • Global high resolution situational awareness
  • National security and defence
  • Infrastructure and asset monitoring
  • Urban heat mapping

DarkCarb imagery provides the capability to differentiate between objects and surfaces of different temperature and emissivity, providing complementary information to traditional optical imagery and the ability to extend imaging opportunities into night time.

DarkCarbís video capability allows for change detection in a single pass. In addition, as the imager can detect temperature differences it should be possible to derive information on recent activity in a scene, such as recently used or moved vehicles, which is not normally discernible in Visible-NIR imagery. DarkCarb also has the potential to assist with disaster support activities; wildfires, volcanic eruptions and flooding for example.

Launch took place in June 2023. The satellite operated only 6 months until the imager failed in December 2023.

Nation: UK
Type / Application: Earth observation
Operator: Satellite Vu
Contractors: SSTL
Configuration: SSTL-42
Propulsion: None
Power: Solar cells, batteries
Lifetime: 5 years (design), 6 months (#1 reached)
Mass: 130 kg
Orbit: 500 km SSO
Satellite COSPAR Date LS Launch Vehicle Remarks
HOTSAT 1 2023-084Y 12.06.2023 Va SLC-4E Falcon-9 v1.2 (Block 5) with W-Series 1, Skykraft Deployer 3, Skykraft 3A, ..., 3D, ICEYE X23, X25, X26, X30, GHOSt 3, Grťgoire, Runner 1, Tomorrow R2, QPS-SAR 6, —uSat 40, ..., 43, Aces 1, ..., 4, HOTSAT 1, AFR, DROID.001, MuSat 1, ION-SCV 011, Outpost Mission 1, EPICHyper 2, Kelpie 2, Spei Satelles, ELO 4, MRC-100, Unicorn 2I, SATLLA 2I, URESAT 1, Istanbul, ROM 2, Orbiter SN3, Otter Pup, MDQSAT 1C, 1D, Pleiades-Squared, GEI-SAT Precursor, XVI, AII-Delta, Ayris 1, 2, EIVE, Lemur-2 166, 167, 168, MISR-A 1, MISR-B 2, Tiger 4, FOSSASat FEROX 1, ..., 4, SpaceBEE 168, ..., 179
HOTSAT 2 (SatelliteVu MWIR Clone) - 2025 with ?


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