
ESA Comet Interceptor 3D modelling (CI3D)
European Space Agency’s Requesting Party Activities (RPA) Programme in Latvia supports the project “Joint modelling of preliminary Comet Interceptor flyby scenarios with photorealistic 3D tools for OPIC, MIRMIS Hyperspectral Imager and EnVisS Compression Algorithm instruments and components” (July 2024 – March 2025), or simply CI3D. The project is led by Nanocraft SIA (Dr. Andris Slavinskis) in Latvia with Ventspils University of Applied Sciences in Latvia and the University of Tartu in Estonia as subcontractors.
Our goal with the CI3D project is to provide synthetic comet flyby datasets by using and contributing to space 3D modelling tools FlyByGen (developed by the University of Tartu in Estonia) and Asteroid Image Simulator (AIS, developed by the Institute of Geology of the Czech Academy of Sciences and the University of Helsinki in Finland). We will work in close collaboration with Comet Interceptor instrument teams to set the requirements for datasets necessary for testing the space cameras. The mission will approach a comet coming from the Öpik–Oort cloud which means the target, currently, is too far to be detected. We might not know the target by the launch of Comet Interceptor in 2029 and this is the first time a mission is developed to an unknown target! The Comet Interceptor mission will be launched along with the Ariel Space Mission to Lagrange Point 2 where it will wait for up to two years until a suitable target will be found and selected for the fast flyby.
As the first pilot project, CI3D will provide datasets to three instruments: OPIC, MIRMIS and EnVisS. These three cameras are placed on two probes, yet another novelty of the Comet Interceptor, and will image in different wavelengths and viewing geometries as well as with different fields of view. All these factors mean that we need to take special care in aligning the datasets for a joint test campaign which in turn is necessary to determine the camera parameters. Take the exposure time for instance and the flyby velocity which can vary by several tens of km/s, depending on the specific Öpik–Oort cloud target. We have to carefully select the exposure time, aperture, sensitivity etc.
The project involves Ventspils University of Applied Sciences as a subcontractor in comet activity modelling. This is rather challenging as the activity is dynamic, can be very different from comet to comet and requires resource-intense modelling of the volumetric scattering in 3D (the reason why your Quake was lagging in smoke). Below is an example of our previous project Space Imaging Simulator for Proximity Operations (SISPO + Space Travel Blog post) which included two synthetic models for 67P/Churyumov–Gerasimenko, visited by the ESA Rosetta mission, gas and dust modelling. In the Comet Interceptor, we have to upgrade to the newest comet activity model.
Gallery: An example of SISPO’s gas and dust model applied to 67P/Churyumov–Gerasimenko’s shape model. Left: OpenGL. Middle: Cycles. Right: Real image from the Rosetta mission (Credit: ESA, CC BY-SA). Source: Pajusalu et al. 2022. Shape model by Mattias Malmer.
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