Thermal image of TEDY (test satellite) 1/3 scale mock-up at NPL (Photo Credit: NPL)
A team of scientists at the National Physical Laboratory (NPL) have developed a new method to take 3D thermal images of satellites.
The method has been developed for prospective use at the European Space Agency's (ESA) largest vacuum facility, the Large Space Simulator (LSS). These measurements will improve the comparision between measurement data and thermal models, confirming their accuracy.
The Temperature & Humidity Group at NPL merged with ESA in 2009 to face this challenge, by developing 2D thermal imaging system that has the capability to image inside a vacuum. Now, as a result of a second collaborative project, the consortium has developed an innovative technology for 3D thermal imaging.
Space scientists traditionally use sensors called 'thermocouples' to measure temperature. In order to get an accurate high resolution measurement, the researchers have to bind thousands of thermocouples to each satellite.
This method is practically impossible and is a significant drawback for space flight, as it will increase the weight of the satellite. However, using only a few thermocouples can produce insufficient measurement data to achieve high resolution and confidence for reliable model comparison.
Enhanced resolution can only be achieved with the use of thermal imaging. Thermal pictures taken on the ground provided supplementary information, which was incorporated by the team first in 2D and then in 3D in order to allow satellite designers to engineer satellite behavior before launch.
This allows the scientists to validate the measurement prior to the launch, while also providing greater confidence, resolution, and eventually reducing the number of thermocouples that need to be used.
The scientist team at NPL along with Swiss 3D measurement company, PhotoCore London-based management consultancy PSI-tran, has been able to resolve this issue by incorporating advance features that deliver traceable and accurate thermal and geometric information from the satellite structure. This feature compensates for the non-perfect emissivity, background radiation, and inter-reflections.
Accurately measuring the geometrical form and thermal distribution of a satellite has been a significant measurement challenge. But we're very pleased with the early results. The consortium has been fantastic to work with and this has been very much a collaborative project. We're excited to see the advances that this technology will bring to this and other fields.
Dr Rob Simpson, Researcher, NPL
The ESA will be using this new technology at the LSS in its European Space Research and Technology Centre, in order to improve measurement data.