BEAGLE 2 Project
The project revolved around the virtual reconstruction of Beagle 2 and was carried out at the instigation and with the kind assistance of Professor Mark Sims, from the Space Research Centre at University of Leicester. Mark was one of the original Beagle 2 team and was mission manager. Images from the HiRISE NASA satellite showed an object on the surface of Mars, Which looks artificial in nature and was similar to the shape of Beagle 2, sent to Mars in 2003. The main objectives of the project and the work conducted by the DMU team were to create a 3D model of the spacecraft and replicate virtually the physical characteristics of the materials used in Beagle 2 and the sun angles at the times the satellite images were taken. This was in order to try and match the simulation (3D renders) and the satellite images in order to ascertain the deployed configuration of Beagle 2 on Mars. The initial suspicion for the failure of Beagle 2 was that not all of the solar panels had fully deployed. Dr. Jim Clemmet former Beagle 2 Chief Engineer advised on technical details of Beagle 2. Colleagues of Mark helped analyse the match between the simulated and real images.
- The software used for the 3D reconstruction was Autodesk Maya 2014.
- The model was constructed, based on the dimensions of the physical spacecraft.
- After the creation of the 3D model and the final modifications of its shape (aimed at achieving a precise replica of Beagle 2) the model was rigged in order to animate a sequence of openings of the solar panels and the antenna. The correct sequencing of the opening of panels was achieved by setting Driven Keys and linking them to a sole Driver within Maya.
- There was an in-depth experimentation with MIA materials (Mental Ray plug-in for Autodesk Maya), which was aimed to assign to the 3D model materials, whose features were as close to the characteristics of the physical materials used for the creation of Beagle 2, as possible.
- The lighting conditions on Mars and the particular sun angles data, provided with the background information for the project were replicated within Maya software with the use of Physical Sun and Sky and the Photographic Exposure
- Virtual cameras were created within Maya and their position was adjusted according to the initial information about the position of satellite cameras in respect to the surface of Mars and the object, considered to be Beagle 2.
- An extensive experimentation was carried out, aimed at testing the different sun angles in combination with different orientations for the Beagle 2 model (including slight tilt of the object), as well as a different configuration of the opening of the solar panels. All scenarios with respect to the possible number of open panels were explored.
- The final renders, exported from Autodesk Maya, were then compared to the original satellite images by degrading their quality (pixelisation), so the number of pixels matches the ones from the satellite images, as well as by shifting the pixels slightly.
- Finally, an image correlation test was undertaken with the ImageJ software and the mathematical representation of pixel intensity values for the image pairs (3D renders and satellite images), used for the experimentation, and was outputted in Microsoft Excel.
The experimentation with different orientation and configuration of open solar panels of the 3D model highlighted a particular orientation with three panels open as being indicative of a strong similarity to the original satellite image, featuring the same sun angle – 136.68⁰ (Fig 1).
|ESP_030908_1915_RED (136.68 degrees)||Lander_136.68_RED_3_Pan (3D Render)|
Figure 1 – Satellite image (left), compared to a render of the 3D model (right)
In order that the image comparison results are as objective as possible, the initial render was pixelated and several variations from it were derived by shifting the pixels – all indicating the similarity between the 3D render and the satellite image (Fig 2). The visual resemblance was supported by the image correlation data, which evidenced the smallest difference between the pixel intensity of the 3D render and the corresponding satellite image and ratio-ing and subtracting the simulated images with the real ones. These techniques showed that at least 3 solar panels had deployed.
|ESP_040363_1915_RED (136.68 degrees)||Lander_136.68_RED_3_Pan_Pixelated_2|
Figure 2 – Satellite image close-up (top left), compared to pixel shift variations
This particular orientation of the 3D model and the configuration with three panels open proved to be consistent when tested with satellite images, featuring different sun angles – 139.76⁰ and 203.76⁰. It was also established that the closest match between the renders, exported from the software and the satellite images is achieved when the model is positioned with a slight tilt (Fig 3 & 4).
Figure 3 – Lander Orientation Diagrams (Tilt) – Top and Cross-Section
Figure 4 – Lander Close-Up Renders – Sun Angle 136.68 Degrees, 3 Panels Open