TestF3G - Results
The results show no significant difference in the final S/C position (SCOBJ) and model accuracy (as measured with CompareOBJ RMS) with respect to the magnitude of S/C position and pointing perturbation within the ranges tested, showing the modeling immune to S/C position and pointing perturbation up to three standard deviations.
It should be noted that S/C position perturbation was divided equally between the SCOBJ components, resulting in a distance from the truth position which was a multiple of the standard deviation of 6.4m. Therefore:
- maximum lateral perturbation was a multiple of 3.7m (6.4m/sqrt(3));
- normal perturbation (wrt body center) was 3.7m (6.4m/sqrt(3)).
It is assumed that the worst case scenario is a lateral perturbation. The maximum possible lateral perturbation tested was 3 x 3.7m = 11.1m.
In all cases, the final SPC-derived S/C position is within an approx. 8m-radius sphere around the true S/C position, but in only two cases is within 2m of the true S/C position. The actual distance from the true S/C position is not dependent on the initial perturbed position - for example in the 0.25 x sigma case, the SPC-derived S/C position (distance from truth: 1.6m to 6.9m) in most cases moves further away from the true S/C position than its initial position (distance from truth: 1.6m).
CompareOBJ RMS
CompareOBJ does not appear to be affected by the magnitude of S/C position and pointing perturbation within the ranges tested.
Image Footprints
The first graph shows footprints for all Detailed Survey PolyCam pictures which were included in the model. The second graph shows the four pictures down-selected due to their coverage of the 20m x 20m evaluation region, and their almost complete containment within the iterated 100m x 100m region.
Distance SCOBJ(truth) to SCOBJ(solution)
SCOBJ is the S/C position from the center of the asteroid.
The distance of the final SPC-derived S/C position from the true S/C position is plotted for the full Detailed Survey PolyCam image set. The evaluation images are plotted in red.
3D graphs of final SPC-derived SCOBJ and true SCOBJ are then plotted for each picture. The first four are the down-selected evaluation pictures, the rest of the set is included for comparison.
The pattern of final SCOBJ for magnitude of perturbation is broadly consistent, indicating that the position correction is mostly a Z-component correction with lateral movement, bringing the modeled S/C position within an approx. 8m-radius sphere around the true position.
Evaluation Pictures
Example nominal SCOBJs:
Final solution SCOBJs:
Remaining Detailed Survey PolyCam Pictures
