Detecting Magnetic Anomalies Of Crater Fields By a Drone

Abstract:

Airless planetary surfaces are covered by multiple impact craters. Such impact cratering processes allow understanding not only deformation that takes place but also the nature of the impactor if the composition of the crater field can be accessed. In this work we focus on impact craters that were created by an iron impactor. One example of such crater is the Arizona crater. Once the iron hits the planetary surface there is evaporation and melting while the initial crater shape is formed. Apart from the ejection and evaporation of both target and impactor material, portion of the impactor material mixes with the target rock and is left in the crater fill. The distribution of the impactor material would relate to the direction and angle of the impact process [1]. In case of iron, we hypothesize that the crater fill would contain inhomogeneous iron distribution, more iron would be contained in the direction of the impact. We also hypothesize that in case of the vertical impact the maximum iron concentration of the impactor material would be in the crater center. However, in the case of e.g. 45 degree angle, the maximum concentration would be off centered approximately half way between the crater center and the crater rim. If the impact angle would be steeper (e.g. 60 degrees) the maximum iron concentration would be closer than half way from the center toward the rim in the impactor direction.

We performed a field testing over the former military testing ground that experienced intense mixing with the iron material. Testing area was measured autonomously, magnetometer data were collected simultaneously with photogrammetric data. Final magnetometer map of the impact structures can be correlated with actual 3D model of the surface which was captured at the moment of acquiring magnetometer data. Our data shows how mixing of iron from the impacts increases away from the roads and forest that was avoided during the testing. While the altitude of the survey was 75 m, we detected the magnetic enhancement constituting about 10 nT from the iron mixing of the soil from the impacts. Magnetometer data were collected with two parallel magnetometers where one served as a ground station and one was part of the autonomous drone.

GACR 17-05935S, and RVO 67985831.

References:[1] Pierazzo, E., and H. J. Melosh (2000). Meteorit. Planet. Sci.,35(1), 117-130.