Dissertation: Space probe camera reveals asteroid composition – aid for mining industry and asteroid impact mitigation
In his dissertation research, Leevi Lind explored how a spectral camera onboard the European Space Agency's (ESA) space probe can be used to analyze the surface composition of asteroids, also known as minor planets.
The Hera probe, currently traveling in space, is equipped with two spectral cameras, one of which is the Finnish-made ASPECT, designed and built by VTT. Lind's dissertation focused on processing the data produced by this camera.
"In addition to advancing scientific knowledge, studying asteroids can benefit humanity in other ways. Some asteroids may be promising targets for future mining activities. On the other hand, determining the composition of asteroids is also important because it can help in mitigating Earth-threatening asteroids," Lind explains.
Asteroid collisions with Earth are the only natural disasters that can be prevented by human intervention. Knowledge of asteroid composition helps in selecting the appropriate mitigation method in the future, in case a threatening asteroid is detected.
Hera will reach its target asteroid at the end of 2026 and begin sending data back to Earth in 2027.
"So far, I have developed computational methods mainly with simulated data. It will be exciting to see how the methods perform with real data," Lind says.
Spectral Camera Reads Surface Reflections – AI Used to Support Analysis
The study uses reflectance spectroscopy to determine the composition of asteroids. This technique is based on examining sunlight reflected from the surface of the object. The features of the reflected light spectrum reveal the properties of the reflecting material.
From Earth, asteroids appear as points of light due to their small size, with light from different areas mixed together. As such, the distribution of materials across the surface can only be determined by sending probes to study asteroids up close.
"The ASPECT imager considered in the study operates differently from previous devices used for imaging asteroids. Therefore, processing the data it produces requires development of new methods and adaptation of old ones," Lind explains.
Turning camera data into useful information requires various calculations. In his dissertation, Lind considered four different stages in the data processing chain: camera calibration, converting measurement data into reflectance maps, predicting the surface temperature of an asteroid, and estimating the amount of minerals.
In the last two topics, the computational method chosen for the analysis was artificial intelligence.
"Utilizing AI can enable faster data processing, and AI-based methods could offer efficient computing for the computers onboard space probes in the future. Processing data onboard the spacecraft could reduce the size of data sent back to Earth and help probes operate autonomously," Lind summarizes.
FM Leevi Lind's dissertation "Calibration, correction, and unmixing for wavelength-scanning spectral imaging of asteroids" will be examined on Friday, June 13, at the University of Jyväskylä.
The opponent will be Docent Jouni Peltoniemi (Department of Geodesy and Geodynamics, Finnish Geospatial Research Institute, National Land Survey of Finland) and the custos will be Assistant Professor Ilkka Pölönen (University of Jyväskylä). The defense can be followed in the Ambiotica building, Auditorium YAA303, or online. The language of the defense will be Finnish.
