2/2017

Asteroid reconstruction resembles mathematical detective work

Post-doc Matti Viikinkoski’s scientific track record of reconstructing asteroids has earned him a special recognition that few mathematicians have received: an eponymous asteroid.

Matti Viikinkoski

 

Matti Viikinkoski works as a postdoctoral researcher in the Inverse Problems Research Group at the Laboratory of Mathematics.

 

Anubis, Brahms, Casablanca, Monty Python, Pavarotti, Rembrandt, Rolling Stones, Tolkien. Thousands of asteroids bear the names of ancient gods, cities, rock stars, fictional characters and famous authors, composers, artists and athletes.

Asteroids are usually named after their discoverers, but occasionally the International Astronomical Union names asteroids in honour of distinguished scientists from other fields. One of the mathematicians to receive this rare honour is Matti Viikinkoski from Tampere University of Technology (TUT). He works as a postdoctoral researcher in the Inverse Problems Research Group at the Laboratory of Mathematics.

His namesake asteroid travelling through the galaxy is called ‘11815 Viikinkoski’.

Premier software for modelling asteroids

Matti Viikinkoski

 

Matti Viikinkoski has developed the world’s most versatile software for modelling asteroids.

 

Matti Viikinkoski has developed the world’s most versatile software for modelling asteroids. It builds on computations performed by the Inverse Problems Research Group and effectively reveals the shapes and spin states of asteroids.

“My software is openly accessible online. The models are based on all the available data sources, such as the brightness of asteroids, radar observations, and images taken by large telescopes,” says Viikinkoski.

A typical example of an inverse problem is the 3D reconstruction of an asteroid that is 100 kilometres in diameter and observed from a distance of more than 200 million kilometres.

“Asteroids are remnants of the early solar system. 3D models enable us to find out how dense they are and what they are made of. It will be possible to mine asteroids for metals in the future, but the first step is to remotely determine their shape and composition. Then a miniature satellite can be launched to take a closer look.”

Viikinkoski is engaged in extensive international efforts to observe and map the surface features of 50 large asteroids.

Sleuthing through inverse problems

Research on inverse problems falls under the umbrella of applied mathematics. Inverse problems arise when causal factors have to be reconstructed based on their effects. The recovery of unknown parameters largely depends on indirect measurements.

“Inverse problems are solved by finding a mathematical model that matches the set of observations. The problems are inherently challenging, because the observations may yield multiple equally good solutions or mathematical models. Additional parameters must be considered to identify the best fit,” says Mikko Kaasalainen, professor in the Laboratory of Mathematics at TUT.

Kaasalainen likens inverse modelling to detective work with emphasis on mathematical expertise. This is especially so when observations are limited, noisy or indirect, meaning that the unknown variables cannot be directly deduced.

“It’s a bit like Sherlock Holmes or CSI trying to identify a killer only by looking at a smear of paint,” Kaasalainen describes.

World-class expertise in inverse modelling and imaging

Inverse modelling can be applied to all types of measurements and imaging. Researchers at TUT are exploring the use of inverse modelling in areas ranging from mathematics and space research to biology and medical imaging.

TUT is part of the Academy of Finland’s Centre of Excellence of Inverse Modelling and Imaging, which has already received funding for its third consecutive term running from 2018 to 2025. The centre comprises researchers from TUT, five other Finnish universities and a geophysical observatory.

Text: Leena Koskenlaakso
Photo: Mika Kanerva

 
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