Mikko K.J. Kaasalainen (1965 – 12 April 2020) was a

Finnish Finnish may refer to: * Something or someone from, or related to Finland * Culture of Finland * Finnish people or Finns, the primary ethnic group in Finland * Finnish language, the national language of the Finnish people * Finnish cuisine See also ...

applied mathematician A mathematician is someone who uses an extensive knowledge of mathematics in their work, typically to solve mathematical problems. Mathematicians are concerned with numbers, data, quantity, structure, space, models, and change. History One ...

and

mathematical physicist Mathematical physics refers to the development of mathematical methods for application to problems in physics. The ''Journal of Mathematical Physics'' defines the field as "the application of mathematics to problems in physics and the developmen ...

. He was professor of mathematics at the department of mathematics at

Tampere University of Technology Tampere University of Technology (TUT) ( fi, Tampereen teknillinen yliopisto (TTY)) was Finland's second-largest university in engineering sciences. The university was located in Hervanta, a suburb of Tampere. It was merged with the University o ...

. Kaasalainen mostly worked on

inverse problem An inverse problem in science is the process of calculating from a set of observations the causal factors that produced them: for example, calculating an image in X-ray computed tomography, source reconstruction in acoustics, or calculating the ...

s and their applications especially in astrophysics, as well as on

dynamical system In mathematics, a dynamical system is a system in which a Function (mathematics), function describes the time dependence of a Point (geometry), point in an ambient space. Examples include the mathematical models that describe the swinging of a ...

Education and career

Kaasalainen received an MSc in theoretical physics at the

University of Helsinki The University of Helsinki ( fi, Helsingin yliopisto, sv, Helsingfors universitet, abbreviated UH) is a public research university located in Helsinki, Finland since 1829, but founded in the city of Turku (in Swedish ''Åbo'') in 1640 as the ...

in 1990, moving shortly afterwards to

Merton College, Oxford Merton College (in full: The House or College of Scholars of Merton in the University of Oxford) is one of the Colleges of Oxford University, constituent colleges of the University of Oxford in England. Its foundation can be traced back to the ...

where he completed his DPhil in theoretical physics in 1994, supervised by

James Binney James Jeffrey Binney, FRS, FInstP (born 12 April 1950) is a British astrophysicist. He is a professor of physics at the University of Oxford and former head of the Sub-Department of Theoretical Physics as well as an Emeritus Fellow of Merto ...

. After a series of post-doctoral and senior positions in Europe, he moved to the University of Helsinki and to his present institute in 2009. He led a research group in the Finnish Centre of Excellence in Inverse Problems Research. Kaasalainen was awarded the first Pertti Lindfors prize of the Finnish Inverse Problems Society in 2001. The asteroid 16007 Kaasalainen, discovered by ODAS in 1999, was named in his honour. The official was published by the

Minor Planet Center The Minor Planet Center (MPC) is the official body for observing and reporting on minor planets under the auspices of the International Astronomical Union (IAU). Founded in 1947, it operates at the Smithsonian Astrophysical Observatory. Function ...

on 7 January 2004 ().

Research

Kaasalainen's research interests mostly focused on mathematical modelling in various fields ranging from

remote sensing Remote sensing is the acquisition of information about an object or phenomenon without making physical contact with the object, in contrast to in situ or on-site observation. The term is applied especially to acquiring information about Earth ...

and space research to planetary and galactic dynamics. Typically, the models and mathematical methods Kaasalainen developed with his colleagues are connected with inverse problems. Two such topics featured prominently in Kaasalainen's research: * Asteroid

lightcurve inversion In astronomy, a light curve is a graph of light intensity of a celestial object or region as a function of time, typically with the magnitude of light received on the y axis and with time on the x axis. The light is usually in a particular frequ ...

, i.e., the reconstruction of the shapes and spin states of

asteroid An asteroid is a minor planet of the inner Solar System. Sizes and shapes of asteroids vary significantly, ranging from 1-meter rocks to a dwarf planet almost 1000 km in diameter; they are rocky, metallic or icy bodies with no atmosphere. ...

s from their brightness measurements ( lightcurves), based on mathematical results and uniqueness and stability theorems that have been transformed into modelling algorithms with which a multitude of otherwise unresolvable asteroids can now be mapped. This method has also been used in the direct verification of the

Yarkovsky–O'Keefe–Radzievskii–Paddack effect The Yarkovsky–O'Keefe–Radzievskii–Paddack effect, or YORP effect for short, changes the rotation state of a small astronomical body – that is, the body's spin rate and the obliquity of its pole(s) – due to the scattering of solar rad ...

in our solar system. * Analysis of large dynamical systems, where torus construction methodsM. Kaasalainen (1995): Construction of invariant tori in chaotic regions. Physical Review E 52, 1193. in phase space allow a compact representation or approximation of the dynamics of the observed system (such as a

galaxy A galaxy is a system of stars, stellar remnants, interstellar gas, dust, dark matter, bound together by gravity. The word is derived from the Greek ' (), literally 'milky', a reference to the Milky Way galaxy that contains the Solar System. ...

References

External links

Mikko Kaasalainen's homepage at the University of Helsinki

Asteroid model website at the Charles University in Prague

Finnish Centre of Excellence in Inverse Problems Research
{{DEFAULTSORT:Kaasalainen, Mikko K. J. 1965 births 2020 deaths Alumni of Merton College, Oxford 20th-century Finnish mathematicians 21st-century Finnish mathematicians