Farinella Prize 2014 Awarded to Czech Physicist David Vokrouhlicky
September 11, 2014

The fourth “Paolo Farinella Prize” is being awarded in 2014 to Prof David Vokrouhlicky (Charles University, Prague), a Czech dynamicist who has made major contributions to our understanding of the dynamics and physics of solar system, including how pressure from solar radiation affects the orbits of both asteroids and artificial satellites. The Prize will be presented on Monday 8th of September, during the opening ceremony of the European Planetary Science Congress (EPSC) 2014, at the Centro de Congressos do Estoril, Cascais, Portugal. The ceremony includes a public lecture by Vokrouhlicky on the topic “non gravitational forces in the Solar System”.
The prize was established in 2010 to honour the memory of the Italian scientist Paolo Farinella (1953–2000) and each year, it acknowledges an outstanding researcher not older than 47 years (the age of Farinella when he passed away) who has achieved important results in one of Farinella’s fields of work.
In the 1990s, Vokrouhlicky and Farinella were the first to realise the full importance of the Yarkovsky effect, a small but significant force experienced by asteroids that is caused when their surfaces absorb sunlight and then re-emit that energy as heat. At that time when radiation forces were seen relevant only for dust particles, Vokrouhlicky and Farinella set a new paradigm by showing that these tiny forces could drive minor bodies into the internal region of the solar system. David Vokrouhlicky not only collaborated with Farinella as a scientist, but also co-authored with him and Bruno Bertotti, “Physics of the Solar System”, a textbook that stands as a comprehensive compendium of the advances in the field. The 2014 prize was adjudicated by an international board of scientists.

Before receiving the prize David Vokrouhlicky commented: “I had the privilege to collaborate with many splendid scientists over the past twenty years and I certainly would achieve only a small fraction of my results without their contribution. So, undoubtedly, I feel like sharing the prize with many of them. That said, Paolo Farinella should be in the first place among them, since I owe him enormously for bringing me from other areas of astronomy to planetary science and helping me to do the first steps in this field. So in one sense I am sad I cannot share the honour of receiving this prize with him. On the other hand, the fact that the prize holds his name is special to me. While certainly Paolo’s memory continues in his work, I am also very happy that “his” prize exists and helps to recall this extraordinary scientist and gentle man to a wider community of planetary researchers and astronomers today.”

The Paolo Farinella prize was established to honour the memory and the outstanding figure of Paolo Farinella (1953–2000), an extraordinary scientist and person, in recognition of significant contributions given in the fields of interest of Paolo, which span from planetary sciences to space geodesy, fundamental physics, science popularization, and security in space, weapons control and disarmament. The winner of the prize is selected each year on the basis of his/her overall research results in a chosen field, among candidates with international and interdisciplinary collaborations, not older than 47 years, the age of Paolo when he passed away on the 25 March, 2000. The prize has first been proposed during the “International Workshop on Paolo Farinella the scientist and the man”, held in Pisa in 2010, supported by the University of Pisa and by IAPS-INAF (Rome). The first “Paolo Farinella prize” was awarded in 2011 to William Bottke, for his contribution to the field of “physics and dynamics of small solar system bodies”. In 2012 the prize went to John Chambers, for his contribution to the field of “formation and early evolution of the solar system” and in 2013, to Patrick Michel, for his contribution to the field of ” collisional processes in the Solar System”.

David Vokrouhlicky, (Charles University, Prague, Czeck Republic) is a dynamicist who has not only made major contributions to crucial questions in the physics and dynamics of the Solar System, but has also brought forward new ideas that are now the basis for broader explorations in the field of small bodies.
David Vokrouhlicky was a close collaborator and friend of Paolo Farinella, David shared Paolo’s interest in the dynamics of both artificial and natural celestial bodies, exploiting this interdisciplinary approach to enrich both disciplines. In the 90’s their collaboration with the group at the Observatoire de la Cote d’Azur (CERGA) led to numerous fundamental papers dealing with how non-gravitational perturbations affect the geodetic satellite LAGEOS (solar radiation pressure and spin-orbit coupling). This spacecraft plays a key role in the realization of Earth’s reference frame.

These early works on artificial space-based objects were critical in setting the stage for their papers on how non-gravitational thermal forces modify the orbits and spin states of asteroids. Their work provided dynamicists a new way to understand the migration of small bodies across the main asteroid belt and onto pathways that could take them to Earth.

More specifically, David and Paolo were pioneers in developing a new unified version of the diurnal and seasonal variants of the so-called “Yarkovsky effect”, allowing them to glean new insights into the importance of thermal forces on the long term orbital evolution of small asteroids. In this era, radiation forces were most often seen as relevant only for dust particles. Their work provided the dynamics community with a new paradigm, namely that these tiny forces could drive small asteroids into planetary resonances that could deliver them onto planet-crossing orbits.

Their predictions have since been confirmed by direct observations of asteroids, and today the Yarkovsky effect is a perennial hot topic. The linear Yarkovsky effect model published by David in 1999 remains one of the primary references for the subject, and his formalism has been used by other noted papers to understand the origin of near-Earth asteroids. David and his collaborators also felpe to popularize so-called YORP thermal torques that strongly affect the spin vectors of asteroids. It has since been shown that YORP largely determined the spin state of small asteroids, with collisions playing a smaller role than previously suggested. Scores of papers on both the Yarkovsky and YORP effects are now published every year as the field finds new variants or applications of these forces.

The contributions of David Vokrouhlicky are well known in the solar system community, with David involved with several key review paper on the Yarkovsky and YORP effect. In 2003 and 2007 David co-authored two Science papers on the first direct detection of the Yarkovsky and YORP effects, respectively, in agreement with his theoretical predictions.

His work combines the best of analytical studies and highly sophisticated theoretical models, with applications that can readily be tested against observations. This combination of skills leads to mathematically clean and elegant papers that also contain valuable physical insights. The textbook “Physics of the Solar System