SRON: planetary research with spectropolarimetry

The interest for planetary research has grown internationally over the last few years. Also SRON Netherlands Institute for Space Research has developed a visible branch of planetary research within the existing Earth oriented research. Therefore the name of the division Earth Oriented Science (EOS) has been adjusted to Earth and Planetary Science (EPS). The planetary research group will focus on determining the composition of (exo)planetary atmospheres and surfaces using spectropolarimetry.

Spectropolarimetry is the measurement of both the total flux and degree of polarisation of the reflected light. This approach has already been successfully used by EPS for the characterisation of aerosol, clouds and (tropospheric) ozone with the GOME(-2) and the SCIAMACHY instrument, for example. These measurements are important for research into the radiative balance, chemistry, climate and air quality of our Earth’s atmosphere.

With the exception of air quality (although you could substitute this with the dust storms on Mars) the same research themes are found in the study of other planets. With this, EPS research makes an important contribution to our improved understanding of the physical, chemical and climatological processes in planetary atmospheres, and the differences between planets. Furthermore, the structure and composition of surfaces provide information about the development of dust storms (Mars), surface ruptures and internal processes of, for example, the moons Europa and Ganymedes of Jupiter.

The Jupiter orbiter with the SPEX instrument (artist impression)
The Jupiter orbiter with the SPEX instrument (artist impression)

For this research a prototype of the SPEX instrument is being developed in cooperation with the Astronomical Institute of Utrecht University (UU/SIU), TNO, S&I and other partners. SPEX (Spectropolarimeter for Planetary Exploration) shall play a key role in various initiatives for missions to other planets and moons within our solar system.

Starlight reflected by a planet is polarised. Consequently, spectropolarimetry can also make an important contribution to the quest for planets outside of our solar system (exoplanets), but in particular to determining the composition of the atmosphere and surface of such planets. Knowledge of the atmosphere and surface will provide information about local conditions for the evolution and presence of life. SRON and UU/SIU will lead efforts to investigate spectropolarimetry within the context of the American mission concept NWO (New Worlds Observer).

The planetary group at SRON-EPS is scientifically headed by dr. Daphne Stam. The group works closely together with the earth atmosphere Group of EPS under the scientific leadership of prof. dr. Ilse Aben. EPS is headed by dr. Avri Selig