SSHADE Databases

University of Helsinki Astrophysical Scattering and Spectroscopy Laboratory (UH-ApS), Planetary System Research group (PSR), Department of Physics, University of Helsinki, Helsinki, Finland

  • Scientific Manager: Karri Muinonen
  • Database Manager: Antti Penttilä
  • Data Providers: Tomas Kohout, Julia Martikainen

The UH laboratory will concentrate on solid and particulate materials with applications on planetary sciences. In particular, we are measuring in ambient atmospheric conditions and in room temperatures, so mineral materials are mostly measured. The materials are natural but can be synthetically processed to, e.g., mimic space-weathering effects. We are particularly interested in measuring meteorites and similar materials.

We are measuring:

  1. Directional-hemispheric reflectance spectra with integrating-sphere spectrometer, in the wavelength range from 250 nm to 3200 nm. Measurement area is from about 1 mm to 1 cm.
  2. Spectro-polarimetric BRDF in the wavelength range from 420 nm to 800 nm and possibility to record different states of linear polarization. Measurement area is from about 1 mm to 1 cm.
  3. single-particle polarimetric scattering for a few filters in visual wavelengths and different states of linear polarization measured from the complete 4 π solid angle from the particle, except for the lobes close to back- and forward scattering directions. The particle to-be-measured should have size between about 5 mm and 3 cm.
  4. spectral backscattering in wavelength range from 470 nm to 900 nm. The measurement area is about 1 cm.

We plan to produce reflectance spectra and photometric BRDF for all the samples we measure. In addition, for some samples we can also produce spectral BRDF, polarimetric BRDF, single-particle scattering matrix (i.e., Mueller matrix or the 2×2 upper left submatrix of the Mueller matrix), and spectral backscattering RDF.

In addition, we will consider providing the modeled absorption coefficient (i.e., imaginary part of the refractive index) for the well-defined solid and particulate samples we measure via light-scattering simulation modeling of the measurements.

The typical applications are in planetary sciences, especially in asteroid regolith studies, and in the general verification and development of light-scattering modeling techniques and algorithms.