Research

Topics of research  –  This page is under construction

 

Interstellar dust trajectory simulations and the role of the heliosphere

Interstellar dust is at the base of the formation of stars and planetary systems and plays an important role in the chemistry of the interstellar medium. To study it, we can use astronomical observations of the extinction or polarisation of starlight, or emission in the InfraRed, but we can also probe the interstellar dust particles in our close neighbourhood: the Local Interstellar Cloud (LIC), a denser cloud of gas and dust than its local surroundings. Because of the relative motion between the Sun and the LIC (ca. 26 km/s), we can investigate the interstellar dust particles in-situ inside the solar system using spacecraft dust detectors like on the Ulysses, Galileo, Helios and Cassini spacecraft, or we can catch them at low relative velocities, and bring them back to Earth for a detailed study in the laboratory (cf. the Stardust mission).

The trajectories of these particles passing through the solar system are governed by solar gravity, solar radiation pressure force and Lorentz force due to the motion of the (charged) dust particles through the Interplanetary Magnetic Field (IMF). Computer simulations of ISD trajectories shed light on the variable ISD particle fluxes and directions, along with the Interplanetary Magnetic Field that changes with solar cycle. With computer simulations, we gained insight in the flow patterns of interstellar dust in the solar system, made predictions for the Cassini, SARIM, JUICE, and Stardust missions, and calculated the filtering or enhancements in ISD flux at different places in the solar system like the asteroid belt, Jupiter and Saturn. The inner heliosphere’s magnetic field was taken into account, the outer heliosphere is the next step to come. My first few papers describe the motion and filtering of ISD in the solar system (see publication page).

 

Porous interstellar dust

Simulations for the 16 years of Ulysses dust measurements were made that include the shift in dust flow direction that was seen and reported on in the data in 2005. From the simulations and the spacecraft data, we concluded that Interstellar Dust has a lower density, or is “fluffier” than anticipated, and that different populations enter the heliosphere at different periods in the solar cycle. See also this paper on the Ulysses measurements and simulations.

 

Interstellar dust: multi-disciplinary approach

Interstellar Dust can be investigated using four different basic methods: astronomy, in-situ measurements, sample return and simulations+data+lab experiments. These methods are complementary and are each a piece of the puzzle to understand interstellar dust in the neighboring cloud. It is important for the different communities to put the hands together.

Current Mission involvement

 

Past topics:

  • Joint Europa Mission (JEM) proposal for the ESA M5 call for medium-class missions. The goal of this mission is to explore the habitability of the Jovian moon Europa in a joint ESA-NASA effort.
  • S2D2 Proposal for ESA science themes for L-class missions: a mission concept consisting of two spacecraft to map the solar system in dust: one in-situ spacecraft for the dust flux and chemical composition in order to link the solar system dust and their parent bodies, and one InfraRed telescope out-of-the ecliptic plane for a birds-eye view on the solar system debris disk. PI: Ralf Srama, Univ. Stuttgart. (2013)
  • Support for the development of the ESA IMEX model (2013)
  • Characterization and mitigation of optical path disturbances of the Darwin mission (2007-2008)
  • History of science: the life and work of Sir Hermann Bondi (2006)
  • Orbit calculations in L2 for the GAIA mission using FEEPS (2002)