Japanese-German Mission to Phaethon Asteroid

Destiny+ probe in earth's orbit (artist's rendering, JAXA)

Geochemists from Heidelberg University are major players in the Destiny+ mission to research the Phaethon asteroid – a joint project of the Japanese Aerospace Exploration Agency and the German Aerospace Center. Researchers working with Dr Frank Postberg and Prof. Dr Mario Trieloff at the Institute of Earth Sciences are helping with mission planning and evaluation as well as developing the main measuring instrument, a dust detector. The mission aims to investigate the source and composition of interplanetary and interstellar dust particles over the next twelve years. Among other things, the researchers hope to gain new insights into the conditions under which our solar system was formed.

The Destiny+ mission is headed to the Phaethon asteroid (artist's rendering, NASA/JPL-Caltech). The asteroid's orbit traverses the trajectory of the Earth and takes it so close to the sun that its surface temperatures reach up to 600°C. Smaller and larger fragments that regularly break free from its fragile structure are distributed along its orbit and are the source of the Geminid meteor shower in December each year.

The orbit of the asteroid 3200 Phaethon comes very close to earth and the sun, depositing dust along the way. “The detector on board the Destiny+ probe can directly measure the composition of the tiniest particles from the Phaethon dust cloud,” explains Prof. Trieloff. “By analysing these particles, we hope to glean information about the properties and composition of the small asteroid- and comet-sized bodies that were the building materials of our Earth 4.5 billion years ago.” The dust detector will also measure interplanetary and interstellar dust populations. “The detector lets us study small particles from the far reaches of our galaxy as well as the dust streams of numerous bodies in our solar system," adds Dr Postberg. “The grains of dust are messengers from their parent bodies, and measuring their composition is like analysing soil samples of asteroids or comets.”

Measurements of extraterrestrial materials are of special significance because they provide detailed insight into the Earth's formation process and support a precise determination of its age compared with our solar system. “Because the exact source of meteorites is often unclear in studies such as this, the direct measurements taken during the Destiny+ mission are invaluable for research,” according to Dr Postberg.

Mario Trieloff and Frank Postberg are researchers at the Klaus Tschira Laboratory for Cosmochemistry, which is part of the Institute of Earth Sciences at Heidelberg University. It is funded by the Klaus Tschira Foundation.

The Destiny+ Dust Analyser will be deployed for the initial measurement phase between 2024 and 2028. It is being constructed by the Institute of Space Systems of the University of Stuttgart. In addition to scientists from Ruperto Carola, researchers from the Max Planck Institute for Astronomy in Heidelberg will also participate in the mission.