An international team of astronomers and astrochemists has reviewed years of data to assess whether cosmic dust is porous. The grains, which help form stars and planets, are found in regions such as the Pillars of Creation, and the work appears in Astronomy and Astrophysics Review. The study involved Professor Martin McCoustra of Heriot-Watt University in Edinburgh among its contributors.

Researchers describe the dust grains as far from solid rocks. They are more like fluffy sponges with many voids, the researchers say. Cosmic dust can influence how light moves through space and forms the raw materials for life.

The European Space Agency’s Rosetta mission to comet 67P/Churyumov–Gerasimenko found extremely fragile, fluffy dust particles with porosities above 99%. McCoustra warned that spongy grains could be more easily damaged by shocks and radiation as they travel through interstellar space. Lead author Dr Alexey Potapov of Friedrich Schiller University Jena said that porosity would give grains a much larger surface area, potentially changing how molecules form and evolve in space. Some astronomers remain divided, with models suggesting very porous dust might be too cold or fragile to match what telescopes observe in interstellar clouds. The authors emphasise that further observations, laboratory work and modelling are needed to resolve the debate.