The mission is planned to study the dark matter halo of 75 different galaxies – a hypothetical component of galaxies that surrounds the galactic disk and extends far beyond the visible part of the galaxy. The mass of the halo is the main component of the total mass of the galaxy, reports the European Space Agency.
Dark matter makes up about 80 percent of the mass of the Universe, but astronomers don’t know exactly what the substance is made of or exactly how it behaves. Developers of a future European Space Agency mission hope to change that.
The mission is known as the Analysis of Resolved Remnants of Accreted Galaxies as a Key Tool for Halo Studies, or ARRAKIHS, and is designed to observe galaxies like our Milky Way in hopes of understanding what drives dark matter. The Spanish-Swiss mission has already received ESA approval – if all goes well, it will launch in 2030.
One of the reasons scientists believe in the existence of dark matter is that they have seen shadows of it.
We can’t see these halos directly because dark matter doesn’t interact with light and is therefore invisible to us, but we can see the effect the matter has on the galaxy. More specifically, dark matter halos are thought to directly influence the rotation of galaxies.