A Russian and European X-ray satellite in search of dark energy and other strange things is safely in space following a successful launch of a Proton rocket on Saturday, Space.com reported.

The Spektrum-Röntgen-Gamma mission, also known as Spektr-RG, is a joint project between the Russian space agency, Roscomos, and the German space agency, DLR. Spektr-RG launched to space from the Baikonur Cosmodrome in Kazakhstan.

Saturday’s launch followed weeks of delays. An attempt to launch the Spektr-RG mission on June 21 was delayed by a battery drain on the Proton rocket’s Block DM upper stage. Roscosmos then postponed a second launch attempt Friday due to an potential issue with the booster.

Spektr-RG will next navigate to a stable orbit in space called a Lagrange point, (specifically, L2), where the gravitational forces of two large objects — in this case, the sun and the Earth — balance each other out. This location will allow Spektr-RG to perform its observations while using a minimal amount of fuel.

The spacecraft is expected to detect 100,000 galaxy clusters, 3 million supermassive black holes, tens of thousands of star-forming galaxies, the presence of plasma (superheated gas) and many more types of objects, the report said.

The observatory includes two X-ray mirror telescopes, called ART-XC and eROSITA. ART-XC (a Russian payload) will examine the higher energies of X-rays, up to 30 keV, while eROSITA (Extended Roentgen Survey with an Imaging Telescope Array) is optimized for an energy range of 0.5 to 10 keV.

“eROSITA will help researchers gain a better understanding of the structure and development of the universe, and also contribute towards investigations into the mystery of dark energy,” Walther Pelzer, executive board member for DLR Space Administration, said.

The DLR worked with the Max Planck Institute for Extraterrestrial Physics to develop eROSITA.

Dark energy is believed to be the force behind the expansion of the universe; scientists discovered in the 1990s that the universe is actually speeding up its expansion as it gets bigger, but why is still poorly understood. One of eROSITA’s goals is to find the cause of this acceleration, the report said.

Scientists believe dark energy makes up about 68% of the universe, while dark matter — which can only be detected through its effect on other objects — makes up 27%. The remaining 5% of the universe comprises everything we can see with our eyes or telescopic observatories.

eROSITA will examine galaxy clusters in hopes of better understanding dark energy’s nature. Because galaxy clusters are very hot, the X-rays they emit could allow eROSITA to track how they move and how fast they are travelling, the report said.

The German telescope will also examine other “hot” phenomena such as superheated gas from supernovas (star explosions), neutron stars (the star core left over after a supernova explosion) and active galactic nuclei (or galaxies hiding supermassive black holes at their hearts).

Meanwhile, “the Spektr-RG orbit observatory has successfully separated from the Blok DM-03 upper stage in the deployment orbit,” the state corporation said in a statement.