A little more than two hours ago, the Spektr-RG space telescope was launched on a Proton rocket from the Baikonur Cosmodrome, Kazakhstan. After about two hours it separated from the rocket’s upper stage to head towards the L2 Lagrangian point, about 1.5 million kilometers from Earth.

The Spektr-RG (Spektr-Roentgen Gamma, SRG) space telescope is a project born from a collaboration of the Russian Roscosmos and German DLR space agencies for the observation of the X-ray sky. This type of astronomy got a bit crippled by the very premature end of the Japanese Hitomi mission while ESA’s XMM-Newton and NASA’s Chandra space telescopes are still active but these are missions that started twenty years ago.

The Max Planck Institute for Extraterrestrial Physics (MPE) provided the main instrument, eROSITA (extended Roentgen Survey with an Imaging Telescope Array), which aims to observe the sky at the so-called soft X-rays, up to 10 keV of energy. It has a sensitivity close to that of XMM-Newton but has a much greater view field allowing it to conduct large-scale observations in a much shorter time, even compared to Chandra. In essence, it’s a refinement of existing technologies.

eROSITA will be able to make such extensive observations thanks to seven mirror modules, each made of 54 nickel mirrors covered with a thin layer of gold. This set can detect a considerable amount of photons in the X-ray frequencies that allow it to observe very weak and distant sources.

The other instrument is ART-XC (Astronomical Roentgen Telescope — X-ray Concentrator), built by the Space Research Institute (IKI) and consisting of seven modules, each made of 28 mirrors to detect X-rays that include those so-called hard ones at energies between 6 and 30 keV.

The destination of the Spektr-RG space telescope is the Lagrangian point called L2, where Sun and Earth are always on the same side with respect to Spektr-RG so it’s possible to conduct observations without interruptions.

There are several goals since X-rays can come from active galactic nuclei, supernovas and other cosmic objects. In particular, the hope is that the investigation of the soft X-rays emitted by the hot gas in galaxy clusters will help to better understand how these enormous structures evolve and consequently provide new clues to the mysterious dark energy.

Now the Spektr-RG space telescope is on its way to L2 point, where it will arrive in about three months. In the meantime, the testing and calibration of the instruments will begin so that upon its arrival in its final position it can begin its scientific mission.