The image above shows the launch of Spectrum-Roentgen-Gamma from the Baikonur Cosmodrome in the Republic of Kazakhstan on July 13, 2019. Spectrum-Roentgen-Gamma (also called Spektr-RG, or SRG for short) is a Russian-German space observatory (with contributions from NASA), which will explore the entire high-energy X-ray Universe. The primary instrument on SRG is the “extended ROentgen Survey with an Imaging Telescope Array” telescope, better known as eROSITA. eROSITA will perform an unprecedented, 4-year long survey of the entire X-ray sky, greatly improving upon the only prior imaging all-sky X-ray survey, obtained by the German-US-UK ROSAT observatory in the early 1990s. The eROSITA survey will be obtained over a 5-times wider X-ray energy band, extending from 0.2 keV up to 10 keV, and to a much higher sensitivity than achieved by the ROSAT All-Sky Survey. The Astronomical Roentgen Telescope – X-ray Concentrator (or ART-XC) on SRG will expand the energy range of SRG to even higher energies, up 30 kilo-electron volts. One of the primary goals of SRG is to detect tens of thousands of distant galaxy clusters to determine the large scale structure in the Universe and test our understanding of the mysterious dark energy which drives the Universe apart. SRG will observe the Universe from a parking orbit at the Sun-Earth L2 point, a region of gravitational stability about a million miles behind Earth along the Sun-Earth axis. SRG will execute its 4-year all-sky survey by orbiting around the Sun-Earth axis every 4 hours. After this survey, SRG will spend 3 years taking detailed observations of individual celestial objects including galaxy clusters, active galactic nuclei, stars, neutron stars and black holes.