"First Map": Russian astrophysicist - on a review of the entire sky, neutron stars and X-ray navigation

- Which of the Russian space exploration projects can be singled out especially?

- A year ago a historical event happened for us. On July 13, 2019, using the Proton launch vehicle and the DM booster, the Russian Spectrum RG observatory with the German eROSITA telescope and the Russian ART-XC telescope was launched into space. Thus began her long journey to her workplace - to a calculated orbit about 1.5 million km from Earth. She flew there for several months. A few more months were spent on calibration observations, we checked all the systems in different modes of both the satellite and telescopes. On December 8 of last year, the observatory began to solve its main task - to survey the entire sky. Such a review is done in about six months.

- So the first review is already completed?

- The first review was completed recently. By the evening of June 11, using both telescopes, the first map of the entire sky was obtained. It covered the entire celestial sphere, whose area is 41253 square degrees. The images clearly show the traces of star death (supernova remnants, the emission of “warm” interstellar gas with a temperature of hundreds of thousands of degrees Kelvin), as well as relatively close stars with crowns that are much more powerful than those of the Sun. 

A preliminary analysis conducted by Russian astrophysicists showed that the ART-XC telescope recorded several hundred objects all over the sky, while about half a million X-ray sources were recorded on the eROSITA telescope, covering half of the sky, which Russian astrophysicists are responsible for processing and analyzing. This difference is due to the fact that the Russian telescope operates in a more rigid energy range, where the number of photons is orders of magnitude smaller than in the eROSITA range. 

As the creator and supervisor of the ART-XC telescope Mikhail Pavlinsky said, “we have every photon worth its weight in gold.” Now we have begun the second review, and there are seven more stages ahead.

• Map of half the entire sky in the range 0.3–0.7 kiloelectron-volts, obtained by the SRG / eRosita telescope during the first sky survey
• © IKI RAS

- Why do you need to do the following seven reviews?

- The main idea is to build the deepest map of the Universe, to look as far as possible. To do this, you need to accumulate a large exposure, get more photons from a particular area of ​​the sky. Therefore, you need to do this eight times, then to add all the cards together. 

- What is the peculiarity of the Russian telescope?

- ART-XC is our pride. This is the first Russian mirror telescope. He surveyed the sky in hard rays in the range of 4-12 keV with such an angular resolution and with such a high sensitivity that instruments of this type were not made. We received the first light from the X-ray pulsar Centaurus X-3, investigated the Crab Nebula and the galactic black hole Cygnus X-1, conducted deep observations of the central region of the Galaxy and discovered new variable x-ray sources. And in eight reviews, in four years of operation, the ART-XC will receive the most detailed map of the universe in this range. Of course, it is also important that it is in a kind of symbiosis with the eROSITA telescope. There are objects that eROSITA does not see, but we see. ART-XC has already discovered several objects that are not visible in soft rays. For example, supermassive black holes that are in distant galaxies. eROSITA sees more objects, but we see unique ones.

- What other tasks does the observatory solve?

“In addition to maps of the entire sky, we carefully study the most interesting areas, for example, the center of our Galaxy, the closest galaxy to us is the Large Magellanic Cloud, in which we also see many sources.

Also at ART-XC we study neutron stars - X-ray pulsars. There are different theories of what they can consist of. These are the most dense objects of the Universe, where the density is higher than nuclear. On Earth, such parameters cannot be achieved. There are no such magnetic fields, temperatures, pressures and densities. Therefore, on the one hand, there is a global fundamental task of studying neutron stars and understanding the equation of state of the substance from which they are formed.

On the other hand, it turns out that they can be used for purely practical purposes. We are working out the principles, exploring the possibilities of a promising autonomous system for navigating spacecraft through neutron stars. Pulsars rotate quickly, send powerful signals, and this is such a natural GLONASS system. The observatory and telescope were not specially prepared for these tasks, but we have already managed to work out some elements of such X-ray navigation. Now we are actively working on creating a specialized experiment on this topic. In general, we hope that with Spectrum RG we will make many more discoveries.

- What can you tell about other space missions?

- At the end of next year, after a long break, our lunar mission starts. Let's try to repeat what our fathers and grandfathers did. This is a daunting task. A descent vehicle has been created — a landing module with scientific tools for soil analysis. Of course, we had to fly to the moon even earlier, but also in our countries and in other countries, because of the coronavirus pandemic, the launches a little “moved to the right”. The first lunar mission will be followed by others, including those involving the delivery of soil to Earth.

- This year, the launch of the European Martian mission ExoMars-2020 with the Russian landing module was also planned ...

- The first ExoMars flew in 2016, and the second is now actively working at our institute, and at the Lavochkina NGO, and foreign partners. A serious large landing module has been prepared, on which more than a dozen scientific instruments will stand. On it, a rover will descend to the Red Planet, on which several more devices will stand. The launch was planned for this year, but because of the coronavirus, it was decided to postpone. The next launch window will appear in two years. So now it will be ExoMars - 2022.

• ExoMars Rover Model
• © Wikimedia commons / Jastrow

- What other upcoming projects can be noted?

- In 2021, a small but very important experiment is expected. The Ionosonde space complex will be launched to solve a wide range of tasks, to monitor the geophysical situation - “space weather”. He will explore the solar and terrestrial connections, plasma, solar wind around the Earth.