Athena (space observatory)

According to the original plan, the project was to be implemented by 2021 by the joint efforts of NASA, the European Space Agency (ESA) and the Japan Aerospace Exploration Agency (JAXA). In May 2008, ESA and NASA established a coordination group with the participation of all three agencies to study the conduct of a joint mission by merging the XEUS and Constellation-X projects. This was the beginning of the proposed joint study by the International X-ray Observatory (IXO). The IXO project competed with two other missions: the Europa Jupiter System Mission (EJSM) and the Laser Interferometer Space Antenna (LISA) ^{[5] [6] [7] [8] [9] [10] [11] [12]} .

The previous Athena telescope was a candidate for the L1 class mission of the Cosmic Vision program, but was canceled with the Jupiter Icy Moon Explorer program. Athena itself is the restart of the IXO project, planned for 2008–2011, the final decision on which was made on June 27, 2014. ^[13] Now it is Athena who is chosen as the second major mission of the Cosmic Vision program. ^[13] . Partly due to NASA's withdrawal from participation in the IXO project in 2011, changes in the preparation for the mission arose ^[14] .

The scientific group was formed by July 16, 2014. ^[15] Primary vibration tests of silicon for optics mirrors took place in August 2014 ^[16] . The meeting of the scientific committee of the European Space Agency's program will be held in 2019 for a full review and final approval of the project before construction starts in the same year ^{[4] [17]} .

The IXO telescope is designed to work for at least 5 years with a predictable performance for 10 years. It is expected that scientific work with IXO will go from 2021 to 2030 ^[7] .

The main task is to study the issues of “hot and expanding Universe” ^[18] : mapping the movement of hot gas structures, determining their physical properties and searching for supermassive black holes .

The chosen science theme “Hot and Energy Universe” aims to answer astrophysical questions: “What happens near the black hole?” “How does ordinary matter gather into large-scale structures that we see today?” What is the relationship between these processes? ”

To solve these problems, IXO will observe orbits close to the horizon of a black hole event, measure the rotational speeds of black holes of several hundred active galactic nuclei , use spectroscopy to determine the characteristics of the environment around the galactic nuclei at their peak activity; search for supermassive black holes with redshift z> 10; search for dark matter in the large-scale structure of the Universe using quasars against matter and observing galactic-scale processes by injecting energy with black holes ^{[19] [20] [21] [22]} .

The launch of the Ariane-5 launch vehicle should lift Athena in 2028 to a halo orbit with a large amplitude around L ₂ Lagrange points by means of directional acceleration. L ₂ was chosen because of its stable thermal environment, good celestial visibility and high efficiency of observations. Athena is planned for annual continuous observations of up to 300 celestial targets, from half an hour to 1 hour each, for no more than 11 days ^[23] .

Athena should use an X-ray telescope with a focal length of 12 m with an effective area of ​​~ 2 m² with a sensitivity of 1 keV ^[1] and two main instruments: an integral X-ray Integral Field Unit, X-IFU with high resolution and medium resolution, but with a large viewing angle wide-field spectrometer (Wide Field Imager, WFI) ^[23] .

The telescope will use optics with silicon cells developed by the European Space Agency, which provides a combination of a large viewing angle and high angular resolution. Each cell is a Voltaire telescope , but only a few mm² in diameter, with two reflectors in each cell focusing X-rays. A total of 1.5 million cells must be used. The telescope will be created in the form of an array of 60-mm silicon plates commercially available for the manufacture of silicon. ^[23]

X-ray Integral Field Unit

This tool uses an array of cryogen-cooled sensors with a detection range of 0.2–12 keV. The total viewing angle is 5 angular minutes ^[24] .

Wide field imager

This tool is an X-ray spectrometer consisting of 5 arrays of field-effect transistors with p- type transitions and a detected radiation range of 0.1-15 keV. Its central chip has a size of 256 x 256 px and a viewing angle of 7.5 angular minutes. Its four external arrays have dimensions of 448 x 640 px and a viewing angle of 40 angular minutes. ^{[25] [26]}

The estimated cost of the project will be 1 billion dollars or 850 million euros. ^[27] .

• Description of the project on the ESA website