Advanced Telescope for High Energy Astrophysics
|Mission type||Space observatory|
|Operator||European Space Agency|
|Mission duration||5 years|
|Launch mass||5,525 kg (12,181 lb)|
|BOL mass||5,353 kg (11,801 lb)|
|Dry mass||5,038 kg (11,107 lb)|
|Power||5.556 kilowatts (5,556 W)|
|Start of mission|
|Reference system||L2 point|
The Advanced Telescope for High ENergy Astrophysics (ATHENA) is a future X-ray telescope of the European Space Agency, under development for launch around 2028. It is the second (L2) large class mission within ESA Cosmic Vision Program. ATHENA will be one hundred times more sensitive than the best of existing X-ray telescopes—Chandra X-ray Observatory, and XMM-Newton.
The primary goals of the mission are to map hot gas structures, determining their physical properties, and searching for supermassive black holes.
History and development
The mission has its roots in two mission concepts from the early 2000s, for the ESA XEUS and NASA Constellation-X missions. In around 2008, these two proposals were merged into the joint NASA/ESA/JAXA International X-ray Observatory (IXO) proposal. However, in 2011 NASA withdrew from IXO due to funding issues, mainly due to large cost overruns on JWST. ESA then decided to proceed with a less costly modification of IXO, which became known as ATHENA. ATHENA was shortlisted for the first (L1) L-class Cosmic Vision selection in 2012, but lost to the Jupiter Icy Moon Explorer; after some modifications ATHENA was selected in 2014 as the second (L2) mission 
The final decision about rebooting the International X-ray Observatory took place on the 27 of June 2014. The selected science topic is "Hot and Energetic Universe" with an objective of answering to questions from astrophysics: How does ordinary matter assemble into the large-scale structures we see today? And how do black holes grow and shape the universe?
The science team was appointed on 16 July 2014. Initial vibration testing of a silicon pore optics mirror module took place in August 2014. ESA's Science Programme Committee will meet in 2019 for a full review and final approval of the project before construction to begin in the same year.
An Ariane 6 launch vehicle will lift ATHENA in 2028 into a large amplitude Halo orbit around L2 point of the Sun-Earth system through a direct transfer burn. L2 was selected due to its stable thermal environment, good sky visibility and high observing efficiency. ATHENA is planned to perform scheduled observations of up to 300 celestial locations per year, with these observations lasting from half an hour up to over 11 days, though can be repointed to observe transient events.
Optics and instruments
ATHENA will utilize a telescope with 12m focal length, and two primary instruments: high resolution X-ray Integral Field Unit (X-IFU), and the Wide Field Imager (WFI) featuring a moderate resolution and a large field of view.
The telescope will use ESA-developed silicon pore optics providing combination of large field of view and high angular resolution. Each pore is a Wolter Type-I telescope only few mm2 in cross-section, with two reflections inside of each pore bringing X-ray in focus. In total, 1.5 million pores will be used. The telescope will be manufactured in 60 mm-wide arrays using commercially available silicon wafers.
- X-ray Integral Field Unit
- Wide Field Imager
The Wide Field Imager (WFI) is an X-ray spectrometer utilizing five arrays of p-channel field-effect transistors with a detection range of 0.1–15 keV. Its central chip has a resolution of 256 × 256 px and a field of view 7.5 arcminutes. Its four outer arrays have a resolution of 448 × 640 px and a field of view 40 arcminutes.:1,9
- Watson, Mike. "Athena Mission Update" (PDF). Retrieved 2015-12-22.
- "ESA's new vision to study the invisible universe". ESA. Retrieved 29 November 2013.
- Jonathan Amos (27 June 2014). "Athena: Europe plans huge X-ray space telescope". BBC News Online. BBC. Retrieved 22 October 2014.
- Jonathan Amos (2 May 2012). "ESA selects 1bn-euro Juice probe to Jupiter". BBC News Online. BBC. Retrieved 13 May 2012.
- "About ATHENA". ESA. 2 April 2012. Retrieved 19 October 2014.
- "ESA Science & Technology: Athena to study the hot and energetic Universe". ESA. 27 June 2014. Retrieved 23 August 2014.
- "ESA appointed Science Study Team". ATHENA website. 16 July 2014. Retrieved 19 October 2014.
- "Vibration testing of silicon pore optics module". ESA. 19 August 2014. Retrieved 19 October 2014.
- Jacob Aron (30 June 2014). "Biggest X-ray eye in space to hunt hot cosmic objects". New Scientist. Retrieved 22 October 2014.
- "ESA Science & Technology: ATHENA". ESA. 19 August 2014. Retrieved 19 October 2014.
- "The X-ray Integral Field Unit (X-IFU)". ATHENA website. Retrieved 19 October 2014.
- "The X-ray Integral Field Unit (X-IFU) for Athena" (PDF).
- "The Wide Field Imager (WFI)". ATHENA website. Retrieved 19 October 2014.
- A. Rau (19 October 2014). "The Wide Field Imager (WFI) for Athena+" (DOCX). Retrieved 19 October 2014.