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Karat platform


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At the end of December 2010, Space Council of the Russian Academy of Sciences, RAN, approved development of the MKA-FKI PN5 (Payload No. 5) ARKA orbital solar observatory in cooperation with the US, where the project was identified as Coronal Science Investigation, CSI. Preliminary scheduled for launch in 2015, the spacecraft would observe the Sun in X-ray range of spectrum during a three-year orbital mission.

Based on the standard platform, known as Small Spacecraft, MKA, developed by NPO Lavochkin, the satellite would carry a pair of solar telescopes with super-high angular resolution reaching around 100 kilometers. One instrument would be developed in Russia by Lebedev Physics Institute, FIAN, IFM in Novgorod and IKI in Moscow. Another instrument could be supplied by the US. In the United States, the Smithsonian Astrophysical Observatory and Marshall Space Flight Center were expected to take responsibility for the project. Two sides also considered an exchange of technologies between two instruments, for example, FIAN was proposing to develop optics or detectors for both telescopes, while US would supply stabilization system for two instruments.

New instruments onboard ARKA promised to increase the resolution of solar observations by 11.5 times comparing to the sensitivity of a telescope onboard Koronas-Foton spacecraft. They would also offer a four-fold and 6.5-fold improvement comparing to the latest US solar observatories – SDO and TRACE, respectively. Due to its very high magnification, telescopes on ARKA would see only a fraction of the solar disc, rather than a global view of the Sun provided by Koronas-Foton and SDO.

In addition to a pair of main telescopes, the available payload mass onboard ARKA offers an opportunity to install a third small instrument, most likely for hard X-ray observations of the Sun disc. It could be developed in a cooperative effort between FIAN and IKI. (447)

As of December 2010, the development schedule for the ARKA project envisioned following milestones:

  • 2011: Preliminary design development;
  • 2012: A mockup development;
  • 2013, end of year: Delivery of the technical prototype of the spacecraft;
  • 2014, end of year: Delivery of the flight version of the spacecraft;
  • 2015: Pre-flight testing and launch.

As of 2008, the mission was expected in 2014. (299) According to official mission objectives formulated by 2012, the ARKA mission would reach following goals:

  • Studies of thin coronal structure and transitional layer of the Sun with a resolution no lower than 100 kilometers by generating high-precision images of the Sun in narrow shortwave range of spectrum invisible from the surface of the Earth;
  • Detection and research of small-scale processes (micro and nano-bursts) in the transitional region between the corona and the surface of the Sun with spatial accuracy no lower than 100 kilometers and timing precision no less than 60 seconds;
  • Studies of a thin structure and dynamics of magnetic fields and plasma in the transitional region of the Sun, including oscillating processes with periods from one minute and higher, as well as transient events with velocities from one kilometer per second.

The ARKA mission would be based on the Karat-200 spacecraft bus carrying an ARKA payload and including a launch vehicle adapter.

On March 14, 2014, the Space Council of the Academy of Sciences, officially rejected the use of the Karat platform for all but the Relek experiment, which was to be Karat's second mission. The Space Council proposed to fold ARKA, as well as the Konus-M experiment from the third Karat mission and the Monika spectrometer (provisionally scheduled to fly on the sixth Karat mission) into the Koronas-K solar-research project. However all these experiments would have to be accommodated as secondary payloads onboard future Russian application satellites.


Next chapter: Navigator platform

Page author: Anatoly Zak; Last update: March 10, 2017

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An early depiction of the ARKA spacecraft. Credit: Roskosmos


A depiction of the ARKA spacecraft circa 2017. Credit: Roskosmos


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