Project Ispolin

[B. Hendrickx]

Starting a program thread on Ispolin, a project of ISS Reshetnev to develop a series of military communications satellites with massive antennas. I first wrote about this project in the thread on ISS Reshetnev satellites in 2019:
https://forum.nasaspaceflight.com/index.php?topic=32423.60
(see Reply 70)

As noted there, ISS Reshetnev was awarded a contract for the project by the Ministry of Defense on May 26, 2017. All that could be learned about its payload at the time was that it would be one of the big reflector antennas being developed by ISS Reshetnev. It has since become possible to determine that this is almost certainly a massive antenna with a diameter of 48 meters that the company has been working on for many years. The very name of the project (“ispolin” means “giant”) was already indicative of that.

LINKING THE 48 M ANTENNA TO ISPOLIN

The 48 m antenna has been described in numerous ISS Reshetnev publications, but these have never linked it to a specific project, so connecting it to Ispolin takes a bit of sleuthing. One piece of evidence comes from a PhD dissertation defended at Tomsk State University in 2019. This deals with the design of both a 12 m and a 48 m reflector. In a review of the dissertation, its supervisor gives the contract numbers of two ISS Reshetnev projects that it is related to. These numbers (1719187308551452246001974 and 47702388027160001250) can be linked through other sources to Ispolin and a project known as Reflektor-2025. Among the goals of Reflektor-2025 was the development of a 12 m reflector for a mobile satellite communications system known as SSKMS (Satellite System for Confidential Mobile Communications). This means that Ispolin most likely is the project involving the 48 m reflector. The PhD dissertation and the review can be downloaded here:
http://ams.tsu.ru/TSU/QualificationDep/co-searchers.nsf/disserpubold2a/BelovSV27122019.html

Another clue comes from an article co-authored by ISS Reshetnev’s former director Nikolai Testoyedov in 2021. Writing about the big antenna, he noted that the research phase (abbreviated in Russian as NIR) had been completed and that actual development (OKR) was to began later that same year, with the first launch expected in six years (2027). Here it is said to have "semi-axes of 41x35 m".
https://sciencejournals.ru/cgi/getPDF.pl?jid=vestnik&year=2021&vol=91&iss=11&file=Vestnik2111013Testoedov.pdf
(p. 1080-1081)

As can be learned from a handful of court documents and other sources, the contract signed for Ispolin in 2017 was indeed for the “NIR” phase of the project, which was supposed to last from 2017 to 2019. Evidence that it moved to the development phase in 2021 comes from an annual report of Novosibirsk State University, which mentions its involvement in the OKR (development) phase of Ispolin under a contract signed in 2021.   
https://education.nsu.ru/priority2030/report-nsu-2021-2.pdf
(p. 92)

The contract number given here (2127187308201452246002193) also shows up in recent court documentation, which relates it to a contract awarded by the Ministry of Defense to ISS Reshetnev on April 30, 2021 for work to be conducted in the period 2021-2027. The name Ispolin is not included (obviously for reasons of secrecy). The documentation does mention the ground segment for “a constellation of satellites”, adding that it will use already existing hardware, including a “unified mission control center” (TsUP-E) that is being modernized for the project.
https://kad.arbitr.ru/Card/e7eea816-6d7c-42c1-a218-4ef43dcb29cd

DEVELOPMENT, DESIGN AND PURPOSE OF THE ANTENNA

The development of the 48 m antenna itself began well before it became part of Ispolin in 2017. Preliminary research started in 2012 as part of a project known as Pribor-Reflektor, assigned to ISS Reshetnev by Roscosmos. This called for building an experimental model of the antenna by the end of 2015, a goal which seems to have been achieved. It is seen in a 2015 television report about a large dome-shaped building (“Hangar 032”) that ISS Reshetnev uses for testing large structures such as antennas and solar panels (see 1:15 to 1:30).



The design of the big antenna is similar to that of the AstroMesh antenna developed by Northrup Grumman late last century. It consists of a front mesh and rear mesh connected by a ring truss and tension ties. The biggest antennas of this type built so far are 12 m diameter reflectors, first flown on the MBSAT and Thuraya satellites early this century.  The 12 m antenna for the SSKMS project also uses the AstroMesh design. The 48 m antenna for Ispolin would become the biggest of its type to fly in space.

Several drawings of the antenna and its deployment sequence have been published. Some show the antenna attached to a satellite platform with a huge feed array. This should give at least some idea of what Ispolin will ultimately look like. Very little is known about the platform, not even if it is a standard Reshetnev satellite platform (Express-2000/Express-4000) or one unique to this satellite. All that has leaked out on the bus is that it will carry KM-75 Hall effect ion thrusters of the Keldysh Research Center. These will probably first fly on ISS Reshetnev’s Repei signals intelligence satellites. Several orbit correction units carrying the engines were said to have completed ground test firings in August last year. 

Nothing has been revealed about the exact purpose of the big antenna, but its size as well as the reported operating frequencies strongly indicate it will be used for mobile communications. According to the technical specifications for Pribor-Reflektor published in 2012, the big antenna was to be designed to operate in the P and L bands (in the frequency range of 200 MHz to 2.0 GHz). One source links the Ispolin antenna only to the P band.  P band generally refers to the frequency range from 225 to 390 MHz and L band encompasses a broader frequency range, spanning from 1 GHz to 2 GHz. Together they constitute the UHF band. These bands are typically used by the military for narrowband mobile tactical communications. They are less vulnerable than other types of satellite communications to weather conditions or other physical limitations, such as dense foliage and challenging terrain. The UHF satellites currently operated by the US Defense Department belong to the Mobile User Objective System (MUOS), which succeeds the earlier UHF Follow-On (UFO) series.  They provide cellular phone-like services to ground forces, allowing them to communicate directly with each other and their commanders even when operating in hostile environments.

Russia currently has no equivalent to MUOS and Ispolin is probably supposed to fill that gap. Meanwhile, SSKMS, a mobile satellite communications project run by Roscosmos, looks like it has been canceled. According to the latest plans announced in 2020, it was to consist of one satellite in geostationary orbit and three satellites in highly elliptical orbits. The 12 m antenna for the satellites was to operate in the S band. A news article published earlier this week said that Roscosmos has decided to drop SSKMS and focus only on a constellation of low-orbiting mobile comsats (Gonets-M(1)). The Ministry of Defense has a similar system (Rodnik, to be replaced by Klyuch), but its exact capabilities are unknown.

STATUS

As for the status of Ispolin, one can only assume that the project must have reached a fairly advanced stage by now. Development of the antenna itself began in 2012 as part of Pribor-Reflektor and paved the way to starting the research phase of Ispolin in 2017, which presumably focused primarily on incorporating the antenna into a satellite and freezing the design. With a contract for actual satellite development signed in 2021, construction should now be underway.  The satellites will be launched from Plesetsk by the Angara-A5 rocket. When former Defense Minister Sergei Shoigu visited the Angara infrastructure at Plesetsk in October 2021, he was shown a floor plan of a new building that is used to prepare payloads for the rocket. One of the satellites listed there was Ispolin.

Whether Ispolin will be able to stick to its 2027 launch date is questionable. Most of ISS Reshetnev’s military projects are experiencing significant delays. Even projects that started well before Ispolin (Sfera (2011), Repei and Gerakl-KV (2014)) are yet to see their first flights. Given the complexity of building satellites with such massive antennas, Ispolin may well suffer the same fate.