Moscow Defense Brief

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#4 (60), 2017


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Russia’s GLONASS Satellite Constellation

Anton Lavrov

One of the final products of the space arms race between the Soviet Union and the United States was the development of global satellite navigation systems. America’s Navstar fleet of satellites, which underpins the Global Positioning System (GPS), and Russia’s GLONASS network were fully deployed well after the break-up of the Soviet Union. The solutions inherited from the Soviet period enabled Russia to complete this vastly complex project in 1995, simultaneously with the United States, and to begin operation of the GLONASS satellite fleet.

From the outset, both of these satellite constellations had a primarily military role. They were to provide users on land, at sea, and in the air with a round-the-clock, all-weather navigation service in any part of our planet. Even satellite guidance of weapons systems was initially seen as a secondary role.

In the mid-1990s, GLONASS was not used for civilian applications because of the lack of compatible hardware. There wasn’t much demand for its military applications, either, due to Russian spending cuts, the general policy of demilitarization, and – once again – the lack of compatible hardware. During the first campaign in Chechnya in 1994-1996, the Russian MoD even resorted to buying a small number of GPS Navstar navigation systems from foreign suppliers. Meanwhile, in the Russian Air Force, many pilots would buy civilian Navstar devices out of their own pocket, for their own informal use during flights; that practice was fairly widespread in the years after the first Chechen campaign.

The first-generation GLONASS systems turned out to be rather unreliable, and the failed satellites could not be replaced in a timely fashion, so a fully operational system soon became inoperable. By 2002, it had a grand total of only seven working satellites. That was nowhere near enough to provide a global coverage; in fact, even Russia’s own territory was not properly covered for most of the day. Besides, the positioning accuracy was an order of magnitude worse than what the American GPS system offered at the time. In such a state, GLONASS was next to useless to both military and civilian users.

In 2002, led primarily by military considerations, the Russian government launched a federal program headlined “Global Navigation System in the 2002-2011 Framework”. The objective of the program was to facilitate a comprehensive development of the GLONASS system, i.e. not just the satellite constellation but also the ground segment, including end-user hardware.

The program began to bear fruit from the mid-2000s, but when the conflict with Georgia broke out in 2008, the Russian armed forces still had very few GLONASS devices. Even the small number of the cumbersome Grot-M individual navigation instruments issued to troops in the North Caucasus Military District were hardly used. Neither did the Russian forces have any satellite-guided high-precision weapons. Nevertheless, Russia did deploy the upgraded Su-24M tactical bombers (it still had very few of them at the time); these were equipped with Gefest-T navigation and targeting systems that used the GLONASS signal.

Satellite navigation was also used by a handful of the upgraded Su-25SM strikers operated by the 368th Strike Air Regiment (Budennovsk). But the satellite navigation systems in those planes could use both the GPS and the GLONASS signal, and the pilots relied mostly on the former. As of August 8, 2008, there were only 16 GLONASS satellites in orbit, of which three were inoperative. The system’s global availability stood at no more than 56% at the time.

In the years that followed, Russia stepped up the production and launches of additional GLONASS satellites, and by December 2011, it once again had 24 operational craft in orbit, which is the minimum required for full global coverage. The GLONASS constellation was formally delivered to the MoD for trial operation. Even though the space segment of the system is performing well, the entire GLONASS system has yet to be formally entered into service with the Russian armed forces due to problems with the space launcher on which the system relies.

The GLONASS satellites operate in two bands: L1 (~1,600MHz) and L2 (~1,250MHz). The unencrypted, standard-accuracy civilian signal and the encrypted high-accuracy military signal are both broadcast on the L1 band. The L2 band was used by the first-generation satellites only for the encrypted high-accuracy military signal. The first satellites of the upgraded GLONASS-M series were put into orbit in 2003. These satellites also broadcast the standard-accuracy civilian signal in the L2 band. This has significantly improved positioning accuracy when using dual-band civilian GLONASS devices. The next generation of the GLONASS satellites, the GLONASS-K, began test flights in 2011. They have added a third band, the L3, broadcasting on the 1202MHz frequency. Unlike the previous bands, which rely on frequency multiplexing, the L3 signal will use code multiplexing, which will further improve accuracy for both civilian and military applications. The main difference of the GLONASS-K2 generation of satellites, which have yet to be launched, is a greater use of locally-made components.

The altitude of the GLONASS satellites’ orbit is about 19,100km, which makes them invulnerable to any of the existing or previously tested anti-satellite weapons systems. The constellation can therefore survive even a large-scale armed conflict. But just like other satellite positioning systems, GLONASS is vulnerable to local jamming of the satellite signal. The system is still relatively new, though, and the number of its users is limited, so foreign armies have yet to receive any weapons that would be effective against it. The ongoing upgrade efforts, which include the addition of new signal bands and multiplexing methods, also make jamming the Russian satellite navigation system difficult, though not impossible.

Because of its orbital parameters, GLONASS has a better average availability in the  Arctic latitudes than GPS Navstar. That is an important advantage for the Russian military and civilian presence in the far north.

It is a common misconception that a constellation of 24 operational GLONASS satellites is entirely sufficient for any applications. The problem is that the use of only space-based positioning signal sources provides for a maximum accuracy to within several meters at best. If a sub-meter accuracy is required, the combat theater must be equipped with ground differential correction and monitoring stations. Without a network of such stations, the receivers that rely only on the GLONASS signal can provide a positioning accuracy to only about 10m horizontal, even in Russian territory. That is not enough for the most demanding applications, from mapping to high-precision weapons.

Russia is currently working hard to build an extensive system of ground monitoring, functional augmentation and differential correction stations for the GLONASS system, both in Russia itself and abroad. Such stations are important not only for civilian but also military use – and that is why in 2013 the United States said it would not allow them in U.S. territory.

Initially, the Russian satellite navigation system lacked the ability for intentionally degrading signal accuracy for civilian users – a capability that has always been present in Navstar. In 2005, however, the U.S. president ordered an end to the practice of intentionally degrading the civilian GPS signal. That spurred a rapid growth of the civilian and commercial use of GPS all over the world.

The Russian system, meanwhile, is moving in the opposite direction. In 2013, GLONASS developers were told to come up with a way of degrading the unencrypted civilian signal without any collateral damage to military users. Of course, that capability will only be required in the event of a major armed conflict.

Military uses of GLONASS

The return of the GLONASS satellite constellation to fully operational status enabled its use for all three key military applications: navigation, high-precision weapons, and automated C&C systems.

Initially, the Russian MoD prioritized the strategic forces (intercontinental ballistic missiles and sea, air, and ground-based cruise missiles) for the use of GLONASS. Even the accuracy to within 20-30 meters achieved with the GLONASS satellites alone, without any ground stations or simultaneous use of the GPS Navstar signal, is entirely sufficient for any target if the delivery system carries a nuclear warhead.

One of the first military applications of GLONASS was a dual targeting system for ICBMs. The technology was pioneered in the upgrade program for the R-29RM submarine-launched ballistic missiles carried by Project 667BDRM nuclear submarines. Launched in 1999, the upgrade program included the addition of satellite guidance capability. The upgraded missile was designated the R-29RMU2 Sineva; it entered into service in 2007. The addition of satellite navigation to the missile’s inertial and astronavigation systems significantly improved its accuracy and simplified the preparation of the launch data, which is especially relevant for submarines. The later Russian nuclear missiles – the Yars and the Bulava – also use the GLONASS course correction capability.

One of the first GLONASS-capable non-nuclear strategic munitions to enter into service was the Kh-101 air-launched cruise missile (the nuclear-armed version is designated the Kh-102). The new missile had a much greater range of 4,500km. Longer range tends to degrade accuracy when the missile relies on the traditional inertial navigation alone over areas with few landmarks, such as the open sea. The use of satellite navigation for course correction resolves that problem once and for all, and reduces the likelihood of the missile “losing its way” or even failing to reach the general vicinity of the target. The projected deviation from the target for the Kh-101 is less than 10 meters. The figure for the previous generation of non-nuclear cruise missiles, the Kh-555, was 25-30 meters, which may be too much for compact or heavily fortified targets.

The use of satellite course correction also reduces the complexity and duration of preparing a cruise missile for launch. For example, America’s Tomahawk cruise missiles had their stated launch preparation time slashed from 80 man-hours to only 1 hour thanks to the introduction of the satellite-guided Block IV version. The improvement for the Russian cruise missiles should be in the same ballpark.

The first GLONASS-capable high-precision weapon delivered to the Russian Army was the Iskander-M substrategic missile complex, which entered into service in 2006. GLONASS navigation is used in both the ballistic missile and the cruise missile versions of that complex.

The arrival of compact satellite signal receivers for tactical munitions in the early 2000s spurred the development of satellite-guided tactical ammunition for the Russian forces. One of the first such devices was the PSN-2001 receiver, which can be bolted onto various airborne munitions, including the KAB-500S bomb. The PSN-2001 can receive the GLONASS signal in the L1 band, as well as the unencrypted civilian signal of the U.S. Navstar system; it can use either or both at the same time. It can also receive signals from the ground differential correction stations. That dual capability enabled Russia to develop and test high-precision munitions even when its own GLONASS system was barely working.

The next generation of Russian satellite-guided weaponry was the KAB-500S precision-guided bomb. It differs from the American JDAM guidance kit that can be mounted on ordinary free-falling bombs, but offers similar performance. The decision not to use thrusters or complex guidance systems makes the KAB-500S somewhat cheaper, but it is still more expensive than a retrofitted old bomb. It can be dropped from altitudes of 500m to 5 km, and has a range of up to 9km. The warhead contains 195kg of high explosive, and can be used with various fuse delay mechanisms. This makes the KAB-500S a versatile tool, capable of engaging a broad range of targets, including underground and fortified ones. The export version of that bomb, which lacks the differential correction capability, is accurate to within 7-12 meters.

A lighter version of this satellite-guided bomb, the KAB-250, was developed by GNPP Region for placement in the internal bays of the Su-27 fifth-generation fighter or in the external pods of other aircraft. The bomb is now undergoing trials, and according to some unconfirmed reports, it has been used in combination with Su-34 planes during the Russian operation in Syria.

Several versions of satellite-guided air-launched missiles have been developed for heavily protected targets. These missiles are costlier than guided bombs, but they can be used to engage the target without entering the adversary’s air defense perimeter. The Kh-25MS and Kh-38MK have a launch range of up to 40km, and the X-59MK2 over 100km.

Other advanced munitions are currently in development. These include versions that use satellite navigation in flight, and other guidance channels on approach to target, making them more effective against mobile targets and achieving a greater accuracy even without differential correction. Such a solution can be used in long- and extra-long-range surface-to-air and air-to-air missiles, as well as long-range anti-ship missiles.

Work is under way to develop satellite-guided 152mm artillery shells. The Russian technology makes it possible to upgrade ordinary shells into high-precision munitions. The satellite guidance module, developed by MKB Kompas, is installed in the detonator slot. If the manufacturer manages to keep the price tag as low as promised, these shells could herald the same kind of revolution in artillery as the JDAM guidance sets once did in airborne weapons. The capability to fire satellite-guided shells has been announced for the new 2S35 Koalitsiya-SV 152mm self-propelled howitzers, which are expected to start arriving in large numbers by 2020. Russian engineers are also developing satellite-guided versions of MLR rockets; they have already created such a rocket for the Smerch 300mm system.

All modern warships are equipped with satellite navigation technology. The same is true of the new armored vehicles, including the latest versions of the T-90 tank and all the armor currently in development. This is a necessary requirement to make them interoperable with automated C&C systems at the tactical and higher tiers. There are even experiments to equip individual soldiers with such systems. Another application that has already been developed is landing assistance for carrier-based helicopters. The military version is used in Project 20380 and Project 20385 corvettes.

Army units, including transport and reconnaissance, are also making progress in incorporating GLONASS technology. They have already begun to receive such systems as the Strelets reconnaissance, control, and communication kit, which can acquire the target’s coordinates and feed them to automated C&C systems and/or the targeting systems of artillery and air-launched weapons.

Satellite coordinates have become essential for military geo-information systems. Such systems are at the core of every automated C&C system. In a dynamic and constantly changing environment, they can be effective only if they have the precise coordinates of the battlefield assets they control and of the targets they must engage. Additionally, the GLONASS signal can be used for precise clock synchronization, which is important for high-precision weaponry and C&C.

Use of GLONASS in Syria

The Russian military operation in Syria that began in September 2015 has been the first military conflict in which Russia could field-test the full range of the capabilities of its satellite navigation system. The Russian forces in Syria have made use of all three key military areas of GLONASS application: high-precision weapons, navigation, and C&C.

Even though several GLONASS satellites have been lost during failed launches, Russia has managed to maintain its GLONASS constellation in a fully operable condition throughout the campaign in Syria. This was achieved thanks to the greater reliability of the second-generation satellites (GLONASS-M). As of mid-2017, of the 27 satellites in orbit, 14 remain operational beyond their projected lifespan, including four craft launched in 2005-2006. There are not enough backup satellites being launched, but there is a sufficient number of fully operational craft already in orbit. In fact, by the time Russia began the campaign in Syria in 2015, it had a backup stock of eight GLONASS-M satellites awaiting launch.

There have recently been only a few occasions when the number of operational GLONASS satellites in orbit dropped to 23, and in one brief period, it was as low as 21 after three satellites failed in quick succession in February 2016. That brief interruption was quickly remedied. Otherwise, the constellation of 23-24 operational satellites has been entirely sufficient for uninterrupted global navigation and military services in Syria. For most of the time, the global availability ratio for the GLONASS system has remained above 95%.

The first Russian GLONASS users in Syria were aircraft equipped with the latest targeting and navigation stations, including the upgraded Su-24M and the new Su-25SM, Su-27SM3, Su-30, Su-34, and Su-35 planes, naval aviation aircraft, and Tu-22M3 long-range bombers. The accurate real-time information on 3D coordinates of the plane and the target, combined with the data on atmospheric conditions in the target area, enable the new systems radically to improve the strike accuracy even for ordinary unguided bombs.

Broad use of satellite navigation technologies has given a new lease on life to old bombs. The bombers can now automatically follow a preset course, and drop unguided munitions at a precise point in their flight. On occasions, this has been done at night or in dense cloud cover, i.e. without visual contact with the target. Previously, that would have been enough to strike a target only the size of a town or an airfield, but with satellite navigation the accuracy has proved sufficient to take out individual field fortifications and buildings.

For example, Su-25SM strikers can now drop bombs to within 10-15m of the target when flying horizontally at an altitude of 200-300m. In Syria, this new capability has made it possible to use them as light bombers. It must be noted, however, that they necessarily have to operate at higher altitudes to avoid the enemy’s air defenses, which inevitably reduces their accuracy even with the new targeting systems. But, in stark contrast with the Five Day War with Georgia in 2008, not a single Russian striker has been lost in over two years of the Syrian campaign.

The best results have been achieved with the satellite navigation-equipped long-range bombers, which delivered massive free-falling bomb strikes against large industrial facilities.

Nevertheless, even these “smart” targeting systems cannot fully replace high-precision weapons. The operation in Syria has been the first Russian campaign in which high-precision weaponry constituted a significant proportion of all the weapons used. The precise proportion of that weaponry has not been disclosed. Information about the types of high-precision weapons used in Syria is also released very rarely. The weapons most frequently mentioned in Russian MoD releases include the Kh-101 and Kalibr cruise missiles, as well as KAB-500S guided air bombs. They probably constitute the vast majority of the GLONASS-capable munitions and high-precision weaponry in general used during the campaign.

Russia has used up over 200 new air-, sea-, and submarine-launched cruise missiles since the campaign began almost two years ago. These missiles were launched one at a time, in salvos of two to four, and in much larger numbers simultaneously. On October 7, 2015, 26 Kalibr-NK cruise missiles were launched at targets 1,600km away from the ships of the Caspian Flotilla. During an airstrike on November 17, 2005, Russian long-range bombers launched 34 Kh-101 and Kh-555 cruise missiles. The MoD has released video footage of these missiles striking their targets with great accuracy, so they have obviously fulfilled their intended purpose.

The cruise missile strike launched from the Caspian Sea has demonstrated the ability of these missiles to follow a complex trajectory over mountainous terrain. The Russian Navy has therefore acquired the ability to deliver long-range, high-precision conventional strikes even against targets situated far inland.

The KAB-500S satellite-guided bombs were mostly dropped from Su-34 bombers. Initially they were used primarily against high-value targets, such as command centers, ammunition depots, and weapons factories. Later on, the Russian Air Force began to use them in close coordination with troops on the ground to take out pockets of resistance on the front line. The Russian MoD says that KAB-500S bomb strikes have achieved an accuracy of within less than 5 meters in Syria.

Highly accurate strikes using GLONASS-guided weapons have been demonstrated in Syria on numerous occasions. This means that at some point during the Russian campaign, Russia must have deployed ground differential correction stations in the area. This should not have been difficult thanks to the friendly government in Damascus. But away from the territory of Russia itself or its allies, where these ground stations would be difficult to deploy, the accuracy of the strikes using the current generation of Russian satellite-guided munitions would inevitably suffer.

The new navigation systems that incorporate satellite technology have radically improved the ability of the Russian aircraft to find their targets. This had always been a problem in Afghanistan and Chechnya, which could be ameliorated only with a very high level of training. In Syria, the Russian forces have had to operate in a completely unfamiliar theater, and to find well-disguised targets in desert or mountainous terrain, with very few landmarks to guide them. Additionally, much of the action is taking place in densely populated areas, requiring extreme accuracy and caution. Effective satellite navigation has enabled the Russian Air Force to overcome these challenges.

Russia has more than 70 UAVs deployed in Syria, and all the missions they have flown also relied on satellite navigation. In fact, it is the primary spatial positioning method used by drones. It also helps them to perform real-life combat missions. Drones are used not only to find targets, but also to acquire their precise coordinates. That information is then fed to high-precision weapons and C&C systems.

Russia has deployed all tiers of automated C&C systems, from tactical all the way up to strategic in Syria. The new Strelets reconnaissance, target designation, and communication systems, which are part of the tactical automated C&C tier, are used to acquire target coordinates on the ground.

The HQ of the Russian forces in Syria has been able to successfully coordinate the deployment of the different branches and services of the armed forces, as well as to coordinate strikes from the ground, sea, and air. At the sub-strategic level, all the data on the coordinates of the battlefield assets and targets is fed to the National Defense Management Center in Moscow.

Outlook for the military segment of GLONASS

The Russian armed forces are now following the same evolutionary path as the U.S. forces before them. The growing use of high-precision weapons and the network-centric concept of warfare require a reliable GLONASS service. Russia is currently facing some minor hurdles with the maintenance of the GLONASS constellation, but that is a temporary situation caused by several failed launches. The reliability of the orbiting constellation itself, as well as the expected lifespan of its satellites, are still lagging behind the GPS/Navstar indicators, but they have shown a significant improvement in recent years. As a result, the GLONASS system is becoming easier and cheaper to maintain.

We expect that very shortly Russia will achieve the capability always to maintain at least 24 operational GLONASS satellites as well as several backup craft in orbit, ready to take over at a moment’s notice. The hot swap capability is especially relevant for military applications, since civilian users can always rely on other satellite navigation systems in the event of a temporary interruption to the GLONASS service. Russia is currently one of only two international actors that has its own fully-capable global satellite navigation system with built-in support for all military applications anywhere on the planet. But the current duopoly will soon be disrupted by China’s BeiDou-2 and Europe’s Galileo systems.

Being a member of this elite club enables Russia to export not only individual advanced weapons systems, but also entire military ecosystems that rely on the Russian satellite navigation service. Apart from the weapons proper, these ecosystems include satellite navigation equipment, high-precision weapons platforms that rely on satellite signals, and automated C&C systems. That is a tangible competitive advantage for the Russian defense industry.

The best example of that advantage being put to a good use is cooperation with India on the BrahMos missile program. These missiles’ targeting systems rely on the GLONASS signal. India also buys lots of other modern Russian weaponry that uses the GLONASS capability. In 2010, Russia and India signed an intergovernmental agreement on granting India access to the encrypted high-accuracy GLONASS signal.

In June 2017, it was announced that Russia’s Collective Security Organization Treaty (CSTO) allies may also be granted access to the encrypted military GLONASS signal. So far, these allies have very few platforms or munitions capable of using satellite signal – but their rollout, which is expected in the near future, will help these countries to augment their military capability.

The number of civilian applications of the satellite navigation technology is countless. Most of us have come to rely on them, one way or another, in our daily lives. It is easy to forget that this technology is equally as important for military applications, and that the number of those applications also continues to grow. In this day and age, an army that lacks full and unconditional access to one of the global satellite navigation systems is at a major disadvantage.

That is why the availability and uninterrupted work of its own global satellite constellation is essential if Russia is to remain a genuinely sovereign state, self-sufficient militarily, and with a globally competitive national defense industry.

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© Centre for Analysis of Strategies and Technologies, 2017