A Russian Soyuz 2-1B rocket blasted off from the Plesetsk Cosmodrome at 6:34 UTC on Tuesday, carrying into orbit the first Tundra EKS Missile Early Warning Satellite, marking the start of the closure of a critical gap in Russia’s early detection system for incoming ballistic missiles. Heading to the south-east, Soyuz fired its three stages for nine and a half minutes before handing off to the Fregat-M upper stage that was tasked with a multi-hour mission to deliver the satellite to its elliptical 24-hour orbit, a setup known as Tundra orbit. Spacecraft separation occurred five hours after launch, marking the successful conclusion of the launch.
Tundra, also known as EKS (Unified Space System), closes a gap in Russia’s space-based missile detection system that spanned several years due to the program’s predecessor running out of service before the Tundra satellites were ready for launch. The previous program known as Oko was initiated in the 1970s and operated two types of satellites, US-K satellites in highly elliptical Molniya orbits to cover the high-latitude regions and US-KMO spacecraft in Geostationary Orbits to provide global coverage. The final Oko satellite headed into orbit in 2012 and stopped working in 2014, marking the end of a program that saw 101 satellites launched to orbit.
The EKS program as a successor to Oko was initiated at the turn of the century with the goal of being ready for launch in 2007, but technical issues pushed the first launch by several years, initially targeting 2012 for the launch of the first EKS satellite. Lawsuits were filed between the Russian Ministry of Defence and satellite manufacturer Energia for a compensation for the continuing delays, however, Energia argued that ever changing specifications and technical modifications beyond what was possible in the industry slowed down their progress. Energia won the case, but the launch of the first EKS satellite kept slipping. No precise information is available on what caused the recent slips.
Technical details on the Tundra satellites are not available to the public given the military nature of the program. The satellites likely use Energia’s Universal Satellite Platform that weighs 1,200 Kilograms and can support payloads of up to one metric ton. The EKS infrared sensing payload is built by TsNII Kometa that also provided the Oko early warning payload systems. The US-KMO satellites used to carry a 1-meter diameter infrared telescope outfitted with a deployable 4.5-meter long sunshade.
The satellites are capable of detecting the infrared signature caused by the hot exhaust of a missile to deliver early warning and tracking information for targeting of a defence strike. Aerospace Defence Force officials noted that the EKS system not only can detect intercontinental ballistic missiles but also tactical theater and tactical missiles.
Absolutely no details were available over the course of the preparation for this launch from Plesetsk that marked the fourth Soyuz mission launched this year from Russia’s primary military launch site. Tuesday’s launch was the first from Plesetsk in a five-month period.
Heading into countdown operations eight hours prior to liftoff, Soyuz was activated and was put through a series of tests including communications, flight control and electrical testing as well as specialized tests of the propulsion system.
The Russian State Commission met around five hours prior to liftoff to review the status of the countdown, providing the formal approval to begin propellant loading four hours prior to blastoff. Over the course of a two-hour sequence, the Soyuz launcher’s boosters, core stage and third stage were filled with a total of 274,140 Kilograms of -183°C Liquid Oxygen and rocket-grade Kerosene. Additionally, the boosters and core stage received Liquid Nitrogen for the pressurization of the propellant tanks during the flight and the third stage received high-pressure helium to serve the same purpose.
Once propellant loading was complete and LOX/LN2 entered replenish, final close outs of the launch vehicle were started. A last round of checkouts was run inside 90 minutes to launch and the Soyuz Guidance System was activated with one hour to go to complete final checkouts and receive its flight software. Around 45 minutes ahead of T-0, the two halves of the Service Structure were retracted from the 46.1-meter tall Soyuz rocket that was fully fueled, weighing 308,000 Kilograms. After final preparatory steps, the Soyuz headed into its automated countdown sequence six minutes prior to liftoff.
The terminal countdown sequence included the pressurization of the 12 propellant tanks aboard the vehicle, the purge of the engines with gaseous nitrogen to ensure a clean ignition, and the transfer of the vehicle to internal power. With one minute on the countdown clock, Soyuz assumed control over the final critical steps leading into the disconnection of the third stage umbilical and the retraction of its mast followed by the launch command at T-20 seconds that coincided with the separation of the Core Stage umbilical tower.
Igniting its RD-107A engines on the boosters and RD-108A on the core, Soyuz started spinning up its hydrogen-peroxide driven turbopumps to reach a total liftoff thrust of 422,000 Kilogram-force.
Soyuz blasted off at 6:34 UTC, beginning a vertical climb that lasted just a few seconds before the rocket began its pitch and roll maneuver to start flying south-east to head to an orbital inclination of 63 degrees. Using its vernier thrusters on the boosters and core stage, Soyuz achieved its precisely planned ascent trajectory.
Consuming 1,600 Kilograms of propellants per second, Soyuz headed uphill, its boosters delivering the majority of thrust for the initial portion of the flight to rapidly accelerate the launch vehicle. Soyuz pushed through Mach 1 and encountered Maximum Dynamic Pressure just after passing 70 seconds into the mission.
One minute and 58 seconds into powered flight, the RD-107A engines of the boosters were shut down after exhausting 39,600 Kilograms of propellants each. Immediately after engine shutdown, the four boosters were jettisoned by pyrotechnic devices and pistons that pushed the boosters outward for a clean separation.
With the 19.6-meter long boosters tumbling back to Earth, the Soyuz headed on powered by its Core Stage alone, its RD-108A engine consuming over 300 Kilograms of propellant per second to deliver 102,000 Kilogram-force of thrust. The 27.8-meter core stage burned until T+4 minutes and 45 seconds, marking the start of the hot-staging sequence employed by Soyuz. At T+4:47, the command to ignite the third stage’s RD-0124 engine was sent followed after a short interval by the initiation of the stage separation pyrotechnics that severed the connection between the third and core stage to allow the thrust of the engine to pull the third stage away from the spent core.
Delivering 30 metric tons of thrust, the 6.8-meter long third stage consumed nearly 23 metric tons of LOX and Kerosene in four and a half minutes, placing the stack on the expected trajectory for Fregat separation that occurred just before the T+9.5-minute-mark. Fregat was tasked with a mission of several hours to deliver the satellite to its Tundra orbit, though the mission profile for this flight was not released to the public.
Fregat uses storable propellants – Unsymmetrical Dimethylhydrazine and Nitrogen Tetroxide that are consumed by a re-startable S5.92 engine delivering up to two metric tons of thrust. Fregat-M measures 3.35 meters in diameter and is 1.5 meters long weighing 6,700 Kilograms including 5,750 Kilograms of storable propellants.
Most likely, Fregat was tasked with a three-burn mission, the first of which was to occur directly after Soyuz finished its job. This burn likely aimed for a Low Earth Parking Orbit for a short coast phase to allow the vehicle to reach the appropriate position in its orbit to set up the targeted orbital parameters with respect to argument of perigee leading to the placement of the position of the orbit’s apogee. This second Fregat burn was to insert the stack into an elliptical transfer orbit with an apogee near Geostationary Altitude. Next was a long coast phase for the third burn to occur closer to the apogee of the orbit to raise the perigee to nearly 2,000 Kilometers and bringing up the apogee above GEO altitude, aiming for an Argument of Perigee at 270° and an apogee over the northern hemisphere.
A Tundra Orbit is a highly elliptical geosynchronous orbit with a high inclination, typically 63.4°, and an orbital period of one sidereal day, four minutes shorter than a solar day. This orbit allows a satellite to spend most of its time over a chosen area of Earth, known as apogee dwell, which makes this particular orbit design suitable for satellites aiming to focus on locations particularly far north or south depending on the mission needs. Forming a Figure 8 with its ground track, a satellite in a Tundra orbit reaches very high elevation angles for the high latitudes which is not possible from Geostationary Orbit over the equator.
Spacecraft separation occurred around five hours after launch, marking the completion of Tuesday’s ascent mission and the long-awaited arrival of the first EKS satellite in orbit. The Tundra satellite was tasked with deploying its solar arrays, establishing a stable three-axis attitude and initiating communications with ground stations for a series of checkouts that will continue for a period of weeks before the satellite enters service.
At least five Tundra satellites are ordered for launch until 2020 to establish a fully functional, global constellation of Missile Early Warning Satellites, ending Russia’s reliance on ground-based missile detection systems that are limited in range and only provide a fraction of the warning time satellites can deliver.