Tundra Orbit

Russia orbits missile-detection satellite

1. Tundra Orbital Motion
2. Tundra Orbital Elements

Military personnel at Plesetsk Cosmodrome in Northern Russia performed the successful launch of a Soyuz-2-1b rocket on September 26, 2019, carrying a classified payload which is believed to be the third satellite for the nation's newest constellation designed to provide the Kremlin with early warning about launches of ballistic missiles around the world.

The classic Tundra orbit has been used by communications satellites previously. Sirius Satellite Radio's Radiosat 1, 2 and 3 all use the classic Tundra orbit at 63.4° inclination to provide satellite radio service to North America. (3) This thesis will examine the TCS design considerations for a meteorological.

Tundra Orbital Motion

Previous page: Development of the EKS system

Soyuz-2-1b rocket lifts off from Plesetsk on September 26, 2019.

Third EKS launch at a glance:

Third EKS/Tundra satellite lifts off

The Tundra orbit is a special type of G eosynchronous Orbit which is highly inclined from the Earth's equator. A Tundra orbit is also elliptical such that the satellite spends more time North of the equator than South of it. At the present time, the only satellite company utilizing the Tundra Orbit is Sirius Satellite Radio. An inclined, elliptical, geosynchronous earth satellite orbit designed to provide communications satellite service coverage at high latitudes; it has an inclination of 63.4° degrees and an eccentricity of 0.2684, so that the satellite spends 16 hours each day over the hemisphere (northern or southern) where service coverage is intended and 8 hours over the opposite hemisphere.

According to the official Russian media quoting the Ministry of Defense, the Soyuz-2-1b rocket with a Fregat upper stage lifted off from Pad 4 at Site 43 in Plesetsk on September 26, 2019, at 10:46 Moscow Time (3:46 a.m. EDT) .

No official information on the nature of the payload has been released but three days earlier the Russian government issued warnings to air and sea traffic to avoid impact sites for rocket stages in Southern Russia and the Pacific Ocean southeast of Tasmania which matched the ground track of the previous two missions known to deliver EKS/Tundra satellites for the nation's early warning constellation. The system is officially known as EKS OiBU for Edinaya Kosmicheskaya Sistema Obnaruzheniya i Boevogo Upravleniya, which can be translated as 'integrated space system for detection, battle command and control' or EKS for short.

The third launch of the Tundra satellite appeared to be following the usual scenario for the deployment of the EKS constellation. The four-stage Soyuz booster lifted off under the simultaneous thrust of the first and second stages, heading southeast along the southernmost corridor available for orbital launches from Plesetsk. The four boosters of the first stage were jettisoned around two minutes into the flight and probably fell around 350 kilometers downrange, most likely at the S28 impact site located in the marshy area where the Vychegda River flows into the Severnaya Dvina River. The second (core) stage continued the powered ascent.

The payload fairing then split into two halves around a minute after the separation of the first stage. Its fragments probably fell in the Western-Siberian Plain, along the Om river.

Less than five minutes into the flight and moments before the second stage completed its burn, the third stage ignited its four-chamber RD-0124 engine, initially firing through the lattice structure connecting the two stages. The second stage then separated and crashed around 1,500 kilometers downrange from the launch site, most likely at the S21 impact site, northeast of the city of Tobolsk.

Around nine minutes into the flight, the third stage released the payload section, including the Fregat upper stage and the EKS satellite, into a suborbital trajectory before reentering the Earth's atmosphere. Any surviving debris from the third stage should have fallen into the Pacific Ocean just South East of Tasmania.

Shortly after the launch, the Russian Ministry of Defense confirmed that the assets of the Titov Chief Test Space Center within the Russian Air and Space Forces, VKS, had begun tracking the vehicle at 10:48 Moscow Time and that at 10:55 Moscow Time, the Fregat upper stage and its payload had successfully separated from the third stage of the Soyuz launch vehicle.

Approximate ground track during the launch of the EKS (Tundra) satellite.

Fregat space tug maneuvers

During the orbital part of the launch, the Fregat was expected to conduct multiple maneuvers to insert the EKS satellite into its orbit. Most likely, three main engine firings had to be made. The first maneuver initiated within a minute after the separation from the third stage likely placed the stack into an initial parking orbit. The Fregat then probably fired its engine again with the goal of stretching the orbit so that the apogee (the highest point) of this intermediate orbit reached the perigee (lowest point) of the final orbit. Finally, the third Fregat burn could increase the apogee to the required altitude by firing near the peak of the target orbit.

Tundra Orbital Elements

Following the separation of the EKS spacecraft, the Fregat upper stage typically conducts collision avoidance and deorbiting maneuvers. In turn, the satellite has its own propulsion system to make necessary orbit adjustments.

Less than half an hour after the spacecraft passed the first apogee of its target orbit around 17:25 Moscow Time on September 26, 2019, the Russian Ministry of Defense confirmed that the Fregat had successfully released the satellite into its planned orbit and it had been taken under control of ground assets of the Air and Space Forces which maintained stable communications with the healthy spacecraft. The satellite received an official designation Kosmos-2541.

Shortly after the launch, NORAD listed two objects associated with the launch, likely representing the satellite and the Fregat, in the orbits with the following parameters:

Page author: Anatoly Zak; Last update: October 4, 2019

Page editor: Alain Chabot; Last edit: September 26, 2019

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Description

In astrodynamics or celestial mechanics an elliptic orbit is a Kepler orbit with the eccentricity less than 1; this includes the special case of a circular orbit, with eccentricity equal to zero. In a stricter sense, it is a Kepler orbit with the eccentricity greater than 0 and less than 1 (thus excluding the circular orbit). In a wider sense it is a Kepler orbit with negative energy. This includes the radial elliptic orbit, with eccentricity equal to 1.

In a gravitational two-body problem with negative energy both bodies follow similar elliptic orbits with the same orbital period around their common barycenter. Also the relative position of one body with respect to the other follows an elliptic orbit.

Examples of elliptic orbits include: Hohmann transfer orbit, Molniya orbit and tundra orbit.

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