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Nov. 21, 2013
Dnepr launch vehicle blasted off from the Dombarovsky Air Base,
A Dnepr launch vehicle blasted off from the Dombarovsky Air Base, Orenburg Region, Russia, on Thursday at 7:10 UTC carrying a total of 32 spacecraft of different shapes and sizes to orbit. The launch was successful and all satellites were released into their desired orbits. This cluster launch of 32 spacecraft surpassed the record for most satellites launched by a single launch vehicle set earlier this week by a Minotaur I that orbited 29 satellites.
Dnepr is a converted R-36M missile also known as SS-18 Satan that was stationed all across the Soviet Union starting in 1966 outfitted with multiple warheads and independent re-entry vehicles. After the end of the cold war and the fall of the Soviet Union, a portion of the R-36 fleet was modified to become Space Launch Vehicles. Dnepr is one of the cheapest launch vehicles that are currently flying. It can deliver payloads of up to 4,500 Kilograms to Low Earth Orbit.
Dnepr launch vehicle liftoff
On Thursday, Dnepr went through a three-hour launch countdown as the launch team reported to the Control Center. Telemetry Equipment was prepared and tracking assets were checked. 90 minutes ahead of launch, the silo door was opened and the launch area was evacuated after final hands-on work was completed at the silo facility. The onboard control system of the launcher was tested at T-1 hour before being deactivated again.
At T-20 minutes, the control system was powered up again and final reconfigurations commenced leading to the final countdown phase starting three minutes before T-0.
At T-3 minutes, the launcher switched to internal power and the launch system was enabled to trigger the liftoff sequence at the precise T-0 time. Ground station telemetry recorders were activated as well to prepare for liftoff.
Dnepr Ejection from Silo description
Clocks hit zero at 7:10 UTC and the silo ejection system was activated. Dnepr uses a black powder mortar system that pushes a special tray at the base of the Dnepr rocket up to rapidly expel the rocket from its silo. As soon as Dnepr was out of the silo, the tray was ejected to the side by a small solid rocket motor in order to enable Dnepr to ignite its first stage engines.
A series of five O-Rings were pyrotechnically jettisoned at T+4 seconds and, at the same time, the RD-264 engine of the first stage ignited. RD-264 is a cluster of four RD-263 engines that share common turbopump equipment and provide a total thrust of 461,200 Kilograms – enough to lift the 211,000-Kilogram Dnepr launcher and its payloads hidden under the launcher’s fairing and gas shield.
Immediately after engine ignition, the 34.4-meter tall Dnepr rocket began its pitch maneuver to start its ascent mission, headed toward an high-inclination orbit. Dnepr’s first stage measures 22.3 meters in length and 3 meters in diameter carrying 147,900 Kilograms of propellants used by the main engines which operate at a high chamber pressure of 220 bar to generate 4,523 Kilonewtons of vacuum thrust. Control during first stage flight was provided by individually gimbaling the engine nozzles.
The first stage shut down and separated from the second stage at approximately T+1 minute and 38 seconds. Upon stage separation, the second stage ignited its RD-256 main engine and RD-257 vernier engine achieving a total thrust of 77,000 Kilograms. The second stage is 5.7 meters long and carries 36,740 Kilograms of propellants. Control during second stage flight is provided by the vernier engine that features four individually gimballed nozzles.
Dnepr flight process description
While the second stage was burning, the launcher jettisoned the upper portion of its payload fairing that had protected the satellites during the initial portion of the ascent when aerodynamic forces would have damaged the payloads. For Dnepr, the fairing is only one of two protective devices, the second being the gas dynamic shield that protects the delicate satellites on the upper deck from engine plumes of the third stage.
The second stage performed a burn of approximately two minutes and 48 seconds before separating from the third stage of the launcher.
Following separation, the third stage completed a short coast phase in order to climb uphill so that the third stage burn could serve as a circularization maneuver, raising the perigee of the orbit to match the apogee of the trajectory. The third stage of the Dnepr launcher uses four RD-869 engines that are firing forward - towards the nose of the launch vehicle. This unusual propulsion scheme is a relic of the original R-36 concept that required the upper stage to perform multiple warhead deployments in a short time frame.
The third stage of the Dnepr launcher uses four RD-869 engines that are firing forward
The engines swung out after stage separation and ignited when the coast was complete - starting the burn in a high thrust mode and immediately beginning a 180-degree flip of the vehicle to start providing positive thrust to the stack - pulling the stack into orbit instead of pushing the vehicle as most rockets do.
The four RD-869 engines deliver 2,070 Kilograms of thrust at nominal throttle and 846kg in throttled mode. Overall, Dnepr’s third stage is 1 meter long and uses a propellant load of 1,910 Kilograms. Control is provided by gimbaling the engines that continue to fire throughout the primary mission.
When the third stage approached the pre-planned orbit, the gas dynamic shield was released and the still burning third stage pulled itself and the space head module away. For this Cluster Mission, the SHM-2 design was used that includes two decks and a bridge to facilitate all the different payload adapters and CubeSat Deployers.
Third stage dynamic shield release
Once the target orbit was reached, the primary payload, DubaiSat-2, was separated and the vehicle pulled away as the engines were still firing. DubaiSat-2 is set for an Earth observation mission using a High Resolution Advanced Imaging System to acquire images of Earth that will be made available to commercial customers. Shortly after the primary satellite was deployed, the secondary satellite, STSat-3, was released as well. It will demonstrate new imaging technology using infrared cameras and a Compact Imaging Spectrometer for Earth imagery and data acquisition.
When the two Deck A payloads were released, the payload platform was jettisoned. With its engines still firing, Dnepr is able to create sufficient distance in between payloads and launcher vehicle equipment as the separation sequence occurs.
Next, the remaining small satellites were deployed as part of a carefully planned sequence of events with delays in between the different deployments. Usually, larger satellites are deployed first before the flood of CubeSats is released via the different Orbital Deployers. The three satellites hosted on the Bridge, SkySat-1 and the two AprizeSat spacecraft were separated first to enable the rest of the Deck B payloads to be deployed. Next to separate were presumably the WINSAT-1, UniSat-5 and BRITE-PL spacecraft ahead of CubeSat release.
The UniSat-5 satellite itself hosts a number of CubeSats and PocketCubes for deployment over the course of the first month of its mission in orbit. Those satellites are carried inside CubeSat launchers and PocketCube Launchers installed on the spacecraft. The PocketCubes launched aboard UniSat-5 are BeakerSat 1, $50Sat, Wren and QubeScout S1 and the CubeSats are Dove-4, HumSat-D, ICube-1 and PUCPSat1 that itself will deploy a 127-gram picosatellite Pocket-PUCP during its mission.
Payloads description
All satellites were deployed in just 30 seconds beginning approximately 17 minutes into the flight.
The mission was targeting a near-circular orbit at 600 Kilometers with an inclination of 97.6 degrees. Following the successful payload deployment, the RD-869 engines continued to fire to move the stage away from the satellites in order to place it into a different orbit to avoid re-contact with the multitude of payloads.
The launch of 24 Payloads was successfully performed by RS-20 rocket (Dnepr Launch Vehicle) from Yasny Launch Base, Orenburg region, Russia, on November 21, 2013 at 11:10:11 Moscow time (07:10:11 UTC).
The launch was executed by the Strategic Rocket Forces of the Russian Ministry of Defense with the support of the Russian and Ukrainian companies, which are part of the ISC Kosmotras industrial team. All payloads have been inserted into their target orbits.
ISC Kosmotras congratulates all the mission participants on the successful launch!
Images, Text, Credits: ROSCOSMOS / Kosmotras / Catherine Laplace-Builhe.
Greetings, Orbiter.ch
