Proton-M & Block DM-03 successfully Launch Ekspress AM-8 Satellite

Originally published on September 15, 2015

Photo: Tsenki
Photo: Tsenki

A Proton rocket lit up the night skies over the Baikonur Cosmodrome on Monday, thundering off on a mission to deliver the Ekspress AM-8 communications satellite directly to Geostationary Orbit. This mission employed the rarely used Block DM-03 upper stage in the third attempt to certify the upper stage for use in future launches for Russia’s Glonass satellite navigation system and for use on the Angara rocket family.

Lifting off from Site 81/24 of the historic Cosmodrome at 19:00 UTC on Monday, Proton-M headed to the north-east on its way into orbit. The rocket burned its first stage for two minutes before handing off to the second stage that used its four engines to push the vehicle out of the atmosphere. Proton’s third stage assumed control of the mission five and a half minutes into the flight and operated for four minutes during which the launcher jettisoned its protective payload fairing.

Just under ten minutes after launch, the Block DM-03 upper stage was separated and began its long operation – tasked with three burns to boost the stack into Geostationary Orbit. Owed to its higher performance, Block DM-03 could complete the Geostationary Insertion with only three burns as opposed to the regularly used Briz-M stage that has a low-thrust engine and needs an additional orbit around Earth to complete a direct GSO injection.

Separation of the Ekspress AM-8 spacecraft into the target Geostationary Drift Orbit occurred at 1:37 UTC on Tuesday morning, six hours and 37 minutes after liftoff.

Photo: Tsenki
Photo: Tsenki

Ekspress AM-8 has a launch mass of 2,163 Kilograms and is outfitted with 24 C-Band, 12 Ka-Band and two L-Band transponders to deliver communications services to Europe, Africa, and the middle east. Stationed at 14 degrees west in Geostationary Orbit, the ISS Reshetnev-built satellite will be operated for at least 15 years in the satellite fleet of the Russian Communications Company.

Heading uphill on the Block DM-03, the Ekspress AM-8 satellite could be the first to be boosted into orbit by this particular upper stage. Block DM-03 is the latest evolution of the Block-D upper stage that was originally designed to be used in the Soviet Moon Program, performing burns in the transit between the Earth and the Moon. Re-purposed for satellite launches, Block-D and its subsequent versions made over 250 missions.

The latest evolution of Block-D, the DM-03 version, has larger propellant tanks and a lighter structure for an improved payload capability. The stage was to become the workhorse of Glonass satellite launches that can be lofted in groups of three atop a Proton-M/DM-03. Certification of the stage was expected in 2010 when a Proton-M/DM-03 lifted off with three Glonass satellites which ultimately failed to reach orbit because the upper stage was overloaded with propellants due to a fault in fueling procedures that left the stage too heavy and led to a speedy re-entry over the Pacific Ocean. The next launch in 2013 again carried a trio of Glonass satellites, but also ended in failure when Proton-M crashed seconds after liftoff due to improperly installed rate sensors on its first stage.

On both of its previous missions, Block DM-03 never got to fire its engine.

As a result of the problems on Proton/DM-03, Glonass missions were shifted to launching one satellite at a time atop the Soyuz rocket. However, Roscosmos was still pushing forward with the certification of DM-03 to go back to the original plan for Glonass. Due to the need to replenish Glonass satellites, Roscosmos pressed ahead with the plan of flying a Block DM-03 stage as early as possible to set the stage for Glonass launches on Proton in the not too distant future.

Photo: Tsenki
Photo: Tsenki

Strapped atop the Proton rocket, Block DM-03 was the first element of the vehicle to be powered up on Monday to head into the ten-hour long countdown operation. Proton and its upper stage had completed comprehensive testing on Friday and Saturday with Sunday reserved to address any open items, none of which were present. Heading into the count, DM-03 received its flight software while the Ekspress satellite finished battery charging and a last set of health checks prior to flight.

As the sun set at the Baikonur Cosmodrome, the Russian State Commission convened to review the results of launch vehicle testing and the status of the launch countdown. With no issues on the vehicle and a good weather outlook, the formal approval for propellant loading was provided.

Proton-M was activated six hours prior to liftoff to head into its final set of tests and reconfigurations, followed a short time later by the initiation of propellant loading. Over the course of the three-hour sequence, the 58-meter tall rocket received 622,075 Kilograms of toxic propellants, Unsymmetrical Dimethylhydrazine and Nitrogen Tetroxide. While the lower three stages of the vehicle were loaded with hypergolics, the Block DM-03 stage entered Kerosene and Liquid Oxygen Loading, being filled with 18,600 Kilograms of propellants for use during the mission.

Because Proton has no umbilical tower, the Block DM-03 upper stage could only have its Liquid Oxygen replenished until the rollback of the Service Gantry 70 minutes prior to liftoff. Rolling away from the 713,000-Kilogram rocket, the Service Structure reached its safe liftoff position, clearing the way for the Proton rocket and allowing personnel to evacuate the launch site after final close outs were completed.

The master Countdown Sequencer was initialized at T-45 minutes and sequencers on the spacecraft, the upper stage, the launch vehicle and the ground were synchronized. Reconfigurations were made to the Proton Launch Abort System and the Spacecraft Abort Unit was configured for flight when clocks passed T-30 minutes.

The Ekspress AM-8 satellite made its transition to internal power and switched to flight mode with a final GO given by the spacecraft team at T-10 minutes. Proton entered its automated countdown sequence at T-5 minutes when the Flight Control System was aligned and the Master Sequencer calculated the precise T-0 time based on the 5-minute hold release. DM-03 made its switch to internal power at T-5 minutes. Proton-M began pressurizing its tanks for flight and all reached a stable pressure.

Proton-M made its transfer to internal power at T-2 minutes and the DM-03 initiated its Master Sequencer that provided a GO signal to the launch vehicle with the LV Ready signal arriving at T-1:53. A final health poll at T-3.1 seconds cleared the way for engine ignition.

Photo: Tsenki
Photo: Tsenki

Proton-M started breathing fire at T-2.5 seconds – igniting its six RD-275M engines that throttled up to an initial thrust stage before ramping up to a full liftoff thrust of 9,942 Kilonewtons – 1,014 metric ton force. Not using a hold down system, Proton started rising as soon as its thrust exceeded its weight, pulling up the main umbilical plate at the base of the rocket until separating which triggered the Contact Liftoff Command and let Proton switch to ascent mode.

Roaring into the dark skies over the Baikonur Cosmodrome, Proton made an on-time liftoff at 19:00:00 UTC, climbing uphill for the first seconds of its flight, balancing by gimbaling its first stage engines. With an initial thrust to weight ratio of 1.42, Proton quickly initiated its roll and pitch maneuver to get aligned with its north-easterly launch trajectory using the standard 61.3° azimuth that has become the usual route to Geostationary trajectories from Baikonur.

Burning its engines at full thrust, Proton consumed 3,600 Kilograms of propellants each second of powered flight, passing Mach 1 and heading through the area of Maximum Dynamic Pressure right around the T+1-minute mark. The first stage of the Proton, featuring the characteristic external propellant tanks, has an overall length of 21.2 meters and a diameter of 7.4 meters, holding a propellant load of 419,000 Kilograms to be consumed by the powerful main engines during the first two minutes of the flight.

The first stage performed as planned and reached the end of its propellant supply one minute and 59 seconds into the flight with staging taking place in hot mode – shutting down the first stage followed immediately by the ignition of the second stage with the firing of separation charges a few moments later so that the stages can be pushed apart by the second stage’s exhaust – sending the first stage towards a crash landing 310 Kilometers from the launch site.

Photo: Tsenki
Photo: Tsenki

With its three RD-0210 engines and single RD-0211 up and running, the second stage delivered a total thrust of 244,600 Kilogram-force. The stage measures 14.5 meters in length and has a smaller diameter of 4.14 meters, holding 176,800 Kilograms of propellant at liftoff.

Real time calls from the launch bunker remained positive throughout the 3-minute and 28-second burn of the second stage, indicating that Proton was on a good trajectory and all systems were functioning to satisfaction.

Separation of the second stage was also accomplished through a hot staging sequence – starting with the ignition of the four-chamber RD-0214 vernier engine of the third stage that reached a thrust of three metric ton force. At T+5:27, the second stage was shut down and the separation pyros fired so that the third stage could pull away under the power of the vernier before igniting the RD-0213 main engine once clear of the second stage that was looking forward to re-entry and an impact 1,990 Kilometers downrange.

Taking control of the flight, the third stage of the Proton delivered 59,450 Kilogram-force of thrust. It is 4.14 meters in diameter and 6.5 meters long, launching with 46,660 Kilograms of propellants to be used up as part of a four-minute main engine burn.

Separation of the fairing was confirmed just shy of T+6 minutes. Proton got rid of no-longer-needed weight as the launcher had left the dense atmosphere at that point and the satellite was no longer endangered by aerodynamic forces.

Photo: Roscosmos/Tsenki
Photo: Roscosmos/Tsenki
Photo: Roscosmos/Tsenki
Photo: Roscosmos/Tsenki

Main engine shutdown on the third stage occurred nine minutes and 31 seconds after liftoff while the vernier fired for another 10 seconds to finish Proton’s job of inserting the orbital unit into a sub-orbital trajectory. Nine minutes and 46 seconds after liftoff, the Block DM-03 stage was separated and assumed control of the mission – tasked with a three-burn to GSO flight profile.

Block DM-03 measures 5.6 meters in length and 3.72 meters in diameter, holding up to 18,600 Kilograms of LOX and Kerosene to be consumed by a single RD-58M main engine that generates 83.4 Kilonewtons of thrust. Outfitted with a navigation platform and bipropellant attitude control thrusters, Block DM-03 can perform autonomous missions of several hours, however, the ultimate performance of the stage its limited by boil-off of the Liquid Oxygen oxidizer.

In Monday night’s mission, Block DM-03 will be tasked with a series of three main engine burns to lift the Ekspress AM-8 satellite to Geostationary Orbit.

After separating from the Proton Rocket, Block DM-03 was set for a coast phase of six minutes to gain altitude and reach a position near the apogee of its sub-orbital trajectory so that the engine burn could place the stack into a circular Low Earth Parking Orbit. Given the performance of Proton-M and the power of the upper stage engine, the first burn was relatively short in duration – 68 seconds (planned), starting at T+15:45. Based on data from its navigation system, Block DM-03 dynamically adjusted the first burn to correct any insertion inaccuracies by Proton-M.

Next was a coast phase of 56 minutes to allow the stack to reach a position on the ascending leg of its orbit, centering the equator passage for the second burn to position the perigee and apogee locations above the equator. Engine start was expected at T+1 hour 13 minutes with an expected burn duration of just over eight minutes, aiming to raise the apogee of the orbit to nearly 36,000 Kilometers and slightly reduce the orbit’s inclination.

Next was the long coast phase to the apogee of the transfer orbit so that the third burn of the Block DM-03 stage could act as a circularization maneuver. Also, the third burn accomplished the majority of the plane change, firing the upper stage out of plane to reduce the inclination to as close to zero as possible. Ignition of the RD-58M engine was expected six hours and 33 minutes after liftoff for a burn of a little over 3.5 minutes to bring up the perigee and reduce the inclination.

After the shutdown of the Block DM-03, it did not take long until Ekspress AM-8 is sent on its way. Spacecraft separation was confirmed at T+6 hours and 37 minutes, 1:37 UTC on Tuesday to mark the successful conclusion of Block DM-03’s long-awaited certification flight. Roscosmos issued a press release confirming that the mission reached the target orbit. After separation, the satellite was to establish attitude control and communications with the ground for its initial set of operations including the deployment of the solar arrays and communication antennas.

Ekspress AM-8

Image: ISS Reshetnev
Image: ISS Reshetnev

Ekspress AM-8 is a Geostationary Communications Satellite operated by the Russian Satellite Communications Company and manufactured in a partnership between ISS Reshetnev building the satellite platform and Thales Alenia Space providing the multi-band communications payload. The satellite will cover Europe, Africa, the Middle East and South America, delivering a variety of communications services.

Part of the Ekspress communications satellite program, the spacecraft will join a project that started back in 1994 to bridge the technology gap between Russian and Western Telecommunications Satellites. Now, Ekspress satellites are delivering global communications services using spacecraft built in Russia, provided by international satellite builders and cooperative efforts between companies creating a robust communications architecture for TV, Internet, radio and data services for commercial and government customers.

The Ekspress satellite fleet includes the most powerful commercial communications satellites under Russian operation with several satellites launched per year to expand services on a global scale.

Photo: ISS Reshetnev
Photo: ISS Reshetnev

Ekspress AM-8 is based on the Ekspress-1000NTB satellite bus manufactured by Reshetnev as a smaller alternative to the Ekspress-2000 spacecraft that hosts powerful communications payloads. Ekspress-1000NTB is capable of hosting mid-sized communication payloads providing propulsion, power generation, power storage and distribution, precise navigation and accurate Earth pointing and stationkeeping capabilities. Two deployable solar arrays deliver a total payload power of 5,880 Watts (EOL).

Ekspress AM-8 has a launch mass of 2,100 Kilograms carrying a payload of 661 Kilograms. The Thales-built communications payload consists of 24 C-Band, 12 Ka-Band and two L-Band transponders.

Two fixed C-Band coverage zones are provided by the satellite, one covering Europe, the northern half of the African continent, and the Middle East, and the other providing coverage to South America and the east coast of North America. The Ka-Band payload serves three coverage zones – a European Beam provides services to Europe and the Middle East, an African Bean delivers coverage to the entire African continent, Madagascar and the Arabian Peninsula; the third Ka-Band zone covers South America in its entirety as well as the eastern regions of the U.S.

Ekspress AM-8 will be stationed at an orbital position of 14 degrees west from where it will operate for at least 15 years.

Photo: ISS Reshetnev
Photo: ISS Reshetnev

Between 1994 and 2001, two first generation Ekspress satellites and four improved Ekspress A satellites were launched (one was destroyed in a launch failure). The Ekspress AM series of satellites was inaugurated in 2003 and represents powerful communication satellites with long on-orbit service lives and flexible communication payloads. Fourteen Ekspress AM satellites were launched to date – Ekspress AM-4 did not reach its correct orbit in 2011 and was disposed via a targeted re-entry and its replacement satellite was lost in a Proton-M launch failure in May 2014. In addition to Ekspress AM satellites, Ekspress MD satellites are being launched to maintain an alternate supplier of communications satellites as the MD spacecraft are built by Khrunichev.

Two Ekspress MD satellites were launched in 2009 and 2012, but the last launch left the satellite in a useless orbit after an upper stage failure – three more MD satellites are on contract for launch in the next decade. Ekspress AM-5 was launched in late 2013 and represented the most powerful commercial communications satellite launched in the Ekspress series.

In 2014, a duo of Ekspress AT satellites was delivered to orbit to provide communication services across the entire Russian territory. The Ekspress AM-6 satellite, also built by Reshetnev, was launched in 2014 providing C- and Ku-Band coverage to Russia, Europe and Africa. The AM-7 satellite joined the fleet very recently, launching in March 2015 to deliver Internet, Radio & TV to Europe, Asia and Africa.

Over the coming years, new Ekspress versions will be inaugurated including the AMU and RV series while launches of the AM series will continue.