Astra 2E Ascent Profile
The Proton-M first three stages place the orbital unit (OU), which consists of a Breeze-M upper stage, adapter system and Astra-2E, into 51.5° inclination suborbital trajectory.
Six RD-276 engines ignite at approximately T-1.75 seconds and are commanded to 107% of nominal thrust, which is increased to 112% six seconds into flight. Lift-off confirmation is signalled at T+0.5 sec.
The staged ignition sequence verifies whether all engines are functioning nominally before being committed to launch.
The launch vehicle ascends vertically for about 10 sec. Pitch control, engine ignition and cut-off times, payload fairing jettison times and attitude control allow Proton-M rocket stages to fall onto nominal drop zones.
The first stage and the second stage separate 120 and 327 seconds after lift-off, respectively.
Engine burns and cut-offs, fairing jettison and rocket attitude are commanded in flight by the control system.
347 seconds after lift-off the payload fairing is dropped on to the second stage booster drop zone. During jettison longitudinal and cross joint clamps unlock, fairing halves are unfolded by means of pushers, following which the halves are broken off. Once in the nominal orbit, the launch vehicle control system shuts down the steering engines, breaks mechanical links between the third and upper stages and ignites solid retro motors in order to withdraw the third stage jettisonable booster.
Proton-M powered flight lasts 582 seconds. The OU powered flight begins with the third stage separation.
The upper stage follows a five-burn injection profile.
The first burn occurs 94 seconds after the Breeze-M separation from the launcher, forming a parking orbit.
The second ignition is performed in the first ascending node of the parking orbit, resulting in an intermediate orbit. The third main engine (ME) burn occurs at the intermediate orbit perigee in an ascending node. The ME ignites for the fourth time 137 seconds after the third ME cut-off. The third and fourth ME burns form a transfer orbit with an apogee close to that of the target orbit.
The additional propellant tank is jettisoned between the third and the fourth ME burns. The fifth ME burn is performed at the transfer orbit apogee in a descending node, placing the OU into the target orbit.
Prior to each ME burn and APT separation, impulse correction motors fire to settle propellants in the tank.
During OU coast flight, i.e. the main engine is off, the upper stage control system turns the OU to provide proper orientation for the spacecraft, generate thrust impulses, support radio control and separate the spacecraft.
In-flight telemetry is downlinked online or played from the memory.
The Astra-2E satellite is released 12 minutes and 36 seconds after the final ME burn, followed by a 300-second manoeuvre to maintain the Breeze-M orientation.
After two withdrawal impulses, the upper stage is put into a safe mode, dropping pressures in all the containers.
The Astra 2E injection from lift-off to spacecraft separation is completed in 33,120 seconds, or 9 hours and 12 minutes.
Launch Delay
After the failure, a commission was formed to determine the root cause of the mishap and recommend corrective actions. The failure was traced back to improperly installed angular velocity sensors that fed incorrect yaw-rate data to the vehicle’s flight control system that started to gimbal the vehicle’s first stage engines because the data fed to the computers indicated that the vehicle was flying in an incorrect attitude. When examining telemetry data and wreckage of the Proton, it was found that the sensors in question were installed upside down which caused the vehicle to fail immediately after launch and gyrate wildly before crashing.
The failure commission recommended improvements to quality control including the implementation of photo and video documentation of Proton’s assembly process. With these findings and recommendations, the work of the commission was complete and Proton’s commercial launch provider, International Launch Services, received a report on the failure investigation that was reviewed by the ILS Failure Review Oversight Board. ILS and the customer for this Proton mission, SES of Luxembourg, agreed to return the Proton to flight.
Astra 2E Pre-Launch
An An-124 transport plane delivered the Astra 2E satellite to the launch site on June 14 2013, and its Briz-M upper stage followed four days later. However the launch preparation campaign was interrupted by the July 2 launch accident. By the middle of July, the mission was re-scheduled for September 15. In the second half of August, the mission slipped to September 17 and the fueling of the spacecraft started by the end of the same month.
On September 12, International Launch Service, ILS, which markets Proton rocket to commercial customers around the world, announced that the mission had been “postponed today for technical reasons associated with the launch vehicle” with a new launch date to be determined at a later time.
According to the company, on September 11, Khrunichev engineers at the launch site received an out-of-tolerance reading in the first stage of the vehicle. It was determined that further investigation had been necessary, requiring the launch vehicle be returned to the processing hall for additional testing. The vehicle and satellite remained in a safe configuration at the launch site, ILS said.
The launch was then rescheduled for September 30.
Astra 2E Launch
The Astra 2E satellite roared into space on board an ILS Proton Breeze M booster at 3:38 am Baikonur time (23:38 CET and 17:38 EDT on September 29). After a 9-hour, 12-minute mission, the Breeze M upper stage of the Proton rocket successfully released the Astra 2E satellite directly into geostationary transfer orbit.
The Proton followed a standard ascent profile delivering the Briz-M Upper Stage and its Astra 2E payload to a sub-orbital trajectory – successfully concluding its portion of the mission and handing control of the flight over to the Briz-M. The Upper Stage then executed its five burn mission profile over the course of more than nine hour to reach Geostationary Transfer Orbit with spacecraft separation taking place at 6:50 UTC on Monday. This marked the first flight of the Proton since the dramatic July 2 failure when a Proton-M/Block DM-03 launch vehicle veered off course immediately after liftoff and exploded when it crashed 30 seconds after launch. With Proton cleared for launch and final launch preparations complete, Countdown Operations began on Sunday at the Baikonur Cosmodrome about 11 hours and 30 minutes before liftoff.
The first step in the countdown was the activation of the Briz-M Upper Stage and checkouts of its Guidance, Navigation and Control System. The Briz-M countdown sequence started at that point as the Upper Stage went through preparations for its long mission. At T-8 hours, the Launch Pad was cleared of all non-essential personnel for Propellant Loading.
The Proton Launcher was powered up at T-6 hours and 10 minutes and the Guidance System started verifications and the Spacecraft Abort Unit was activated.
The Russian State Commission completed its final review and gave the go-ahead for Proton-M propellant loading that started at T-5 hours. A total of 622,075 Kilograms of Unsymmetrical Dimethylhydrazine Fuel and Dinitrogen Tetroxide Oxidizer were loaded. Loading the launcher with these toxic propellants required about 2.5 hours after which the launch pad was re-opened and technicians could finish a final set of configuration tasks, buttoning up the rocket for flight.
One hour ahead of T-0, the Service Structure was retracted to its launch position at a safe distance to the launcher. Also at that time, all personnel retreated to their launch positions for the final countdown phase. At T-45 minutes, the Master Sequencer was activated and the individual sequencers of Ground Support Equipment, the spacecraft, launcher and Upper Stage were aligned.
The Proton Launch Abort System and the Spacecraft Abort Unit were activated and configured for flight. The Astra 2E satellite was switched to its flight sequence late in the Countdown and was transitioned to Internal Power as the Terminal Countdown Phase approached. At T-10 minutes, the Satellite Team was polled for a GO/No GO for launch, allowing the countdown to press into T-5 minutes.
