Soyuz VS12 Launch Updates - Galileo FM-5 & FM-6
Launch Vehicle Overview, Countdown Timeline, Galileo Overview, Ariane Archive
Next Galileo Satellite Pair enters Orbit after successful Soyuz Launch
September 11, 2015
The overnight countdown to the VS12 launch was initiated eight hours ahead of the precisely calculated T-0 time, beginning with the launch team reporting to console to start tracking the progress of preparations for propellant loading that began out at the launch pad. All ground systems and tracking stations were prepared in the hours leading up to the countdown to provide an all-clear status to the team inside the Jupiter Mission Control Room.
The Russian State Commission, also overseeing launches from the faraway Soyuz launch site, convened at L-5 hours to review the results of launch vehicle testing performed Tuesday and Wednesday and check the status of launch preparations. With no outstanding items, the State Commission gave the formal approval for the launch of the Soyuz, allowing the vehicle to head into propellant loading operations.
Propellant loading commenced inside L-4 hours when the launch pad had been cleared by non-essential personnel. Liquid Oxygen systems went through a brief chilldown sequence to condition transfer lines and tanks before the -183°C oxidizer started flowing into the boosters, core stage and third stage of the Soyuz rocket. Kerosene loading picked up around the same time and Soyuz also received Liquid Nitrogen to act as pressurant gas on the boosters and core stage while the modified third stage received Helium to serve the same purpose.
All in all, the 12 tanks of the Soyuz rocket were loaded with 272,140 Kilograms of LOX and Kerosene over the course of the two-hour fueling sequence that wrapped up when Kerosene tanks had been fully loaded and topping on the cryogenics started to keep them at flight level as countdown clocks continued to tick down.
Pressing into the Automated Countdown Sequence at T-6 minutes, Soyuz began running through a highly choreographed set of steps to transition to its autonomous launch configuration. The telemetry system of the Soyuz went to launch mode at T-5 minutes. At the same time, Fregat made its switch to battery power, entering its liftoff configuration.
With four minutes left in the countdown, Soyuz began purging the RD-107A engines on the four boosters and the RD-108A engine on the Core Stage with Nitrogen gas to remove any combustible substances from the plumbing to ensure a clean and controlled ignition. After propellant drainback, the Soyuz tanks closed their fill and drain valves and safety valves to begin the process of pressurizing for liftoff. All 12 tanks built up pressures and Soyuz separated the Fregat and Payload Umbilical, causing a loss of signal from the two Galileo satellites, their signals to be heard the next time when deployed into orbit.
Heading out of the dense atmosphere, Soyuz jettisoned its protective payload fairing three and a half minutes into the flight when passing 110 Kilometers in altitude. Since the two Galileo satellites and Fregat Upper Stage could no longer be harmed by aerodynamic forces, shedding the fairing allowed Soyuz to lose some no-longer-needed weight to improve its performance heading up the hill. Now exposed for the rest of the way into orbit, the two satellites were sitting side by side atop their specially-built payload dispenser.
Immediately after separation, Fregat began using its Hydrazine-fueled Attitude Control Thrusters to enter a pre-programmed three-axis orientation to set up for main engine start. Ignition was preceded by the typical ten-second propellant settling maneuver. Lighting up its S5.92 main engine ten minutes and 24 seconds into the flight, Fregat started a very long burn that aimed for an elliptical transfer orbit.
Flying in the MT configuration - its largest - the Fregat Upper Stage carried 7,100 Kilograms of storable propellants for consumption by the S5.92 engine that can operate at two thrust settings - 19.85 Kilonewtons and a reduced thrust level of 14kN while 12 hydrazine thrusters are used to deliver three-axis attitude control.
Upon completion of its first burn, Fregat entered a coast phase of three hours and 15 minutes to climb up to the apogee of its orbit so that the second burn can act as a circularization maneuver.
The second main engine burn of the Fregat upper stage is expected to commence three hours and 38 minutes into the mission and last four minutes and 22 seconds. The two Galileo satellites are targeting slots in Plane A of the satellite constellation orbiting the Earth at 23,522 Kilometers, inclined 57.4 degrees. Spacecraft separation is expected three hours, 47 minutes and 57 seconds after launch as the two satellites are pushed away from the payload adapter at the same moment, heading off into different directions to begin their long missions.
Soyuz Rocket set to Launch next Galileo Satellite Pair from French Guiana
September 9, 2015
Though the mission was still half a year away at the time, the Soyuz hardware was already at the launch site and Russian specialists were still present after VS11 - allowing assembly of the next rocket to be completed. The 27.8-meter Core Stage had its four liquid-fueled boosters installed on it followed by the attachment of the third stage so that Soyuz could be placed in a storage mode, awaiting its liftoff.
The two Galileo satellites finished assembly and testing earlier in 2015 and were placed in storage at their manufacturer, OHB Systems in Germany. Shipping of the two satellites was completed in late July using a Boeing 747 cargo aircraft to fly them to French Guiana where they completed the last leg of their journey via truck.
Being unpacked inside a clean room facility, the two satellites first underwent a series of inspections before completing a fit check that confirmed both had a good fit on the payload adapter that will carry them into orbit side by side for a simultaneous separation into different directions.
Next for the two satellites was a set of stand-alone tests to make sure both were in good condition and ready to be loaded with 73 Kilograms of Hydrazine propellant for use in orbit corrections and maintenance. Fueling and final testing took place over the course of August.
Loaded with propellants and pressurant gas, the two satellites were installed atop the RUAG-built payload adapter by August 28.
Results of pre-launch testing will be reviewed as part of the Launch Readiness Review that will provide clearance for the start of Soyuz countdown operations eight hours ahead of the T-0 target.
Countdown & Launch Sequence:
The first step of the countdown is the activation of the Soyuz launcher for pre-launch checks while teams at the pad complete final hands-on tasks such as the installation of batteries on the Soyuz, the removal of protective covers from the launcher and close-outs of the rocket and service structure.
Pending approval from the Russian State Commission, propellant loading on the Soyuz will begin four hours ahead of liftoff. Over the course of the two-hour propellant loading sequence, the boosters, core stage and third stage of the Soyuz will receive a total of 272,140 Kilograms of -183°C Liquid Oxygen oxidizer and Kerosene fuel. For launch, Soyuz is also loaded with liquid Nitrogen for booster and core stage tank pressurization and Helium to serve the same purpose on the third stage of the vehicle.
After fueling and final launch system tests, the rocket is exposed by retracting the Mobile Service Structure at L-60 minutes. Launch Command Power is activated at L-30 minutes and the spacecraft are switched to internal power 18 minutes ahead of liftoff.
Ten minutes before launch, the final pre-launch status check is performed. At the same time, the Soyuz Inertial Guidance System is activated and on-board recorders become active. At L-8 minutes, the final GO for launch is given before the countdown heads into the Automated Sequence six minutes before liftoff.
Fregat-MT is 3.35 meters in diameter and 1.5 meters long capable of holding 7,100 Kilograms of Unsymmetrical Dímethylhydrazine fuel and Nitrogen Tetroxide oxidizer. Fregat is an autonomous Upper Stage that is equipped with its own power, propulsion and control system to perform flights of up to 48 hours. S5.92 is operated in two thrust modes – 2,025 Kilograms and 1,430 Kilograms.
After a very short coast period of just one minute, the Fregat Upper Stage ignites its S5.92 engine to boost the stack into a Parking Orbit. Performing a long burn of 13 minutes and eight seconds, Fregat will boost the stack into an elliptical transfer orbit with the apogee already matching the target altitude above 23,000 Kilometers.
Following completion of the first Fregat burn, the stack will be coasting for three and a quarter hours to climb all the way up to apogee so that the second upper stage burn can raise the perigee and circularize the orbit.
The second Fregat burn is planned to commence three hours and 38 minutes into the flight and last four minutes and 22 seconds. Galileo FM-5 and FM-6 are targeting an insertion orbit of 23,522 Kilometers at an inclination of 55.04 degrees in Plane A of the Galileo constellation. Spacecraft separation is planned at T+3 hours 47 minutes and 57 seconds as the two spacecraft are released simultaneously, being deployed into opposite directions to prevent a collision of the satellites.
Following orbital insertion, the two spacecraft will complete a series of pre-programmed steps that include the deployment of the solar arrays, the acquisition of a stable three-axis orientation and the initiation of communications with ground stations. The spacecraft will complete several days of initial testing before heading into commissioning and starting to transmit navigation signals for further testing.
Fregat will finish its mission with two small engine burns that move it into a disposal orbit for passivation.
Galileo will provide horizontal and vertical position measurements with sub-meter accuracy. Basic services with a lower precision will be available for free and open to anyone with a receiver compatible with Galileo. Full accuracy services will be available for government and military users, but also to all paying commercial customers. The Galileo constellation also provides global Search and Rescue Function with feedback to the user.
Serial production of the Galileo satellites suffered a one-year delay due to tooling and production issues, pushing the launch of the first two FOC satellites into 2014. The first 22 FOC satellites are booked for launches on five Soyuz rockets (two satellites per launch vehicle) and three Ariane 5 ECE vehicles (four satellites per launcher). Initial operations of the constellation will begin when the first 18 satellites are operational.
Each Galileo FOC satellite weighs 732.8 Kilograms and measures 2.91 by 1.7 by 1.4 meters in dimensions when its solar arrays are stowed - the core satellite body is 2.5 by 1.2 by 1.1m in size. In orbit, with both arrays extended, the satellite has a span of 14.67 meters from tip to tip.
The satellite consists of seven modules including a plug-and-play propulsion module for a simplified production and integration as part of the serial production of Galileo satellites.
The Galileo satellites are equipped with a Hydrazine monopropellant propulsion system consisting of a central Hydrazine tank and two thruster banks, each containing four 1-Newton thrusters. The propulsion system is used for orbit adjustments and constellation maintenance, attitude control and the maneuver to a disposal orbit at the end of the satellite's mission.
The heart of the Galileo satellites are four clocks - two passive hydrogen maser clocks and two Rubidium clocks. The hydrogen maser clocks are atomic clocks that use the ultra-stable 1.4 GHz transition in hydrogen atoms to achieve a timing accuracy of under 0.45 nanoseconds of drift over a 12-hour period. Rubidium atomic clocks are commonly used in space applications due to their robustness and reliability, but they achieve a lower accuracy of <1.8 nanoseconds over 12 hours.
The satellites are configured to run one hydrogen maser clock in primary mode and a Rubidium clock as hot backup. Should the hydrogen maser encounter any problem, an instantaneous switchover to the Rubidium clock would be performed.
In case of a failure of the primary hydrogen maser, the two spare clocks would automatically start up. On ground command, the secondary hydrogen maser could be activated to take over within a period of days as part of a highly redundant system that ensures that the satellites provide continuous timing signals.
Signals sent by the satellites include pilot signals which are data-free signals that only include a ranging code, not modulated by a navigation data stream. The ranging code is a Pseudo-Random Noise (PRN) sequence of 0s and 1s that allow the receiver to determine the signal's travel time. Data signals include binary-coded messages containing information on the satellite ephemeris (position and velocity), clock bias parameters for error correction, satellite health status and other complementary information.
Up to 150 active beacons can be received by one satellite simultaneously. The distress message is then modulated onto the L6 signal at 1,544 MHz and transmitted to dedicated ground stations with a latency of less than ten minutes. The position of the distress beacon is calculated with an accuracy of at least five Kilometers and can reach an accuracy of a few meters if the terminal is equipped with a Galileo receiver. Unique to Galileo is that the satellites provide feedback to the distress beacons acknowledging the reception of the signal.
The Galileo satellites use S- and C-Band for housekeeping communications. Two S-Band antennas are installed on the satellite for the transmission of telemetry data to ground stations and the uplink of commands for satellite operations. The S-Band terminal also receives and transmits ranging signals that provide precise orbit determination. C-Band is used to uplink mission data from Galileo uplink stations including clock bias data and integrity data about how well each satellite is functioning. These messages are relayed via the data signals in the navigation bands to allow receivers to correct for known errors.