Ariane 5 - VA223 Launch Updates (DirecTV 15, Sky Mexico-1)
Launch Vehicle Overview, Countdown Timeline, Satellite Overview, Mission Timeline
Ariane 5 lofts ComSat Duo into Orbit, conducts Engineering Tests in Space
May 27, 2015
At that time, Ariane 5 underwent control system initialization and received its flight software before the alignment of the Inertial Navigation System. Also, the Attitude Control System was pressurized in preparation for the flight. At L-5 hours, technicians departed the launch complex and cleared the blast-danger area in preparation for propellant loading.
Avionics and battery heaters were activated at that point to keep equipment at a stable temperature. Also, the Vulcain Ignition System’s heaters were activated in preparation for launch. 70 Minutes prior to T-0, final Telemetry, Tracking and Command Systems checks picked up to make sure Ariane was ready for liftoff. At L-30 minutes, the launch team started preparations for the Synchronized Countdown Sequence starting at T-7 Minutes. These final preparatory steps also included the transition of the two satellite payloads to internal power.
One minute before blastoff, the rocket switched to internal power. On-board recorders were activated as the final seconds of the countdown began.
The ignition sequence started at T-37 seconds. The attitude control system on the first stage was enabled and the POGO System that is used to prevent any engine related oscillations was pressurized for flight. Six seconds before ignition, the Cryogenic Umbilical Arms retracted, control was handed over to the launch vehicle’s computers and the Hydrogen Burn-Off System was activated.
Clocks hit zero at 21:16 UTC and the Vulcain 2 engine of the rocket soared to life, throttling up to its liftoff thrust of 97,900 Kilograms. Ignition was carefully monitored by computers to make sure the engine reached operational conditions. With the engine up and running, the ignition command was sent to the Solid Rocket Boosters at T+7.3 seconds.
The first stage continued to operate until T+8 minutes and 54 seconds when the Vulcain 2 engine shut down at an altitude of 171 Kilometers when the stack was traveling 3.4 Kilometers per second. Stage separation was commanded six seconds later and the pyrotechnic separation system was initiated. At T+9:00, the HM-7B engine of the Upper Stage ignited on a 16-minute and 9-second burn to boost the stack into orbit. HM-7B is 2.01 meters long, has a diameter of 0.99 meters and a dry weight of 165 Kilograms. It provides 6,400kg of thrust. It does not have any throttle range and is only operated at 100% of rated performance. The engine provides a gimbal capability of 3°
Over the course of the 50-minute DEMOLIGHT sequence, the ESC upper stage will go through a series of operations implemented to validate the thermodynamic behavior of the stage, specifically the tanks, to evaluate the effectiveness of the in-flight engine chilldown procedure and study propellant settling provided by the attitude control system.
DEMOFLIGHT begins at T+43 minutes and 15 seconds after collision avoidance maneuvers are complete. The first operation is the self-pressurization of the ESC-A propellant tanks followed by a propellant settling maneuver by igniting the reaction control thrusters to deliver a small acceleration that causes the propellants to form a two-phase system to ensure the engine only receives liquid propellants without gas bubbles when being re-started. Propellant settling will continue for the third operation that occurs at T+59 minutes when the tanks will be pressurized with Helium. For that, the VA223 mission is carrying an additional Helium bottle on its second stage.
The satellite provides precise Earth-pointing capabilities and stationkeeping accuracy is +/-0.05 degrees. E-3000 provides the option of adding an electric propulsion system.
DirecTV 15 hosts a powerful communications payload comprised of 30 high-power Ku-Band Transponders, 24 Ka-Band transponders and 18 transponders operating in the reverse band between 17 and 27 GHz permitting uplink in frequency bands used for Direct Satellite Broadcast. The satellite is designed to operate from up to five orbital locations from 99° to 119° West to support a high degree of flexibility responding to customer demand and changes in DirecTV’s satellite constellation.
The satellite will cover the continental United States, Alaska, Hawaii and Puerto Rico initially starting out at a position of 103°W in Geostationary Orbit. DirecTV 15 will provide back-up capacity and expansion capability for DTH services to private and commercial customers. The satellite will operate for a service life of at least 15 years.
The Sky Mexico-1 satellite hosts 24 Ku-Band transponders and two active Reverse-Band transponders that permit the uplink in frequency ranges used by Direct Broadcast Satellites. Two 2.5 x 2.7 meter single shell super elliptical deployable reflectors are installed on the satellite.
Sky Mexico-1 will be stationed at a position of 78.8 degrees West in Geostationary Orbit to provide coverage to Mexico, Central America and the Caribbean. The satellite will ensure the continuation and expansion of Sky Mexico Direct to Home Television Services, operating for at least 15 years.
|0:00:00.00||Vulcain Engine Ignition Sequence|
|0:00:07.05||Solid Rocket Booster Ignition|
|00:01:08||Maximum Dynamic Pressure|
|00:02:23.2||SRB Burnout and Jettison|
|00:03:26.7||Payload Fairing Jettison|
|00:07:52.6||Acquisition by Natal Tracking Station|
|00:08:51.1||Core Stage shutdown|
|00:09:02.3||2nd Stage Ignition|
|00:13:40.0||Acquisition by Ascension Tracking Station|
|00:18:25.4||Acquisition by Libreville Tracking Station|
|00:23:09.4||Acquisition by Malindi Tracking Station|
|00:25:11.2||Second Stage Shutdown|
|Target Orbit: 250 by 35,786km - 6.0°|
|00:25:21||Re-Orientation for DirecTV 15 Separation|
|00:27:47.2||DirecTV 15 Release|
|00:29:47.6||Sylda 5 Separation|
|Re-Orientation for Avoidance Maneuver|
|LOX Tank Passivation|
|01:44:30.6||Ariane 5 - End of Mission|