Vega finds a gap in the weather to attempt Falcon Eye-1 launch

Arianespace’s Vega rocket is set to launch the Falcon Eye-1 spacecraft for the United Arab Emirates. The launch has been delayed by several days due to unacceptable upper-level winds. Tuesday’s attempt is targetting a window occurred at the top of the launch window that opens at 01:53 (UTC) on Wednesday (10:53:03 local time on Tuesday) from the European Spaceport in French Guiana.

This will be Arianespace’s sixth launch of the year, and the 15th Vega mission since this launcher began its career at the Guiana Space Center in 2012 Flight VV15 marks the 12th Earth observation mission for Vega, although the mission has had to wait several days until the unacceptable upper-level winds subsided.

Flight VV15 will be performed from the Vega Launch Complex (ZLV). The pad was built on the site of the former Ensembele de Lancement Ariane 1 (ELA-1) launch pad which was used by twenty-five Ariane 1, 2 and 3 rockets between 1979 and 1986.

An even earlier launch pad on the site, CECLES, had been used for a single launch of the Europa II rocket – an earlier European satellite launch project under the European Launcher Development Organisation (ELDO) – which failed in 1971.

This Earth observation satellite for the United Arab Emirates was developed by Airbus Defence and Space as prime contractor and Thales Alenia Space as co-prime.

FalconEye1 is the first of two spacecraft that will compose the United Arab Emirates’ FalconEye satellite system, which is to serve two primary purposes: supporting the needs of this country’s armed forces and supplying the commercial market with imagery.

The satellite was produced by Airbus Defence and Space as prime contractor and Thales Alenia Space as co-prime. The follow-on FalconEye2 spacecraft, also manufactured by the Airbus Defence and Space/Thales Alenia Space teaming, is scheduled to be orbited before the end of 2019 on a separate Vega mission.

Falcon Eye-1 during processing – via Arianespace

The FalconEye satellite is a high performance optical Earth-observation satellite system for the Armed Forces of the United Arab Emirates (UAEAF) manufactured by Airbus Defence and Space as prime contractor and Thales Alenia Space as co-prime.

The overall system is based on two identical satellites, FalconEye1 and FalconEye2, in Sun-synchronous orbit (SSO). Each satellite features an Earth observation payload, with very-high-resolution optical capabilities. It is equipped with a ground system for monitoring, receiving and processing the images.

The FalconEye1 satellite will be the first space component of the system, and will have a dual use purpose: support the needs of UAE Armed Forces, and provide the commercial market with images. It will weigh approximately 1,197 kg. at launch and will be raised to a heliosynchronous orbit at 611 kilometers.

As satellite prime contractor, Airbus Defence and Space was in charge of the satellite design, integration and tests, and supplied the platform. Thales Alenia Space, as co-prime, designed and supplied the Optical Instrument and the image chain.

The countdown for Vega’s launch began nine hours and ten minutes before the rocket was due to lift off. As the clocks ticked towards zero the rocket’s systems – including the inertial reference system (IRS), multi-functional unit (MFU) and onboard computers were brought online and tested.

Vega ahead of launch – via Arianespace

Three hours and fifteen minutes before liftoff the mobile gantry used to assemble and access the rocket will retract away from the vehicle – a process that takes about three quarters of an hour to complete. Once the gantry has reached its retracted position, the rocket’s inertial reference system is aligned, and its communications and telemetry systems activated.

The final four minutes of the countdown is the “synchronized sequence”, where computers control all operations. Once the countdown reaches zero, the P80 solid rocket motor powering Vega’s first stage ignites and the rocket lifts off.

The P80 burns for one minute and 54 seconds, propelling the rocket to a velocity of 1.78 kilometers per second (3,980 miles per hour) and an altitude of 53 kilometers (33 miles, 29 nautical miles). The first stage separates at burnout, with the second stage igniting its Zefiro 23 motor almost immediately for a one-minute, 43-second burn. Ignition of the third stage Zefiro 9 motor comes around fourteen seconds after the second stage burns out and separated – with this stage firing for two minutes and 34 seconds before it also separated. About five seconds into the third stage burn,

Vega’s payload fairing separates from the nose of the rocket, exposing Falcon Eye-1 to space for the first time.

Vega’s fourth stage, Avum, uses liquid propellant and can be shut down and restarted in flight. It made three burns during this launch – two before spacecraft separation, with a third burn to deorbit itself after successfully deploying Falcon Eye-1.

Vega Avum fourth stage – via ESA

Avum is powered by a Ukrainian RD-843 engine, derived from engines that the Yuzhnoye Design Bureau and Yuzhmash production plant developed for the third stage of the Soviet Union’s R-36 family of intercontinental ballistic missiles.

The mission profile calls for a 57 minute flight to the separation of the spacecraft. About fifty minutes after spacecraft separation, Avum made its third burn to deorbit itself, ensuring that no unnecessary debris was left in orbit from this mission.

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