Tuesday, March 7, 2017

Vega Flight VV09 Sends Sentinel-2B Satellite to Space

Liftoff of the Vega rocket on flight VV09 with the Sentinel-2B satellite, March 6, 2017. Photo Credit: ESA / CNES / Arianespace

Cloudy skies posed no issue as Arianespace‘s Vega launch vehicle successfully delivered its Sentinel-2B payload into orbit on Flight VV09. The Earth-observation satellite, part of Europe’s Copernicus program, left the pad on time at 8:49 p.m. EST March 6 (01:49 GMT March 7), 2017, from the Guiana Space Center in South America.

“Through Copernicus, Europe is developing its own global monitoring system to better address our environment and security issues,” Luce Fabreguettes, Arianespace’s senior vice president for missions, said in a news release. “This objective is fully in line with our mission to provide autonomous and independent access to space to Europe, at the service of a better life on Earth.”

At the precise liftoff time, Vega’s flight computer sent the command to ignite the first stage P80 solid rocket motor (SRM). Unlike liquid-fueled engines, which need time to reach flight-level thrust before lifting off, Vega’s SRM provided nearly instantaneous power and the vehicle quickly cleared the tower.

Shortly after rising from the complex, the Vega rocket began its pitch, roll, and yaw maneuvers to assume a proper northerly flight heading to deliver the satellite into its Sun-synchronous orbital slot.

Approximately 30 seconds after leaving the jungle, Vega and its payload exceeded the speed of sound. The P80 consumed its 193,367 pounds (87,710 kilograms) of solid fuel in 113 seconds, providing up to 677,799 pounds (3,015 kilonewtons) of vacuum thrust as it soared spaceward.

The P80, its job complete, separated from the vehicle shortly after burnout. This was closely followed by ignition of the second stage’s Zefiro 23 SRM.

Like its first stage sibling, the Zefiro 23 burned a hydroxyl-terminated polybutadiene (HTPB) 1912 solid propellant. The stage continued to build velocity during its 73 seconds of operation and separated from the third stage roughly three-and-a-half minutes after liftoff.

After a 12 second coast, the third stage’s Zefiro 9 engine ignited. This was followed shortly by jettisoning of the payload fairing.



Although smaller than its first and second stage counterparts, the Zefiro 9 actually had the longest burn time. During its two minutes of operation, it consumed 23,296 pounds (10,567 kilograms) of solid fuel and separated from the AVUM orbital propulsion module six-and-a-half minutes after leaving the Guiana Space Centre.

Although the three SRMs did a good job of lofting the Sentinel-2B satellite to orbit, the spacecraft needed more precision for its orbital insertion than was capable from the solid-fueled rockets.

To that end, the Attitude and Vernier Upper Module (AVUM) provided the fine control necessary for precise orbital operations.

The monopropellant-fueled AVUM completed two burns. The first lasted seven minutes. That was followed 40 minutes later by a two-minute push to place the Sentinel-2B spacecraft in its proper orbit.

Once the satellite separated from AVUM, the propulsion module fired one last time to place itself on a suborbital trajectory so as to not leave unnecessary hardware in orbit.

Sentinel-2B will undergo orbital check-out procedures before joining its Sentinel-2A sibling in providing Earth-observation data with a particular focus on vegetation and pollution. Once operational, the pair will provide full Earth coverage every five days.

The successful launch of flight VV09 marks the third of 2017 for Arianespace and the ninth overall for the Vega launcher since its debut in 2012. Up next for the France-based commercial launch provider is the launch of two telecommunications satellites on an Ariane 5 rocket, which is tentatively scheduled for no earlier than March 21, 2017.

Written by: Curt Godwin
Original source: spaceflightinsider.com

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