Автор tnt22, 03.05.2019 12:28:07
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Цитата06/20/2019 17:12 Stephen ClarkToday's mission is numbered VA248 in Arianespace's flight sequence. It's the 248th launch of an Ariane rocket since 1979, and the 104th flight of an Ariane 5 since its debut in 1996.Liftoff is set for 2143 GMT (5:43 p.m. EDT; 6:43 p.m. French Guiana time).AT&T's T-16 satellite, set to join a fleet of broadcasting spacecraft originally deployed by DirecTV, is riding in the upper berth of the Ariane 5's payload fairing today. The Eutelsat 7C video distribution satellite will be in the lower position inside the fairingThe T-16 satellite will provide high-power direct-to-home TV broadcast services over the continental United States, Alaska, Hawaii, Puerto Rico and U.S. Virgin Islands. The 13,955-pound satellite was assembled by Airbus Defense and Space in Toulouse, France, and will use a hydrazine-fueled main engine to circularize its orbit at geostationary altitude over the equator some 22,000 miles (36,000 kilometers) over the equator following today's launch.The Eutelsat 7C satellite, owned by Paris-based Eutelsat, will head to a geostationary position at 7 degrees east longitude, where it will be co-located with the Eutelsat 7B spacecraft launched in 2013.Eutelsat 7C, manufactured by Maxar Technologies (formerly known as SSL) in Palo Alto, California, will provide data and video services over Europe, Africa, the Middle East and Turkey during its mission. The spacecraft is the first commercial all-electric communications satellite built by Maxar, relying entirely on plasma thrusters for orbit-raising and in-space maneuvers.The Eutelsat 7C satellite will launch in the lower berth of the Ariane 5's dual-payload accommodation. Once AT&T's T-16 satellite deploys from the rocket, a Sylda adapter structure will jettison to reveal the roughly 7,500-pound (3,400-kilogram) Eutelsat 7C spacecraft for release.The final countdown commenced at 1018 GMT (6:18 a.m. EDT), with clocks at the Guiana Space Center timed for a targeted liftoff at 2143 GMT (5:43 p.m. EDT; 6:43 p.m. French Guiana time). The launch window extends for an hour and 47 minutes. Скрытый текст: Electrical systems checks on the Ariane 5 began at 1108 GMT (7:08 a.m. EDT).Workers have also put finishing touches on the launch pad, including the closure of doors, removal of safety barriers and configuring fluid lines for fueling. The flight program for today's launch was also be loaded into the rocket's computer.The launch team will begin the process to fuel the rocket with super-cold liquid hydrogen and liquid oxygen propellants around 1705 GMT (1:05 p.m. EDT). First, ground reservoirs and the rocket's helium tank were pressurized, then the fuel lines will be chilled down to condition the plumbing for the flow of super-cold liquid hydrogen and liquid oxygen, which are stored at approximately minus 423 degrees Fahrenheit and minus 298 degrees Fahrenheit, respectively.It will take approximately two hours to fill the Ariane 5 core stage tanks.A similar procedure for the Ariane 5's cryogenic upper stage is scheduled to commence at 1815 GMT (2:15 p.m. EDT).Chilldown conditioning of the Vulcain 2 first stage engine will occur at 1825 GMT (2:25 p.m. EDT), and a communications check between the rocket and ground telemetry, tracking and command systems is scheduled for 2038 GMT (4:38 p.m. EDT).A final weather briefing will come at T-minus 10 minues, and then the computer-controlled synchronized countdown sequence will begin seven minutes before launch to pressurize propellant tanks, switch to on-board power and take the rocket's guidance system to flight mode.The Vulcain 2 engine will ignite as the countdown clock reaches zero, followed by a health check and ignition of the Ariane 5's solid rocket boosters seven seconds later to send the 1.7 million-pound launcher skyward.Five seconds after blastoff, the rocket will begin pitching east from the ELA-3 launch pad, surpassing the speed of sound less than a minute into the mission. The Ariane 5's twin solid rocket boosters will jettison nearly two-and-a-half minutes after liftoff.Once above the dense atmosphere, the launcher's payload fairing will fall away at an altitude of more than 70 miles -- about 112 kilometers -- at Plus+3 minutes, 22 seconds. The Ariane 5's first stage will shut down 8 minutes, 39 seconds, after liftoff, followed moments later by stage separation and ignition of the hydrogen-fueled cryogenic HM7B upper stage engine.The rocket's upper stage will fire more than 16 minutes, accelerating to a velocity of 21,000 mph, or more than 9.3 kilometers per second, to reach an orbit with a planned high point of 35,756 kilometers (22,218 miles), a targeted low point of 250 kilometers (155 miles) and an inclination of 6 degrees.The release of AT&T's T-16 satellite will come first at Plus+27 minutes, 43 seconds.Once the T-16 is deployed, the Ariane 5 rocket's barrel-shaped Sylda 5 dual-payload adapter will be jettisoned at Plus+29 minutes, 23 seconds.Eutelsat 7C will separate from the lower portion of the payload stack at 33 minutes, 59 seconds.Both satellites will use their own propulsion to raise their orbits to a circular perch along the equator at an altitude of nearly 22,300 miles (35,800 kilometers).
Цитата06/20/2019 23:59 Stephen ClarkHere's a view of the Ariane 5 rocket on the launch pad yesterday after rollout from the final assembly building.
Цитата06/21/2019 00:03 Stephen ClarkMinus-40 minutes. The Ariane 5 is now fully fueled with cryogenic liquid hydrogen and liquid oxygen propellants.
Цитата06/21/2019 00:13 Stephen ClarkMinus-30 minutes. Some statistics on today's flight:[/li]248th launch of an Ariane rocket since 1979310th Arianespace mission104th launch of an Ariane 5 rocket since 199671st launch of an Ariane 5 ECA rocket since 200279th flight of a Vulcain 2 engine103rd flight of an HM7B engine89th Ariane 5 launch targeting GTO5th launch from the Guiana Space Center in 20192nd Ariane 5 launch in 2019