Tonight, watch SpaceX launch one of its heaviest satellites yet

[Buster's Uncle]

Tonight, watch SpaceX launch one of its heaviest satellites yet
But that means no landing this time
The Verge
by Loren Grush@lorengrush   May 15, 2017, 9:44am EDT   

<a href="http://www.youtube.com/watch?v=ynMYE64IEKs" target="_blank" class="aeva_link bbc_link new_win">http://www.youtube.com/watch?v=ynMYE64IEKs</a>

This evening, SpaceX will attempt to launch its sixth Falcon 9 rocket of the year, sending a communications satellite into orbit for the company Inmarsat. But don’t expect one of the company’s signature landings after launch this time. Unlike most of its missions these days, SpaceX will not try to recover the Falcon 9 post-takeoff.

That’s because the requirements of this mission would make it pretty hard to land the rocket after launch. The satellite that SpaceX is launching, called Inmarsat-5 F4, is larger than a double-decker bus and weighs nearly 13,500 pounds. That makes it perhaps the heaviest single probe that the Falcon 9 has ever lifted. Plus, the satellite is going into a particularly high orbit called Geostationary Transfer Orbit — a path 22,000 miles above the Earth’s surface. Both of these factors combined mean that the Falcon 9 will need to use a whole lot of propellant during launch to get the satellite where it needs to go. That means there will be very little propellant leftover to perform a landing. (Learn more about that here.)

However, today’s launch is still significant for SpaceX, since it marks the company’s first mission for Inmarsat. The satellite that’s going up tonight will join three additional I-5 probes already in orbit, making up the Global Xpress constellation for Inmarsat. This satellite group is responsible for providing high-speed, mobile broadband service to airliners, ships, and more.

Additionally, today’s launch comes just over two weeks after SpaceX’s last mission — and the company’s next launch is tentatively scheduled for just over two weeks from now. That means SpaceX may finally be getting to the launch cadence that the company has boasted for a while now. In February, SpaceX president Gwynne Shotwell told Reuters that the company planned to launch “every two to three weeks” this year, after one of the company’s launchpads in Florida became operational. It seems like SpaceX may be on track for meeting that goal.

Tonight’s Falcon 9 is scheduled to take off around 7:20PM ET from pad 39A at NASA’s Kennedy Space Center in Florida. The company has a 49-minute launch window, during which time the Falcon 9 can still take off. If for some reason tonight’s launch is scrubbed, SpaceX has a backup launch date for tomorrow at 7:21PM ET. Though weather is looking good for tonight so far; there’s an 80 percent chance that conditions will be right for launch, according to Patrick Military Air Force Base. Check back here about 15 minutes prior to takeoff to watch SpaceX’s coverage of the launch live.


https://www.theverge.com/2017/5/15/15640268/spacex-launch-watch-live-stream-falcon-9-rocket-inmarsat