SpaceX is setting up to launch Inmarsat-5 Flight 4, a mission that will put a communications satellite into geostationary orbit for commercial satellite operator Inmarsat. SpaceX’s window lasts 49 minutes, and opens at 7:21 PM ET (4:21 PM PT) on Tuesday, with another window opening at the same time tomorrow in case of any issues resulting in a scrub.
The launch payload is the fourth satellite in Inmarsat’s Global Xpress (GX) constellation of craft, which aims to provide globe-spacing high-speed mobile broad band using the Ka-band spectrum.
The GX network first started offering service nearly two years ago, but this fourth unit adds additional load capacity for the overall network, and some redundancy in case anything goes wrong with one of the other satellites in the constellation.
For SpaceX, the launch is significant because it’s the heaviest orbital payload a Falcon 9 rocket has every carried to date, which is why SpaceX won’t be attempting to recover the first stage of the rocket as it usually does. The Falcon 9’s rocket requires a different kind of configuration to maximize its load capacity, which results in a rocket that’s fully expanded via the launch process.
Today’s launch takes place from LC-39A, the launch facility at Kennedy Space Center in Florida that SpaceX is leasing, and that was used by NASA for historic launches including multiple Apollo launches, as well as many Space Shuttle missions over the years. The launch live stream should go live via the embed above starting around 20 minutes or so prior to launch.