As reported by Tech Crunch,
UPDATE 12:55 PM EST: SpaceX called a hold in the countdown with 30 seconds remaining. It hasn’t shared details about the cause yet, but they did confirm that they won’t be attempting the launch today and will advise as to the next attempt window.
SpaceX is already having a banner year, with major accomplishments including its first human spaceflight, and it’s aiming to pad its current record-breaking launch year with a 25th flight today. The launch will carry SiriusXM-7, a broadcasting satellite for satellite radio service SiriusXM, delivering it to a geostationary transfer orbit from Space Launch Complex-40 in Florida.
This is actually the second launch that SpaceX has conducted just this week, after flying its 21st commercial resupply mission to the International Space Station for NASA on December 6. SpaceX has a nearly two hour window for today’s launch, beginning at 11:21 AM EST (8:21 AM PST), and weather is currently looking good. UPDATE: SpaceX updated the launch time to 12:55 PM EST.
The booster used on this launch flew during Demo-1, the first crewed flight for SpaceX ever, which brought astronauts to the ISS in May, as well as during a RADARSAT launch, and four separate Starlink launches during 2020. This will be its seventh flight, tying a record for SpaceX’s flight-proven first-stage boosters. It’ll attempt to land aboard the company’s drone landing ship in the Atlantic Ocean after deploying its second stage and cargo.
The broadcast above should begin around 15 minutes prior to the opening of the launch window, so long as everything is tracking on time.