The SpaceX Falcon 9 launch from Kennedy Space Center was aborted today on December 17. The targeted launch time was set for 9:45 a.m. on Thursday, December 17. However, the auto-abort was initiated at T-1:53 due to the "second stage sensor reading". Later, around 11:10 a.m., SpaceX ended the launch attempt and decided to call it a day. The launch window closed at 12:00 p.m. EST. The new time announced is the three-hour launch window that opens at 9 am ET (6 am PT) tomorrow on December 18. 

The December 17 launch was postponed because there was an unusually high pressure reading in the upper-stage liquid oxygen tank -- it was a technical problem that the company hopes to resolve by tomorrow.

What to expect in the live telecast

If launched successfully on December 18, Falcon 9 rocket will fly northeast from the Florida coast. The rocket’s reusable first stage booster will shut down its nine kerosene-fueled Merlin engines and separate at T+plus 2 minutes, 18 seconds, then use cold gas control thrusters to flip around and begin heading back to Cape Canaveral. A boost-back burn using some of the rocket’s Merlin engines will start guiding the booster back to Florida’s Space Coast, followed by an entry burn and a final landing burn using the first stage’s center engine.

The mission, called the NROL-108, is geared to carrying a spy satellite for the U.S. National Reconnaissance Office (NRO) into orbit. SpaceX attempting a landing back at its landing pad at Cape Canaveral Space Force Station is in contrast to its use of its two drone landing ships positioned out in the ocean. This means that as per the mission’s parameters, there is a provision for a “return home" trip.

How to watch the launch live

According to SpaceX's website, the company will be using Launch Complex 39A (LC-39A) at Kennedy Space Center, Florida, tomorrow. Friday’s three-hour launch window closes at 12 noon ET, like today, and begins at 9 am ET. You can watch the launch live on the company's website. The live webcast will begin about 15 minutes prior to liftoff. At the request of the NRO, SpaceX’s webcast is expected to end coverage of the second stage’s climb into orbit with the spy agency’s top-secret payload right after payload fairing separation. However, the company’s live video stream will continue tracking the booster’s return to Cape Canaveral.

The launch's secret cargo for the National Reconnaissance Office sets this mission apart -- it is the first time the department has broken with standard practices to procure the launch commercially, outside of the government’s established contracting schemes like the U.S. Space Force’s National Security Space Launch program. The details of the mission were under wraps when it was revealed in early October that it was supposed to launch on October 25. But the flight has been delayed several times already amid changing SpaceX launch schedules and other NRO launch activity at Cape Canaveral. Tomorrow's launch, if successful, will be SpaceX’s 26th and final planned launch of 2020.