SpaceX's last launch of the year is taking its time getting off the ground.
Strong high-altitude winds on Saturday scrubbed the company's third attempt to launch a Falcon 9 rocket and the first in a new generation of Global Positioning System satellites from Cape Canaveral Air Force Station.
The fourth try is planned at 8:51 a.m. Sunday, at the opening of a 26-minute window.
The weather forecast is excellent, with less than a 5 percent chance of conditions that would violate launch rules, according to the Air Force's 45th Weather Squadron.
The outlook looked good Saturday, too, but less predictable upper-level winds, which could blow a rocket off course, proved too powerful.
SpaceX pushed back the targeted launch time to the end of the window at 9:21 a.m., and began fueling the two-stage, 230-foot Falcon 9 a little over a half-hour earlier, hopeful that the winds would subside.
But a final weather balloon returned unwelcome news: Upper-level winds were "no-go."
That scrubbed the attempt, but the launch team continued to count down until T minus 30 seconds to collect data with fueling nearly complete.
A problem with the booster's liquid oxygen system during fueling had scrubbed the first launch attempt on Tuesday, Dec. 18.
Vice President Mike Pence and Air Force Secretary Heather Wilson were at Kennedy Space Center to watch the launch that day. Pence took the opportunity to announce the re-establishment of a U.S. Space Command, or USSPACECOM, as the military's 11th unified combatant command, responsible for military space operations.
Severe weather scrubbed the mission's second try on Thursday, Dec. 20, with parts of the Space Coast under a tornado watch.
The third try unfolded amid a partial federal government shutdown that did not affect the Department of Defense, whose 2019 budget is already approved.
NASA, however, planned to furlough 96 percent of its civil servants, or more than 16,700 staff.
Kennedy Space Center identified 196 positions out of roughly 2,000 that would continue working full- or part-time to protect life or property, or to support specific missions like the International Space Station, currently home to a three-person crew including NASA's Anne McClain.
The KSC Visitor Complex, run by contractor Delaware North without tax dollars, remains open, including bus tours to the Apollo/Saturn V Center inside the spaceport's secure perimeter.
The shutdown was triggered the day after NASA celebrated the 50th anniversary of the launch of Apollo 8 from KSC's pad 39A. Frank Borman, Bill Anders and Jim Lovell became the first astronauts to orbit the moon, and the first to spend Christmas in space.
If the launch of the first GPS III satellite happens Sunday, it will be SpaceX's 21st of the year, and the 20th mission overall to fly from the Space Coast in 2018.
Contact Dean at 321-917-4534 or jdean@floridatoday.com. And follow on Twitter at @flatoday_jdean and on Facebook at https://www.facebook.com/SpaceTeamGo.
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Launch Sunday
Rocket: SpaceX Falcon 9
Mission: First Global Positioning System III satellite for the U.S. Air Force
Launch Time: 8:51 a.m. EST
Launch Window: 26 minutes, to 9:17 a.m. EST
Launch Complex: 40 at Cape Canaveral Air Force Station
Landing: None
Weather: 95 percent “go”
