Update Aug. 11, 9:15 a.m. EDT: SpaceX landed the booster on its droneship.
After four scheduled and unsuccessful launch attempts, the fifth time proved to be the charm as SpaceX managed to launch 24 satellites for Amazon’s Project Kuiper internet service from Cape Canaveral Space Force Station on Monday morning.
Liftoff from Space Launch Complex 40 at Cape Canaveral Space Force Station in Florida happened at 8:35 a.m. EDT (12:35 UTC), a couple hours after sunrise.
Technical issues with the Falcon 9 rocket prevented launches on Thursday and Friday and poor weather stymied launch attempts on Saturday and Sunday.
“Just want to make everyone aware that we have no-go conditions on recovery weather,” the SpaceX launch director said about 1.5 minutes ahead of the planned liftoff. “We will be standing down at T-minus 30 seconds. At 3-0 seconds we will be calling ‘hold.’ Standby for that ‘hold’ call.”
The 45th Weather Squadron, based at Cape Canaveral, gave the mission a 75 percent chance of acceptable weather for launch, which improved to 90 percent favorable by the time Monday morning rolled around. The primary concerns in the forecast issued Sunday were for violations of the cumulus cloud and anvil cloud. Meteorologists also said the booster recovery weather on Monday was a “moderate” risk on a low-moderate-high scale.
“A stationary boundary will remain draped across northern Florida Monday, maintaining deep atmospheric moisture across the Space Coast,” launch weather officers wrote. “While conditions aloft look more stable Monday compared to the weekend, there remains a small chance of a shower or thunderstorm in the morning across the Spaceport during the launch window.
“The stalled boundary could generate elevated winds and a higher chance of showers Monday near the booster recovery location.”
However, weather improved enough to allow for the launch to proceed on Monday.
This was the fifth scheduled launch attempt for the mission, designated KF-02. During the first countdown on Thursday, SpaceX stopped the clock prior to the start of fueling and later said on social media it had delayed the launch a day to allow for “additional vehicle checkouts.”
The Falcon 9 was lowered into the horizontal position at pad 40, presumably to work on a technical problem with the rocket. Then, just a few hours before the planned T-0 on Friday, the company announced the launch was called off and rescheduled for Saturday.
For Saturday’s launch attempt, the 45th Weather Squadron was forecasting only a 40 percent chance for favorable weather but offered some hope that rain clouds would stay offshore. However, it was not to be. The countdown was halted by the launch director with 28 seconds left on the clock, as heavy rain started to fall at the pad.
The booster for the KF-02 mission, tail number B1091, was a converted Falcon Heavy core stage that flew for the first time. In a May 7 social media post, Jon Edwards, SpaceX vice president of Falcon and Dragon, said that B1091 will be used as a Falcon 9 booster “a handful of times before being reconfigured and flying as a Falcon Heavy” center booster.
The Falcon 9 flew on a north-easterly trajectory, and the first-stage booster safely landed on SpaceX’s droneship ‘A Shortfall of Gravitas’ a little more than eight minutes later. This was the 120th booster landing on this vessel and the 486th booster landing to date.
About eight and a half minutes into flight, Falcon 9’s second stage placed the Kuiper satellites into an initial parking orbit, before it makes a short three-second burn almost 53 minutes into flight to circularize the orbit. The approximately seven-minute satellite deployment sequence begins at T+56 minutes, 18 seconds.
The rescheduled launch took place around the time students are arriving for the first day of school in Brevard County, where Cape Canaveral Space Force Station is located.
