A stack of Starlink satellites on a Falcon 9 rocket during a recent launch. Credit: SpaceX

Forecasters are predicting a 50-50 chance of good weather at Cape Canaveral for the launch of SpaceX’s next batch of Starlink internet satellites on Sunday on a Falcon 9 rocket.

Fifty-three other Starlink internet satellites are packed inside the nose cone of a Falcon 9 rocket for liftoff at 10:20 a.m. EDT (1420 GMT) Sunday from Pad 40 of Space Force Station Cape Canaveral. The launch will mark the 31st Falcon 9 flight of the year, equaling the total number of Falcon 9 launches completed by SpaceX in 2021.

The official weather forecast from the US Space Force’s 45th Weather Squadron calls for isolated rain showers and cloudy skies at launch Sunday. The main weather hazards for the launch are heavy clouds, anvil clouds and cumulus clouds, which could pose a risk of rocket-triggered lightning as the Falcon 9 climbs through the atmosphere.

The weather forecast for Monday morning is better, with an 80% chance of good conditions for takeoff.

SpaceX is on pace to nearly double its record launch rate set last year and has been averaging more than one launch per week since early January. Seventeen of SpaceX’s 30 Falcon 9 launches so far this year have been dedicated missions deploying satellites for the company’s own Starlink internet network.

Sunday’s launch, designated Starlink 4-22, will follow a similar profile to most of SpaceX’s recent Starlink missions, with the Falcon 9’s guidance computer targeting an elliptical orbit whose altitude is between 144 miles and 210 miles ( 232 by 338 kilometres). The two-stage rocket will launch northeast to place the 53 Starlink satellites in an orbit inclined at 53.2 degrees to the equator.

Nine kerosene-fueled Merlin 1D engines will rev up to full power to propel the 229-foot-tall (70-meter) Falcon 9 rocket out of the pad at Cape Canaveral.

The Falcon 9 first stage will shut down about two and a half minutes after liftoff, beginning an arcing trajectory toward a landing on SpaceX’s “Just Read the Instructions” drone stationed in the Atlantic Ocean about 400 miles (630 kilometers) away. ) northeast of Cape Canaveral.

The booster – tail number B1051 – flying on Sunday is one of the oldest in SpaceX’s fleet of reusable rockets. It debuted in March 2019 with the first unmanned test flight of SpaceX’s Crew Dragon spacecraft. Since then, the booster has launched Canada’s Constellation Radarsat mission, SiriusXM’s SXM 7 radio broadcast satellite, and nine Starlink missions.

The B1051 will become the third booster in SpaceX’s inventory to reach the 13-flight milestone. SpaceX has certified the Falcon 9 boosters for at least 15 missions, an extension of the original certification of 10 flights.

File photo of a SpaceX Falcon 9 rocket heading towards Cape Canaveral with a payload of 53 Starlink internet satellites. Credit: Michael Cain / Spaceflight Now / Coldlife Photography

Falcon 9’s upper stage will burn up its lone Merlin until near T+plus 9 minutes, then cross the North Atlantic Ocean before releasing all 53 Starlink satellites at T+plus 15 minutes, 28 seconds.

The upper stage will rotate before the deployment of the Starlink satellites. The flat-packed spacecraft, each with a mass of more than a quarter ton, will fly without the Falcon 9 after the rocket jettisoned the retention rods that keep the satellites firmly attached to the spacecraft during ascent .

Once released from the rocket, the satellites will roll out, deploy solar panels and fire up their krypton-powered ion engines to climb to an altitude of 335 miles (540 kilometers).

Starlink satellites provide high-speed internet service to SpaceX customers around the world.

With the 53 satellites launched on Sunday, SpaceX will have launched 2,858 Starlink spacecraft into orbit, including prototypes and already decommissioned satellites. SpaceX has more than 2,500 Starlink satellites currently working in space, either in service or maneuvering to their final operational orbits, according to Jonathan McDowell, an astrophysicist and expert spaceflight activity tracker.

That’s about six times as many satellites as the second-largest fleet of spacecraft in orbit — the constellation of 428 internet satellites owned by OneWeb.

SpaceX’s first-generation network will consist of 4,408 operational satellites flying in five orbital “shells” at varying inclinations. The Federal Communications Commission has authorized SpaceX to operate as many as 12,000 Starlink satellites, and SpaceX has signaled it may launch more if it sees sufficient commercial demand.

Sunday’s launch will be the fourth SpaceX mission of July, following previous Falcon 9/Starlink launches from Cape Canaveral on July 7 and from Vandenberg Space Force Base in California on July 10. A Falcon 9 rocket launched from Kennedy Space Center Thursday with Dragon cargo heading for the International Space Station.

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