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A Falcon 9 Block 5 blast off from Space Launch Complex 4E at the Vandeberg Space Force Base in California. Image Credit: SpaceX

SpaceX to launch first upgraded Starlink satellites into polar orbit

The American aerospace manufacturer and telecommunications services provider SpaceX, is targeting Monday, September 13, 2021 for the launch of the first upgraded Starlink V1.5 satellites. The 51 spacecraft are scheduled to blast off from Space Launch Complex 4E (SLC-4E) at the Vandenberg SFB in California atop a Falcon 9 rocket on Monday evening at 20:55 PDT / Tuesday morning at 03:55 UTC. The two-stage, liquid-fueled, medium-lift launch vehicle is expected to launch the satellites into a low polar Earth orbit, expanding the Starlink satellite constellation’s coverage area to Earth’s polar regions.

The first stage of the Falcon 9, which previously supported the launch of Telstar 18V, the Iridium 8 mission and seven Starlink launches, will land back on Earth on the droneship “Of Course I Still Love You” in the Pacific Ocean, once its mission of boosting the upper stage and the payload into space is complete.

The Starlink constellation

Starlink is a satellite constellation currently under construction by SpaceX. By launching several thousand satellites into low Earth orbit (Low Earth orbit), the company plans to provide high-speed, low-latency broadband Internet access to rural communities all around the planet. The first two technology demonstration satellites, known as Tintin A and Tintin B, were launched into space as secondary payloads with the Spanish PAZ reconnaissance satellite in February 2018 atop a Falcon 9 from Vandenberg. The first operational spacecraft were placed into orbit in May 2019. Since then, the aerospace manufacturer has launched over 1,700 Starlinks into LEO and has begun offering Starlink services to different countries in North America, Europe and Oceania.

A batch of 60 Starlinks attached to a Falcon 9 upper stage. Image Credit: SpaceX.
A batch of 60 Starlinks attached to a Falcon 9 upper stage. Image Credit: SpaceX.

The Falcon 9 launch vehicle

The Falcon 9 is a two-stage, partially-reusable, medium-lift launch vehicle developed and operated by SpaceX. The Falcon 9 Block 5, the latest version of the vehicle and the rocket used to launch the upcoming Starlink mission, is about 70 m in height, 3.7 m in diameter and has a launch mass of around 549 tonnes.

The rocket’s first stage is equipped with nine Merlin rocket engines, burning the rocket kerosene “RP-1” and liquid oxygen (LOX) as propellants in a gas-generator power cycle. Each engine generates about 845 kN of thrust, enabling the Falcon 9 to carry up to 22,800 kg of cargo into a low Earth orbit, or 8,300 kg into a geostationary transfer orbit.

The rocket’s second stage, which separates from the booster stage about 2 1/2 minutes into the flight, is powered by a single vacuum-optimized Merlin engine and carrys the payload into its target orbit. Due to its restart capability, the stage is capable of launching multiple spacecraft into different orbits in a single launch. In fact, during a mission in January of this year, a Falcon 9 launched a record setting 143 satellites into a low Earth Sun-synchronous orbit.

A Falcon 9 Block 5 blast off from Space Launch Complex 4E at the Vandeberg Space Force Base in California. Image Credit: SpaceX

From the beginning, SpaceX tried to lower the cost of a Falcon 9, by reusing several components of the vehicle multiple times. To achive this goal, the rocket’s first stage conducts up to three additional burns of its engines after separating from the upper stage, to slow down ahead of a soft landing on one of SpaceX’ three autonomous droneships, or at one of the three landing sites at Cape Canaveral (LZ-1 and LZ-2) in Florida and the Vandenberg SFB (LZ-4) in California. The booster used for the upcoming Starlink mission, booster B1049, will perform its tenth flight and is expected to land back on Earth on the droneship “Of Course I Still Love You” in the Pacific Ocean.

A Falcon 9 first stage lands back at Landing Zone 1 at the Cape Canaveral SFS in Florida. Image Credit: SpaceX.

The company also reuses the rocket’s two payload fairing halves, by slowing them down with parafoils and softly landing them in the ocean.

The Falcon 9 had its maiden flight in 2010 and has since flown over 120 missions. The rocket not only launches satellites into orbit, but also carries supplies and astronauts to the International Space Station under the Commercial Resupply Services contracts and the Commercial Crew Program.

Mission profile

At T-3 seconds, the nine liquid-fueled Merlin rocket engines on Falcon 9’s first stage will ignite, lifting the rocket and its payload off the pad and toward low polar orbit.

About a minute after launch, the vehicle will experience “Max Q”, the point of maximum mechanical stress, and will break the sound barrier.

2 minutes and 32 seconds into the flight, the first stage’s engines will shut down, the upper stage will separate from the first stage and the single vacuum-optimized Merlin engine of the second stage will ignite.

Once the rocket reaches a certain altitude, the two fairing halves will be jettisoned, exposing the 51 Starlinks to the vacuum of space. This milestone is expected to occur about three minutes after liftoff.

To slow down ahead of the landing on the droneship, the booster will conduct a ~21 seconds long entry burn beginning at T+6 min and 46 s. This will be followed by the landing burn at 8 minutes and 24 seconds, and the subsequent landing on “Of Course I Still Love You”. After the first stage has been secured, the droneship will be towed back to shore, to prepare the rocket stage for its next flight.

At T+8 min, 51 s, the upper stage’s engine will shut down and the rocket will enter a short coast phase.

15 min and 32 s after the launch from Vandenberg, the 51 satellites are scheduled to be deployed from the second stage, completing the Falcon 9’s mission.

Over the next couple of weeks, the Starlink spacecraft will deploy their solar arrays and use their own onboard propulsion system to raise their preliminary transfer orbits to their final operational orbits.


Sources:

https://www.starlink.com

https://www.spacex.com/launches/

https://www.spacex.com/vehicles/falcon-9/

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