SpaceX is geared up to launch another 47 Starlink satellites to low Earth orbit. The liftoff is scheduled for 9:25 AM EST (14:25 UTC) on Thursday, March 3, from the historic Launch Complex 39A at NASA’s Kennedy Space Center in Florida. This mission will mark SpaceX’s ninth launch of 2022 and their first launch of the month.

The 45th Weather Squadron at Patrick Space Force Base forecasts a 90% chance of favorable weather for launch, with a low risk of violating weather criteria in the booster recovery area. If the launch is scrubbed for any reason, a backup launch opportunity exists on Friday, March 4, with another 90% chance of acceptable weather forecasted.

The Starlink satellites will be placed into an initial 53.2º inclination, 307 x 313-kilometer orbit. Over the coming months, they will make use of their onboard krypton-propellant ion engines to slowly reach their operational 540-kilometer circular orbits.

The slightly lower parking orbit — compared to 337 x 325 kilometers for the previous Starlink Group 4-8 mission — allows for a launch of 47 satellites instead of 46. These orbital altitude adjustments come in the wake of a geomagnetic storm that doomed 40 Starlink spacecraft last month while the satellites were maneuvering within their low insertion orbits.

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As the Falcon 9 lifts off, the rocket will head southeast from Cape Canaveral, hugging the coast of the Bahamas as the upper stage performs a slight dogleg maneuver to avoid flying over populated areas.

Stationed 642 kilometers downrange from LC-39A is one of SpaceX’s Autonomous Spaceport Drone Ships, Just Read the Instructions (JRTI), tugged by Zion M Falgout in the Atlantic Ocean. Alongside JRTI is SpaceX’s multipurpose vessel, Bob. Named after one of the astronauts who flew on SpaceX’s Demonstration mission-2, Bob is providing ASDS support for this mission and will recover the fairings as they splash down on the Atlantic Ocean.

The Falcon 9 booster supporting this mission is B1060, having previously launched to space 10 times. It has supported the launch of the US Space Force’s GPS III-3 satellite, Turksat-5A, the Transporter-2 rideshare mission, and seven Starlink missions.

B1060’s missions
Launch Date (UTC)
Turnaround Time (Days)

GPS III-3
May 30, 2020 19:22
NA

Starlink V1 L11
July 20, 2020 21:30
66

Starlink V1 L14
October 6, 2020 11:29
42

Türksat 5A
December 6, 2020 16:17
87

Starlink V1 L18
January 24, 2021 15:00
28

Starlink V1 L22
March 11, 2021 08:13
49

Starlink V1 L24
April 7, 2021 16:34
37

Transporter – 2
May 15, 2021 22:56
63

Starlink Group 4-3 & BlackSky
November 13, 2021 12:19
156

Starlink 4-6
January 13, 2022 15:25
49

Starlink Satellite Constellation

Starlink is SpaceX’s constellation of internet satellites in low Earth orbit that aims to provide internet access to most of Earth, primarily serving areas devoid of a fiber connection. One of SpaceX’s two most capital-intensive projects, it has been under development for some time, with the first regulatory filings dating back to 2014.

Over the years, the plan underwent various changes, but in February 2018, SpaceX’s Tintin A and B satellites, experimental precursors to the operational Starlink satellites, were launched as secondary payloads from the then Vandenberg Air Force Base.

The constellation consists of five groups of satellites, or “shells,” which will operate at different altitudes and orbital planes. As denoted by the first number in the mission name — in this case, “4” for Starlink 4-9 — the mission targets the fourth shell of the Starlink Constellation.

Shells
Inclination (°)
Orbital Altitude (km)
Planes
Satellites per Plane
Number of Satellites
Active Satellites

Shell 1
53
550
72
22
1584
1538

Shell 2
70
570
36
20
720
51

Shell 3
97.6
560
6
58
348
3

Shell 4
53.2
540
72
22
1584
356

Shell 5
97.6
560
4
43
172
0

SpaceX is actively filling up the fourth shell of the mega-constellation, which when complete will increase the capacity and reduce the latency for customers located between 52 degrees North and 52 degrees South latitude.

The company is hoping to launch 40 Starlink missions this year to complete this shell, after which they are expected to start filling the second shell.

Launch Timeline

At T-38 minutes, the Launch Director will give a go for propellant loading. At T-35 minutes, SpaceX will begin loading sub-cooled RP-1 kerosene onto both the first stage and the second stage as well as super-chilled LOX (liquid oxygen) onto the first stage.

SpaceX, unlike other launch providers, uses RP-1 which is cooled to -7 degrees Celsius along with LOX that is cooled to -205 degrees Celsius. Using supercooled propellants increases the performance of Falcon 9 by densifying the fluids, packing more energy into a smaller space. This is beneficial for reuse, since the first stage must reserve some energy for landing.

Just before T-20 minutes, the second stage RP-1 load will be complete, which is marked by a large vent from the T/E (Transporter Erector). This vent indicates the purging of the T/E lines ahead of the start of LOX load onto the second stage at T-16 minutes.

At T-7 minutes, the Falcon 9 will allow a small amount of liquid oxygen to enter the nine Merlin 1D engines on the first stage. This process will cool the engines slowly so they do not get damaged from thermal shock when super chilled LOX starts to flow through them at full volume during engine start.

The signature “T-20 minute vent” is seen during a scrubbed launch attempt for the Starlink v1.0 L12 mission in October 2020. (Credit: Thomas Burghardt for NSF)

At T-1 minute, the Falcon 9 will enter start up and begin pressurizing its tanks for flight. At this point, Falcon 9’s onboard computers will assume full control of the countdown, and any technical aborts from this point forward would be handled autonomously and not by the ground operators.

At T-45 seconds, the Launch Director will verify that all positions go for launch. At T-3 seconds, the F9’s flight computer will command the ignition of the nine Merlin 1D engines on the first stage. The ignition happens in pairs, within milliseconds of each other to reduce startup transients and loads on the vehicle.

Once the computers ensure all systems are working nominally, they’ll command the hydraulic clamps at the base of the vehicle to release, letting the Falcon 9 lift off from the pad.

B1060 will fire its engines for approximately two and a half minutes before shutting down, once again in a staggered formation to reduce loads on the vehicle.

The first stage will separate from the second stage using pneumatic pushers, followed by ignition of the second stage’s single vacuum optimized Merlin engine seconds later. Meanwhile, after coasting up to its apogee and then beginning its descent, B1060 will perform two burns to softly touch down on Just Read the Instructions.

Just Read the Instructions droneship is in position, 640 km downrange, ahead of its first booster landing in over 2 months!

Starlink 4-9 Net March 3rd, 9:45am ET. pic.twitter.com/S8Q9I91Lxs

— Gav Cornwell (@SpaceOffshore) March 2, 2022

The second stage, meanwhile, will continue to burn toward orbit. At around two minutes and 47 seconds after launch, the vehicle will command the latches connecting the fairing halves to release. The fairing halves will then use their onboard RCS thrusters to reenter into the Earth’s atmosphere before softly splashing down in the Atlantic. They will then be recovered by Bob.

About eight minutes and 46 seconds after launch, the second stage will shut down its Merlin Vacuum engine, beginning an approximately 48-minute coast phase. At T+56 minutes, the second stage will re-ignite for just a second to circularize its orbit. From this point, the vehicle will use its RCS thrusters to start rotating around its x-axis.

At T+65 minutes 47 seconds, the vehicle will command the deployment of the tension rods used to keep the stack of Starlink satellites together, and the satellites will slowly drift away from the second stage.

Shortly after, the second stage will perform a deorbit burn and destructively reenter Earth’s atmosphere, leaving only the tension rods as debris objects which will naturally decay. The Starlink satellites will, meanwhile, begin maneuvering toward their operational orbits.

(A Falcon 9 rocket stands vertical at LC-39A before launching the Imaging X-Ray Polarimetry Explorer (IXPE) for NASA in December 2021. Credit: Stephen Marr for NSF/L2)

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