Continuing with their high launch cadence, SpaceX is set to launch another Falcon 9, this time carrying 49 Starlink satellites to a 339-kilometer orbit, with a 53.22-degree inclination. The launch is scheduled for 1:13 PM EST (18:13 UTC) on Thursday, February 3, from the historic Launch Complex 39A at NASA’s Kennedy Space Center in Florida.

In addition to reusing a Falcon 9 first stage, both fairing halves are being reused from previous missions. One half will be flying on its sixth mission, setting a new record for SpaceX.

The 45th Weather Squadron at Patrick Space Force Base forecasted an 80% chance of favorable weather for launch with a moderate 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, February 4,  with a 70% chance of acceptable weather forecasted.

This launch will mark the sixth mission of the year for SpaceX, having already launched two Starlink missions, Transporter-3CSG-2, and NROL-87.

As the Falcon 9 lifts off, it’ll head towards the southeast corridor from Cape Canaveral, hugging the coast of the Bahamas as it performs a dogleg maneuver to avoid flying over the populated areas. This maneuver is the reason why SpaceX launches fewer satellites on this mission, compared to other launches from Florida, which launched 53 Starlink satellites.

A Shortfall of Gravitas arrives at Port Canaveral for the first time in July 2021. (Credit: Julia Bergeron for NSF/L2)

Stationed 640 kilometers downrange from LC-39A is SpaceX’s newest ASDS (Autonomous Spaceport Drone Ship), ASOG (A Shortfall of Gravitas). Alongside ASOG will be SpaceX’s multipurpose vessel named Doug. Named after one of the astronauts who flew on SpaceX’s Demonstration mission-2, Doug will provide ASDS support for this mission and recover fairings as they splash down on the Atlantic Ocean.

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The Falcon 9 booster supporting this mission is B1061, which has launched to space six times. Its debut launch was SpaceX and NASA’s first operational commercial crew mission to the International Space Station: Crew 1. It went on to support the Crew-2 mission, the CRS-23 resupply mission to the ISS, the launch of a radio satellite for SiriusXM, and an X-ray space observatory — named IXPE — for NASA.

The record-breaking fairing half making its sixth flight on the Group 4-7 mission supported five previous Starlink missions. The other half, also being reused, previously flew on the Transporter-1 mission as well as two Starlink missions.

Starlink Constellation

Starlink is SpaceX’s Internet Constellation in low Earth orbit that aims to provide satellite internet access coverage 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 quite a while, 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, which were experimental precursors to the operational Starlink satellites, were launched as secondary payloads from then Vandenberg Air Force Base.

The constellation consists of five groups of satellites, or “shells,” which will operate at different altitudes and orbital planes. This mission, named Starlink 4-7, will launch satellites to the fourth shell. SpaceX is actively scheduling and launching to fill 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.

Launch Timeline

At T-38 minutes, if everything is going as planned, the Launch Director will give a GO for propellant loading. At T-35 minutes, SpaceX will begin loading sub-cooled RP-1 onto both the first stage and the second stages as well as super-chilled LOX (Liquid Oxygen) onto the first stage.

SpaceX, unlike any other company in the industry, uses RP-1 which is cooled to -7 degrees celsius and the LOX is cooled to -205 degrees celsius. Using supercooled propellants increases the performance of Falcon 9 — something that is essential for reuse —since low temperatures increase the density of propellants.

Just before T-20 minutes, the second stage RP-1 load will be completed, which will be marked by a large vent from the TE (Transporter Erector). This vent will be followed by the purging of the TE lines ahead of the start of LOX load to the second stage at T-16 minutes.

Falcon 9 streaks southeast from Cape Canaveral in January 2022 carrying the Starlink 4-6 group to orbit. (Credit: Brady Kenniston for NSF)

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 down the engines slowly so they do not get damaged from the thermal shock when super chilled LOX starts to flow through them at full volume during engine ignition.

At T-1 minute, the Falcon 9 will start up and begin pressurizing its tanks for flight. At this point, Falcon 9’s onboard computers will be fully in charge of its countdown, and all 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 if all positions go for launch. Once given a GO for launch, the countdown will continue. At T-3 seconds, the F9’s flight computer will command the ignition of the 9 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 have ensured all systems are nominal, it will command the hydraulic clamps at the base of the vehicle to release, letting the Falcon 9 lift off from the pad.

B1061 will burn 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.

Falcon 9 flies southeast from Cape Canaveral on the Starlink Group 4-5 mission in January 2022. (Credit: Stephen Marr for NSF/L2)

After coasting up to its apogee and beginning its descent, B1062 will perform two burns to softly touch down on A Shortfall of Gravitas, the Autonomous Spaceport Drone Ship.

The second stage, meanwhile, will continue to burn toward orbit. At around three minutes after launch, the vehicle will command the latches connecting the fairing halves to release.

The fairing halves then use their onboard RCS thrusters to reenter into the Earth’s atmosphere before softly landing on the water. They will then be recovered by SpaceX’s fairing recovery vessel, Doug.

About nine minutes after launch, the second stage will shut down its Merlin Vacuum engine. From this point, the vehicle will use its RCS thrusters to start rotating around its X-axis.

At T+15 minutes 31 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 enter Earth’s atmosphere.

(Lead photo: B1063 stands vertical at LC-39A prior to launching the IXPE mission in December 2021. Credit: Julia Bergeron for NSF/L2)

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