As part of the Starlink Group 4-27 mission, SpaceX successfully placed another group of Starlink satellites into Low-Earth Orbit (LEO) by sending a Falcon 9 rocket into space carrying the payload. At 19:21:20 UTC on Friday, August 19, the rocket was launched from Space Launch Complex 40 (SLC-40), which is located at the Cape Canaveral Space Force Station in Florida.
On the 19th of August, 2022, at 9:30 AM Eastern Daylight Time, Space Launch Delta 45 published a launch mission execution forecast (13:30 UTC). The 45th rated the weather a 50% chance of being suitable for launch, based on three different rules: the cumulus cloud rule, the surface electric field rule, and the lightning rule.
In the event that the launch was called off, there was a backup possibility to take off little under 24 hours later, with the likelihood of having favourable weather increasing to 70 percent.
During the launch, the Falcon 9 booster B1062 took to the skies for the ninth time, making it the sixth rocket in the fleet to attain this milestone. With a total turnaround time of 26 days, 5 hours, and 43 minutes, it was also the third quickest turnaround time for a booster overall.
Additionally, this was the third of at least nine successive Starlink missions that SpaceX intends to carry out over the course of a month and a half’s time.
At the 35-minute mark of the launch countdown, the time-honored automated launch countdown process was activated, marking the beginning of Falcon 9’s 170th mission to orbit. At this time, the ground computers initiate the meticulously orchestrated sequence of propellant loading operations, beginning with the loading of RP-1 (a refined form of kerosene) onto both stages of the rocket and loading liquid oxygen (LOx) onto the first stage.
After 15 minutes, the RP-1 load had finished being transferred to the second stage, and the propellant lines on the strongback of the Transporter/Erector — also known as the T/E — were purged, which resulted in the creation of the classic T-20 minute vent. After waiting another four minutes, the purge was finally accomplished, and the LOx load on the second stage got underway.
At the seven minute mark, the Falcon 9’s first stage Merlin 1D engines started going through the procedure that allows them to cool down. In this step, a modest volume of liquid oxygen is sent via the oxidizer turbopump in order to bring the temperature down in preparation for the full flow that occurs after engine ignition. This prevents the sudden evaporation of the oxygen during the beginning stages of the engine’s initiation, which has the potential to cause cavitation in the pumps and damage to the impeller blades.
The RP-1 load is finished on the first stage at around T-6 minutes, and a minute after that, the tanks are pressurised in preparation for the strongback to be retracted. The top clamps are released at around T-4 minutes, which is followed by a rotation away from the rocket of approximately 1.5 degrees. This is the beginning of the retraction process.
At T-3 minutes and T-2 minutes, respectively, the loading of liquid oxygen into the first and second stages is successfully completed. At this stage, the ground systems are being cleaned in preparation for liftoff.
At the T-1 minute mark, the computers on the ground pass over control of the automated countdown sequence to the computers that are aboard the rocket in a procedure that is commonly referred to as “starting.” A few seconds later, the launch director announced that the launch would go ahead as planned and gave the all clear signal.
The onboard computers sent the instruction to ignite all nine Merlin 1D engines on the first stage at T-3 seconds, and these engines reached peak power approximately 2.8 seconds after the ignition was given. The Falcon 9 then gave the ground computers the command to release the rocket for takeoff at the T-0 mark, after performing a short check of the engine’s health.
Following a powered flight of the first stage that lasted for two minutes and fifty seconds, the Main Engine Cut-Off (MECO) procedure, stage separation, and ignition of the Merlin 1D Vacuum (MVacD) engine on the second stage were all included in the flight profile. This engine burned for approximately six minutes, and the second stage and the Starlink satellites aimed for a deployment orbit that was 232 kilometres long, 336 kilometres wide, and inclined at 53.22 degrees.
After it severed its connection with the second stage, the first stage rotated itself into an engines-first attitude in order to get ready for the entry and landing phases. Around T+6.5 minutes, there was an entrance burn that lasted for a total of 25 seconds. At the beginning of this burn, the centre engine, which is designated by the number E9, is ignited, and then two of the engines located on the ring around it follow shortly after (E1 and E5). The exterior engines are the ones that stop their entry burn earliest, while the engine in the middle is the one to stop its burn last.
In addition, the booster’s centre engine is used for a landing burn that lasts for a total of thirty seconds. The purpose of this fire is to achieve a gentle landing of the booster on SpaceX’s Autonomous Spaceport Drone Ship (ASDS). A Deficiency In Gravitas (ASOG). The ASOG was located in the middle of the Atlantic Ocean, 656 kilometres downrange.
About ten seconds after the firing of the second stage engine, the two halves of the fairing that were used for this flight separated and made a splashdown in the Atlantic Ocean with the assistance of parachutes. Doug, SpaceX’s multi-purpose recovery vessel, will be the one to bring these back to Earth.
Following the termination of MVacD operations, the second stage began an end-to-end rotation manoeuvre in order to prepare for the separation of the Starlink satellite, which is expected to take place roughly 15 minutes after flight.
Following the separation of the satellites, the second stage will use the MVacD engine to perform a second burn in order to deorbit and then dispose of the spent rocket over the Pacific Ocean.
With the completion of this mission, a total of 3,108 Starlink satellites have now been placed into orbit as part of the first generation of the company’s constellation. Out of these, 264 have already returned to Earth, 44 are still in orbit but are either unresponsive or not moving, and 2,313 are now in an operational orbit.
It was SpaceX’s 56th dedicated Starlink flight, their 37th launch of the year, and their fourth launch of this calendar month as they successfully lifted off on Friday. One additional launch of a Starlink mission is scheduled to take place from Vandenberg, and another Starlink launch is scheduled to take place from LC-39A at the Kennedy Space Center in the remaining days of August.
SpaceX plans to launch at least four more Starlink missions in September, two of which will include rideshares, and will switch back and forth between their SLC-40 and LC-39A launch sites. This may be the longest string of consecutive Starlink missions ever flown by the company.
(The featured image is of a Falcon 9 rocket being prepared for the Nilesat-301 launch. (Credit for this one goes to Stephan Marr for NSF)