SpaceX is preparing to launch its second batch of upgraded Starlink satellites after some of the first version 2 (v2) buses deorbited earlier than planned. Liftoff aboard a Falcon 9 rocket is scheduled for April 19 at 8:27 AM EDT (12:27 UTC) from Space Launch Complex 40 (SLC-40) at the Cape Canaveral Space Force Station.
This mission will be launching 21 of the Starlink v2 satellites into low Earth orbit. In December 2022, the Federal Communications Commission (FCC) gave SpaceX approval to launch up to 7,500 next-generation Starlink satellites, known as Gen 2. That’s still a much smaller number than the original 29,988 the company originally requested.
These upgraded satellites will eventually be operating in circular orbits with altitudes of 525, 530, and 535 km and inclinations of 53, 43, and 33 degrees, respectively, using frequencies in the Ku- and Ka-band.
The original plan was to launch full-sized v2 satellites aboard Starship. However, as the vehicle is not read, SpaceX sent an updated plan to the FCC stating it would utilize Falcon 9 to conduct launch operations on what is being called v2 Mini.
Despite the name, they are still quite large. In fact, this mission with 21 satellites onboard is launching fewer than half the number of satellites that the company has been launching on each mission with the still-flying Starlink v1.5 design. This puts the mass of each satellite between 750 kg and 800 kg, which is more than twice the mass of the Starlink v1.5 satellites and more than half the mass of the full-size Starlink v2 satellite.
Despite being smaller, the v2 Mini variants still contain the majority of the upgrades that will fly on the standard v2 satellites. These include providing four times more capacity than the earlier v1.5 satellites as well as using argon for the Hall Effect thrusters aboard each satellite. SpaceX adds that each new v2 launch will introduce more capacity into the overall system.
However, there were some problems with the first batch of v2 Mini satellites. Less than two months after launch, observers noted some of the satellites were in the process of deorbiting or had already burned up in Earth’s atmosphere. When asked about this on Twitter, SpaceX CEO Elon Musk noted there was a “[l]ot of new technology in Starlink V2, so we’re experiencing some issues, as expected. Some sats will be deorbited, others will be tested thoroughly before raising altitude above [the International] Space Station.”
The Falcon 9 booster supporting this mission is B1073. Having previously supported three Starlink missions, SES-22, HAKUTO-R Mission 1, Amazonas Nexus, and CRS-27, the booster will be flying for its eighth time.
Teams plan to land the booster following this launch on the drone ship A Shortfall Of Gravitas (ASOG), located approximately 637 km southeast of the launch site.
35 minutes before liftoff, equipment at the launch pad begins to load the Falcon 9 with RP-1 fuel, a type of refined kerosene. At the same time, liquid oxygen (LOX), the oxidizer for the Falcon fleet of rockets, begins loading into the first stage.
T-16 minutes until liftoff, LOX load gets underway on the second stage. Seven minutes before launch, the engines are chilled to prime them ahead of the supercooled cryogenics that flows through them at liftoff. This prevents a potentially dangerous shock at ignition.
At T-1 minute, Falcon 9 goes into “startup,” meaning the onboard computers have full control of the countdown as the propellant tanks are pressurized for flight. At T-3 seconds, the command is given to ignite the nine Merlin 1-D engines at the base of the first stage followed by liftoff at T0.
The flight profile for this mission follows a similar one to all recent Starlink missions to shell four from Cape Canaveral, where the vehicle turns to the northeast over the Atlantic Ocean. The rocket then passes through the area of maximum dynamic pressure, or Max-Q, at T+1 minute and 12 seconds.
Around two minutes and 25 seconds into the flight, a series of events happen in quick succession. The first stage engines have main engine cutoff , followed three seconds later by separation of the first and second stages. Six seconds after that, the second stage engine starts in what’s known as SES-1. Just three minutes and six seconds into flight, the fairing halves separate and begin their journey back toward the Atlantic Ocean for recovery and use on another flight.
The first stage will execute its traditional two burns for entry and landing before touching down on ASOG in the Atlantic Ocean.
The second stage will shut off its engine at T+8:36. The stage will then coast until T+54:23, when the MVacD engine will ignite for three seconds, before shutting down and coasting for another 10 minutes.
The second stage and payload will then start its end-over-end flip maneuver. This helps the satellites spread out after deployment, which will happen one hour, five minutes, and 13 seconds after liftoff.
(Lead photo: B1077 on SLC-40 ahead of the Inmarsat I-6 F2 launch. Credit: Max Evans for NSF)
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