On the two main coasts of the United States, SpaceX is preparing to launch a number of low Earth orbit communications satellites for three different networks, with both launches scheduled to occur just over eight hours apart on the same day.
The first launch, Starlink Group 6-3, is scheduled to fly on Friday, May 19 at 12:41 AM EDT (04:41 UTC) from Space Launch Complex 40 (SLC-40) at the Cape Canaveral Space Force Station in Florida. An on-time launch would be just under five days after the last flight from the same pad.
This would break the pad’s turnaround time between launches that was set between the Amazonas Nexus and Starlink 5-4 launches earlier this year. The turnaround time then was five days, three hours, and 38 minutes, and if Starlink 6-3 launches any time during the Friday morning window, it will break this record.
The launch periods available for Starlink 6-3 span from 12:00 to 4:20 AM EDT (04:00 to 08:20 UTC) on Friday and 11:35 PM EDT Friday night to 3:55 AM EDT (03:35 to 07:55 UTC) Saturday morning, with multiple launch opportunities within these periods.
The available T0 times for Friday morning are as follows: 12:41 AM EDT (04:41 UTC), 1:31 AM EDT (05:31 UTC), 2:19 AM EDT (06:19 UTC), and 3:09 AM EDT (07:09 UTC). An on-time launch would set the new SLC-40 turnaround record at four days, 23 hours, and 38 minutes.
If one of the other times is used, the new turnaround record would be five days, zero hours, 28 minutes, five days, one hour, and 16 minutes, and five days, two hours, and six minutes, respectively. Fast turnarounds between launches from the same pad are important to keeping up SpaceX’s current launch cadence.
Twenty-two Starlink v2 Mini satellites will be launched on a southeast trajectory inclined 43 degrees to the equator. They will be inserted into an initial orbit of 344 km by 353 km. The satellites will be boosted to their operational 530 km circular orbits in the coming weeks and months using their onboard argon ion thrusters.
View of a stack of 21 Starlink v2 Mini satellites before being enclosed in their fairing ahead of a previous launch. (Credit: SpaceX)
Starlink 6-3 will use B1076 on its fifth flight, which will mark the 30th Falcon 9 and 32nd orbital launch for SpaceX in 2023. The booster is scheduled to land on the drone ship A Shortfall of Gravitas positioned 636 km downrange in the Atlantic. This core has previously flown the CRS-26, OneWeb #16, Starlink 6-1, and Intelsat 40e/TEMPO missions.
This same booster is also scheduled to be converted to a Falcon Heavy side booster for use on the Echostar 24 (Jupiter 3) mission set for no earlier than this coming August. Falcon 9 boosters can be converted into Falcon Heavy side boosters, and the reverse is also true.
Eight hours after the scheduled Starlink 6-3 launch time, another Falcon 9 is set to launch from Space Launch Complex 4E (SLC-4E) at Vandenberg Space Force Base in California. The available windows for this flight will be from 6:04 to 7:12 AM PDT (13:04 to 14:12 UTC) on Friday and 6:00 to 7:07 AM PDT (13:00 to 14:07 UTC) on Saturday.
B1063 will be making its 11th flight, the 31st Falcon 9 flight of this year, and SpaceX’s 33rd flight of 2023, with liftoff scheduled for 6:19 AM PDT (13:19 UTC). The flight — scheduled to land on the drone ship Of Course I Still Love You stationed in the Pacific Ocean — will fly a polar trajectory to the south, carrying five Iridium NEXT and 16 OneWeb satellites on board.
The five Iridium NEXT satellites will act as replacements for some of the satellites SpaceX launched for the company between 2017 and 2019. The constellation consists of 66 operational satellites, nine on-orbit spares, and six ground spares.
The OneWeb second generation demonstrator “JoeySat” developed with assistance from ESA and the UK Space Agency. (Credit: ESA)
Though OneWeb’s initial operational constellation of 618 satellites is now in orbit, 16 satellites will be flown on this mission. 15 of these satellites, of the same type as the operational satellites, will become on-orbit spares, while one of the satellites is a second-generation demonstrator spacecraft, known as “JoeySat.”
The Iridium/OneWeb launch will be the second flight for the new, shortened second-stage engine nozzle. The shorter nozzle, designed to reduce costs and increase launch cadence, made its debut on the Transporter-7 launch in April. The shortened nozzle slightly reduces performance, so it will only be used on missions that do not need Falcon 9’s full performance capability.
For this flight, the total payload mass is 6,600 kg, as opposed to the 17,600 kg for the Starlink 6-3 launch. The Iridium Next satellites will be placed in an initial 615 km circular orbit inclined 86.4 degrees to the Equator, while the OneWeb satellites use a 1,200 km circular orbit inclined 87.9 degrees to the Equator.
The Iridium satellites will be moved up to 625 km for checkouts, and one of them will move to its operational orbit at 760 km altitude. The other four satellites will be placed into different orbital planes at 625 km.
The weather is a watch item for the Starlink 6-3 launch. The 45th Weather Squadron’s latest forecast shows a 60 percent chance of launch criteria violation due to weather at the beginning of the available window, decreasing to a 40 percent chance of violation at the end of the window.
The main concerns for the May 19 window are the anvil, debris, and cumulus cloud rules, while the forecast looks better for the backup window 24 hours later.
For a 24-hour delay, there is a 40 percent chance of violation at the beginning of the window and a 30 percent chance at the end of the window. The remaining concerns for the backup window are the anvil and cumulus cloud rules.
Starlink 6-3 launch weather forecast. (Credit: USSF)
There is no official forecast out yet for the Iridium NEXT/OneWeb launch out of Vandenberg, but a local forecast shows the usual fog cover in the area for the morning hours. Fog is not typically a constraint to launch for the Falcon 9.
The pair of launches is scheduled to be followed by the Axiom-2 crewed spaceflight from Launch Complex 39A at the Kennedy Space Center the following week as SpaceX attempts to fly up to 100 orbital missions this year.
(Lead image: Falcon 9 poised on SLC-4E ahead of a previous mission from Vandenberg. Credit: Jack Beyer for NSF)
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