SpaceX enters busy December with Starlink launch from Florida

Kicking off a busy end to the company’s 2021 launch campaign, SpaceX is poised to launch a group of Starlink satellites from Florida on Wednesday evening. The Group 4-3 mission, carrying 48 Starlink satellites and two rideshare payloads to low Earth orbit, will lift off from SLC-40 at the Cape Canaveral Space Force Station at 6:12 PM EST (23:12 UTC).

The 45th Weather Squadron at Patrick Space Force Base forecasts a greater than 90% chance of favorable weather for launch. Should the launch need to be delayed for any reason, a backup opportunity exists on Friday, with another greater than 90% chance of acceptable weather forecasted.

The Falcon 9 first stage tasked with the launch is B1060-9. After flying northeast from Cape Canaveral and separating from the second stage, the booster will make a landing on one of SpaceX’s autonomous spaceport drone ships, A Shortfall of Gravitas. The second stage will power the stack of Starlink satellites, plus a pair of Earth observation satellites for BlackSky Global, toward payload separation into a 53.2-degree inclination orbit and an altitude of approximately 430 kilometers.

The Starlink Group 4-3 flight is the first of at least four planned SpaceX launches for the month of December. A few miles north of pad 40, and following a United Launch Alliance Atlas V launch on December 5, another Falcon 9 is slated to launch NASA’s Imaging X-ray Polarimetry Explorer (IXPE) no earlier than December 9 from LC-39A. This is to be followed by a Turksat-5B communications satellite as early as December 18 back at SLC-40.

Then, only about 54 hours after Turksat, another Falcon 9 is slated to launch from 39A, this time with the CRS-24 Cargo Dragon spacecraft carrying supplies to the International Space Station. While these four launches alone make for a very busy month, it’s not impossible that an additional Starlink launch could occur before the year is out from either Florida or Vandenberg Space Force Base in California.

Before this especially active finale to the 2021 launch year can occur, Starlink Group 4-3 must successfully get off the ground. The Falcon 9 stack, including both stages and the satellites enclosed within the payload fairing, rolled out to SLC-40 on Monday. On Wednesday evening at 6:30 PM EST, a successful static fire test of the rocket’s first stage was completed.

Meanwhile, the vessels tasked with recovering Falcon 9’s reusable components made their way to their respective landing zones. A Shortfall of Gravitas, towed by Finn Falgout, departed Port Canaveral on November 27. The drone ship will be stationed approximately 639 kilometers downrange, northeast of Cape Canaveral.

Following a successful launch, booster B1060-9 will attempt to land on A Shortfall of Gravitas for reuse on future missions. The booster debuted on the GPS-III-SV03 mission in June 2020, the first of nine flights prior to Starlink 4-3. B1060 supported the Turksat-5A and Transporter-2 missions, as well as five previous Starlink missions.

The drone ship will be supported by the multi-purpose vessel named Bob, which departed Port Canaveral on Monday. Bob will also be tasked with the post-splashdown recovery of both payload fairing halves.

The payloads onboard include 48 Starlink satellites, which will join the over one thousand spacecraft already deployed for SpaceX’s satellite internet constellation. The Group 4-3 mission is the third Starlink flight in support of new “shells” of satellites, after the first such shell’s launches were completed in May. The Group 2-1 mission from Vandenberg, California in September and the Group 4-1 mission from Florida in November were the first two missions with these new, upgraded, satellites, which also occupy different orbits than the first shell.

The Group 4-3 satellites will be deployed into low Earth orbit inclined 53.2 degrees to the equator and an altitude of 430 kilometers. This is a higher injection orbit than usual, as most Starlink missions deploy into lower orbits in order to enable faster reentry of malfunctioning satellites and the tension rod debris objects from the payload stack’s deployment mechanism.

Following stage separation, a single, six minute long upper stage burn will place the payloads into orbit. After second stage engine cutoff (SECO) just under nine minutes after launch, the stage and payload stack will coast for just under an hour.

A pair of BlackSky Global satellites are prepared for integration on the Starlink v1.0 L9 mission in August 2020. The satellites on the Group 4-3 mission will be similarly integrated. – via Spaceflight Inc.

Joining the Starlink stack on this flight are a pair of BlackSky Global satellites, as part of a rideshare mission designated SXRS-2 and managed by Spaceflight, Inc. The BlackSky satellites will be mounted on top of the stack of Starlink spacecraft and be deployed prior to separation of SpaceX’s satellites at T+ 63 and 66 minutes, respectively. Deployment of the 48 Starlink satellites will occur an hour and a half after launch.

BlackSky previously launched a pair of satellites on the Starlink v1.0 L9 mission in August 2020 in a very similar manner. The Earth observation constellation has utilized multiple rideshare launch opportunities, including an Indian PSLV launch in November 2018, the Spaceflight, Inc. SSO-A mission on Falcon 9 in December 2018, and Rocket Lab Electron launches in June 2019, August 2019, and March 2021.

BlackSky has also launched spacecraft on dedicated Rocket Lab launches. The first such launch in May 2021 failed due to a second stage failure, but the second in November successfully launched two BlackSky Global satellites to orbit. Another dedicated launch for BlackSky by Rocket Lab is scheduled for this month, to be followed by another in 2022.

(Lead photo: Falcon 9 B1060 at SLC-40 prior to the launch of Transporter-2 in June – via Stephen Marr for NSF/L2)

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