Launch Roundup: Falcon 9 returns to flight, China launches Earth observation satellites

by Martin Smith

The launch schedule in the past few weeks had been notably quieter than usual. Last week, a Chang Zheng 4B launched the latest set of Gaofen-11 high-resolution Earth observation satellites in the early hours of Friday, July 19 — the only launch of the week of July 14 through July 20.

Following a Falcon 9 second stage anomaly during the Starlink Group 9-3 mission on July 12, Falcon 9 had been grounded while SpaceX and the Federal Aviation Administration (FAA) conducted a mishap investigation. SpaceX has since posted an update on July 25 following its own internal review, highlighting the removal of a second stage engine sensor and sense line on future vehicles in the near term.

Falcon launches were anticipated to return as soon as last weekend and restarted from Saturday, July 27, while the investigation continues. The first three launches took place within 28 hours of each other, in the process marking the 300th reuse of a Falcon 9 booster.

Rocket Lab was initially set to launch its next Electron on Saturday, July 20, but has since moved this launch to give its customer Capella Space sufficient time to complete testing of the payload.  The mission, “A Sky Full Of SARs,” is expected to launch in August and the company’s next launch, “Owl For One, One For Owl” for Synspective, is now set for July 30.

Chang Zheng 4B launches Gaofen-11 05 on July 19 from LC-9. (Credit: CCTV / CASC)

Chang Zheng 4B | Gaofen-11 05

The first launch of a Chang Zheng 4B this year lifted off from LC-9 at the Taiyuan Satellite Launch Center in China on Friday, July 19, at 03:03 UTC.

Since 1999, Chang Zheng 4B has launched various Earth observation, weather, and experimental payloads, including several Shijian and Gaofen satellites. The rocket has launched from both LC-9 and Site 9401 at the Jiuquan Satellite Launch Center and flew only once last year, carrying a Fengyun-3G precipitation-measuring satellite to a low-Earth orbit.

Onboard was the latest in the Gaofen-11 group of satellites, the last of which launched in December 2022. The Gaofen satellites are a series of civilian high-resolution satellites for the state-sponsored China High-Definition Earth Observation, or CHEOS, program.

Booster B1069 launches Starlink Group 10-9 from LC-39A as Falcon 9 returns to flight on July 27, 2024 (Credit: SpaceX)

Falcon 9 Block 5 | Starlink Group 10-9

This mission was the first Falcon 9 to launch since the Starlink Group 9-3 mission two weeks prior, during which an in-flight anomaly occurred.  The launch took place from pad LC-39A at the Kennedy Space Center in Florida, carrying another payload of 23 Starlink v2 Mini satellites. Lift-off took place at 1:45 AM EDT (05:45) UTC) on Saturday, July 27,  over an hour into the four-hour launch window.

This was also the first flight from LC-39A since the pad was reconfigured following the launch of the GOES-U satellite on a Falcon Heavy in June. Booster B1069 made its 17th flight and has supported 12 other Starlink missions, SES-18 and 19, OneWeb 15, Hotbird 13F, and began its career with the CRS-24 cargo mission to the International Space Station. The booster landed around eight minutes into the mission on the autonomous droneship Just Read The Instructions, waiting approximately 600km further downrange. This marked the 256th consecutive successful landing, Falcon 9’s 70th mission of the year, and the 180th launch dedicated to Starlink.

Falcon 9 Block 5 | Starlink Group 10-4

As the week progressed this mission had originally appeared to be the most likely to launch first, following a return to flight. Lift-off took place on Sunday, July 28, at 1:09 AM EDT (05:09 UTC), less than an hour into the four-hour launch window carrying 23 more Starlink satellites. The mission launched from SLC-40 at the Cape Canaveral Space Force Station in Florida – the same pad on which a static fire test was conducted on a Falcon 9 earlier in the week on Wednesday.

Before the Starlink Group 9-3 anomaly, the drone ship A Shortfall of Gravitas had headed out northwest towards the landing zone for this mission and, once Falcon 9 was grounded from all future flights, the droneship returned to port. A Shortfall of Gravitas once again supported this mission and left Port Canaveral again during the week in readiness. Booster B1077 was taking its 14th flight and landed successfully on the droneship around 8 minutes into the mission. This first stage has supported seven previous Starlink missions in addition to carrying both crew and cargo to the International Space Station. It carried Crew-5 on its maiden flight and went on to transport the CRS-28 and CRS-NG-20 cargo missions in addition to launching the Inmarsat I-6 F2, Galaxy 37, and GPS-3 6 satellites. SpaceX noted this was also the 300th reuse of a Falcon 9 booster.

Falcon 9 Block 5 | Starlink Group 9-4

Starlink Group 9-4 launched from SLC-4E at the Vandenberg Space Force Base in California — the first mission to fly from this site in two weeks since the troubled Starlink Group 9-3 mission on July 11. Potential launch opportunities shifted during the week and this mission took place on Sunday, July 28, at 2:22 AM PDT (09:22 UTC).

Onboard was a payload of 21 Starlink satellites, of which 13 are the newer Direct to Cell variant. Booster B1071 was flying for the 17th time and landed on the autonomous droneship Of Course I Still Love You. It has supported nine previous Starlink missions and three for the National Reconnaissance Office, including its previous flight on the NROL-146 mission. It has also carried Transporter 8 and 9, SWOT, and SARah 1 into space. This was SpaceX’s 73rd mission of the year and the 136th orbital launch attempt in 2024.

Booster B1063 atop a droneship after launching Starlink Group 9-3. (Credit: SpaceX)

Upper stage issues

Problems with rocket upper stages have been a recurring theme in recent weeks. The largely successful maiden launch of the Ariane 6 rocket on July 9 experienced a problem with the auxiliary propulsion unit (APU) that enables the second stage engine to be restarted multiple times. While the primary payload of 11 satellites was deployed successfully, the APU shut down almost immediately when trying to restart the engine for the second time. As a result, the stage could not perform a deorbit burn, and will likely remain in orbit for around 15 years. A secondary objective to release two final customer capsules that would test heat shields during reentry was also not achieved due to the issues with the APU.

The following day, on July 10, the Chinese Hyperbola-1, also known as the Shuang Quxian-1, experienced a malfunction on its fourth stage. This resulted in the loss of the payload of three Yunyao weather satellites.

Lastly, just two days later, Falcon 9’s second stage Merlin Vacuum engine failed to complete its second burn during the Starlink Group 9-3 mission. Unusual amounts of ice were seen near the engine on the live stream, which SpaceX later confirmed was due to a liquid oxygen leak that had developed on the second stage. The payload of 20 Starlink satellites was subsequently deployed in a lower-than-intentioned orbit with a perigee of only 135 km.

Liquid oxygen ice buildup near the upper stage Merlin Vacuum engine during the Starlink Group 9-3 mission. (Credit: SpaceX)

Despite the team’s efforts to command an early burn, the satellites were unable to generate sufficient thrust to raise their orbits. The onboard hall-effect thrusters are very efficient but low on thrust, which is why Starlink satellites can take months to reach their final target orbit. Of the 20 satellites launched, 18 have reentered Earth’s atmosphere, where they disintegrated.

The FAA deemed a mishap investigation necessary and will need to approve SpaceX’s final report, including any corrective actions that may emerge. In a statement to NSF, the FAA noted that, on July 15, SpaceX had requested that the FAA make a public safety determination as part of the ongoing investigation. It added that “when a public safety determination request is received, the agency evaluates safety-critical systems, the nature, and consequences of the anomaly, the adequacy of existing flight safety analysis, safety organization performance, and environmental factors”.

This approach is what enabled the fourth flight of SpaceX’s Starship to proceed while the investigation from the third flight was ongoing. The FAA continued, saying, “If the FAA agrees no public safety issues were involved, the operator may return to flight while the investigation remains open, provided all other license requirements are met.” SpaceX requested several hazard notices for up to four Starlink missions, initially between July 19 and July 22, which have since been revised daily.

SpaceX’s launch manifest had already been shuffled in the days before the Starlink 9-3 anomaly. The Transporter 11 rideshare mission, once anticipated to launch on Thursday, July 18, was initially delayed to a date later in the month. Additionally, the launch of the WorldView Legion 3 & 4 mission from the Cape had also been pushed out of last week’s schedule. These are two examples of commercial missions that will now be further delayed due to the grounding, which also delayed the Arctic Satellite Broadband Mission that had been due to launch last week in their place.

In addition to these commercial missions, the crewed Polaris Dawn mission has been affected by the grounding. The teams are currently aiming for a “late Summer” launch once other obligations are met. The Crew-9 mission is currently targeting Aug 18 which remains subject to one of the two docking ports on the International Space Station (ISS) becoming free. NASA still intends this to be made available through Starliner departing the Station by the end of next week. The upcoming CRS NG-21 cargo resupply mission to the ISS currently remains scheduled for August 3.

SpaceX noted that it remained “positioned to rapidly recover and continue our pace” in an official statement released following Starlink Group 9-3. A Falcon 9 ignited its nine Merlin engines for the first time since the anomaly, conducting a static fire test at midnight on Wednesday, July 24 on the pad at SLC-40. Both drone ships on the East Coast returned to sea, together with their support ships, signaling further that a return to flight was anticipated for this weekend.

On Thursday, July 25, SpaceX posted an update regarding its own comprehensive and thorough investigation, noting that a failed sense line and sensor will be removed from the second stage engine on near-term Falcon launches. This change was verified through tests at the McGregor facility, having established that alternative sensors on the engine can be used and that this sensor is not used by the flight safety system. “An additional qualification review, inspection, and scrub of all sense lines and clamps on the active booster fleet led to a proactive replacement in select locations”, the company added. During NASA’s Crew-9 briefing, SpaceX confirmed that the FAA formally approved a return to launch on July 25.

(Lead image: Falcon 9 launches a batch of Starlink satellites into orbit. Credit: Julia Bergeron for NSF)

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