SpaceX has achieved its long-sought-after goal of at least ten missions for a single Falcon 9 booster, following Sunday’s pre-dawn liftoff of the veteran B1051 core from storied Space Launch Complex (SLC)-40 at Cape Canaveral Space Force Station, Fla. Launch occurred on time at 2:42 a.m. EDT and saw B1051 deliver the initial push uphill for another 60 Starlink satellites, bringing its personal tally of these low-orbiting internet providers to 417. Sunday’s flight also marked the 125th launch from SLC-40 since June 1965, a complex whose heritage extends back almost six decades across the Titan III and Titan IV rocket families.
Weather conditions proved highly favorable, with the 45th Weather Squadron at Patrick Space Force Base predicting an 80-percent chance of acceptable conditions, deteriorating slightly to 70 percent in the event of a scrub to Monday. “High pressure continues to move across the southeastern U.S.,” it noted in its Saturday morning update. “Slightly cooler and drier air has begun to overspread the area. There will likely be scattered cumulus clouds later this afternoon and evening. Another storm system is developing over the south-central U.S., which will begin to increase winds slightly over the area as it develops this weekend.”
All told, these conditions were expected to produce a “small” threat of a delay, with the main lingering worry being a potential violation of the Cumulus Cloud Rule. But the 45th cautioned that a slip to Monday, and a corresponding movement of the storm system into the Mississippi Valley with a resultant tightening of the pressure gradient, would likely produce increased winds both at the launch site and booster recovery locations.
In readiness for the mission, the tug Finn Falgout duly towed the Autonomous Spaceport Drone Ship (ASDS)—nicknamed “Just Read the Instructions”—out of Port Canaveral last Wednesday, bound for a position about 390 miles (630 km) offshore in the Atlantic Ocean. It proved a remarkable turnaround for JRTI, which only ten days ago also supported the safe recovery of the B1060 core from its own Starlink mission.
This neatly eclipses the 14 days which elapsed between two prior JRTI “catches” of boosters from the Türksat 5A and Starlink-16 flights in January. Today’s mission also marked only the third occasion that life-leading B1051 had returned to alight on JRTI, following two previous touchdowns last January and in December 2020.
With all 14 Falcon 9 missions thus far in 2021 having been launched atop previously-used boosters, it has become customary to see particularly dirty core stages, their hulls blackened and scorched from earlier high-energy ascents and re-entries. Indeed, this year’s flights to date have been accomplished using only six boosters, one of which has launched four times already.
But in addition to the core stage itself, the payload fairing “halves” for Sunday’s mission were also blackened and scorched, having previously seen service to support last November’s launch of the fourth Block III Global Positioning System (GPS).
B1051 first flew way back in March 2019 to deliver an unpiloted Crew Dragon vehicle to the International Space Station (ISS) for the critical Demo-1 mission in support of the Commercial Crew Program. She subsequently lifted Canada’s three-spacecraft Radarsat Constellation Mission (RCM) the following June.
Those first two missions saw B1051 fly both from Pad 39A at the Kennedy Space Center (KSC) in Florida and from Space Launch Complex (SLC)-4E at Vandenberg Air Force Base, Calif.
Following her stint on the West Coast, B1051 headed east to fly seven missions between January 2020 and March 2021, delivering a grand total of 357 Starlinks and SiriusXM’s SXM-7 high-powered radio broadcasting satellite aloft. In doing so, B1051 became the first Falcon 9 booster to launch both four times and five times within a single calendar year.
She also gained plaudits on her April 2020 Starlink mission by eclipsing the United Launch Alliance (ULA) Atlas V as the most-flown operational U.S. launch vehicle. And in January 2021, she set a new record—now beaten—for the shortest launch-to-launch interval of a single orbital-class booster.
Sunday’s 2:42 a.m. liftoff proceeded with characteristic perfection as B1051’s nine Merlin 1D+ first-stage engines burned furiously with an estimated 1.7 million pounds (770,000 kg) of thrust for the first 2.5 minutes of flight. The core was then jettisoned and, guided by its suite of hypersonic grid-fins, deployable landing legs and Entry and Landing Burns, alighted smoothly on the deck of JRTI a little over 8.5 minutes after launch.
“Falcon 9’s first stage has landed on the Just Read the Instructions drone ship,” SpaceX tweeted triumphantly, “completing this booster’s tenth launch and landing.” Meanwhile, the second stage, powered by a single Merlin 1D+ Vacuum engine, continued the push uphill to insert the 60 Starlinks into orbit. Deployment of the stack took place a little over an hour into the mission, bringing the total number of these low-orbiting internet communications satellites launched since May 2019 to over 1,600.
This remarkable reusability of Falcon 9 boosters extends right back to March 2017, when the B1021 core successfully flew the second mission in its career to lift the powerful SES-10 communications satellite on the initial leg of its trek up to geostationary altitude. Since then, a further 26 Falcon 9 cores have flown at least twice.
The first three-times-used booster was B1047 in December 2018, after which B1048 flew a fourth time in November 2019 and a fifth time in March of last year. Frequent-flying B1049 was first to fly sixth and seventh missions last August and November, with B1051 becoming first to launch eight times in January, nine times in March and ten times this morning.
Back on Earth, it also marked the 125th launch for SLC-40, which today played host to its 70th Falcon 9 mission since June 2010. Added to that list, the venerable complex—which first saw service way back on 18 June 1965—has seen 26 Titan IIIC launches, eight Titan 34D launches, the entire four-flight career of the Commercial Titan III and 17 Titan IVs. Its last Titan launch occurred in April 2005, after which it was leased by the Air Force to SpaceX and has served as a Falcon 9 pad ever since.
In addition to a long history of military missions, the pad saw the launch of NASA’s ATS-6 experimental communications satellite in May 1974, the Intelsat-603 communications satellite—later retrieved by the shuttle—in March 1990 and the Mars Observer and Cassini planetary missions in September 1992 and October 1997.
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