More than a month since its most recent launch, SpaceX finally put the gremlins of the last few weeks behind it at 7:29 a.m. EDT Tuesday with a spectacular Falcon 9 liftoff shortly after sunrise. It brought a suitable end to a troubled first few days of October, nicknamed “Scrubtober”, in light of scrubbed launch attempts which have affected SpaceX, Northrop Grumman Corp. and United Launch Alliance (ULA).
The previously-flown B1058 core—veteran of two earlier launches and only the fourth Falcon 9 to have flown as many as three times in 2020—took flight from historic Pad 39A at the Kennedy Space Center (KSC) in Florida after being repeatedly stalled by a toxic and seemingly intractable mix of poor weather and technical issues.
A little more than an hour after launch, its payload of 60 Starlink low-orbiting internet communications satellites were successfully deployed, putting the total number of these flat-packed SpaceX birds sent into space since May 2019 at 773.
Weather conditions for Tuesday morning’s liftoff were predicted to be about 70-percent favorable, according to meteorologists at the 45th Weather Squadron at Patrick Air Force Base. “The remnant boundary that has been lingering across the state over the past week is expected to drift just enough northward later today to allow the prevailing flow to become more easterly and a slight drying to occur over the Spaceport,” it was noted on Monday morning. The 45th added that shower coverage would be highest on Monday morning and would continue into Tuesday morning, but “the exact coverage and placement of this activity will be hard to pin down in advance”.
Launch of this particular Falcon 9 came after no fewer than four delayed attempts since the middle of last month. Initially targeted to fly on 17 September, it was postponed at least 24 hours in response to the indirect threat posed to the Space Coast by Tropical Storm Sally.
Although SpaceX noted that it would be closely “watching the weather” on the 18th, it ultimately opted to stand down from further launch preparations, pointing to predicted poor sea conditions in the booster recovery area. This likely would have hampered the efforts of the Autonomous Spaceport Drone Ship (ASDS), “Just Read the Instructions”, to safely execute its third planned East Coast “catch” of a returning Falcon 9 core. “Current was too strong for drone ship to hold station,” SpaceX founder Elon Musk tweeted. “Thrusters to be upgraded for future missions.”
As such, this marked one of very few occasions where SpaceX prioritized the safe return of a booster as a deciding factor in scrubbing a launch. Of course, Starlink is an in-house SpaceX program and on a commercial or government launch the safe return of the booster ordinarily would not be prioritized over the safe delivery of the payload.
Following the scrub, JRTI returned to Port Canaveral on 20 September and a few days later her sister ASDS, “Of Course I Still Love You”—veteran of over 30 successful Falcon 9 recoveries since April 2016—put to sea in her stead, bound for a position about 390 miles (630 km) off Cape Canaveral in the Atlantic Ocean.
Another launch attempt on 28 September seemed doomed from the start, with gloomy conditions at the Cape, a mere 40-percent likelihood of acceptable conditions at T-0 and heaving seas visible from cameras on the ASDS deck. Nonetheless, SpaceX pressed on with fueling and countdown operations, targeting a mid-morning liftoff, despite a solid “Red” (“No-Go”) status from the Eastern Range.
Inevitably, a scrub was called at T-31 seconds. A third try on 1 October took place under picture-perfect skies, before an abrupt cutoff at T-18 seconds, due to an “out-of-family ground system sensor reading”. The fourth attempt yesterday (Monday) also came to nothing, as rain continually lashed KSC.
With two Falcon 9 missions thus poised for many days on the Space Coast—the veteran B1058 with Starlink on Pad 39A and the brand-new B1062 core with the fourth Block III Global Positioning System (GPS) satellite out on Space Launch Complex (SLC)-40 at neighboring Cape Canaveral Air Force Station—it therefore came as a breath of fresh air when the backlog began to clear Tuesday morning, despite a risk of cumulus clouds along the flighth path.
Liftoff came on time at 7:29 a.m. EDT, just a few minutes after local sunrise, and B1058 provided 1.5 million pounds (680,000 kg) of thrust for the first 2.5 minutes of flight, before separating from the stack and returning to a perfect touchdown on the deck of OCISLY. The drone ship was situated about 388 miles (624 km) downrange of the Cape.
Meanwhile, the second stage continued to power uphill and the 60 Starlinks were successfully deployed into a circular orbit a little over an hour into the mission, courtesy of two “burns” by the Merlin 1D+ Vacuum engine. To date, SpaceX has flown 13 “stacks” of production-design Starlinks since May 2019 and with today’s flight a total of 773 of these flat-packed internet communications satellites have been put into low-Earth orbit.
Hopes of launching as many as four Falcon 9s in September may have come to nothing, but SpaceX may—just may—achieve that figure in October. A date for the delayed GPS III-04 mission has yet to be announced, but with an expectation for at least one more Starlink flight before month’s end and the Halloween launch of Crew-1 astronauts Mike Hopkins, Victor Glover, Shannon Walker and Soichi Noguchi to the International Space Station (ISS), this may yet be achieved. If it is, four flights in a single calendar month will set a new “personal best” for SpaceX.
At the same time, SpaceX is looking ahead to the next flight by its gargantuan, triple-barreled Falcon Heavy, sometime next year. “A Falcon Heavy side booster that will support the USSF-44 mission for the @SpaceForceDoD next year completed a full-duration static fire test last week at SpaceX’s rocket development facility in McGregor, Texas,” the company noted late Monday.
Only three Falcon Heavy launches have been conducted to date, most recently in June 2019. And the USSF-4 payload for the U.S. Space Force forms part of a $297 million, three-mission contract signed between SpaceX and the Department of Defense in February 2019. According to the details of the contract, the geostationary-bound USSF-44 “is expected to be completed by February 2021”, although it remains to be seen if this target can be achieved.