More than a week later than originally planned, a previously-flown SpaceX Falcon 9 core stands primed on historic Pad 39A at the Kennedy Space Center (KSC) in Florida, ready to deliver another 60-strong batch of Starlink internet communications satellites into low-Earth orbit at 10:22 a.m. EDT Monday.
In the meantime, a swing-arm issue on Space Launch Complex (SLC)-37B at neighboring Cape Canaveral Air Force Station has obliged United Launch Alliance (ULA) to wait until no earlier than Tuesday to send a triple-barreled Delta IV Heavy on its way with the highly secretive NROL-44 payload for the National Reconnaissance Office. And the promise of a third launch in less than two days may be realized as early as 9:55 p.m. EDT Tuesday, when a brand-new Falcon 9 aims to lift the fourth Global Positioning System (GPS) Block III navigation and timing satellite from the Cape’s storied SLC-40 on behalf of the U.S. Space Force.
Month’s end was already shaping up to be a “Tale of Three Launches”, with ULA expected to be first out of the gate with its Delta IV Heavy after a frustrating month of delays. The 235-foot-tall (72-meter) rocket—which comprises three gigantic Common Booster Cores (CBCs), strapped side by side, and each powered by an Aerojet Rocketdyne RS-68A engine—has been on the pad since mid-November of last year and in the second week of January 2020 was put through a Wet Dress Rehearsal (WDR) to simulate its countdown. This included fueling the CBCs with liquid oxygen and hydrogen. Originally targeted to fly in June, the mission slipped to 26 August, for undisclosed reasons.
The NRO requested an additional 24-hour slip to the 27th, which was itself called off when a ground pneumatics control system issue required attention. A third attempt on the 29th came right down to the wire. At T-3 seconds, the launch kwas scrubbed in a visually dramatic “Hot Fire Abort”. A fourth attempt on Saturday, 26 September was also postponed, initially to Sunday and eventually No Earlier Than (NET) Tuesday, due to an issue with the swing-arm at SLC-37B.
“Additional time is needed for the team to test and evaluate the swing-arm retraction system,” ULA noted on Saturday. “We are taking our time to thoroughly review the data to determine the appropriate path forward.” In a tweeted comment, ULA CEO Tory Bruno provided more detail. “Working an issue with the hydraulic system that retracts the swing-arm,” he explained. “Bird and payload remain healthy.”
For its part, SpaceX always intended to close out September with two launches of its own. The veteran B1058 Falcon 9 core—ready for its third mission, having previously lofted Dragon Endeavour for “Bob and Doug’s Excellent Adventure”, last 30 May, and South Korea’s ANASIS-II military communications satellite on 20 July—was originally slated to fly again as soon as 17 September, but was routinely postponed by 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 East Coast “catch” of a 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.” This is one of very few occasions where SpaceX has 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 would ordinarily not be prioritized over the safe delivery of the payload.
Following its 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.
Assuming an on-time launch tomorrow morning, the Starlink deployment is anticipated to occur just over an hour later, bringing the total number of these low-orbiting internet communications satellites to over 770. SpaceX anticipates having thousands of Starlinks in orbit by the mid-2020s.
Rounding out this week’s potential “triple-header” (assuming ULA does indeed also fly on Tuesday) is the GPS III-04 mission, targeted to fly atop the never-before-used B1062 core from SLC-40 during a 15-minute “window”, which opens at 9:55 p.m. EDT Tuesday.
This forms part of a three-mission, $290.5 million contract awarded to SpaceX by the Air Force back in March 2018. The Block III satellites are destined for Medium Earth Orbit (MEO), about 12,550 miles (20,200 km) above the planet. GPS III-04 was formally “called-up” by the U.S. Space Force in January 2020, for an anticipated launch in the summer, although schedules slipped in response to the COVID-19 coronavirus pandemic.
The 8,500-pound (3,900 kg) satellite was delivered to the Cape in July aboard a C-17 Globemaster III aircraft, whereupon it was ensconsced in Astrotech’s payload processing facility for fueling and final tests. And early last Friday, B1062 put its muscle to the test, burning its nine Merlin 1D+ first-stage engines for a few seconds in a customary Static Fire Test. Such tests were, until earlier in 2020, an absolute staple before each Falcon 9 launch, although in recent months SpaceX has elected not to perform them on a number of its Starlink missions.
In addition to these three tentatively scheduled launches—Starlink at 10:22 a.m. EDT tomorrow, NROL-44 (possibly) on Tuesday and GPS III-04 at 9:55 p.m. EDT Tuesday—several forthcoming missions edged steadily closer to their own dates with destiny. The Sentinel-6 Michael Freilich ocean altimetry spacecraft departed Munich Airport in Germany and arrived safely at Vandenberg Air Force Base, Calif., on 24 September, aboard an Antonov 124 aircraft, where it will be readied for its 10 November launch atop a Falcon 9.
And last Friday NASA formally selected SpaceX to launch the Interstellar Mapping and Acceleration Probe (IMAP) mission in October 2024. From a position at the L1 Lagrange Point, about a million miles (1.5 million km) beyond Earth, IMAP will put its ten scientific instruments to work investigating the acceleration of energetic particles in the heliosphere and the interaction of the solar wind with the local interstellar medium.