The first launch of SpaceX’s Falcon Heavy rocket in almost two years has entered the final stages of preparation – flight hardware acceptance testing, delivery and assembly.
Comprised of five main elements, the vast majority of the challenges of building and launching the Falcon Heavy come from the rocket’s three first-stage boosters – each roughly equivalent to a single-core Falcon 9 booster. Falcon Heavy’s double-sided boosters are by far the most visually recognizable signal of this similar but different nature, thanks to the need for aerodynamic nosecones instead of a normal Falcon booster interstage (a hollow cylinder).
Although easily recognizable, the central core is the most technically specific part of the Falcon Heavy of SpaceX’s partially reusable heavy cargo rocket, requiring a unique structure in relation to the side cores, which are essentially Falcon 9 boosters with some main accessories. It is one of those Falcon Heavy side boosters that was seen traveling by road from SpaceX’s test facility to a launch pad in Florida on Tuesday, January 26th.
For unknown reasons, although SpaceX currently has two reused Falcon Heavy side boosters that flew for the second time in the United States Air Force’s STP-2 mission, the company manufactured entirely new boosters – probably at the request of the U.S. military – for the fourth rocket launch. Rebadged from AFSPC-44 to USSF-44, this mission will see SpaceX attempt its first direct launch to GEO, nominally launching a mysterious multi-ton satellite directly into geostationary orbit (GEO).
The main challenge of direct launches to GEO is the need for a particular upper stage of a given rocket to slide for hours in orbit and rekindle after that period of several hours on the coast. The direct launch profile also requires more delta-V (propellant) than alternative transfer orbits (GTOs) – a propellant that must be launched in orbit beyond the customer’s payload. This requires the use of extremely large and / or efficient rockets, which is why SpaceX is launching the USSF-44 with the Falcon Heavy instead of a much cheaper and simpler Falcon 9.
Unlike all other direct GEO launches in history, however, Falcon Heavy Flight 4 will (hopefully) mark the first time that a rocket launches a payload in geostationary orbit while still recovering a large part of its first stage. After takeoff, the Falcon Heavy B1064 and B1064 side boosters will attempt the first double drone to land at sea, while the central core of the custom built rocket will be intentionally spent. According to CEO Elon Musk, sacrificial-center-core the configuration theoretically allows Falcon Heavy to achieve ~ 90% of its disposable performance while still recovering two reusable boosters.
Since the appearance of the first USSF-44 side reinforcement in Louisiana, at least one other reinforcement (probably the secondary mission reinforcement) has already been located at SpaceX’s development facility in McGregor, Texas and may have completed its own acceptance round of static fire testing. Given the three-month gap between the static fire of the first USSF-44 side booster and the appearance of a side booster in transport, there is a distant possibility that the booster sighted on January 26 was the second of the two side boosters to be sent to the east, but this is unlikely, given how many Falcon boosters stand out on the road.
Ultimately, assuming the static fire acceptance test of the second USSF-44 side reinforcement went well, the only major Falcon Heavy-specific hardware that SpaceX needs to ship from its headquarters in Hawthorne, CA is the B1066 core. An upper stage and payload fairing will also have to pass acceptance tests and head to Florida, but both will likely be standard Falcon 9 hardware, minimizing uncertainty for small batches.
If SpaceX delivers the B1066 to McGregor in the next week or two, the central core should be ready to ship to Florida in March or April, leaving SpaceX two or three months to integrate, fire static and prepare the Falcon Heavy for its fourth release. According to the latest official information from the US armed forces, the USSF-44 is scheduled to launch no earlier than (NET) “late spring 2021”, probably implying the end of May or June.