According to several of its satellite passengers, SpaceX’s second launch of Falcon Heavy – this time with three Falcon 9 Block 5 boosters – is understood to be targeted for no earlier than November 2018 and will mark the first commercial mission for the world’s most powerful operational rocket.
Under the blanket label Space Test Program-2 (STP-2), Falcon Heavy’s first operational mission will be conducted for the US Air Force and see 25 various spacecraft – some weighing as much as 500 kilograms – launched into an equally varied selection of orbits, requiring a complex series of restarts and burns for the rocket’s upgraded Block 5 second stage. STP-2 also includes a huge 5000-kilogram ballast mass as a result of the decision to fly the mission as a demonstration of Falcon Heavy instead of a less powerful but cheaper and simpler single-booster Falcon 9. The total mass of all 25 payloads is likely far beneath the powerful rocket’s actual capabilities, as are the performance and propellant reserves required for the upper stage to inject different spacecraft into a number of orbits, hence the inclusion of so much dead mass.
Falcon 9 Block 5 shows off its interstage heat shielding and titanium grid fins. Falcon Heavy’s three boosters will likely look nearly identical. (Tom Cross)
Of those 25 distinct payloads, a number even include their own co-passenger satellites and experiments and have orbit requirements ranging from a basic circular low Earth orbit (~700km) to an odd, elliptical orbit with ends at 6000 and 12000km. For Falcon Heavy’s second flight, SpaceX will be fielding three highly reusable Block 5 boosters and a Block 5 upper stage with upgrades that enable the vehicle to operate far longer on orbit and reignite its Merlin Vacuum engine three or more times.
Unlikely to seriously tax Falcon Heavy’s brute-force payload lifting capabilities even with five metric tons of ballast, STP-2 will still be a lengthy and complicated endeavor for SpaceX’s Falcon upper stage – perhaps the most complex the company has yet to attempt. However, above all else, the most difficult aspect of the USAF STP-2 mission is almost certainly the comparatively mundane act of coordinating dozens of wildly different satellites and spacecraft from an equally varied number of different and geographically disparate institutions, companies, and government agencies, all of which must be ready for launch and attached to the same SpaceX payload adapter at roughly the same time to prevent mothballing launch delays.
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SpaceX’s first Falcon Heavy completed its spectacularly successful debut earlier this year with a mission that saw CEO Elon Musk’s own Tesla Roadster launch into orbit around the sun and culminated in the truly extraordinary near-simultaneous landings of the rocket’s two flight-proven side boosters. Those boosters both completed their first launches in 2016, nearly two years prior to their second and final flights, and the reinforced center core was built as a new but now-outdated Block 3, lessening the blow from its failure to land aboard the drone ship Of Course I Still Love You after separating from the upper stage. Like all Block 5 versions of Falcon, the second Falcon Heavy’s Block 5 boosters should be expected to support a number of launches before retirement, ranging from several to as many as 100.
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