Falcon Heavy launches USSF-52 spaceplane

by Justin Davenport

As 2023 draws to a close, the US Department of Defense’s X-37B spaceplane returned to space on the OTV-7 mission aboard a SpaceX Falcon Heavy rocket. USSF-52, the fifth Falcon Heavy flight of the year, and ninth overall, lifted off on Dec. 28 at 8:07 PM EST (01:07 UTC on Dec. 29). USSF-52 flew from pad 39A at the Kennedy Space Center.

USSF-52 was initially pushed back to Tuesday, Dec. 12, but was delayed again due to the need to complete system checkouts, as per SpaceX, before the latest delay from Dec.13. The Space Launch Delta 45’s launch mission execution forecast gave the weather an 80% chance of being favorable for launch.

USSF-52 became the 95th SpaceX Falcon-family orbital flight of 2023, and the eighth SpaceX flight this month.

The Falcon Heavy launched initially on a northeast trajectory. However, a dogleg to a much higher inclination is possible, as per a navigational warning that could be related to the second stage disposal into the North Pacific. Dr. Marco Langbroek’s thread on X discusses this flight’s possible — but not confirmed — trajectory. Two line element sets for launch launch have not been released yet to verify the initial orbit.

Initially, the payload was placed into low-Earth orbit, though it is possible the X-37B could end up in a much higher final orbit. Testing in new orbital regimes is thought to be one of the objectives of this mission, along with space domain awareness, and NASA has the Seeds-2 experiment on board that can take advantage of this to explore the long-term effects of radiation on plant seeds.

In addition to NASA’s experiment, the X-37B can — and does — carry military experiments and payloads of various kinds, and even launched small satellites like the US Air Force Academy FalconSat-8 in the past. Notably, the vehicle’s orbital path would take it over several regions of the world where tensions are high or have broken into active warfare, including southern Ukraine, the Middle East, Taiwan, and Guyana.

The Falcon Heavy for this mission used B1084 as the core vehicle for its first and only flight. While the core, specially built as a Falcon Heavy core vehicle, is expended, the side boosters B1064-5 and B1065-5 returned to the launch site for touchdowns on Landing Zone-1 (LZ-1) and Landing Zone-2 (LZ-2) concrete pads. 

Falcon Heavy side boosters landing at LZ-1 and LZ-2. (Credit: SpaceX)

Although recovery attempts have been made on past Falcon Heavy launches, the performance requirements for these flights often require that at least the center core be expended so that adequate performance is available to complete the mission. On this flight, the boosters can be returned, which has not always been the case for Falcon Heavy flights. B1064-5 successfully landed on LZ-1, while B1065-5 will use LZ-2.

The X-37B encapsulated in its fairing before flying aboard the Falcon Heavy on USSF-52. (Credit: Boeing)

B1064 and B1065 have flown four flights each, and though side boosters can be converted to single-stick Falcon 9 vehicles and vice versa, these boosters have only flown as Falcon Heavy side boosters so far. They debuted together during the USSF-44 mission in late 2022 and also flew the USSF-67, EchoStar 24, and Psyche missions this year.

The X-37B Vehicle 2 is making its fourth flight, having flown the OTV-2, OTV-4, and OTV-5 missions. If the fairing halves are reused in the future after being recovered by SpaceX’s ship Doug, then the only parts of the Falcon Heavy stack not to be reused will be the core and second stage.

The second stage also does not have a gray thermal protection stripe on it, meaning that the stage did not have an extended flight time like what is required for direct geosynchronous orbit insertion. USSF-52 also did not fly due east, unlike missions that send satellites to geosynchronous orbits.

If a high altitude is achieved, it would be more like a Molniya orbit, a high-inclination orbit that flies to altitudes much higher than typical low-Earth orbit missions. The Soviet Union pioneered using these orbits with Molniya-class communications satellites to cover the entire country including Arctic areas.

Ralf Vandebergh photographed Vehicle 2 in orbit in 2019 during OTV-5 and posted this on X. The X-37B, massing on the order of approximately 5,000 kilograms, uses a deployable solar panel to power its systems. This allows for much longer missions than the Space Shuttle was capable of.

The X-37B has demonstrated the ability to fly over 900 days — nearly three years — in orbit. OTV-6, using the first X-37B to fly — Vehicle 1 — landed in November 2022 at the Shuttle Landing Facility on the Kennedy Space Center grounds after 908 days in space. OTV-6 was also the first mission where the X-37B carried a service module for additional experiments, and it is possible that OTV-7 will carry this as well.

OTV-7 is the first competitively won military mission for Falcon Heavy, as SpaceX’s $130 million bid won out over ULA’s Delta IV Heavy, which is now down to its last-ever launch. After the NROL-70 mission no earlier than this coming March, the Delta family will come to an end, while ULA’s Atlas V is flying out its remaining manifest.

Falcon Heavy launching the Psyche asteroid probe on Oct. 13, 2023. (Credit: Sawyer Rosenstein for NSF)

SpaceX won the OTV-7 bid in 2018 under an earlier program. The company has now won additional bids under Phase 2 of the National Security Space Launch contract, while ULA is also going to fly Phase 2 missions. Phase 3 of the national security launch contract is due to make awards in mid to late 2024, and a third launch provider could be added to “Lane 2” which assigns the most demanding and performance-intensive military space missions.

While the Falcon Heavy will have made five flights in 2023, the next mission for this type will be no earlier than this coming April when the GOES-U weather satellite is scheduled to fly. Falcon Heavy has three flights scheduled for next year, with GOES-U followed by Europa Clipper in October and the Griffin Mission One lunar lander carrying the NASA VIPER rover in November.

Artist’s impression of the Europa Clipper in the Jupiter system. (Credit: NASA)

The side boosters for USSF-52 are also scheduled to fly on the Europa Clipper mission, where under current plans B1064 and B1065 would make their sixth and final flight, being expended along with the core as maximum performance would be needed to get the probe to the Jupiter system for arrival in 2030.

(Lead image: Falcon Heavy launches X-37B. Credit: Max Evans for NSF)

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