The world’s most powerful rocket finally returns after a 3-year absence

As early as Tuesday morning, the Falcon Heavy will take flight for the first time since June 2019, ending a long period of inactivity for the world's most powerful, operational rocket. Under the power of 27 Merlin engines in its first stage, the rocket will carry two space technology payloads into orbit for US Space Force.

Ahead of this much-awaited USSF-44 launch, it is natural to ask why it has been more than 40 months since the rocket last flew. And perhaps more importantly, does this suggest that the Falcon Heavy—developed internally at SpaceX, at the company's own expense, for half a billion dollars—was a mistake?

But first, some details about the launch, which is set for 9:41 am ET (13:41) on Tuesday from Kennedy Space Center, in Florida.

Meet me at GEO

This will be SpaceX's first "direct-to-GEO" mission, which means the powerful Falcon Heavy rocket will launch its payload directly into a geostationary orbit nearly 36,000 km above the Earth's surface. Typically such payloads are injected into a transfer orbit, and then the spacecraft's onboard propellant is used to raise the vehicle to a circular geostationary orbit. In this case, however, Falcon Heavy's first and second stages will be doing all the work.

Not much is known about the two spacecraft launching on this mission for Space Force. The primary payload is classified. The secondary payload is a small satellite called Tetra-1, which is a prototype for a kind of satellite the US military hopes to fly one day in geostationary orbit—to do something.

In an emailed news release discussing the launch, Space Force was not particularly helpful with its description of the satellites: "The Long Duration Propulsive EELV Secondary Payload Adapter (LDPE ESPA)-2 and Shepherd Demonstration will carry a variety of payloads that will promote and accelerate the advancement of space technology for the benefit of future Programs of Record."

Thanks, guys, that's super clear. Maybe you could mix in a few more inscrutable acronyms next time.

What we do know is that this mission will require the Falcon Heavy's upper stage to operate for a far longer period than usual, with about six hours between the initial firing of its Merlin vacuum engine and a final firing. This will provide a good test of the upper stage's ability to perform for an extended period.

Why so long?

The long gap between flights has not occurred due to a shortage of Falcon Heavy rockets. At its essence, the Falcon Heavy consists of a core stage that is a modified version of a Falcon 9 rocket's first stage, and two side-mounted boosters that are somewhat less modified. There are other structural adaptations, but basically, SpaceX could manufacture (and reuse hardware) for just about as many Falcon Heavy rockets as the market desires.

It's just that, well, there has not been an overwhelming desire. To put the demand for Falcon Heavy into perspective, in the 40 months since the last heavy launch, SpaceX has flown the Falcon 9 rocket 111 times. That does not mean there is 100 times the demand for the Falcon 9, but it suggests that by continuing to improve the performance of the single-core Falcon rocket, SpaceX eroded some of the potential market for Falcon Heavy when it was designed about a decade ago.

However, there is still demand. Of late, the problem has been delayed payloads. The USSF-44 mission was originally scheduled for December 2020. Another Space Force mission on the Falcon Heavy, USSF-52, was originally supposed to fly in October 2021. NASA's Psyche Asteroid mission was supposed to fly in September but was also delayed after the payload was not ready.

In truth, there is a reasonable amount of demand for a large rocket like the Falcon Heavy. On SpaceX's current manifest, there are 10 more Falcon Heavy missions between now and the end of 2024. Some of those may well get pushed back due to payload readiness, but there are customers out there.

Who is buying?

The short answer is the government. Including USSF-44, the next 10 most likely missions to fly on the Falcon Heavy include five flights for NASA, three for the US Space Force, and two primarily for commercial satellite customers.

The US military is especially keen to see a proven Falcon Heavy. While the Falcon 9 rocket is powerful, it does not have the ability to hit all nine of the Department of Defense's reference orbits required for its launch providers to hit. So with the Falcon Heavy, SpaceX is at an advantage in terms of bidding on military launch contracts. The only other operational US rocket capable of this is United Launch Alliance's Delta IV Heavy rocket, but it is retiring in two years. Its replacement, Vulcan, has yet to fly.

SpaceX's forthcoming Starship and Super Heavy booster, of course, will be able to reach all nine orbits. Although it is likely years away from a "stable" configuration required by the government, it is nevertheless on the way. Because of this, Falcon Heavy is likely to have a limited shelf life, said Todd Harrison, managing director for Metrea Strategic Insights.

"Once SpaceX's new Super Heavy is operational and has a proven track record to assure national security customers, Falcon Heavy will no longer be needed," Harrison said. "So I suspect its useful life is perhaps less than five years and likely only a handful of launches during that time. But it is a beauty to behold when it launches, especially when those side boosters return to land in sync."

Falcon Heavy has also proven popular for some key NASA science missions, including the Psyche spacecraft, Nancy Grace Roman Space Telescope, and the Europa Clipper. NASA awarded the latter mission to SpaceX about a year ago, for a launch in 2024. This was a huge validation of the Falcon Heavy rocket, as NASA entrusted a spacecraft that cost about $4 billion to the large rocket.