Pi day 2024 saw SpaceX launch the behemoth two-stage Starship Super Heavy prototype, a third integrated flight test performed with the experimental solar system-class vehicle. Flying from the remote Texan village of Boca Chica, now called Starbase, the Super Heavy booster stage fired all its 33 Raptor engines, lifting off with the second-stage Starship from SpaceX’s reinforced orbital launch mount. 

The flight marked a few new milestones in Starship's development. Its Raptor engines demonstrated full-duration engine burn to orbit, the Super Heavy booster performed a boost-back burn and demonstrated re-ignition of Raptor engines in-flight, SpaceX operated Starship's payload bay, and for NASA's Artemis moon missions, Starship demonstrated the transfer of cryogenic propellant in orbit. While the mission ended with Starship attempting hypersonic re-entry before its destruction over the Indian Ocean, the vehicle is beginning to demonstrate that its interplanetary goals will soon be in reach.

Starship Super Heavy, designed to propel humans and cargo back to the moon and beyond, powered through its ascent after a smooth launch at 9:25 AM ET on Thursday, March 14th. At 2 minutes and 42 seconds into flight, the Super Heavy booster powered down all but three of its Raptor engines. As it reached the point of stage separation, Starship ignited all of its engines to move away from the booster; a unique system known as Hot Staging. Starship continued its trajectory to orbit while the Super Heavy performed a flip maneuver and reignited 13 Raptor engines to make its way to the targeted splashdown in the Gulf of Mexico.

Descending through the thicker parts of the atmosphere, the booster was guided by its grid fins, similar to how Falcon 9 adjusts its trajectory before landing. 7 minutes after liftoff, as the Super Heavy neared the splashdown point, it re-ignited several of its engines for the final time in an attempt to softly splash down but disintegrated over the Gulf, what SpaceX calls a Rapid Unscheduled Disassembly (RUD). It blew up.

Meanwhile, 6 Raptor engines on Starship continued its ascent. 8 minutes and 37 seconds into the flight, all engines powered down as the Ship reached its intended orbit. The launch targeted an unstable orbit by design so that Starship could return back to Earth even if SpaceX had lost control of it, thereby not contributing to the space junk which poses a threat to operational satellites.

Once in orbit, Starship tried to stabilize itself using its reaction control system (RCS) but was unable to do so throughout its coast phase. The vehicle was seen in a constant (but slow) roll but it didn’t stop SpaceX from carrying out their additional test objectives. The teams successfully opened and closed Starship’s payload door, referred to as the “pez dispenser” by SpaceX. It is a temporary system designed to specifically deploy Starlink satellites before the vehicle is fully operational and ready for larger commercial payloads.

Starship also conducted the first-ever propellant transfer demonstration which involved transferring the cryogenic liquid oxygen from Starship’s header tank to the main tank. This demonstration was carried out under NASA’s Tipping Point contract for $53 million to demonstrate in-orbit cryogenic propellant transfer, critical for Starship’s launch architecture and under development in collaboration with NASA’s Marshall Space Flight Center in Alabama.

“Storing and transferring cryogenic propellant in orbit has never been attempted on this scale before,” said Jeremy Kenny, project manager, NASA’s Cryogenic Fluid Management Portfolio at Marshall. “But this is a game-changing technology that must be developed and matured for science and exploration missions at the Moon, Mars, and those that will venture even deeper into our solar system.”

Starship was scheduled to reignite their Raptor engines to demonstrate re-ignition in space; however, it wasn’t performed because of the vehicle’s unstable orientation. 46 minutes after the liftoff, Starship went to re-enter the atmosphere for the first time. During this phase, the telemetry and the uninterrupted live video stream were provided through Starlink, completing yet another crucial test for in-space use of SpaceX’s internet satellite system. A bright red plasma started surrounding the vehicle as it entered Earth’s atmosphere at 26,700 kilometers per hour (16,591 miles per hour) at an altitude of 100 kilometers (62 miles). Plasma is very rarely seen in spaceflight coverage due to the communications outage it causes.

Starship wasn’t able to sustain the high heat level of the plasma generated for long, disintegrating over the Indian Ocean. Although unsuccessful, this re-entry attempt provided teams with valuable data on heating and vehicle control during hypersonic re-entry that will be used to improve systems for their next test. 

“With each flight test, SpaceX attempts increasingly ambitious objectives for Starship to learn as much as possible for future mission systems development. The ability to test key systems and processes in flight scenarios like these integrated tests allows both NASA and SpaceX to gather crucial data needed for the continued development of Starship HLS,” said Lisa Watson-Morgan, HLS Program Manager at NASA’s Marshall Space Flight Center in Huntsville, Alabama. Human Landing System [HLS] is the Starship’s lunar-optimized variant currently in development to land Astronauts back to the Moon under NASA’s Artemis program.

SpaceX President and COO Gwynne Shotwell expects the next integrated flight test to occur in early May. While the teams are still analyzing the flight data, the focus of the next flight will be to perfect Ship’s re-entry. Shotwell mentions an aggressive Starship development goal for this year, which is to reach orbit, deploy satellites and recover both Ship and the Booster. The flight profile and general objectives are expected to remain the same on Starship's next flight test.

SpaceX will be conducting a now-routine mishap investigation in-tandem with the FAA before being certified for flight. FAA’s Associate Administrator for Office of Commercial Space Transportation, Kelvin Coleman, says that SpaceX is aiming for 6-9 more Starship launches this year.

Starship has become the largest and most powerful rocket to successfully launch into Earth’s orbit but it still has a long way to go before it delivers on SpaceX’s ambitious goals. This isn’t just a development of new rockets but a radical launch architecture that includes multiple efficient launch pads and ground support equipment, different Starship variants, and most importantly, the in-orbit refueling system which promises to enable deep space missions to the Moon, Mars, and beyond.

Getting to orbit just represents one of many challenges ahead for the Starship launch system. Once operational, it’ll attempt to revolutionize space transportation, giving rise to new opportunities in commercial, defense, scientific research, and human spaceflight ventures.

Decade after decade, NASA’s flagship missions are becoming increasingly capable but are primarily limited by the launch vehicle’s mass and volume constraints. This pushes the engineers to find clever solutions, often increasing R&D costs and mission risks. The James Webb Space Telescope was plagued by this issue as NASA engineers had to develop new technologies to build its 6.5-meter primary mirror with Beryllium and complex systems to fold those segments such that it is light and compact enough to be launched on the Ariane 5 rocket

A larger and more powerful launch vehicle like Starship would enable such missions to have flexible mass requirements, allowing the use of simpler, heavier components with less exotic materials and incorporating more robust engineering margins.

"The availability of greater mass and volume capability, at lower cost, enlarges the design space," said Charles Lawrence, the chief scientist for astronomy and physics at NASA's Jet Propulsion Laboratory. 

Lawrence, along with astrophysicist Martin Elvis and Sara Seager argued how Starship can accelerate astrophysics research in an article published in Physics Today. 

NASA’s next flagship mission after the Roman Space Telescope can greatly benefit from future launch vehicles with greater capabilities but the agency won’t be able to bank on them anytime soon. Recommendations from the 2020 decadal survey have led NASA to work on the Habitable Worlds Observatory mission. However, to keep its development within NASA’s astrophysics budget, its launch dates have been pushed to the 2040s while the mission will be developed to launch on a rocket operational in the 2020s, thereby not accounting for the rise in new technologies in the future. 

“Studies of the largest flagship missions that NASA commissioned took three years and were completed by 2019. The unfortunate timing meant that the capabilities of Starship could be only briefly considered in the Astro2020 deliberations,” stated authors in the paper Accelerating astrophysics with the SpaceX Starship.

It might take a while before NASA’s Science Directorate benefits from Starship’s capabilities but there’s no denying it can lower the complexities of many missions and this is already apparent. 

Starship is set to launch Voyager Space and Airbus’ Starlab space station in LEO in 2028 and thanks to its large payload volume, it’ll require just a single launch to deliver the entire station to orbit. This will avoid in-orbit assembly which can be expensive and induce higher risk to the mission. Once in orbit, the station will be ready for human missions almost immediately. 

Starship’s unique abilities have given rise to innovative concepts to bridge the gap to astrophysics observation from space. SpaceX reportedly is working with Dr. Saul Permutter at UC Berkeley on a space-based telescope launched on Starship. The concept involves using Starship itself as a structure for a telescope, with a resolution 10 times greater than the Hubble Space Telescope, per Elon. 

The Department of Defense also has a keen eye on Starship’s upcoming capabilities. In general, larger and cheaper rockets will enable larger payloads to orbit while lowering the mission costs but the advantages aren’t just limited to space. The US Transport Command (USTRANSCOM) and the Air Force Research Lab (AFRL) are studying the possibility of transporting cargo via Starship from one point on Earth to another. Starship’s second stage is in itself a powerful launch vehicle and can theoretically transport passengers and payload across the Earth with hypersonic velocities. SpaceX concepts show Starship launching into a suborbital trajectory, completing most international trips in around 30-40 minutes. Combined with its rapid reusability and high launch cadence, it can be used to transport emergency cargo at a rapid pace, faster than any current aircraft. In 2021, AFRL awarded SpaceX with a $102 million contract under their Rocket Cargo Program and since then has gained new confidence in Starship’s reusability and rapid turnarounds, crucial for it to be competitive with cargo transports by a Boeing C-17 Globemaster aircraft.

“We can insert cargo transport as part of their regular launch rate progression, and treat it just like another satellite in their flow, or have contracts in place where we can inject it into their flow,” said Gregory Spanjers, chief scientist for rocket cargo program at AFRL at Space Mobility Conference on January 30, 2024.

AFRL has been working with SpaceX on ways to “containerize” military cargo so that it can go on a rocket, and the challenge is to come up with a standard container design that can also be used on other modes of transportation.

 “The plan is to continue to refine the concept as vehicles and delivery systems evolve. What we’re trying to do is set ourselves up to be an early adopter of these big rockets as they mature.”

DoD has also expressed their interests in commandeering Starship as a government-owned and operated asset for “sensitive and potentially dangerous missions”, per a recent report in Aviation Week. Usually, DoD contracts SpaceX when they require their launch services, however, this proposed arrangement calls for the Pentagon to take control of the vehicle on its own. 

”We have had conversations and it really came down to specific missions, where it's a very specific and sometimes elevated risk or maybe a dangerous use case for the DOD where they’re asking themselves: 'Do we need to own it as a particular asset; SpaceX, can you accommodate that?'" said Gary Henry, Senior Advisor for National Security Space Solutions at SpaceX said at the 2024 Space Mobility Conference.

"We've been exploring all kinds of options to kind of deal with those questions," Henry added.

Such commercial and government opportunities could accelerate the development of the launch architecture which is critical to enable human spaceflight missions to the Moon and Mars, and potentially beyond.

Starship HLS is expected to return humans back to the Moon under NASA’s Artemis program in the next few years. The agency awarded SpaceX with a $2.1 billion contract to develop technologies that can land Starship on the Moon for Artemis 3 mission and beyond. Starship HLS will launch atop the Super Heavy booster and rendezvous with a fuel depot in low earth orbit to refuel before heading to a Near Rectilinear Halo Orbit. The lander will await the arrival NASA’s Orion spacecraft, launched onboard the Space Launch System (SLS). Once Orion reaches NRHO, it’ll dock with Starship as 2 of 4 astronauts will board the HLS and descend down the surface. The landing is slated to take place during the Artemis 3 missions with SpaceX planning to demonstrate this ability beforehand with an uncrewed lunar landing and ascent test.

Although there are no plans in motion for a permanent presence on the Moon, a gradual decrease in lunar mission costs and the ability to land over 100 metric tonnes of cargo on the lunar surface can help establish a permanent base on our nearest celestial neighbor. 

While it may be contracted for lunar missions, SpaceX’s Starship goals have always centered around putting humans on Mars and establishing a city. The launch system has been designed from ground up for interplanetary missions. High launch rate, full reusability, little to no refurbishment, and propulsive landing with in-orbit refueling are all important components needed to reach Mars, transport large cargo shipments, and ultimately enable a permanent human presence.

Methane as a propellant was specifically chosen since it can be produced on Mars via the Sabatier reaction. The current plan involves a crew-rated Starship to launch onboard the Super Heavy booster to low-Earth orbit. It’ll then rendezvous with the fuel depot to refuel before coasting to Mars. Once arriving, Starship will perform a propulsive landing on the red planet resembling the way Falcon 9 touches down at Cape Canaveral. Initial cargo flights will have the equipment needed for the first human missions, including in-situ fuel production. Locally produced Methane and Liquid Oxygen will fuel the Starship for the return journey to Earth. Owing to Mars’ low gravity, Super Heavy isn’t required for the Starship to reach Mars’ orbit.

Its large habitation volume — equaling the International Space Station — won’t require immediate establishment of a base and is sufficient for human presence for early missions. It just doesn’t stop there, local fuel production can help establish a fuel depot in Martian orbit, which can enable even heavier payloads to launch in the outer solar system and beyond. 

With the potential to revolutionize the space industry, Starship is still in its initial stages of development and a long road lies ahead before it can fulfill SpaceX’s grand ambitions of making humanity a multi-planetary species and even an interstellar one. As sci-fi as that sounds. "This Starship is designed to traverse our entire solar system and beyond to the cloud of objects surrounding us. A future Starship, much larger and more advanced, will travel to other star systems," said Elon Musk on X. 

Getting out of the solar system and traveling to our nearest star, Proxima Centauri located 4.2 light years away or 40 trillion kilometers (25 trillion miles), will require far greater leaps in propulsion technology development, one that is not even comprehensible today and would require decades of research. The small leaps taken today iteratively will enable large ones in the future.