Early Sunday morning, SpaceX will try something no one has ever done before. If all goes according to plan, around seven minutes after lifting off from South Texas, the huge stainless steel booster from SpaceX's Starship rocket will come back to the launch pad and slow to a hover, allowing powerful mechanical arms to capture it in midair.
This is SpaceX's approach to recovering Starship's Super Heavy booster. If it works, this method will make it easier and faster to reuse the rocket than it is to recycle boosters from SpaceX's smaller Falcon 9 launch vehicle. Falcon 9's boosters usually come down on a floating drone ship stationed hundreds of miles out to sea, requiring SpaceX to return the rocket to shore for refurbishment.
“We’re going for high reusability," said Bill Gerstenmaier, SpaceX's vice president of build and flight reliability.
Sunday's test flight will be the fifth launch of SpaceX's full-scale Super Heavy/Starship rocket, the largest flying object ever to take off from planet Earth. The fully stacked launcher stands 397 feet (121 meters) tall and measures 30 feet (9 meters) wide. The Super Heavy booster's 33 methane-fueled Raptor engines will generate nearly 17 million pounds of thrust, more than twice the power of NASA's Saturn V rocket from the Apollo lunar program.
The Federal Aviation Administration approved a launch license Saturday for SpaceX to launch Starship, ending a prolonged regulatory review of SpaceX's flight plan that largely focused on the impacts of the sonic boom created by the returning Super Heavy booster.
Early Sunday morning, around 50 minutes before liftoff, SpaceX will begin loading cryogenic methane and liquid oxygen propellants into the two-stage rocket.
The 30-minute launch window opens at 7:00 am CDT (12:00 UTC), about a half-hour before sunrise at SpaceX's Starbase launch site near Brownsville, Texas. You can watch the launch live on SpaceX's X page or on one of several third-party YouTube livestreams. We have embedded a livestream from LabPadre and Spaceflight Now here.
The rocket's 33 Raptors will fire more than two-and-a-half minutes to propel Starship into the rarefied uppermost reaches of the atmosphere. Then, the Super Heavy booster, itself 232 feet (71 meters) long, will detach from the Starship upper stage, flip around to point its engines in the direction of travel, and reignite some of the Raptors to reverse course and return to Starbase. Super Heavy's supersonic descent will culminate in another restart of some of its engines to steer itself into position for the launch tower's two arms—sometimes called "mechazilla arms" or "chopsticks"—to close around the rocket.
This first-of-its-kind return-to-launch-site maneuver is risky. It took SpaceX several tries before the company finally accomplished a smooth on-target landing of a Falcon 9 booster.
“We’ll see the booster fly back and land at the tower and be captured by the arms, or we’ll take out the tower," Gerstenmaier joked on October 9 in a meeting of a National Academies committee on scientific research in space.
If this works, expect a rowdy celebration from SpaceX mission control. Elon Musk, SpaceX's founder and CEO, first revealed the plan to catch the Super Heavy booster in a post on Twitter, now known as X, in December 2020.
Musk announced SpaceX's approach to landing and reusing Falcon 9 boosters in 2011 and achieved the first successful recovery four years later. A successful recovery of the Super Heavy booster Sunday would also come four years after Musk's announcement of the catch method.
On its previous test flight in June, the Super Heavy booster made a pinpoint splashdown in the Gulf of Mexico just offshore from the Starbase launch site. The rocket performed all of its return maneuvers exactly as prescribed, giving SpaceX officials the confidence to try the same thing Sunday but aiming for the launch pad instead of the sea.
“We landed with half a centimeter accuracy in the ocean, so we think we have a reasonable chance to come back to the tower," Gerstenmaier said.
Launch playbook
The Starship upper stage, meanwhile, will light six Raptor engines to accelerate to nearly orbital velocity, giving the rocket enough oomph to coast halfway around the world before falling back into the atmosphere over the Indian Ocean.
This is a similar trajectory to the one Starship flew in June, when it survived a fiery reentry for a controlled splashdown. It was the first time SpaceX completed an end-to-end Starship test flight. Onboard cameras showed fragments of the heat shield falling off Starship when it reentered the atmosphere, but the vehicle maintained control and reignited its Raptor engines, flipped from a horizontal to a vertical orientation, and settled into the Indian Ocean northwest of Australia.
After analyzing the results from the June mission, SpaceX engineers decided to rework the heat shield for the next Starship vehicle. The company said its technicians spent more than 12,000 hours replacing the entire thermal protection system with new-generation tiles, a backup ablative layer, and additional protections between the ship's flap structures.
From start to finish, Sunday's test flight should last approximately 1 hour and 5 minutes.
Here's an overview of the key events during Sunday's flight:
•T+00:00:02: Liftoff
•T+00:01:02: Maximum aerodynamic pressure
•T+00:02:33: Super Heavy MECO (most engines cut off)
•T+00:02:41: Stage separation and ignition of Starship engines
• T+00:02:48: Super Heavy boost-back burn start
•T+00:03:41: Super Heavy boost-back burn shutdown
•T+00:03:43: Hot staging ring jettison
• T+00:06:08: Super Heavy is subsonic
• T+00:06:33: Super Heavy landing burn start
• T+00:06:56: Super Heavy landing burn shutdown and catch attempt
• T+00:08:27: Starship engine cutoff
• T+00:48:03: Starship reentry
• T+01:02:34: Starship is transonic
• T+01:03:43: Starship is subsonic
• T+01:05:15: Starship landing flip
• T+01:05:20: Starship landing burn
• T+01:05:34: Starship splashdown in Indian Ocean
SpaceX officials hope to see Starship's heat shield stay intact as it dips into the atmosphere, when temperatures will reach 2,600° Fahrenheit (1,430° Celsius), hot enough to melt aluminum, the metal used to build many launch vehicles. SpaceX chose stainless steel for Starship because it is strong at cryogenic temperatures—the rocket consumes super-cold fuel and oxidizer—and has a higher melting point than aluminum.
Eventually, SpaceX wants to also recover and reuse the Starship upper stage, but the company wants to master on-target landings at sea before bringing the ship itself back to the launch site.
Reusing both stages of the rocket will not only bring down costs but also enable a much higher flight rate than achievable with an expendable launch vehicle. SpaceX's Falcon 9, for example, flies as often as once every three days, on average, from three active launch pads in Florida and California.
Over the last few months, SpaceX constructed a second launch tower for Starship in Texas. The company also has its eyes on two launch pads at Cape Canaveral, Florida for Starship.
SpaceX needs to get to a high flight rate—perhaps on par with where the company is today with Falcon 9—to pull its contract with NASA to land astronauts on the Moon with a version of Starship. SpaceX also wants Starship to rapidly deploy larger, more powerful versions of its Starlink Internet satellites and send cargo and humans into deep space.
Any Starship voyage beyond low-Earth orbit will require SpaceX to refill the rocket with liquid propellants in space. SpaceX is developing different versions of Starship, such as a tanker and an orbiting propellant depot, to make this a reality.
NASA has awarded SpaceX contracts to deliver two Starship lunar landers for astronauts to ride to and from the lunar surface on the Artemis III and Artemis IV missions, and the agency expects to buy more. Artemis III, the program's first lunar landing mission, is officially scheduled for September 2026, but this date is widely expected to slip several years.
“There's no doubt that the Human Landing System is the critical path for for Artemis III," said Lori Glaze, acting deputy associate administrator for NASA's exploration systems development division.
Glaze's division oversees all of the elements agency's Artemis program, including Starship, the Space Launch System rocket, and the Orion spacecraft, which will ferry astronauts between Earth and the vicinity of the Moon, where they will transfer into Starship for the final descent.
“The next really big milestone for Human Landing System, for Starship, is being able to demonstrate the prop transfer," Glaze said on October 9 in a discussion with the National Academies' aeronautics and space engineering board. "That's going to be a really big deal. We've got to be able to demonstrate that they can do that effectively and that we understand any nuances associated with that."
The first docking and propellant transfer between two Starships could happen next year. SpaceX must activate its second launch pad at Starbase to have the ability to launch two Starships in a relatively short period. Ars has previously reported that NASA and SpaceX are assessing alternative mission profiles for Artemis III in case the Starship lunar lander faces longer delays.
Gerstenmaier, who led all of NASA's human spaceflight programs for 14 years before joining SpaceX, said a lunar landing mission with Starship will require approximately 16 launches of refueling tankers. However, this number isn't set in stone, and engineers will learn more about the efficiency of the propellant transfer operation during the upcoming refueling test. Early this year, a SpaceX official estimated that each Starship lunar landing mission would require "10-ish" tanker flights over the course of several weeks.
The upside of SpaceX's architecture is that, with refueling, Starship can theoretically ferry payloads of 100 metric tons or more to the Moon or Mars, significantly more capacity than any other rocket.
"The pacing item is the rate at which SpaceX can launch the systems that can fuel the depot so that it's prepared to fuel Starship for a lunar landing," Glaze said. "So the real key there is them being able to get to a rate where they can launch at a rapid enough cadence.”
More launch pads will help with the flight rate. So will reusing Super Heavy boosters. That's why, although NASA's isn't directly involved in Sunday's flight, agency officials will be watching closely to see if SpaceX is successful in recovering Super Heavy in Texas.
"Once they've demonstrated that capability, I think that will certainly move things in the right direction," Glaze said.
