What NASA wants to see from SpaceX’s second Starship test flight

SpaceX's Starship rocket on a launch pad in Texas awaiting liftoff on a test flight.
Enlarge / SpaceX’s Starship rocket on a launch pad in Texas awaiting liftoff on a test flight.


NASA managers are in South Texas this weekend as SpaceX prepares to launch its second full-sized Starship rocket. If the rocket flies perfectly, it will unlock additional tests beginning as soon as next year to prove that SpaceX can transfer hundreds of tons of super-chilled methane and liquid oxygen between two spaceships in orbit.

This is a fundamental part of the architecture SpaceX has designed to fly Starship missions beyond low-Earth orbit. With two NASA fixed-price contracts valued at more than $4 billion, SpaceX is on the hook to develop and fly two human-rated lunar landers based on the Starship design (and likely many more missions, assuming these first two work as advertised).

Depending on who you ask, SpaceX may need to launch a dozen or more refueling tankers to fill up the methane and liquid oxygen tanks on the Starship lunar lander, which will have emptied its tanks just to get into low-Earth orbit following launch on top of a Super Heavy booster. The Starship lander will use this fuel to boost itself out of low-Earth orbit toward the Moon, descend to the lunar surface with astronauts, and climb back into space to deliver the crew to their Earth return vehicle—an Orion spacecraft.

But first, SpaceX needs to get Starship into space. That’s the goal for Saturday with the second test flight of the full-scale Super Heavy rocket and the Starship upper stage. If all goes according to plan, Starship will accelerate to nearly 17,000 mph, just shy of the velocity required to reach a stable orbit around Earth. That will leave the vehicle on a trajectory to naturally re-enter the atmosphere for a targeted splashdown near Hawaii, following a trip most of the way around the world.

The Starship upper stage, in the end, will evolve into multiple designs, creating a fleet of landers, space transporters, refueling tankers, and propellant depots. It’s a bold bet on the future of space exploration.

Unlocking the future

“Tomorrow is a test and we’re going to learn a lot either way,” Lisa Watson-Morgan, who manages NASA’s Human Landing System program, told Ars in an interview this week. “We’d love to see it go off perfectly, but frankly, if it doesn’t, it’s still going to be a great learning event, and it still will give us progression on the schedule for the different flight tests, and then we’ll know the areas we need to more deeply penetrate.”

Despite different cultures, NASA—the often-bureaucratic and conservative government agency—and SpaceX—the fast-moving company that likes to design, break, and fix things—are tied at the hip. Without SpaceX, US astronauts would still be totally reliant on Russian to fly to the International Space Station. Without NASA support, SpaceX probably wouldn’t be here today.

NASA officials have said that their cooperation with SpaceX in developing the Crew Dragon spacecraft for space station ferry flights has laid a foundation for their newer partnership on the Starship lander, which will be NASA’s first Human Landing System, a critical piece of the agency’s Artemis program to return astronauts to the Moon.

“The Starship that will be tested (Saturday) is clearly not as mature as the Human Landing System Starship that we will eventually have,” Watson-Morgan said. “It is a precursor or early demonstration.”

There is a roadmap for SpaceX to quickly mature Starship, introducing new technology and capabilities over a series of test flights set to run through 2024. The big priorities for Starship are to move forward with iterating the design to support NASA’s lunar lander needs and to start deploying new-generation Starlink Internet satellites, allowing SpaceX to grow the broadband network significantly faster than possible with its existing Falcon 9 rockets.

How quickly SpaceX makes progress with Starship hinges on a lot of things. At the top of that list is the result of the Starship test flight set to take off Saturday from Cameron County, Texas. SpaceX has a 20-minute launch window opening at 7 am CST (13:00 UTC).

Ars has covered all the upgrades and changes that SpaceX made since the first test flight of the nearly 400-foot-tall rocket back in April. Watson-Morgan said that NASA engineers will be watching how everything performs for the next test launch. This includes the modified launch pad, the 33 Raptor engines on the Super Heavy booster and six more on the Starship upper stage, the flight software, guidance, navigation, and control, and the new “hot staging” technique SpaceX will try out on the second test flight.

Starship has six Raptor engines that will power the vehicle into orbit, where it can be refueled for more Raptor burns to head for more distant destinations, like the Moon.
Enlarge / Starship has six Raptor engines that will power the vehicle into orbit, where it can be refueled for more Raptor burns to head for more distant destinations, like the Moon.

“All the engineering disciplines, all the functional systems that you would expect, the NASA team gets insight into that and then from that we can see how their system, their design and development, how it’s maturing,” Watson-Morgan said. “We do provide feedback and our experience base if we see things.”

At least five of the booster’s 33 Raptor engines failed on the first Starship test flight earlier this year. After analyzing data from that flight, engineers discovered there were fuel leaks that led to fires in the booster engine compartment. The Raptor engines, each burning methane fuel and producing about a half-million pounds of thrust, need to be a lot more reliable for SpaceX to move on to in-orbit refueling tests and Starlink launches using Starship, not to mention meeting NASA’s stringent safety standards for astronauts.

“We do anticipate the Raptor engines will perform better for this test,” Watson-Morgan told Ars. The engines on the next Starship test flight are a mixture of first- and second-generation Raptors, whereas the first launch in April primarily used the older engine model.

“By the time of the Human Landing System Starship, we will be on a much later generation of Raptor, thereby having the predictability of the engines that is required for human-rating of the Starship itself,” Watson-Morgan said.

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