SpaceX’s Starship, the largest and most powerful rocket ever built, is supposed to land NASA astronauts on the surface of the moon in a couple of years.
Even more ambitiously, Elon Musk, who owns and runs SpaceX, has said that the company would send about five Starships to Mars next year — sans astronauts, but with Optimus robots built by his electric car company, Tesla.
The past two test flights of Starship have ended in explosive failures. The latest flight’s upper-stage vehicle successfully made it to space and is now coasting toward re-entry over the Indian Ocean.
But not every objective of the flight was achieved. SpaceX for the first time was trying to re-fly a Super Heavy booster. While it succeeded on the way up, it was lost as three engines lit up to simulate a landing over the Gulf of Mexico. However, SpaceX was attempting various tests to push the performance of the booster, suggesting that the outcome may not have been a major setback.
When did the rocket lift off?
Around 7:37 p.m. Eastern time the ninth test flight of Starship lifted off from SpaceX’s Starbase site in South Texas.
The countdown was paused 40 seconds before the opening of the launch window at 7:30 to allow engineers more time to assess the rocket. It soon resumed with flight controllers proclaiming “go for launch” before another pause in the countdown occurred. The countdown then resumed and the vehicle lifted off, beginning journey that can last for as long as an hour.
SpaceX continues to provide live coverage on its website, or you can watch the feed in the video player above.
What happened during the last flights?
SpaceX takes pride in its “fail quickly and fix quickly” approach to rocket design, so it is not surprising that none of the eight test flights so far have worked perfectly. But the last two — flight seven in January and flight eight in March — were more disappointing. They could not repeat the successes of earlier test flights.
For both flights, the upper-stage vehicles, known as Starships, exploded during ascent. Showers of falling debris over the Atlantic Ocean surprised sky watchers in Caribbean countries and Florida, and disrupted air traffic in the region. No one was injured.
In contrast, the vehicles used in flights four, five and six made it into space, coasted halfway around the world, survived re-entry into the atmosphere and simulated landings in the Indian Ocean.
In flights seven and eight, both explosions occurred at about the same point in the flight, just before the second-stage engines cut off. But the causes were “distinctly different,” SpaceX said in an update last week.
For the seventh flight, SpaceX said that the probable cause was stronger than expected rhythmic oscillations. The vibrations caused leaks of propellant that caught fire.
Fixes intended to damp the vibrations worked during the eighth flight, SpaceX said.
However, during the eighth flight, a flash was seen near the bottom of the second-stage vehicle near one of the center engines. That engine then failed. Three other engines then shut down, and SpaceX lost control of the vehicle about nine and a half minutes after launch.
SpaceX said the most probable cause was a hardware failure in one of the engines “that resulted in inadvertent propellant mixing and ignition.”
While the upper-stage vehicles failed during the last two launches, the giant first-stage boosters, known as Super Heavy, each successfully returned to the launch site, where they were caught in midair by giant mechanical arms.
What was different during this launch?
SpaceX performed more than 100 test firings of its Raptor engines, trying to understand what had failed. It made improvements to the design so that the next version of Raptor, which was already under development, would be more reliable.
This launch is trying to conduct tests that were left undone during the two previous flights. Those included attempting to deploy simulators of SpaceX’s next-generation Starlink internet satellites and tests of the spacecraft’s thermal protection system. However, the payload door failed to open, and the simulators remained inside the spacecraft.
Instead of catching the Super Heavy booster this time, SpaceX had a different, more ambitious plan: It reflew the booster from flight seven, hoping to demonstrate that its design is, indeed, reusable. SpaceX said a large majority of the hardware, including 29 of the 33 Raptor engines, were used during the earlier flight.
The booster also attempted several experiments to make re-entry through the atmosphere more efficient. It also tested whether it can still perform a landing maneuver if one of the center engines shuts down and a different engine has to be used. This is the point of the flight that the booster failed.
The booster disintegrated over the Gulf of Mexico.
Why did the F.A.A. approve the launch after two failures?
The F.A.A. approved the launch last week, saying it was satisfied that SpaceX had addressed the causes of the earlier mishaps and that the launch did not pose a danger to the public.
“The F.A.A. finds SpaceX meets all of the rigorous safety, environmental and other licensing requirements,” the agency said.
Kenneth Chang, a science reporter at The Times, covers NASA and the solar system, and research closer to Earth.
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