The latest flight of SpaceX’s Starship, the largest and most powerful rocket ever built, got all the way up to space but not all the way back down to Earth.
The upper-stage vehicle coasted through space Tuesday, surpassing flights in January and March that ended in explosions and showers of debris over the Atlantic Ocean. But halfway through its journey, the spacecraft sprang a propellant leak. That caused it to start spinning out of control. The Starship vehicle used in the test flight was not able to survive the intense heat, breaking up as it fell back into the atmosphere.
By design, the debris fell into the Indian Ocean, far from areas inhabited by people.
That suggests SpaceX engineers still have much work to do with Starship, especially the upper-stage vehicle, before the spacecraft can be reused frequently, a necessity for fulfilling the vision of Elon Musk, who founded the company in order to send people to Mars one day.
Several tests that SpaceX planned to perform during the flight, including deploying simulators of the next-generation Starlink satellites and assessing improvements to the vehicle’s heat shield, were not conducted.
There was nonetheless progress during the flight, the ninth so far, which lifted off from Starbase, Texas, at 7:37 p.m. Eastern.
The company appears to have fixed the problems that caused the spacecraft to explode during the ascent of the two previous test flights. The mission also flew a booster that had been used for an earlier test flight in January — important progress toward demonstrating a rocket that can be flown over and over.
But that, too, was an incomplete achievement. While the re-flown Super Heavy booster worked 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.
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 reentry 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 9 1/2 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 reentry 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 where the booster failed.
The booster disintegrated over the Gulf of Mexico.
Why did the Federal Aviation Administration approve the launch after two failures?
The FAA 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 FAA finds SpaceX meets all of the rigorous safety, environmental and other licensing requirements,” the agency said.
This article originally appeared in The New York Times.
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