SpaceX spacecraft took a beating, but held on for its first return from space

Enlarge / It is not a simulation. Plasma spills onto the aerial surfaces of SpaceX’s Starship during its reentry high in the Indian Ocean.

SpaceX demonstrated Thursday that its towering Super Heavy booster and Starship rocket could one day be recovered and reused in the same way Elon Musk has made his vision for the future of space exploration.

For the first time, both elements of the nearly 400-foot-tall (121-meter) rocket not only successfully launched from SpaceX’s Starbase facility near Brownsville, Texas, but also returned to Earth for controlled splashdowns at sea. . This demonstration is a precursor to future Starship test flights that will bring the booster, and eventually the upper stage, to Earth for reuse again and again.

The two-stage rocket lifted off from Starbase at 7:50 a.m. CDT (12:50 UTC) and headed east over the Gulf of Mexico with more than 15 million pounds of thrust, about double the rocket’s power. NASA’s Saturn V from Apollo. lunar program of the 1960s and 1970s.

Checking all the boxes

Starship, the largest and most powerful launch vehicle ever built, is key to the SpaceX future. NASA also has an interest in Starship’s success because the agency selected it to play the role of human-rated lunar lander for the Artemis program to transport astronauts to and from the surface of the Moon.

There will be dozens more Starship flights before anyone boards the Starship lander, and this probably won’t happen before the latter part of this decade. But some of Starship’s other goals, such as recovering and reusing the entire rocket, appear to be within reach.

“Starship’s fourth flight made great strides to move us closer to a rapidly reusable future,” SpaceX said in an update to its website. “Their achievements will provide data to drive improvements as we continue to rapidly develop Starship into a fully reusable transportation system designed to transport crew and cargo to Earth orbit, the Moon, Mars and beyond.”

Thursday’s test flight was the fourth launch of a full-size Starship rocket and was the first to end with the booster and ship reaching the Earth’s surface in one piece. The results coincided with the best of all possible scenarios prior to Thursday’s flight.

It did not reach total perfection, but the flight cannot be described as anything other than a success. “The payload for this test was data,” SpaceX said. “Starship delivered.”

The fourth full-scale test flight of SpaceX's Starship rocket lifted off from Starbase, the company's private spaceport near Brownsville, Texas.
Enlarge / The fourth full-scale test flight of SpaceX’s Starship rocket lifted off from Starbase, the company’s private spaceport near Brownsville, Texas.

Two of the 33 methane-fed Raptor engines on the Super Heavy booster failed on Thursday’s test flight: one on climb and another during final braking of the booster just before landing in the Gulf of Mexico. Still, the remaining engines guided the booster to a relatively gentle splashdown in the ocean after a vertical descent just off the coast of Starbase approximately seven and a half minutes after liftoff. SpaceX came close to achieving this milestone on Starship’s third flight in March, but lost contact when most of its landing engines failed to restart.

Engineers blamed a filter blockage in the lines that feed liquid oxygen propellant to the Raptor engines for the March landing failure. This did not appear to be a major problem on Thursday. SpaceX also made another change to booster descent with the jettison during descent of the rocket’s hot staging ring, where Starship’s upper stage connects to Super Heavy for launch.

Meanwhile, six Raptor engines in Starship’s upper stage burned a few seconds longer than planned to make up for the booster performance shortfall. This put the spacecraft on the right suborbital trajectory to reach a maximum altitude of 213 km (132 miles) before Earth’s gravity pulled the 50-meter (165-foot) long vehicle into the atmosphere about 47 minutes later. of the launch.

The flight here was just the prelude to the grand finale.

On SpaceX’s third Starship test flight in March, the searing heat of reentry destroyed the rocket as it descended into the upper atmosphere over the Indian Ocean. SpaceX said clogged thrusters caused the craft to lose the ability to control its orientation in space. This caused the Starship to fall into the atmosphere in the wrong orientation, subjecting the unprotected parts of the vehicle to the extreme heat of re-entry.

SpaceX's Super Heavy booster and Starship rocket rise through a hazy sky over south Texas.
Enlarge / SpaceX’s Super Heavy booster and Starship rocket rise through a hazy sky over south Texas.

Stephen Clark/Ars Technica

This time, Starship remained in control throughout the flight. Dazzling live views from cameras aboard the rocket, transmitted to the ground via SpaceX’s Starlink broadband network, showed purple and orange plasma pouring over the vehicle as it slid through the atmosphere over the Indian Ocean.

A few moments later, a camera showed pieces of the rocket, presumably ceramic thermal protection plates, breaking away. There appeared to be damage to the hinge joint that connects one of the ship’s control flaps to the main body. However, the damaged flap could still move and help control the craft using aerodynamic forces as it dived deeper into the atmosphere.

“Starship performed a controlled reentry, successfully passing the maximum warm-up and maximum aerodynamic pressure phases and demonstrating the ability to control the vehicle using its fins as it descends through the atmosphere at hypersonic speeds,” SpaceX said. These were the main mission objectives outlined by Musk before launch.

Eventually, three of Starship’s Raptor engines reignited and the rocket transitioned from an upside-down orientation to an upright position a few hundred feet above the middle of the Indian Ocean, according to SpaceX. It was difficult to understand what the live camera footage was showing because the splashdown occurred at night, halfway around the world from Texas.

But live telemetry data indicated that the rocket slowed to a near stop when it reached the sea, then the communication transmission was cut off about 1 hour and 6 minutes into the mission.

“Despite the loss of many chips and a damaged flap, Starship managed a soft landing in the ocean!” Musk posted on X, his social media platform. “Congratulations to the SpaceX team on an epic achievement.”

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