SpaceX launches Super Heavy-Starship rocket on third test flight

SpaceX's huge Super Heavy-Starship rocket, by far the most powerful ever built, blasted off on its third test flight Thursday morning. The test aimed to boost the unpiloted upper stage into space on a sub-orbital hop to a controlled re-entry and splashdown in the Indian Ocean.

The giant rocket's 33 Raptor engines, gulping 40,000 pounds of liquid oxygen and methane propellants per second, thundered to life with a ground-shaking roar at 9: 25 a.m. EDT and quickly throttled up to liftoff thrust.

A moment later, the 394-foot-tall rocket began climbing skyward, blasting through billowing clouds of dust and steam generated by the booster's fiery exhaust vaporizing torrents of water being sprayed upward at the base of the pad to ease the shock of engine ignition.

Smoothly accelerating it consumed propellants and lost weight, the Super Heavy-Starship arced away to the east over the Gulf of Mexico, putting on a spectacular show for thousands of area residents, tourists and a throng of journalists watching from the launch site and nearby South Padre Island a few miles to the north.

All 33 Raptors appeared fire normally, boosting the rocket past the region of maximum aerodynamic stress as it accelerated through the speed of sound and out of the dense lower atmosphere.

Two minutes and 42 seconds after liftoff, the Raptors began shutting down as planned, followed seconds later by ignition of the Starship upper stage's six engines while the booster was still attached, a recent modification known as "hot staging." A moment later, the Super Heavy and Starship stages cleanly separated.

The booster then flipped around and began heading back toward shore for a controlled descent to splashdown in the Gulf of Mexico. The Starship continued on toward space.

The Starship's Raptors completed shutdown as scheduled eight-and-a-half minutes after liftoff. Re-entry and splashdown in the Indian Ocean was expected about an hour later.

Problems with previous test flights

Two previous test flights ended with spectacular self-destruct conflagrations — the first, last April, after multiple Super Heavy engine shutdowns and a stage separation malfunction and the second, in November, just before the Starship would have started a planned loop around the planet for a splashdown in the Pacific Ocean north of Hawaii.

SpaceX engineers modified multiple systems in the wake of the failures, including work to beef up the rocket's self-destruct system, to improve engine performance and to protect the pad with a high-power water deluge system that also deadens the acoustic shock of engine ignition.

The company also implemented the "hot staging" technique in which the Starship's six Raptor engines ignite while the stage is still attached to the Super Heavy booster. Hot staging, used for decades by Russian Soyuz rockets, helps ensure a more efficient stage-separation sequence.

"Starship's second flight test achieved a number of major milestones and provided invaluable data to continue rapidly developing Starship," SpaceX said on its website. "This rapid iterative development approach has been the basis for all of SpaceX's major innovative advancements."

For its third test flight, the primary goals were roughly the same, to boost the Starship into space for a sub-orbital test flight and high-speed re-entry and to carry out controlled landings by both stages, the Super Heavy in the Gulf of Mexico and the Starship in the Indian Ocean.

SpaceX pioneered technology that allows the company to recover and reuse smaller Falcon 9 boosters. But no Starship has never attempted coming back down through the atmosphere from space, subjecting insulating tiles on its belly to temperatures higher than 3,000 degrees.

While both stages are designed to be fully reusable, there were no recovery plans for the third test flight. Both stages were expected to attempt rocket-powered descents mimicking actual landing procedures but both were expected to break up and sink on ocean impact.

During the Starship's coast toward entry, flight controllers planned to test a payload door that will be used on future flights to launch Starlink satellites.

More important to NASA, the rocket was to attempt moving cryogenic propellants from one tank to another in the weightless environment of space and to carry out the first restart of a Raptor engine outside the atmosphere.

The propellant transfer test and Raptor restart are critical milestones for NASA, which is paying SpaceX billions to build a Starship variant to serve as the Human Landing System, or HLS, for the agency's Artemis moon program.

The HLS will require automated refueling in Earth orbit by multiple Super Heavy-Starship tankers before restarting its engines to head for the moon to await the arrival of astronauts who will use the spacecraft to carry them to and from the surface.

Up to 10 or so refueling flights will be necessary for one HLS flight to the moon.

Largest rocket ever built

While clearly a challenge, the fully reusable Super Heavy-Starship, known collectively simply as "Starship," is a potential game changer, a potentially revolutionary step intended to increase payload weight to orbit while vastly reducing the cost.

It is the largest rocket ever built, standing 39 stories tall, measuring 29.5 feet wide and generating more than 16 million pounds of thrust from its SpaceX-designed Raptor engines, twice the power of NASA's Space Launch System moon rocket and the agency's legendary Saturn 5.

The Super Heavy first stage alone stands 23 stories tall while the Starship upper stage, designed to carry cargo, passengers or both, towers another 164 feet and is equipped with six Raptor engines of its own.

The Super Heavy is designed to fly back to its launch pad, either in Boca Chica or at the Kennedy Space Center in Florida, after boosting the Starship upper stage out of the lower atmosphere and then descend to touchdown, captured by two huge robotic arms on the launch gantry.

Starships are designed to fly themselves to touchdowns anywhere landing pads are available as well as the moon and, eventually, Mars.

SpaceX launched the Super Heavy-Starship on its maiden flight last April 20, but the rocket suffered multiple engine failures or shutdowns. The rest continued firing after the expected shutdown time and the first and second stages failed to separate normally. The self-destruct system was triggered, but it took longer than expected to activate.

Visibly tumbling, the rocket blew itself up four minutes after liftoff. Maximum altitude was 24 miles.

In its second test flight last Nov. 18, the Super Heavy booster operated normally, the hot-staging procedure worked as planned and the Starship upper stage separated normally to continue the climb to space on the power of its six Raptor engines.

The Super Heavy, meanwhile, flipped around as expected and began flying back toward the Texas coast for splashdown. But moments after turning around, the rocket exploded in a shower of debris. The Starship stage flew itself to space as planned but just before or during engine shutdown, it, too, exploded.

Getting the Super Heavy-Starship flying on a regular basis is critical to NASA's Artemis moon program. NASA gave SpaceX at $2.9 billion contract in 2021 to develop a variant of the Starship upper stage to carry astronauts from lunar orbit down to the surface and back. Artemis crews will travel to and from the moon using Lockheed Martin-built Orion capsules.

NASA's contract requires one unpiloted lunar landing test flight before astronauts will make an actual landing attempt. Artemis managers are targeting late 2026 for the first lunar landing with astronauts on board.

But that will depend on SpaceX launching enough Super Heavy-Starship flights to demonstrate reliability. While SpaceX's philosophy is to fly frequently, learn from mistakes and fly again, NASA will require a long string of successful flights before the agency will deem it safe to put astronauts aboard.

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