Beginning of new era in rocket recovery

The largest, and the most powerful, rocket ever constructed has launched once more. This time, it has successfully returned to Earth. SpaceX launched its 400-foot-tall (122-metre) Starship rocket for the fifth time on Sunday (October 13). The massive vehicle took off from its Starbase site in South Texas at 8.25 am EDT (12.25 pm GMT; 7.25 am local Texas time). The mission set out to achieve new milestones for both the Starship rocket and space travel overall.

The key improvement for this test was SpaceX’s attempt to recover the first-stage, super-heavy booster. The plan was for the booster to return to the launch site, where two mechanical arms, often called ‘chopsticks’, attached to the same launch tower, would catch and hold it. This required the booster to carry out precise boost-back and landing burns to steer it back to the launch pad. The super-heavy booster, called Booster 12, proved itself equal to this task.

The highlight of the mission came when the tall first-stage booster separated from the rocket at about 70 km altitude and began its bold return to Earth. As it descended towards the launch pad, three of its engines reignited, slowing its fall just in time for the booster to be caught by the giant metal arms of the launch tower.

The 71-metre-tall booster made a bold descent toward the pad and, about seven minutes after launch, it was successfully caught by the tower’s giant arms. Using small bars beneath its grid fins, the booster latched onto the tower as planned, thrilling SpaceX engineers and fans. This mid-air ‘catch’ marked a major milestone for the company.

Successfully returning and landing the booster on the launch pad was crucial for SpaceX’s goal of quickly reusing the vehicle for future flights. In SpaceX’s vision, the booster could be quickly prepared for another launch right on the pad, with a new Starship attached, ready to fly again in just days—or even hours. The success of the catch seemed to surprise even the company’s leaders. Gwynne Shotwell, president and chief operating officer of the company, shared a video of the landing on social media, saying, “I don’t know what to say!”

Preceding the launch, Bill Gerstenmaier, vice-president of build and flight reliability, expressed optimism about the booster catch bid. “We landed with half-centimetre accuracy in the ocean during the previous flight,” Gerstenmaier had said at an October 9 meeting of the National Academies’ Committee on Biological and Physical Sciences in Space.

Catching the booster was not the only goal for Flight 5. SpaceX also planned to launch Starship’s 165-foot-tall (50-metre) upper stage, called Starship—or just Ship—into space and then bring it back for a splashdown in the Indian Ocean. The Starship vehicle, Ship 30, followed a suborbital path similar to its June flight, reaching a maximum altitude of 212 kilometres, travelling at a blistering speed of 17,000 miles per hour.

The vehicle seemed to handle re-entry better than during the previous flight, as SpaceX had made improvements to Starship’s heat shield with newer-generation tiles, a backup ablative layer and additional protections between the flap structures. The vehicle made a controlled descent into the Indian Ocean by firing three of its six engines about 66 minutes after launch. It was not meant to be recovered and, a few seconds after hitting the water, it exploded.

“Ship landed exactly on target!” Elon Musk, SpaceX’s CEO, posted shortly after the landing. “We’ve successfully achieved the second of our two goals.”

Starship: Progress over 4 Test Flights

Starship’s earlier four test flights took place in April and November 2023 and in March and June of this year. The rocket has improved with each flight. The first mission lasted only four minutes. SpaceX had to blow up the rocket in the sky above Texas because the two parts of Starship did not separate as expected. Flight 4, launched on June 6, was a total success. The Ship reached orbital speed and both it and the super-heavy booster returned safely to Earth, landing in their planned splashdown areas.

‘Last-Minute Approval of the Licence’

The launch happened within 24 hours of the Federal Aviation Administration (FAA) issuing a revised launch licence. This licence had been a topic of controversy in recent weeks, as SpaceX complained that the FAA had told them the updated licence would not be ready until late-November.

The Adjustments for Safety and Sound

SpaceX recently had to update its environmental assessment due to changes in its flight plan. These updates specifically addressed two key areas:

1) Expanding the Drop Zone for the Inter-stage Ring:

The inter-stage ring, also referred to as the forward heat shield in official FAA documents, is a part of the rocket that protects it during flight. Once it is no longer needed, it separates from the rocket and falls into the ocean. The updated plan expands the area in the Gulf of Mexico where this piece could land, ensuring it falls safely without posing any risks.

2) Analysing Sonic Boom from Super Heavy Booster:

The return of the super-heavy booster, the powerful first stage of SpaceX’s rocket, creates a sonic boom as it travels faster than the speed of sound. A sonic boom is a loud shockwave produced when an object breaks the sound barrier. The updated environmental assessment required an analysis of this boom to understand its effects on the environment and nearby communities. This ensures that noise levels are managed and any potential impacts are minimized.

In simpler terms, these updates were necessary to ensure that both the falling rocket parts in the Gulf of Mexico and the noise from the sonic boom met all environmental and safety requirements. The environmental analysis—signed and released just a few hours before the licence was approved—concluded that no significant damage to buildings or other structures was expected from the sonic booms. It also stated that no negative effects on wildlife in the Gulf of Mexico were expected from the proposed new landing area for the forward heat shield.

What Is Ahead for Starship and SpaceX

Sunday’s test flight was a key achievement for SpaceX as it keeps working on improving the technology behind Starship. The rocket, which is the biggest and most powerful ever built, is designed to achieve the same level of reusability as SpaceX’s smaller Falcon 9 rockets. For years, those boosters have been landing successfully, usually on floating platforms or solid landing pads located far from where they launch.

Starship, however, presents a greater challenge due to its 33 methane-powered engines and its goal to transport people and cargo not only into orbit, but also to the Moon—and, eventually, to Mars. NASA has already ordered two Starships to transport astronauts to the Moon’s surface later this decade.

(The author of this article is a Defence, Aerospace & Political Analyst based in Bengaluru. He is also Director of ADD Engineering Components, India, Pvt. Ltd, a subsidiary of ADD Engineering GmbH, Germany. You can reach him at: girishlinganna@gmail.com)

(Disclaimer: The views expressed above are the author’s own and do not reflect those of DNA)