Sign up for CNN’s Wonder Theory science newsletter. Explore the universe with news about fascinating discoveries, scientific developments and more.
SpaceX’s Starship, the most powerful launch vehicle ever built, will make its fourth launch Thursday. The highly anticipated event is the company’s second unmanned test in 2024.
SpaceX aims to mark new milestones this time, such as demonstrating the reusability of the Starship vehicle.
The 120-minute launch window begins at 7:00 a.m. CT (8:00 a.m. ET), with the launch expected at 7:50 a.m. CT (8:50 a.m. ET), and the company will stream live coverage on the launch. According to SpaceX, weather conditions are 95% favorable for the launch.
The Starship launch system, which includes the upper Starship spacecraft and a rocket booster known as the Super Heavy, will attempt to fly from the private Starbase facility in Boca Chica, Texas.
The test flight comes two days after the Federal Aviation Administration, which licenses commercial rocket launches, gave SpaceX its approval. And the test comes one day after SpaceX’s competitor under NASA’s Commercial Crew Program, Boeing, successfully launched the first crewed Starliner mission, which will carry two experienced NASA astronauts to the International Space Station.
Each Starship test flight has several objectives that build on lessons learned and milestones achieved during the previous flight.
SpaceX is now focusing on “demonstrating the ability to return and reuse Starship and Super Heavy. The main objectives are to conduct a landing and soft landing in the Gulf of Mexico with the Super Heavy booster, and achieve a controlled entry of the Starship,” according to a company press release.
The spaceship is expected to crash in the Indian Ocean.
The Starship team performed software and hardware upgrades to the launch system to integrate learnings from the third flight.
“Starship’s fourth flight will bring us closer to the rapidly reusable future on the horizon,” SpaceX said. “We continue to rapidly develop Starship, placing flight hardware in a flying environment to learn as quickly as possible, while building a fully reusable transportation system designed to transport crew and cargo to Earth orbit, the Moon, Mars and beyond .”
Three wild test flights
The first two attempts to get Starship up to orbital speeds in 2023 ended in explosions, with the spacecraft and booster going up in flames before reaching their intended landing sites.
SpaceX has been known to embrace serious mishaps in the early stages of spacecraft development, saying these failures help the company quickly make design changes that lead to better results.
SpaceX has said its approach to rocket development is focused on speed. The company uses a technical method called “rapid spiral development.” This process essentially boils down to a desire to build prototypes quickly and willingly blow them up to learn how to build a better prototype – faster than if the company relied solely on ground testing and simulations.
After the explosive first and second Starship test flights, the company immediately tried to cast these mishaps as successes.
The nearly hour-long third test flight, conducted in March, reached several milestones before breaking up upon return, rather than crashing into the Indian Ocean.
First, Starship reached speeds close to what would be needed to launch the vehicle into orbit. Normally such a feat requires speeds in excess of 17,500 miles per hour (28,000 kilometers per hour). The spacecraft achieved its orbital speed target and did not intend to enter orbit on the third flight.
The spaceship’s payload door – a hatch that must open to allow the spacecraft to deploy satellites into orbit after reaching orbit – swung open before being closed again in a crucial test of that mechanism.
SpaceX also performed a “propellant transfer demonstration,” which involved moving some of the propellant on board the Starship vehicle from one tank to another. SpaceX engineers designed the demo to test how Starship will be refueled on future missions while in orbit.
But after a bright halo of red plasma, created by extreme heat and pressure as the spacecraft reentered Earth’s atmosphere, glowed around the vehicle, the team lost communication with the spacecraft.
However, SpaceX never planned to retrieve Starship after this test flight.
The Super Heavy booster was also expected to make an autonomous, controlled landing in the ocean, but the booster was lost after all its engines failed to turn on.
But both the Starship spacecraft and booster made it further into flight than the two previous tests in 2023.
Starship’s massive goals
Much depends on Starship’s ultimate success. SpaceX CEO Elon Musk has repeatedly characterized the rocket as central to the company’s founding mission: putting humans on Mars for the first time.
NASA has selected the Starship spacecraft for a key role in its Artemis program to return humans to the moon for the first time in more than five decades. Under the federal space agency’s current roadmap, Starship would complete the final leg of a crewed mission to the moon, picking up astronauts from a spacecraft in lunar orbit and returning them to the surface. The United States is in a race with China, vying to be the first to develop a permanent lunar outpost and set a precedent for deep space settlements.
Milestones such as propellant transfer from the third test flight targets for the future. Replenishing the spacecraft’s fuel will be critical for Starship’s high-profile missions down the road.
When Starship under Artemis makes a trip to the moon, it will have to sit in orbit close to Earth while SpaceX launches separate support vehicles that will transport fuel to the spacecraft. To reach the moon, SpaceX may need to make more than a dozen refueling stops.
The first astronaut landing under the Artemis program is expected to take place as early as September 2026.
For more CNN news and newsletters, create an account at CNN.com