SpaceX for a third time on Tuesday prepared to launch its Starship megarocket after scrubbing the launch twice in two days.
The 10th test flight comes after a string of explosive failures that have raised doubts about whether the world’s most powerful launch vehicle can fulfill founder Elon Musk’s vision of colonizing Mars or helping Nasa return astronauts to the moon.
Standing 403ft (123 meters) tall, the stainless steel behemoth was scheduled to lift off from the company’s Starbase in southern Texas during a window opening at 6.30pm local time (2330 GMT).
Monday’s launch scrub was blamed on weather as thick clouds, hanging overhead for much of the day, forced a delay with a mere 40 seconds left on the countdown clock. A Sunday attempt was scrubbed due to a liquid oxygen leak at the Starship launchpad, billionaire Musk wrote on X overnight.
Much is riding on the mission, after the last three flights ended with the upper stage exploding: twice over the Caribbean and once after reaching space. In June, an upper stage blew up during a ground test.
“We’ve had so many tests and it hasn’t proven itself reliable,” Dallas Kasaboski, a space analyst for consulting firm Analysys Mason, told AFP. “The successes have not exceeded the failures.”
The goal is to send the upper stage ship – eventually intended to carry crew and cargo – halfway across the globe before splashing down off north-western Australia.
Outfitted with prototype heat-shield materials, it will deploy dummy Starlink satellites while flying a trajectory meant to stress-test its rear flaps.
The booster, known as Super Heavy, will splash down in the Gulf of Mexico. While SpaceX previously wowed observers by catching the booster in the launch tower’s “chopstick arms”, this flight will instead focus on data collection under less-than-ideal flight profiles.
Despite recent setbacks, Starship is not seen as being at a crisis point. SpaceX’s “fail fast, learn fast” philosophy has already given it a commanding lead in launches with its Falcon rockets, while Dragon capsules ferry astronauts to the International Space Station and Starlink has become a geopolitical asset.
Still, Starship presents new challenges. Musk has identified developing a fully reusable orbital heat shield as the toughest task, noting it took nine months to refurnish the space shuttle’s heat shield between flights.
“What we’re trying to achieve here with Starship is to have a heat shield that can be flown immediately,” he said on a webcast Monday.
SpaceX’s Starlink satellite internet business, a major source of company revenue, is also tied to Starship’s success. Musk aims to use Starship to launch larger batches of Starlink satellites, which have so far been deployed by SpaceX’s workhorse Falcon 9 rocket into space.
Musk, for his part, remained bullish. “In about 6 or 7 years, there will be days where Starship launches more than 24 times in 24 hours,” the entrepreneur said on Sunday, replying to a user on X.
Another hurdle is proving Starship can be refueled in orbit with super-cooled propellant – an essential but untested step for the vehicle to carry out deep-space missions.
Time is running short to ready a modified version as Nasa’s lunar lander for 2027, and for Musk to make good on his vow to send an uncrewed Starship to Mars next year.