SpaceX update

Elon Musk was in South Texas yesterday to deliver an update on the happenings at Boca Chica and elsewhere. It was by invitation only. The video is below, followed by a story from Ars Technica.

Elon Musk, Man of Steel, reveals his stainless Starship

BOCA CHICA BEACH, Texas—Elon Musk spoke about his vision of a brighter future for humanity on Saturday evening in South Texas.

Musk acknowledged that there are a lot of problems here on Earth, and it is important for those to get fixed. But it is also important to give people hope for the future and a sense of optimism. He believes the exploration of space, and human expansion into the Solar System, provides this kind of a hopeful vision.

And so, beneath a big Texas sky full of stars, he offered hope in the form of a large spaceship. Mere hours after a team of SpaceX engineers, technicians, and contractors completed assembly of a prototype of the Starship vehicle, Musk revealed it to the world. He did so in an open-air shipyard by the Rio Grande River, where he intends to build dozens if not hundreds of Starship spacecraft.

The prototype loomed behind Musk as he addressed a crowd of a few hundred people, including employees, local residents from Brownsville and surrounding towns, and members of the media. Earlier, as the Sun dipped below the horizon, reddish hues glinted off the Starship's surface. As night fell and Musk climbed onto a small dais, it rose tall, dark and imposing.

"This is the most inspiring thing that I have ever seen," said Musk, dressed in a black blazer, t-shirt, and jeans, of the towering spaceship. The crowd cheered. In the moment, Mars seemed a little closer than it had before.

Progress

Three years ago, Elon Musk took the stage in Guadalajara, Mexico, to share the full scope of his Mars ambitions for the first time. He spoke of building a large, interplanetary spaceship—it was not yet named Starship— and a large rocket booster with dozens of engines that would carry 100 people to Mars at a time.

At the time, it seemed audacious, mad, and brilliant at the same time. But mostly the vision seemed like science fiction. Standing in a field in South Texas on Saturday night, it felt a little more like science, and a little less like fiction.

Three years ago, the idea of flying 37 engines on a single rocket seemed fanciful. And then, in early 2018, the company launched with Falcon Heavy with 27 engines. Three years ago, the notion of landing and re-flying a large rocket multiple times seemed distant. But now SpaceX has done this dozens of times.

But most futuristic of all seemed the notion of a 50-meter tall spaceship that could launch into space, fly on to the Moon or Mars, and return to Earth. And yet this was what Musk put on display with the Starship Mk 1 vehicle. Soon, perhaps within one or two months, it will launch to an altitude of 20km. Simultaneously, the company is building a second prototype, Mk 2, in Cocoa, Florida. It will start work on a third version in Texas later this fall, and so on.

Each design will iterate on the last. Engineers will look for ways to shave mass—the Mk 1 prototype weighs 200 tons, and SpaceX would like to eventually cut the overall mass to 110 tons to maximize Starship's lift capacity. Ultimately, a slimmed-down Starship should be able to lift 150 tons of payload into low-Earth orbit, Musk said. Its first orbital flight, launched by a big booster named Super Heavy, could come next year.

This payload capacity is more than any other launch system built before, and would be especially remarkable given that SpaceX has designed both the booster and Starship to be fully reusable. "A rapidly reusable orbital rocket is only barely possible given the physics of Earth," Musk said.

Man of steel

During the presentation, Musk offered several updates on changes to Starship's design. However he spent the most time discussing the use of stainless steel as the skin of the vehicle. "Stainless steel is by far the best design decision we have made," he said.

Yes, Musk said, steel is heavier than carbon composite or aluminum-based materials used in most spacecraft, but it has exceptional thermal properties. At extremely cold temperatures, stainless steel 301 does not turn brittle; and at the very high temperatures of atmospheric reentry, it does not melt until reaching 1500 degrees Centigrade. Starship therefore requires only a modest heat shield of glass-like thermal tiles.

Another benefit is cost, which matters to a company building Starships on its own dime, with the intent to build many of them. Carbon fiber material costs about $130,000 a ton, he said. Stainless steel sells for $2,500 a ton.

"Steel is easy to weld, and weather resistant," Musk added. "The evidence being that we welded this outdoors, without a factory. Honestly, I'm in love with steel."

Original.