The wild science behind Starship, Elon Musk's planet-hopping rocket - Wired.co.uk

Imagine a rocket that could launch and land 1,000 times a year with the reliability of an airplane. Sound unbelievable? That’s what Elon Musk is touting as SpaceX’s next great venture, and among the considerable hype surrounding the project, there just might be some method to the madness.

On Saturday, September 28, Musk unveiled the first prototype Starship vehicle to a rapt audience in Boca Chica, Texas. First teased by Musk three years ago, the 50 metre tall vehicle is intended to carry to space humans, satellites, cargo or whatever you can fit into it.

Its lifting capacity of 100,000 kilograms is more than any rocket currently in operation, while the whole system is designed to be reusable – making frequent and plentiful trips to and from space. It will launch atop a large booster called Super Heavy, itself measuring 68 meters tall.

Also designed to be reusable, and sporting 37 of the company’s new Raptor engines compared to the six found on Starship, Super Heavy will be the backbone of getting Starship and its crew or cargo on a journey to another world. Together, the two represent a launch vehicle that’s huge both in its size and ambition.

“The scale of it [is unique],” says Jonathan Goff, president and CEO of startup Altius Space Machines. “Their upper stage [Starship] is bigger than the Space Shuttle’s external tank, which is huge. This thing is bigger than the Statue of Liberty from the platform up. And their first stage [Super Heavy] is almost as big as the Saturn V.”

The ultimate goal of Starship is to launch up to 100 people at a time per flight. While Musk has ambitiously suggested it could launch humans as early as next year, the road to get there – whenever such flights do happen – will be intriguing to watch, however long it takes.

Starship is being built as a series of prototypes escalating in purpose. At the event in Texas, Musk unveiled what is known as the Mark 1 prototype. This vehicle, an early glimpse at what Starship may ultimately look like, will use its three Raptor engines to fly to an altitude of 20 kilometres in a month or two with no humans on board.

SpaceX will then work through a series of further prototypes being built both at Texas and in Florida. The Mark 3 prototype will be designed to reach orbit, while a later version will ultimately carry humans. And this step by step processes, with all the successes and failures along the way, represents a big shift in how rockets are built.

“It’s extraordinary and extraordinarily ambitious,” says Robin Hague, Rocket Engineer at UK launch company Skyrora. “It may actually be SpaceX’s greatest innovation. [Normally] you would have to build the vehicle essentially complete and test it all up.”

One key to this was a design decision to switch from building the rocket out of carbon fibre to stainless steel about a year ago. Aside from a massive cost saving, with steel costing $2,500 (£2,031) a tonne to carbon fibre’s $130,000 (£105,000), steel’s ruggedness allows for a more rustic build process.

“Starship is being built not in a factory but outside using welding,” says space consultant Charlie Garcia from the Massachusetts Institute of Technology (MIT). “This is kind of a big deal, because last time we were doing steel rocket ships welding was not really advanced enough. The fact they were able to [build it] outside in the elements is quite a testament to the ingenuity of the engineers.”

Early Starship prototypes will launch alone, but the later full version will launch atop Super Heavy. The two will travel together for several minutes before Super Heavy separates, coming back to land on the ground, ready for another mission while Starship carries out its intended mission.

For satellite launches it boasts a large payload pay at the front, with a hatched nosecone that opens up to release whatever it has carried into space. Measuring nine meters in diameter and 19 meters high, SpaceX says this is the “largest usable payload volume of any current or in development launcher,” allowing for ambitious missions such as large telescopes.

For missions beyond Earth orbit, such as to the Moon or Mars, Starship will likely need to refuel with another Starship vehicle in orbit before making its journey. SpaceX then intends to land and launch the entirety of the vehicle on other worlds.

The details of what the ride on Starship will be like are under wraps at the moment. And so far, SpaceX has just one customer – Japanese billionaire Yusaku Maezawa – signed up for a flight. But Musk has spoken before about having entertainment on board for the longer trips, like the eight-month or so journey to Mars.

When Starship returns to Earth steel comes into its own once again, providing another benefit over carbon fibre in that it is more resilient to the extreme temperatures of re-entry. Normally spacecraft must have a significant head shield to cope with these temperatures, but Starship will need just a thin coating of ceramic tiles.

As it re-enters the atmosphere after the completion of its mission, large fin-like structures on the vehicle will act as air brakes, slowing and controlling its descent. The vehicle will fall through the atmosphere in a belly-flop position, before it rotates and descends vertically for a landing on the ground, just like SpaceX’s existing Falcon 9 rockets.

“It’s an ingenious re-entry approach,” says Hague. “Those things that look like wings aren’t wings, they’re best thought of as air brakes. Because Starship when it comes back will travel sideways, it’s going to be pancaking through the air, using its flaps for control.”

SpaceX’s approach to Starship has not been devoid of criticism, however. One issue surrounds how life support will work on the vehicle, something that SpaceX has not yet explained. But, notes Garcia, it makes more sense to develop this at a later stage when the rocket itself has been ironed out. “Musk is saying we don’t need to worry about it right now,” he says.

Another criticism is the lack of a launch abort system on Starship and Super Heavy, something that saved the lives of two astronauts last year on a Soyuz rocket. The Space Shuttle notably also did not have a launch abort system, leading to the loss of seven astronauts on the Challenger disaster in 1986.

“It’s kind of risky,” says Goff. “But the problem is, if you’re flying 100 crew, launch abort becomes kind of difficult.”

The lack of a launch abort system ties into SpaceX’s ultimate goal for this vehicle, however, to operate it like an aircraft and require minimal or no checks between flights. Musk has talked about a single Starship vehicle being reused 1,000 times a year, and reducing the amount of refurbishment needed – something the Shuttle relied heavily on – is crucial to that.

“Elon’s ultimate goal here is airline-like reusability and operations,” says Garcia. “His goal is to get Starship to a level of reliability through experience. Would you rather be on the first flight of an airliner or the 50th?”

Starship, if or when it comes to fruition, will be a big shift in the global launch industry. Providing rapid reusable flights to Earth orbit and beyond, it would change forever how we launch to and access space. Even if Starship only launches satellites it will be regarded as a success, being dramatically cheaper to operate even than SpaceX’s Falcon rockets.

But the ultimate goal for Musk has always been to make humans multiplanetary. To have any hope of doing so, he’ll need some sort of futuristic vehicle that looks like it’s been plucked out of science fiction. A Starship, perhaps.

Search

The wild science behind Starship, Elon Musk's planet-hopping rocket - Wired.co.uk

More great stories from WIRED

0 Response to "The wild science behind Starship, Elon Musk's planet-hopping rocket - Wired.co.uk"

Post a Comment