Starship passes a huge test

SpaceX's Starship, which is designed to become SpaceX's workhorse, lifting cargoes and people into LEO (low earth orbit), and with in-orbit refuelling, journeying to the Moon and Mars, needs to solve two key problems.

First, for journey back from Mars, it needs a methane engine, because RPG (the kind of kerosene most rockets now use) would be tricky to manufacture on Mars, whereas methane will be a lot simpler.  Also, if rockets become re-usable, the major cost in launches will be the fuel.  Methane is much cheaper than RPG, here on Earth.  So SpaceX had to build a methane engine.

Second, SpaceX had to find a material which would withstand the 1700 degrees C of re-entry.  The first designs for Starship used carbon-fibre composite materials, with a heat shield on the windward side of the Starship's body to absorb the heat, or more accurately to burn off and produce a layer between the highly compressed air in front of the spaceship and the spaceship itself.  If the Starship is to be re-usable, the kind of ceramic tiles used by the Space Shuttle would be useless, because they had to be individually inspected at prodigious cost after every landing.   SpaceX decided to solve this problem by using a special kind of stainless steel.  Above 300-400 degrees C carbon-fibre starts to disintegrate, while the melting point of stainless steel is around 1500 C. 

So the first key hurdle for SpaceX was to build a methane engine, and then to test it.  They've just done so, successfully, spectacularly.

Locals at the southern tip of Texas took in an otherworldly sight on Thursday night: A giant mirror-polished machine roared to life near a beach, and through a billowing cloud of orange-coloured smoke, rose six stories into the sky, hovered, and then gently landed.

Though the launch lasted less than a minute, the late-night spectacle was the first true flight of SpaceX's Starhopper rocket ship. It represents a key step in company founder Elon Musk's quest to send people to the Moon and Mars.

Starhopper, which resembles a three-legged water tower, was hardly visible through the smoke and darkness, but Musk said on Twitter that the test worked.

"Starhopper flight successful. Water towers *can* fly haha!!" Musk tweeted after the test launch, later sharing the footage of the flight.

Starhopper isn't designed to fly into space. Instead, it's a test bed for technologies that could eventually power a much larger and more powerful launch system known as Starship.

Musk envisions Starship as a nearly 400-foot-tall, fully reusable, and stainless-steel vehicle that can ferry about 100 people and more than 100 tons of cargo at a time to Mars.

Starhopper stands about 60 feet tall, 30 feet wide, and uses one Raptor rocket engine; meanwhile, a full-scale Starship headed for deep space could use more than 41 such engines, according to Musk.

The rocket engines are essential yet expensive, which is why SpaceX is testing limited numbers of them on crude vehicles like Starhopper – to discover any issues early on, save money, and develop the Raptor into safe and reliable spaceflight hardware.

Musk's eventual goal is for Starship to be capable of launching and landing many times with little to no refurbishment required. This, he says, may reduce launch costs by 100- to 1,000-fold compared to traditional, single-use rockets.

"Full and rapid reusability is the holy grail of access to space and is a fundamental step towards it, without which we cannot become a multi-planet species," Musk recently told Time's Jeffrey Kluger in an interview for CBS Sunday Morning.

"We cannot have a base on the Moon, we cannot have a city on Mars without full and rapid reusability."

But getting to that stage will likely require years of testing, and Wednesday's launch was a crucial first step.

With a successful untethered flight under its belt, the company is now aiming to launch Starhopper on a flight to more than 650 feet (200 meters) "in a week or two," Musk said early Friday morning.

SpaceX's current government licence permits the company to launch experimental vehicles like Starhopper on flights lasting no more than six minutes and up to a maximum altitude of 3.1 miles (5 kilometers).

But SpaceX isn't stopping there: It's now building much bigger 180-foot-tall (55-meter-tall) rocket ships, called Starship Mark 1, which Musk says could fly from Texas or Florida in two to three months and reach orbit by the end of the year.

Musk tweeted in March that SpaceX is "working on regulatory approval" for orbital flights of those prototypes, which will have three Raptor engines each instead of one.

SpaceX plans to launch a full-scale Starship before the end of 2020. Then sometime in 2021, Musk says, the company may trying landing a full-scale, uncrewed Starship on the Moon (perhaps as a bold demonstration to NASA).

Around 2023, SpaceX plans to launch Starship's first human passengers, a Japanese billionaire and his hand-picked crew of artists, on a voyage around the Moon.

SpaceX president and COO Gwynne Shotwell has reportedly said the company hopes to send its first uncrewed payloads to Mars by 2024. Following that, perhaps in 2026, SpaceX may try to put boots on the red planet.

[Read more—a lot more—here]

Source: ScienceAlert.

The next tests will be larger hops and then suborbital flights and then orbit.  I was going to say it could be ages before we get to orbital flights,  but given how rapidly SpaceX has got this far, I think their forecast of a mid-2021 first commercial launch looks very likely. So does the uncrewed mission to Mars in 2022, the Dear Moon circumlunar expedition in 2023 and the first steps by humans on Mars in 2024. 

With luck I shall live to see it: the culmination of a lifetime's fascination with space.  I was inspired by the Apollo 11 mission, by '2001 A Space Odyssey', and of course by the first three Star Wars films.  And now, 50 or so years later, we'll be there.  What a TV newsreel that will be.