Despite an explosion, Elon Musk is closer to his new space age
9 min read
THE FIRST FLIGHT lasted a bit less than four minutes. With 30 of its 33 engines firing, the first of SpaceX’s “Super Heavy” boosters lifted off its launch pad in Boca Chica, on the Texas coast at 13:33 GMT. A minute later it passed through “max Q”, the point at which the stress on the vehicle caused by thrust of the engines and the resistance of the atmosphere peaks. Two minutes in, the rocket had reached an altitude of 20km (12 miles) and was travelling at 1,600kph, even though at least two more of its engines had shut down.
By minute three, though, it was clear that something was wrong. The rest of the engines had not cut off at the appointed time; the rocket seemed to be changing its orientation strangely; the separation of the second stage, a prototype spaceship called Starship, from the Super Heavy was not progressing as intended. As video showed the rocket continuing to tumble, John Insprucker, a SpaceX engineer providing commentary for the company’s live feed, delivered a technical understatement for the ages: “obviously…this does not appear to be a nominal situation”. A few seconds later, with the rocket clearly out of control, its “flight termination system” did what it was meant to and blew it up over the gulf of Mexico.
Quite what went wrong was not immediately clear, at least to outside observers. Taking off with too few motors running and losing more during the ascent may have been crucial, but there are other possibilities. The good news is that SpaceX says it is building Super Heavies and Starships at a healthy clip; it should in principle be possible to rerun the test reasonably soon once the nature of the problem becomes clear and a fix is found. The bad news is that the structure which supports the Super Heavy as it launches seems to have been damaged to an extent that may well require a significant redesign rather than simply repair. That could entail significant delays.
The company, and its many supporters, will accentuate the positive. The rocket made it into the air and through max Q, both things it had not done before. And the point of flight testing is to find problems in processes which cannot be tested on the ground. In that sense the test was a success. And if that is a slightly rosy view, it is at heart a fair one. For the flight to have gone off entirely as planned would have been a truly phenomenal coup. Getting some of the way and being ready to try again soon is certainly good enough. The possibility that the Starship system will mark a huge leap forward in space travel remains one to take very seriously.
Not a leg to stand on
The Super Heavy is the most powerful rocket ever built; its thrust at take-off would normally be more than twice that of the Saturn V rockets that put men on the Moon, though with three engines out it might not quite have reached that goal. The Starship which is to act as its second stage will, when it gets there, be the largest spacecraft placed in orbit by a single launch since the days of the space shuttle.
If SpaceX puts right both the problems that struck today and the others that the test programme will surely uncover, the Starship system will not just be able to put larger payloads into orbit than any competitor, it will be able to do so at a cost per tonne far lower than any the industry has seen before. That low cost is one of the advantages offered by a system with just two parts, both of which are fully reusable. Another is that a system which can take off, land and take off again in short order opens up a new range of possibilities for flights beyond Earth orbit. If it lives up to the hopes of Elon Musk, SpaceX’s boss, the Starship system will be capable of taking human crews to the surface of the Moon and even Mars.
But there are a lot of further capabilities to add before that becomes a reality. Even had it been fully successful, this first test would only have been the beginning of a development process that will take a great deal more effort and investment.
The flight plan for this first mission was very like those that have become routine for SpaceX’s Falcon 9s, the rockets with which the company has come to dominate the satellite-launch business. The first-stage booster was meant to fly to the edge of space and then return, under power, to the surface as the second stage went on to orbit.
But there were two crucial differences. When a Falcon 9 booster returns to Earth it deploys its legs and lands. If the Super Heavy had executed the manoeuvres needed to get that far it would have plunged straight into the Gulf of Mexico.
The principal reason for this difference is that although the Super Heavy is intended to be fully reusable, just as the Falcon 9 first-stage boosters are, unlike a Falcon 9 booster, it has no legs on which to land. Deployable legs sturdy enough to support it would add an unacceptable amount to its weight. Instead Super Heavies will come down on to the pads from which they were launched, where they will be caught and cradled in mid-air by huge mechanical arms.
The gantry at the launchpad used for Thursday’s testflight, known to its fans as “Mechazilla”, is equipped with just such arms. They were used to lift up the Starship and stack it on top of the Super Heavy on the Boca Chica launchpad a couple of days before launch. Understandably, though, SpaceX wants to be sure that it knows how to return the big boosters to Earth with the requisite accuracy before it tries to catch one, not least because test rockets are expendable in a way that launch pads with a lot of infrastructure are not. The only outcome from the first test that the company would have had to acknowledge as a real failure would have been an explosion that took the gantry out. Fake “landings” at sea are the obvious way to develop faith in the booster’s performance before trying to catch one on the fly.
The second difference between the plans for the test flight and a standard Falcon 9 flight was that when a Falcon 9 puts something into orbit it stays there until its operator decides to bring it back. The Starship that was perched on top of the Super Heavy and shared its fate would have lasted in orbit for little more than an hour even if everything had worked perfectly. Its engines were going to put it onto a trajectory that would have seen it re-enter the atmosphere over the Pacific before it had made a complete circuit of the Earth. Its final resting place was to be a patch of sea approximately 100km off the northwest coast of Kauai, the northernmost main island in the Hawaiian chain.
Eventually, Starships will go into orbit, deploy satellites, then re-enter and land in the embrace of a Mechazilla gantry. But before that can happen they have to show that they can survive re-entry.
Neither Falcon 9 boosters nor the Super Heavy hit the lower atmosphere fast enough to need heat shields. Starship does, which is why the bits of it which will face the most heat are covered in hexagonal “thermal protection” tiles. How well they work, though, will not be known until, in future tests, the company attempts to bring Starships down in one piece. The system is significantly more ambitious than the heat shields used on the company’s much smaller Dragon spacecraft, currently used to take crews to and from the International Space Station. It is probably the aspect to the Starship system that is furthest beyond the capabilities SpaceX has demonstrated to date.
The prize for getting right will be a launch system of unparalleled capabilities. The company says that a Starship launched by a Super Heavy will be capable of lifting 100-150 tonnes of cargo to orbit. That far exceeds the capacity of today’s most powerful commercial launcher, SpaceX’s Falcon Heavy, which is basically three Falcon 9s strapped together so as to be able to lift up to 64 tonnes. The cargo which could be lifted with a space shuttle was just 24 tonnes.
It’s big, but it’s not yet clever
It is also more than that of any of the three big new launchers other companies are working on: the Ariane 6 being developed by ArianeGroup, a joint venture of Airbus and Safran, a French defence contractor; the Vulcan Centaur, a project run by ULA, a joint venture between Lockheed Martin and Boeing; and New Glenn which is being developed by Blue Origin, a company founded by Jeff Bezos, the executive chairman of Amazon (see diagram). An operational Starship system will not only be bigger than all of them. Because it will be fully reusable it should also be a lot cheaper, too. Ariane 6 and Vulcan Centaur take a one-and-you’re-done approach, though ULA hopes eventually to be able to recover its Vulcan first-stage engines. New Glenn is designed to have a fully reusable first stage, as the Falcon 9 does.
The Starship system, though, is intended to do more than take payloads up to Earth orbit. NASA has chosen a version of the Starship as the spacecraft with which it will return humans to the surface of the Moon. Mr Musk has always planned for it to be the vehicle which will take them to Mars. For either of these things to happen another new technology is needed: on-orbit refuelling.
A rocket needs fuel and oxidiser in order to work. For the Raptor engines which power both Super Heavy and Starship, the fuel is liquid methane and the oxidiser liquid oxygen. By the time Starship reaches orbit, it has used up most of its supply of both. So if it needs to go further it needs refuelling. SpaceX plans to build a fleet of Starships configured as tankers to allow this.
The plan for NASA’s first Artemis moon landing, due in the second half of this decade, show the level of effort that will be necessary. The first step in the plan is to launch a Starship configured as a refuelling station into orbit around the Earth. A subsequent series of tanker missions then fills it up with liquid oxygen and methane. SpaceX’s agreement with NASA suggests a remarkable 14 tanker missions would be required; Mr Musk has since said it might be possible with considerably fewer. Once the refuelling station is full, a special version of the Starship is sent up to dock with it, refuels, and heads out to an orbit close to the Moon. There it takes on board astronauts who have reached the same orbit by other means, and ferries them down to the surface. When their mission is done it ferries them back up to orbit.
For this to work two things are necessary. One is the technology required to dock two spacecraft together, move significant amounts of very cold liquid from one to the other, and then decouple them. Automatic docking is already fairly routine; the transfer of lots of liquids from one spacecraft to another is not.
The second is for heavy launches to become a truly workaday experience. If you need to fly lots of tankers for every crewed mission, you need to be able to turn the tankers around quickly and cycle rockets through your launch facility at a speed far beyond anything anyone has managed to date. SpaceX currently launches Falcon 9s a bit more than once a week, which is a cadence higher than any other company or country has achieved. But to fly a significant number of crewed Starships to destinations beyond Earth orbit it will need to be able to handle launches daily and quite possibly more frequently still.
If it is to fulfil Mr Musk’s dreams of interplanetary flight, the Starship system needs a huge amount of further development. Its Super Heavies need to be able to fly back to their landing sites with unerring precision, its mechazilla system has to be able to perform its magic routinely, its Starships need to master re-entry, and its whole set up needs to be able to operate at a cadence the industry never previously imagined, let alone attempted. It is tempting to see the construction of the most powerful rocket ever as the easy bit.
But it was not easy, and it has been done. And SpaceX’s previous record in innovation is a remarkable one. There are many obstacles ahead; but it is not too hard to imagine them, too, being surmounted. ■
