Finally: an uneventful Starship test!

Pressure test SN2
Source: Boca Chica Gal/NASA Space Flight via Teslarati

We all know Musk's methods by now:  test beyond breaking point, then improve, and test again, iteratively, until you get something that works.  Well, the latest Starship pressure test was 100% successful.  In fact, even better, the pressure test was conducted while the methalox tanks were being pushed up by a hydraulic jack to simulate the pressure caused by firing one raptor engine, thus showing it can handle the double stresses of rocket launch and overpressurised tanks.

Teslarati comments:

According to Elon Musk, SpaceX has successfully completed its latest Starship prototype test in a uniquely uneventful fashion, great news for the next-generation rocket’s next steps and first flight tests.

The SpaceX CEO revealed the news some 12 hours after the company wrapped up the Starship tank test at its Boca Chica, Texas facilities. Another excellent example of SpaceX’s preferred process of agile development, the test followed just nine days after the Starship SN01 prototype’s first cryogenic test unexpectedly unearthed a design flaw. SpaceX analyzed the results of Starship SN01’s unintentional launch debut and drew up plans to rapidly repurpose a Starship tank initially destined for the SN02 prototype.

By using existing hardware to test an upgraded iteration of the part that destroyed Starship SN01, SpaceX has now effectively retired the risk posed by that prior failure less than two weeks after it occurred. Elon Musk specifically noted that the former SN02 engine section “passed cryo pressure & engine thrust loads,” confirming that there was more to the exceptionally uneventful evening of March 8th than met the eye. While putting on much less of a show for local observers, this particular boring test is a great sign for the next few steps of SpaceX’s Starship development program.

Musk’s description of the test suggests that SpaceX’s intention with the SN02 test tank – built in just two weeks – was to stress it up to (and likely beyond) the pressures and mechanical stresses Starship engine sections will need to survive in flight. In simpler terms, they likely tried to burst the tank by pressurizing it with liquid nitrogen, a supercool cryogenic fluid. It’s unclear exactly how far SpaceX pushed the tank, but it’s safe to say that it went at least as high as past test tanks, meaning 7-8.5 bar or 100-125 psi. At a bare minimum, a test that failed to reach Starship’s minimum flight pressure of 6 bar (90 psi) would be of dubious value for the actual orbital ship.

A step further, SpaceX installed a hydraulic jack underneath the test tank in a bid to simulate the stresses it would experience with a single Raptor engine. Capable of producing approximately 150-200 tons (1500-2000 kN) of thrust, even Raptor is relatively minor compared to the Starship tank’s likely ~500 metric ton (1.1 million lb) mass. Still, the fact that the SN02 test tank survived the combination of a highly pressurized tank and the simulated thrust of a Raptor engine suggests that SpaceX is now ready for a more successful repeat of Starship SN01 testing.

[Read more here]

Just a reminder: SN2's tank and hull structure was constructed in just 9 days.  SpaceX is obviously rapidly building up to its interim target of one Starship per week.  Responding to a question on Twitter, "What's the path forward now? Static fire with SN3 and hop with SN4?," Musk replied, "Static fire & short flights with SN3, longer flights with SN4, but spooling up the whole Starship/Raptor production line is really what matters."  A production line which aims to produce 50 Starships a year at a cost of just $5 million each.  The low cost is only possible through using an assembly line.

What will all those Starships be used for?   Originally, when Starship (then the BFS) was first proposed, Musk said that 6 ships would be needed for the first expedition to Mars.  But if the new stainless steel Starship costs just $5 million, about one tenth of the cost of a carbon-fibre composite BFS, 60 ships could be sent for the same cost (there's additional fuel cost, but it is small in the context of the capital costs.)  Even if these Starships are just used once, to fly to Mars, the total capital cost would be just $250 million.  Of course, there will also be the Super Heavy first stages, but they will be fully re-usable, so fewer of them will be needed.  (NASA's current plans to get to Mars estimate cost at $100 BILLION.  For 5 people.)

In addition, there is the point-to-point market for suborbital travel on Earth.  Most places on Earth will be about an hour apart by suborbital SpaceX Starship shuttle.  Since spaceports won't be built close to cities, because of the noise and fears about rocket ship safety, the city-centre to city-centre trips will take, say, three or four hours.  But it currently takes 14 hours to fly from New York to Beijing, 22 hours to fly to Sydney (the Australian one, not the Canadian!)   There's surely a huge market for intercontinental shuttle flights.

But wait!  Those are not all the potential markets.  Cheap launch to LEO (low Earth orbit) will mean for more space activity.  It used to cost $22,000 to lift  a single kilogram into LEO.  With the Starship/Super Heavy combo, that cost will fall to $20/kg, or lower.  Space tourism will become a thing.   And the cost won't be prohibitive.  Lifting a 100 kg person with 100 kg of food/luggage into orbit will cost just $4000.  Even with a 100% profit margin, that's still withing the range of anyone who now pays for intercontinental business class flights.  There will be millions who would like to take a "spacecation".  There will be rotating space stations for longer stays, financially feasible because of the low cost of lifting material into orbit.  And such low launch costs mean that a Moon base, or many Moon bases, will happen too.  Oh, and don't forget Starlink, SpaceX's global high speed internet service.

Just as after WW2, when air travel plunged in cost and rose in quality, leading to an explosion of passenger air traffic, so will space travel when Starship is operating.  Starship will make its own market.  Every one of the Starships SpaceX produces will be needed.   In fact, there prolly won't be enough of them!