A common joke in the medical world is, “The operation was a success, but the patient died.” The irony comes from how we might define “success”. On April 20th SpaceX conducted the maiden launch of the fully assembled Starship, including a Starship rocket on top of a super heavy lifter. The initial launch seemed success and the rocket flew well for several minutes. However, it then started to become erratic, and at 3:59 into the flight the onboard computers triggered the Flight Termination System (ie it’s self-destruct) and blew up the rocket as a safety precaution.

This was an uncrewed test flight, so it can be said that as a test it fulfilled its primary mission, to provide data about how the fully assembled Starship and associated launch pad will perform. Pre-launch SpaceX indicated that as long as the ship clears the tower, that would be considered a successful test. The goal is data, and they got lots of data. SpaceX says:

With a test like this, success comes from what we learn, and we learned a tremendous amount about the vehicle and ground systems today that will help us improve on future flights of Starship.

However, the rocket did also fail, and they need to figure out exactly why that happened. The proximate cause is likely the failure of several of the 33 raptor engines. I was at the Air and Space museum over the weekend, and had a chance to look at a rocket engine of the Saturn V rocket –  which had five giant engines. SpaceX decided to go in a different direction with lots of smaller engines. With 5 or more of these engines out the rocket could still lift off the pad, but they were unable to compensate for the imbalance this produced, which is likely what resulted in the loss of control of the rocket. But then, why did the engines fail?

We don’t yet know, but one possibility that has been raised is that there was damage to the rocket itself from debris from the launch pad. SpaceX decided not to use a water deluge (as NASA does when launching powerful rockets) under the rocket. When the SLS recently launched you will see a giant plume of water vapor. This is because they use a water deluge system that releases 450,000 gallons of water very quickly. This protects the launchpad itself from the thrust of the launch, about 9 million pounds for the SLS.

Starship produces about 17 million pounds of thrust, almost twice that of SLS. And yet SpaceX decided not to use a water deluge system to protect the launch pad. The result was a tremendous amount of damage to the pad. You can see in videos large chunks of concrete flying and doing damage. It’s possible that some of the raptor engines were damaged from this flying debris during the launch. This might have causes other damage to the Starship as well. We will likely learn more over the next two months while SpaceX is preparing their next test.  If true, at least the fix is obvious – SpaceX needs to use a water deluge system while launching the Starship.

This is an inherent problem to launching very large and powerful rockets. There is an economy of scale that we get when launching larger rockets – the relative amount of cargo is larger and the cost of getting stuff into space is reduced. SLS can deliver 46 tons into low Earth orbit. Starship can deliver about 100 tons. As an aside, the largest rocket ever conceived was the Sea Dragon, which could theoretically lift 550 tons into orbit. While the ship was designed and NASA had some interest, it was never developed. The idea is that it would be launched while floating in the ocean, because it was simply too powerful to launch from land.

We may be getting close to a theoretical limit for land launches with Starship, and even then a water deluge system or something similar may be necessary. Otherwise you will simply have too much debris flying around.

In the end I do consider this maiden launch of Starship to be a success. The ship survived long enough to gather usable data, and that was the goal. This was a test flight, and the plan was, if it survived long enough, to ditch the whole thing into the ocean anyway. So it’s not like they lost anything. The plan was always to crank out these Starship mass-production style. They were always planning on having multiple test flights that would be sacrificed before the system is reliable enough to launch cargo or eventually people.

The test also highlights how complex and critical the launch pad itself is as a piece of technology. It’s natural to focus on the rocket, and we may naively think that the launchpad is a minor part of the whole system. But it is a complex and critical set of technology of its own, part of the overall launch system, especially when you get to these more powerful rockets.

If ultimately successful, and it seems that it eventually will be, the Starship system will be the most powerful rocket ever launched into space. This will have a significant impact on the space industry. One of the likely applications will be to accelerate the launching of the Star Link satellites into orbit. NASA also plans to use a modified Starship component as a lunar lander. I still haven’t seen a fleshed out plan on how this will work, so I suppose they are still working it out. I suppose one or more Starships will be launched into lunar orbit. They will have to be able to dock with the Orion capsule so that Artemis astronauts could go into the Starship which will then land on the Moon and blast off from the Moon to return the astronauts to the Orion. If the Starship lunar lander can be refueled, either in orbit or while on the lunar surface, then it could be reused over and over as a lander. Something like that is likely, but I’m interested in the details when they are available.

Hopefully we won’t have to wait too long for the next Starship test flight. This one will be a good indication of how close SpaceX is to making this system work.