More Changes To Starship Before The Next Flight
By now, the list of changes from Starship’s first integrated test flight to the upcoming launch is extremely long. This has to do with the fact that a few different problems occurred during the first flight, not to mention that when Starship first launched there were already more advanced prototypes waiting for their turn to fly. Combine these two factors and the next launch will feature somewhat of a different rocket both internally and externally.
Only days ago Elon Musk revealed more changes with one of the most significant being a new stage separation method. This is a big deal and a risky change however the company believes it’s the best way to successfully reach orbit. Not to mention pad changes and the new water cooled steel plate which will be put to the test.
We are even getting estimates from Musk that the first launch could be just over a month away. However, this could be a very ambitious goal with all the work and changes still left. Here I will go more in-depth into the most recent Starship changes, the other differences between the first and upcoming launch, what to expect in the coming weeks, and more.
More Starship Changes
A few days ago on the 24th, during a Twitter discussion, Musk provided some new information on the next flight and specifically the Starship prototype. He first said that SpaceX had recently decided to switch to a “hot-staging” approach where the Starship upper stage will ignite its engines while still attached to the Super Heavy booster.
During the discussion he commented, “We made sort of a late-breaking change that’s really quite significant to the way that stage separation works. There’s a meaningful payload-to-orbit advantage with hot-staging that is conservatively about a 10% increase” he said. Hot-staging involves igniting the engines on one stage while still attached to its lower stage. Musk said that, for Starship, most of the 33 Raptor engines on the Super Heavy booster would be turned off when the engines on the Starship upper stage are ignited. This is meant to avoid the loss of thrust during traditional stage separation, where the lower stage shuts down first.
This change is big enough to warrant some alterations both on the inside and outside of Starship. Specifically, Musk said SpaceX is working on an extension to the top of the booster “that is almost all vents” to allow the exhaust from the upper stage to escape while still attached to the booster. SpaceX will also add shielding to the top of the booster to protect it from the exhaust.
As far as how we know these changes are will be implemented for the next flight, he was quoted saying, “This is the most risky thing, I think, for the next flight,”.
In the past and during the previous integrated launch attempt, Starship and Super Heavy didn’t use a traditional stage separator setup. Normal rockets have actuators that will push the two stages apart, since the upper stage engine is usually tucked into the inter-stage that is attached to the 1st stage, but the 2nd stage engine needs to be clear of the 1st during ignition. In other words, there is no pusher separation mechanism like the Falcon 9 for example (springs push the second stage away) in this case the plan was to unlatch the starship clamps to the booster and let its momentum separate it from the first stage. This required Starship to perform a slight flip maneuver to free the upper stage for engine ignition and separation from Super Heavy.
During the first test flight this exact process of one a few different problems. Around 2 minutes and 50 seconds into the flight you can hear the call to begin the flip maneuver and eventually stage separation but nothing happens. Not long after the rocket is out of control and eventually terminated. It’s likely that this first attempt combined with a few other factors encouraged the company to change this process and try something else. While some changes have to be made in a lot of ways this new hot staging approach is simpler and removes some moving parts. Even still, Musk believes this will be the riskiest part of the entire next integrated test flight.
A Long List of Improvements
While the new stage separation plan is a big deal, it only joins a large list of other changes throughout the entire launch vehicle and launch pad. Prior to Musk’s discussion online just days ago, we already knew a few of the changes to the booster however he recently gave a bit more insight on what to expect. Musk said SpaceX made a “tremendous number” of other changes to the vehicle, “well over a thousand.” He also pointed out that the company was continuing work to upgrade the launch pad to avoid the damage caused by the first Starship launch, including the “steel sandwich” water deluge system. “We’re actually going for overkill on the steel sandwich and the concrete, so that should leave the base of the pad in much better shape than the last time” he said.
He also talked about the Raptor engines and SpaceX described the first Starship integrated launch vehicle as using a “hodgepodge” of engines built over time. The Raptors on the new vehicles include changes to the hot gas manifold in the engine to reduce fuel leakage.
Starship’s first test flight was with Booster 7 and Ship 24. Even before the first launch, in an interview, Elon was quoted saying, “We are actually dying to get this rocket off no matter what happens to it because there are so many improvements between booster 7 and booster 9, literally hundreds. Some major ones, we moved from hydraulic thrust vector control to electric, and the entire heat shield structure on the base on Booster 9 is completely redesigned from Booster 7. Booster 7 has kinda a retrofitted heat shield system between the engines, and this is very important because if you think about 33 engines, if anyone of them goes wrong, it’s like having a box of grenades, really big grenades, and if one goes off you don’t want the others to go off also. We just want to take off and move on to Booster 9” he said.
He believes that there is an 80% probability of reaching orbit with Starship this year, and close to 100% chance of reaching orbit within 12 months.” He finished by making a few comments on what to expect for the next flight. First, he pointed out, “For the next flight, “we’re going to start the engines faster and get off the pad faster.” From engine start to moving Starship “was around 5 seconds, which is a really long time to be blasting the pad.” Going to try to cut that time in half. It was actually good to get this vehicle off the ground because we’ve made so many improvements” in Super Heavy Booster 9 “and beyond. Really just needed to fly this vehicle and then move on to the much improved booster.
Out of everything Booster 9 seems to have the most changes. The only competition would be the pad itself and the new water cooled steel plate. The only protection during flight was a special heat resistant concrete that the company believed would hold up at least for one launch. They based that idea on a partial thrust static fire that didn’t damage the pad that much. However, now the company is going from a special concrete to an industrial steel plate with significant plumbing that stretches underneath the entirety of the launch mount.
As partially mentioned prior, Elon pointed out that he believes they are going overboard with the amount of protection and development of the steel plate. In other words, he is very confident that this system will at least leave the pad in a much better state than the first launch.
As far as when this next launch will be, Musk didn’t commit to a specific launch date. “A lot of variables here that are outside of our control. We think, probably, the launch pad upgrades, and the booster and ship, are ready in about six weeks.”
This being said, it’s important to point out that Musk is often very ambitious with these launch timelines and more often than not things take a bit longer. Whether or not this is the case, the 6 to 8 week estimate is very promising. With this new stage separation method joining the list of changes, it’s hard to believe in that short period of time the company could be ready. In the next few days or weeks, we can expect to see the new booster hardware at the site as they prepare to alter the Starship prototype expected to fly on the next integrated test flight.
In one last quote Musk said “I think the probability of this next flight working, getting to orbit, is much higher than the last one. Maybe it’s like 60%.” These are decent odds for a second test flight and something to look forward to very soon. Besides the launch vehicle and pad changes, the flight profile should be exactly the same.
It will start with launch, followed by stage separation and some of the first major events. This includes the booster falling back towards Earth for a controlled water landing. Finally, a full 1 and a half hours after liftoff, and the Starship upper stage is expected to splash down in the pacific ocean. This is some of the flight profile assuming everything goes as planned
Conclusion
SpaceX is not far away from the second integrated test flight of Starship. With this comes a bunch of new changes including a new stage separation plan. This along with all the other improvements will hopefully yield even better results. We will have to wait and see how it progresses and the impact it has on the space industry.
