SpaceXs Starship Flight Test 2 To Have 1000 Upgrades & Rocket On Rocket Firing

After the first Starship test flight in April, SpaceX is making more than a thousand upgrades to the rocket before it makes another attempt soon, according to details shared by its chief Mr. Elon Musk. Musk shared fresh updates about Starship in a Twitter space yesterday, where he outlined that SpaceX plans to change the staging profile of its rocket to increase the performance and improve the odds of the first and second stages of the rocket separating. Stage separation was the point of failure of the first Starship test flight, and the rocket continued to flip in the air without it taking place. SpaceX has also upgraded the rocket's engines and will add a steel plate to the pad to avoid damage from the thrust generated by the world's largest rocket.

SpaceX Makes Key Upgrades To Raptor Engine Following Starship Flight Test

Musk shared the details in a Twitter space yesterday, as he outlined that the Starship flight test 2  will feature more than a thousand upgrades. According to him, these also improve the odds of the test succeeding. SpaceX has a lot riding on a successful orbital test flight. It has invested billions of dollars into Starship, and the rocket also sits at the center of its plans to build out the Starlink satellite internet constellation and land the first humans on the Moon under NASA's Artemis program.

Musk believes the probability of a successful launch sits at sixty percent, depending on whether the first and second Starship stages successfully separate. Due to changes made by SpaceX for the Starship flight test 2, stage separation is even more important, according to the executive:

So we made a sort of late breaking change, that's really quite significant, to the way that stage separation works. Which is to use a hot staging, what's called hot staging where we light the engines of the upper stage or ship while the first stage or booster stage engines are still on. So we shut down most of the engines on the booster, leaving just a few running. And then at the same time, start the engines on the ship, or upper stage, which results in kind of blasting the booster stage so you've got to protect the top of the boost stage from getting incinerated by the upper stage engines.

This is something that the Soviets or the Russians have used quite a bit in their rocket science. There's a meaningful payload to orbit advantage with hot staging, that you know conservatively is about a ten percent improvement. Well depends on what it's been compared to, but let's say in this case roughly ten percent improvement in payload.

The first and second stages of the Falcon 9 rocket race away from each other during a December 2022 launch. Image: SpaceX

Hot Staging Will Be Riskiest Part of Test Flight Believes Musk

SpaceX's Falcon 9 rocket uses a pusher mechanism that separates the first and second stages to allow them to reach a safe distance before the second stage's lone Merlin 1D engine fires up for the remaining journey. As the rocket briefly loses power, it loses out on maximum payload capacity but becomes safer overall as the first stage is protected from the thrust and force of the second stage.

However, introducing 'hot staging' will perhaps be the riskiest part of the Starship flight test 2, with Musk sharing:

The moment the rocket stops its engines, it actually, it starts falling. So you don't want to be coasting, you don't want to be in a situation where the engines are not on because you just immediately start falling back to Earth unless you're already in orbit. So you want to have a kind of a non stop thrust situation. We also have some concerns about. . . so you want to just, so you want to start the ship engines before you've completely shut down the booster engines. In order to do this, you actually have to have vents, that basically the super hot plasma from the upper stage engines got to go somewhere. So we're adding an extension to the booster that is almost all vent essentially. So that allows the upper stage engine plume to go through the sort of vented extension of the booster and not just blow itself up. So this is the most risky thing I think for the next flight. And we will have to add a bunch of shielding to the top of the booster.

Final moments for the SpaceX's Starship second stage SN11 prototype as its video feed froze during an anomaly during landing. Image: SpaceX

He believes that the launch pad and the Starship system will be ready for the second test flight in six weeks from now. SpaceX is significantly upgrading the launch pad after the damage from April's launch attempt. These include adding concrete and a water-cooled steel plate to cool the site from the millions of pounds of thrust that Starship generates.

Details about the upgrades are as follows:

 You know there's a lot of variables here that are out of our control. Probably the launch pad upgrades and the booster ship are ready in about six weeks. There's a massive upgrade of the launch site that's happening. So we're putting roughly a thousand cubic meters of steel reinforced high strength concrete below the pad and on top of that we are, we have a sort of a steel sandwich. Which is basically a very thick, two thick plates of steel that are welded together with channels going through. So you basically have like this water cooled steel sandwich and then there are perforations at the top. So it will actually shoot a lot of water out of the, it's basically, think of it like a gigantic upside down showerhead. It's gonna basically blast water upwards while the rocket is over the pad to counteract the massive amount of heat from the booster.

Like the booster is basically the world's biggest cutting torch with a massive amount of force, it's not just heat, but also a massive amount of force. 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 last time. We'll also be doing a higher thrust to weight liftoff, so it will just spend less time, yeah we'll spend less time on the ground.

SpaceX's Starship rocket blasts off from the launch pad in April. Image: SpaceX

Major Upgrades Made To Rocket Engine After Multiple Failures In April

While the launch pad dominated headlines after the first Starship test flight, another concern during the test was multiple engines losing power. This started early in the flight, as Starship 'hovered' over the launch pad before throttling up to attempt to reach orbit. SpaceX will also modify the flight profile to increase the rocket's thrust-to-weight ratio so that it leaves the pad sooner, and design changes on the Raptor 2 engine include crucial components such as its hot gas manifold.

These changes, according to Musk, are:

The engines on the last rocket were somewhat of a hotchpotch so they were, those engines were built and tested over a period of a year. . .So we have what's called a hot gas manifold. It takes the fuel rich gas from the fuel site powerhead, transfers it to the main chamber. Or transfers it to an area above the main chamber where it then mixes it with ox rich gas and goes to the main chamber and combusts. We've made a number of improvements to that hot gas manifold, which is arguably the most risky, the riskiest part of the engine. It's also something that is subject to hot gas leakage, which is sort of methane rich hot gas leaking through the bolt holes of the fuel manifold. So that's something that gets very hot, and if it gets very hot, it can gap. So an improved design of the hot gas manifold, as well as higher torque up on the bolts of the hot gas manifold to minimize potential for hot gas fuel leakage at high pressure. That's one of the single biggest improvements.

There are really a tremendous number of changes between the last Starship flight and this one. Well over a thousand. So I think the probability of this next flight working is, you know getting to orbit, is much higher than the last one. You know, maybe it's like sixty percent, it depends on how well we do at stage separation.

The hot gas manifold on the Space Shuttle's engine is visible in black. Image: Boeing/Rocketdyne

A hot gas manifold is one of the most essential components of a rocket engine. It is responsible for taking the fuel and the oxidizer from the numerous pumps and lines that the pair flows through for pressurization, cooling and other purposes. These make their way into the manifold and then are sent to the combustion chamber, mixed and ignited to generate thrust.

This requires the component to handle hot and cold gasses at different pressures to ensure the combustion chamber can work flawlessly. Combustion chamber problems have surfaced on the Raptor engine as well, with SpaceX's first Starship tests seeing the engine emit green flames, which indicates the chamber melting due to an oxygen-rich environment.

Written by Ramish Zafar