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Starship Flight 5: Launch and booster catch [video]

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Re: Starship Flight 5: Launch and booster catch [video]

#701

Post by _dain_ »

cpeterso wrote: post #654
ChuckMcM wrote: post #516

Pretty impressive. The engineering team at SpaceX is really something. Some thoughts; The 'chopsticks catch' was amazing to watch. Seems like it adds a lot of risk and clearly the booster needs additional fire suppression systems :-) perhaps the tower could mount something that sprays the booster like the barges have for the F9 boosters. The heatshield held out for a much longer time, the asymmetric heating on the fl…

What’s the advantage of catching the booster over landing it in the ground? Catching it seems like an extra complication.

Why send the landing mechanism to space when it isn't needed there? Whatever kit you put on a rocket has to be brutally miniaturized to limit how much you eat into the payload mass. Also has to be rugged enough to withstand tremendous vibrations and thermal stresses. That adds cost and more points of failure. You want to move as much of the complexity off the rocket as possible. Then doesn't matter if the catching mechanism on the launch tower is big and heavy.

Re: Starship Flight 5: Launch and booster catch [video]

#702

Post by creer »

creer wrote: post #686
creer wrote: post #585

Earlier quoted context omitted.

Eventually it convinces everybody that "quantity in space" is possible. Moving to projects where you don't have to count every ounce. It opens the path to wild schemes, in amount of weight that could be moved. And why "eventually"? SpaceX should have already convinced people of that. Yeah it's not yet in production, but the momentum and progress have been amazing to witness. (The previous one was convincing everyone…

An interesting question (because all the others will probably be too slow) is what does that change for SpaceX itself (which can be fast)? It gets to complete and upgrade Starlink. Sure. And that keeps it busy for what? Two years? At most. Sure. Done. Just kidding, that provides some background launches as a guaranteed customer going forward. But nowhere near enough to make a dent in what will be the new SpaceX launc…

One answer might be "infrastructure". Infrastructure in space will become big if space becomes big (beyond launching telecom, observation and science - which are small for now, compared to their launch potential.) SpaceX will need infrastructure itself - like refueling, landing stuff in exotic places, cargo delivery to other spacecraft, de-orbiting stuff, spacecraft to spacecraft networking, bringing cargo back to earth, carrying / delivering crew around, spacecraft repair, emergency access, etc.

A bit like Amazon then: if SpaceX needs some capability in their grand plan to Mars or whatever, they could try and package that as a commercial service after using the bare bones version for themselves.

Re: Starship Flight 5: Launch and booster catch [video]

#703

Post by gibolt »

ghc wrote: post #23

Nothing could have prepared me for how that catch looked. I was sure the rocket was careening into the tower at the last second before it straightened out. The control algorithms must be incredible for the landing system to work within those small tolerances.

Prior launch landed 0.5cm away from the target location. This is equivalent to landing a 25 story building right on the foundation.

Absolutely impressive accuracy and precision.

Re: Starship Flight 5: Launch and booster catch [video]

#704

Post by MPSimmons »

__d wrote: post #674
cpeterso wrote: post #654

Earlier quoted context omitted.

What’s the advantage of catching the booster over landing it in the ground? Catching it seems like an extra complication.

I can speculate ... I think the primary reason would be that landing legs are heavy, and it wastes performance to carry them. If your landing mechanism is mostly on the ground, you get that performance back. Secondary reasons might include that it's simpler to get the booster right back to the pad. Once things have settled into an operational cadence, it's likely feasible to lower and lock the booster onto the stool,…

To my knowledge, you're right, but in reverse order. I believe the driving force is time, rather than mass overhead, but certainly both play a large part.

Re: Starship Flight 5: Launch and booster catch [video]

#705

Post by kedv »

nordsieck wrote: post #526
ChuckMcM wrote: post #516

Pretty impressive. The engineering team at SpaceX is really something. Some thoughts; The 'chopsticks catch' was amazing to watch. Seems like it adds a lot of risk and clearly the booster needs additional fire suppression systems :-) perhaps the tower could mount something that sprays the booster like the barges have for the F9 boosters. The heatshield held out for a much longer time, the asymmetric heating on the fl…

> The detonation at the end was pretty spectacular too, but I suspect that structurally the tanks failed as the rocket hit the water vs anything that was an engineering failure. It's possible that SpaceX programed the AFTS to trigger some time after the rocket touched down in the water. Just to make sure that it completely submerges quickly. > I can easily imagine that flight 6 will be nominal end to end without any…

Why is SpaceX choosing to land the booster on the Mechazilla arms instead of performing a soft ground landing like the Falcon 9 booster?

Re: Starship Flight 5: Launch and booster catch [video]

#706

Post by gibolt »

cryptonector wrote: post #519
api wrote: post #311

Earlier quoted context omitted.

I thought it was plausible given the accuracy of F9 landings, though I still wonder how it will work at scale if one failure destroys the landing site. That could ruin the cost benefits. Where his vision hit a lot of speed bumps is second stage reusability. Starship is a beautiful second stage to throw in the ocean. They’ll probably get it landing but the heat tiles will require a lot of refurbishment between flights…

I'm expecting that SpaceX will have lots of towers, not just one (currently) or 3 or 4 (under way). It won't just be for redundancy. The duty cycle of a tower might simply not allow for the cadence that SpaceX wants to maintain. With Falcon 9 they currently have a 3x weekly launch cadence (which is unbelievable enough). With full reusability they might be able to get to daily and better cadence, so if the duty cycle…

A flight to Mars is currently going to require 10 tanker flights just to get enough fuel into orbit for 1 Starship trip. Containing liquid fuel for long in orbit will not be easy.

This likely means they are targeting 10 flights in a day at least. They've mentioned 1000 trips to Mars during one transit window, which means ~10000 Earth launches within 3 months, or >100 per day.

Re: Starship Flight 5: Launch and booster catch [video]

#707

Post by cyberax »

diebeforei485 wrote: post #472
moffkalast wrote: post #336

Earlier quoted context omitted.

Well I mean going to Mars isn't that hard per se, a fair few countries have done it... but carrying enough supplies and shielding to last people 2 years until the return trip and then actually getting back are way harder problems. Seeing Starship get burnthrough on these suborbital launches really shows how hard it'll be to do Mars return entry with a fair few extra km/s.

Only the US and China have landed successfully on Mars. China achieved this in 2021. Russia/USSR tried multiple times and didn't succeed. Other countries have sent satellites to orbit around Mars, which is not the same thing.

> Russia/USSR tried multiple times and didn't succeed.

Pedant mode: the USSR did land softly on Mars, but the lander got caught in a dust storm and was not able to transmit back the data ( https://en.wikipedia.org/wiki/Mars_3 ).

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