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Comment by AtlasBarfed | Hacker News Reader

I could be wrong, but I though SpaceX catches its entire rocket (all stages) now with rafts/boats, doesn't it? What does this add over that already-implemented system?

Wouldn't blimps be a far better tech to keep the net aloft?

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Peter Beck (Rocket Lab CEO) has explained in a few interviews that maintaining a fleet of boats is incredibly expensive, and that this cost is one of the major reasons why they didn't go this route. Operating helicopters is much cheaper in comparison.

He has quoted actual numbers in the past, such as in this December 2021 interview (https://youtu.be/gcuOSXjevGs?t=751): "Do you have any idea what it costs to operate a ship? It's way way cheaper for Electron to fly it with a helicopter than it is to put a ship out there for a couple of days. It's just ridiculous. Marine assets are SO expensive. […] The Bell 429 that we operate is like $3,000 an hour. […] It's a 2.5, 3 hours flight. […] It's like $60-70,000 for the ship just to sit in the port! Not even going anywhere, it's $60,000 a day. And that's just a tiny little ship."

> It's like $60-70,000 for the ship just to sit in the port!

This sounds out of context. Maybe a speciality ship (stabilizers? crane?), capable of dragging/lifting a 1000-ton payload, in harsher weather, and can loiter if required.

If you build your own 2000-ton ship (excluding r&d, construction, depreciation) what would be the daily operating cost (crew/fuel/insurance) etc?

It means the rocket doesn't have to reserve fuel for a landing burn, and has more leeway in how it positions itself after re-entry, since the helicopter can move at least a bit to intercept. (NB SpaceX Falcon 9 boosters are too large to be snagged in midair by any extant helicopter -- and conversely, RocketLab has already announced that they'll be attempting SpaceX-style propulsive landing for their upcoming, much larger Neutron rocket.)

> I could be wrong, but I though SpaceX catches its entire rocket (all stages) now with rafts/boats, doesn't it?

Only some Falcon 9 launches recover the first stage. For performance reasons sometimes the booster burns all fuel and crashes into the ocean. The second stage has never been recovered and no attempt has ever been made. Early concepts may have mentioned it but I don’t believe the capability even exists on current Falcon 9s.

Starship is an entirely different rocket which has never been launched from a booster nor recovered from orbit. That is the eventual goal but SpaceX is far from achieving it for anything approaching “all” launches.

> Only some Falcon 9 launches recover the first stage

Almost all boosters are are recovered.

Flights that need enough acceleration to make the landing impossible are extremely rare. Falcon 9 already provides more payload capacity than most sats need.

I think some upcoming Falcon Heavy launches will expend the main booster though.

If we are going to argue semantics the only thing that matters in this context is that less than all boosters attempt recovery.

Peter Beck gives great interviews on YouTube. About this, he said that helicopters are much, much cheaper compared to doing anything with boats. Rocket Lab's rocket is small enough that a helicopter can handle it, SpaceX's first stage is just too big.

Blimps don't really exist, there's 25 of them in the world. You can't just go out and get a blimp and operate it the way you can a helicopter.

I understand the low number of blimps, but it's not complicated technology-wise, and we're talking about a space company.

Let me rephrase from blimp: How about balloons? Just use more.

The failure situation of helicopters getting hit by the booster, snagging on the net, running into each other, etc seem all way worse that if blimps were doing the work. Although maybe if you had drone style helicopters it might be better, but like you said with blimps, do those exist in retail?

> I though SpaceX catches its entire rocket (all stages) now with rafts/boats, doesn't it?

SpaceX doesn't catch anything at the moment.

The first stage lands itself either at the launch site or on the autonomous barge at sea.

The fairings for the second stage get pulled out of the ocean by ship after they splash down. They used to try to catch these and that's what you're thinking of but they weren't that successful at it. I believe they redesigned the fairings to be okay spending a short amount of time in salt water and they seem to be having a pretty good success rate for this.

The second stage of the Falcon burns up in the atmosphere. Their Starship project is attempting to fix this.

The advantage of this approach for Rocket Lab is that they'll be able to re-use the first stage. At the moment SpaceX is the only one doing that and it's why they have such a commanding position in the market. I haven't seen an explanation for why (I'm sure it's out there, I just haven't seen it) but my guess is that the Electron is a much smaller rocket than the Falcon and they can't spare the lift capacity to propulsively land the vehicle.

Also there should be a weight/fuel reduction for not having to hold enough fuel to land itself and every bit counts. Along with not having to worry about igniting/firing your rocket engines a second time in a flight which is reduced complexity and also allows for solid booster recovery.

Indeed.

Reusable SpaceX rockets have 30% small payload compared to non-reusable ones, as they have to carry extra fuel for landing.

Catching the rocket instead of landing it could be significantly more efficient as you wouldn't have to carry much more weight except for the parachute.

You would also have to build your rocket such that it can survive the shock of braking via parachute. That eats at least some of the weight savings.

This isn't a 5-layer cake we're talking about here. A structure that can survive being caught between a payload on one end and a rocket motor on the other is going already have the strength you need in most of the places you need it in order to hang from a parachute. The hard part is going to be attachment point real-estate since the most logical choice is going to have it fighting for space with rocket motor bits.

"The second stage of the Falcon burns up in the atmosphere. Their Starship project is attempting to fix this."

Just in case: Starship is a whole new rocket, not just an evolutionary upgrade of extant Falcon 9 to full reusability.

SpaceX's first stage lands itself, either on a droneship or on a landing pad near the launch site. The payload fairings splash down in the ocean, and get fished up for reuse. The second stage is not recovered.

Rocket lab just has a different approach to the same problem.

This is a different company (Rocket Labs) so they wouldn't get to reuse SpaceX's capture methods. This method appears like it would allow them to use commodity helicopters instead of having to develop and build their own drone ship tech, which has the additional hassle of having to maintain a boat and have a dock they can use to haul the rocket. I'm guessing this is for their "Small Launch" offering so the heli option makes sense at that weight.

Maybe they're afraid of Blue Origin? BO has a patent that covers "Sea landing of space launch vehicles and associated systems and methods"[0].

Of course, BO sued SpaceX and lost, so I'm not sure that they could win against Rocket Labs.

[0]https://patents.google.com/patent/US8678321B2/en

They don't recover stage two. That's a much different problem from recovering stage one, which has a ballistic trajectory; stage two goes into orbit.

For some mission profiles, SpaceX boosters land right back where they took off. Neat as can be.

Here's a photo capturing launch and landing at Cape Canaveral in the same view.

https://en.wikipedia.org/wiki/Landing_Zones_1_and_2#/media/F...

Well, they return to a landing pad within a few hundred yards of where they took off. A difference worth pointing out because the plan for their next generation rocket is to actually return directly to the launch site.

Blimps and dirigibles are the solution for sure. Love those things on principle.

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