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I disagree. For mega constellations it’s about cost per kg to orbit, and for reusable it’s about launch rate. If you build too big, your launch rate isn’t high

I disagree. For mega constellations it’s about cost per kg to orbit, and for reusable it’s about launch rate. If you build too big, your launch rate isn’t high enough to get the full advantage of reuse. I think Starship is awesome, but even Falcon 9 is so big it leaves some room for something a bit smaller. 8 tons is in the Soyuz/R7 range, which is what the other megaconstellation is using. And it has had well over 1000 launches and still holds the record (in the 70s and 80s) of the most number of launches per year for a single rocket type, which makes it a good target class for size of a reusable rocket. 8 tons is about where Falcon 9 v1.0 started out, by the way. How many customers wish they had that built the smaller falcon 5. Additionally, a smaller rocket is useful for some human spaceflight applications. If you only need to launch two astronauts in orbit to fix a satellite, it’d be nice to have a smaller rocket option. An 8 ton first stage reusable rocket is also big enough to eventually have a reusable upper stage and still carry a a couple astronauts, their space suits, a small (Gemini-sized) vehicle (possibly integrated with the reusable upper stage), and some tools and parts to repair the satellite. Launch costs could in principle be less than $1 million, which is about the propellant costs alone for Starship. Starship is awesome. But we don’t have JUST 757s and 777s. We also have smaller utility aircraft. I’ve long thought that something just under 10 tons, partially or fully reusable, is a good market opportunity. Makes a lot more sense than tiny rockets for megaconstellations.

DennisP 6y ago
But we do have just airplanes that are 100% reusable. So far, Rocket Lab only talks about reusing the first stage; second-stage reuse is hard, and a huge cost savings. But maybe until Starship gets the launch rate to reach its potential, there's room for smaller rockets with disposable upper stages. SpaceX is banking on the space industry expanding well beyond megaconstellations, but that will take a few years. By the time we get there, maybe other companies will manage reusable upper stages too.
- Robotbeat 6y ago
  Right. Having a decent sized reusable first stage on Neutron gives RocketLab the option of a reusable upper stage down the road. It’s pretty tough to justify going for full reuse before you have even accomplished partial reuse. Something similar to the recovery method of Electron’s first stage would be appropriate for a reusable upper stage. (And at one time, SpaceX was planning it for Falcon 9’s upper stage... ballute/heatshield and parachute for Falcon 9 upper stage recovery).
CarVac 6y ago
> If you build too big, your launch rate isn’t high enough to get the full advantage of reuse. But if you throw away second stages, your rate of reuse goes waaay down. I don't think an 8-ton lift vehicle is going to achieve second stage reuse.
- Robotbeat 6y ago
  On the contrary, there are MORE viable methods for reuse with a smaller vehicle. They can do mid-air recovery with such an upper stage, for instance, but no hope of that with a Starship-sized upper stage.
  - CarVac 6y ago
    More ways to land, but the performance penalty of heat shielding will be crippling on a smaller stage.
    - Robotbeat 6y ago
      I doubt that. SpaceX was going to make Falcon 9 fully reusable, and it wouldn’t have been crippling. Might be too small to launch a full crewed Dragon or 60 Starlinks, but I doubt if its payload would’ve even been halved compared to partial reuse.
Diederich 6y ago
> Starship is awesome. But we don’t have JUST 757s and 777s. We also have smaller utility aircraft. This, and the rest of your comment, is quite reasonable. What it mostly comes down to is $/kg -> orbit. I know Musk constantly over-promises, but there's at least a good chance that Starship/Superheavy will get their total per launch cost below a million dollars. Perhaps well below that. Gwynne Shotwell, someone known for being almost infinitely more realistic than Musk, has stated multiple times that she firmly believes Starship will become a viable on-Earth passenger/cargo carrier. And that can only happen if a Starship/Superheavy total launch/mission cost is on the order of a long-haul aircraft. That is, well less than a million dollars. It's also possible that the fundamental physics of Earth surface -> LEO in a fully re-usable way can only be done with large machines. As an analogy: I'm not aware of any 'not large' machines that can transport anything economically across Earth's oceans. The physics, as I understand it, just don't allow it. Having said all that, I love the hell out of all of the innovation and potential competition coming around in this area. That's the best way to really test the assumptions (many of which I've just stated) that might be holding us back.
- Robotbeat 6y ago
  An Airbus A380 is the closest comparable aircraft to Starship. It can handle about 82,000 liters of fuel. Until the last 5 years or so, jet fuel fuel was $3/gallon (peaking at $4/gallon) in the US, higher in Europe and Asia. It’d need about 3 or 4 refuelings to travel to the other side of the world and back with about the same payload as Starship. That’s about $1 million worth of fuel. The rental price to charter an A380 to the other side of the world and back is about $1.3million not counting fuel or the time spent on the ground fueling and going to/from charter location. So I’d say a couple million per Starship launch would be on the order of a long-haul aircraft price. Still has plenty of room for smaller and cheaper per-launch fully reusable rockets.
  - Diederich 6y ago
    Thanks for the specific numbers. > Still has plenty of room for smaller and cheaper per-launch fully reusable rockets. Upon further reflection, I'm getting more on board with this, with two big relevant factors: first, how quickly can these new companies work out the fully reusable mojo. SpaceX is clearly many years ahead, but having a predecessor company actually demonstrating a technology surely makes it somewhat easier to re-implement. Second: back to the physics. I don't have a good intuition for this, but I do hope that it's physically possible to efficiently do small scale orbital transport. One way or another, I'm happy as can be that there are smart people (outside of SpaceX/Blue Origin) really pressing into this problem.
vkou 6y ago
Ninety nine times out of ten, launching two humans into orbit to fix a satellite is going to cost you a lot more than just launching a replacement satellite. The number of one-off, irreplaceable, you-have-to-fix-them-if-they-break satellites currently in orbit can be counted on one finger. As launch costs go down, this is not going to change.
- Judgmentality 6y ago
  > Ninety nine times out of ten I know this was an accident but I'm stealing this.
  - codercotton 6y ago
    I do not believe this was an accident. Or am I accidentally misreading..? :p
    - dwaltrip 6y ago
      99 / 10
    - vkou 6y ago
      I really wanted to drive that point home.
- Robotbeat 6y ago
  Yes it will. When costs change by orders of magnitude, trades change. Space hardware will always have some non-trivial cost, just like how equipment on the ground still has significant cost in spite of low logistics costs. As reuse lowers cost of space access by orders of magnitude, the relative cost of trashing vs fixing changes dramatically. When the space hardware costs 100x more than the launch, then it makes sense to fix than to trash. Also, astronauts are MUCH faster at assembly than robots.
  - vkou 6y ago
    Here's a few problems with fixing satellites. 1. From the ground, you have no idea what is wrong with the satellite, whether or not the problem is fixable, and even if it is, what exact tooling/replacement parts need to be brought up. 2. Satellites are not designed to be easily taken apart. 3. Doing any kind of technical work in a spacesuit is incredibly difficult. The extra cost of building your satellite with sufficient self-diagnostics, with a design that lets someone in a spacesuit take it apart and conduct meaningful repairs on it is going to be paid every single time you launch that satellite. This cost, in both design, and engineering is not trivial. And the only time you'll ever get any value from it is if you go ahead and do another, even more expensive space launch - this time human-rated. This launch is likely to head on up, and discover that no, they don't have the right tools, replacement parts, or even ability to access the broken parts of the satellite. The overwhelming cost of a satellite is the R&D that goes into designing it. If space launches are cheap, the correct economics to follow are "Just build two of them, and if the first one breaks, launch the second one."
nickik 6y ago
> Additionally, a smaller rocket is useful for some human spaceflight applications. If you only need to launch two astronauts in orbit to fix a satellite, it’d be nice to have a smaller rocket option. That's a nice theory. But that requires an actual capsule that is capable of all of these things. If you want to repair a sat, you need a EVA suit and so on. Its very unlikely to be cheaper to repair a sat with human, then to simply launch another one, or launch a human controlled robot. Also, such a capsule does not exist, and if SpaceX is any indication, development of such a capsule would cost 1-2 billion at least, do do it according to NASA spec. RocketLab does not have that kind of money and I don't see NASA or private financing come up with that. > Starship is awesome. But we don’t have JUST 757s and 777s. We also have smaller utility aircraft. While that is true, its not an analog. From Starship once you are in Orbit you can do all that stuff too. There are already companies like Momentus and others who whole business is to make connecting flights. RocketLab might be in a good position to be 'second best' and launch stuff that people don't want to put on SpaceX rockets. They will have to compete with New Glenn for that. I wish them luck. Where they will get an engine that capable, in that short a time is also really questionable to me. Maybe they are already deep in development, but it doesn't seem like it.

DennisP 6y ago

But we do have just airplanes that are 100% reusable. So far, Rocket Lab only talks about reusing the first stage; second-stage reuse is hard, and a huge cost savings. But maybe until Starship gets the launch rate to reach its potential, there's room for smaller rockets with disposable upper stages. SpaceX is banking on the space industry expanding well beyond megaconstellations, but that will take a few years. By the time we get there, maybe other companies will manage reusable upper stages too.

Robotbeat 6y ago
Right. Having a decent sized reusable first stage on Neutron gives RocketLab the option of a reusable upper stage down the road. It’s pretty tough to justify going for full reuse before you have even accomplished partial reuse. Something similar to the recovery method of Electron’s first stage would be appropriate for a reusable upper stage. (And at one time, SpaceX was planning it for Falcon 9’s upper stage... ballute/heatshield and parachute for Falcon 9 upper stage recovery).

CarVac 6y ago

> If you build too big, your launch rate isn’t high enough to get the full advantage of reuse. But if you throw away second stages, your rate of reuse goes waaay down. I don't think an 8-ton lift vehicle is going to achieve second stage reuse.

Robotbeat 6y ago
On the contrary, there are MORE viable methods for reuse with a smaller vehicle. They can do mid-air recovery with such an upper stage, for instance, but no hope of that with a Starship-sized upper stage.
- CarVac 6y ago
  More ways to land, but the performance penalty of heat shielding will be crippling on a smaller stage.
  - Robotbeat 6y ago
    I doubt that. SpaceX was going to make Falcon 9 fully reusable, and it wouldn’t have been crippling. Might be too small to launch a full crewed Dragon or 60 Starlinks, but I doubt if its payload would’ve even been halved compared to partial reuse.

Diederich 6y ago

> Starship is awesome. But we don’t have JUST 757s and 777s. We also have smaller utility aircraft. This, and the rest of your comment, is quite reasonable. What it mostly comes down to is $/kg -> orbit. I know Musk constantly over-promises, but there's at least a good chance that Starship/Superheavy will get their total per launch cost below a million dollars. Perhaps well below that. Gwynne Shotwell, someone known for being almost infinitely more realistic than Musk, has stated multiple times that she firmly believes Starship will become a viable on-Earth passenger/cargo carrier. And that can only happen if a Starship/Superheavy total launch/mission cost is on the order of a long-haul aircraft. That is, well less than a million dollars. It's also possible that the fundamental physics of Earth surface -> LEO in a fully re-usable way can only be done with large machines. As an analogy: I'm not aware of any 'not large' machines that can transport anything economically across Earth's oceans. The physics, as I understand it, just don't allow it. Having said all that, I love the hell out of all of the innovation and potential competition coming around in this area. That's the best way to really test the assumptions (many of which I've just stated) that might be holding us back.

Robotbeat 6y ago
An Airbus A380 is the closest comparable aircraft to Starship. It can handle about 82,000 liters of fuel. Until the last 5 years or so, jet fuel fuel was $3/gallon (peaking at $4/gallon) in the US, higher in Europe and Asia. It’d need about 3 or 4 refuelings to travel to the other side of the world and back with about the same payload as Starship. That’s about $1 million worth of fuel. The rental price to charter an A380 to the other side of the world and back is about $1.3million not counting fuel or the time spent on the ground fueling and going to/from charter location. So I’d say a couple million per Starship launch would be on the order of a long-haul aircraft price. Still has plenty of room for smaller and cheaper per-launch fully reusable rockets.
- Diederich 6y ago
  Thanks for the specific numbers. > Still has plenty of room for smaller and cheaper per-launch fully reusable rockets. Upon further reflection, I'm getting more on board with this, with two big relevant factors: first, how quickly can these new companies work out the fully reusable mojo. SpaceX is clearly many years ahead, but having a predecessor company actually demonstrating a technology surely makes it somewhat easier to re-implement. Second: back to the physics. I don't have a good intuition for this, but I do hope that it's physically possible to efficiently do small scale orbital transport. One way or another, I'm happy as can be that there are smart people (outside of SpaceX/Blue Origin) really pressing into this problem.

vkou 6y ago

Ninety nine times out of ten, launching two humans into orbit to fix a satellite is going to cost you a lot more than just launching a replacement satellite. The number of one-off, irreplaceable, you-have-to-fix-them-if-they-break satellites currently in orbit can be counted on one finger. As launch costs go down, this is not going to change.

Judgmentality 6y ago
> Ninety nine times out of ten I know this was an accident but I'm stealing this.
- codercotton 6y ago
  I do not believe this was an accident. Or am I accidentally misreading..? :p
  - dwaltrip 6y ago
    99 / 10
  - vkou 6y ago
    I really wanted to drive that point home.
Robotbeat 6y ago
Yes it will. When costs change by orders of magnitude, trades change. Space hardware will always have some non-trivial cost, just like how equipment on the ground still has significant cost in spite of low logistics costs. As reuse lowers cost of space access by orders of magnitude, the relative cost of trashing vs fixing changes dramatically. When the space hardware costs 100x more than the launch, then it makes sense to fix than to trash. Also, astronauts are MUCH faster at assembly than robots.
- vkou 6y ago
  Here's a few problems with fixing satellites. 1. From the ground, you have no idea what is wrong with the satellite, whether or not the problem is fixable, and even if it is, what exact tooling/replacement parts need to be brought up. 2. Satellites are not designed to be easily taken apart. 3. Doing any kind of technical work in a spacesuit is incredibly difficult. The extra cost of building your satellite with sufficient self-diagnostics, with a design that lets someone in a spacesuit take it apart and conduct meaningful repairs on it is going to be paid every single time you launch that satellite. This cost, in both design, and engineering is not trivial. And the only time you'll ever get any value from it is if you go ahead and do another, even more expensive space launch - this time human-rated. This launch is likely to head on up, and discover that no, they don't have the right tools, replacement parts, or even ability to access the broken parts of the satellite. The overwhelming cost of a satellite is the R&D that goes into designing it. If space launches are cheap, the correct economics to follow are "Just build two of them, and if the first one breaks, launch the second one."

nickik 6y ago

> Additionally, a smaller rocket is useful for some human spaceflight applications. If you only need to launch two astronauts in orbit to fix a satellite, it’d be nice to have a smaller rocket option. That's a nice theory. But that requires an actual capsule that is capable of all of these things. If you want to repair a sat, you need a EVA suit and so on. Its very unlikely to be cheaper to repair a sat with human, then to simply launch another one, or launch a human controlled robot. Also, such a capsule does not exist, and if SpaceX is any indication, development of such a capsule would cost 1-2 billion at least, do do it according to NASA spec. RocketLab does not have that kind of money and I don't see NASA or private financing come up with that. > Starship is awesome. But we don’t have JUST 757s and 777s. We also have smaller utility aircraft. While that is true, its not an analog. From Starship once you are in Orbit you can do all that stuff too. There are already companies like Momentus and others who whole business is to make connecting flights. RocketLab might be in a good position to be 'second best' and launch stuff that people don't want to put on SpaceX rockets. They will have to compete with New Glenn for that. I wish them luck. Where they will get an engine that capable, in that short a time is also really questionable to me. Maybe they are already deep in development, but it doesn't seem like it.