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Italian firms D-Orbit and Group of Astrodynamics for the Use of Space Systems (GAUSS) as well as U.S. companies Momentus, Northrop Grumman Innovation Systems and Spaceflight Inc. have developed, manufactured, tested or flown orbital transfer vehicles. Seven additional companies are preparing to enter the market with initial flights scheduled in the next three years. The companies are: Atomos, Exotrail, Firefly Aerospace, Launcher, Space Machines, Exolaunch and Impulse Space.
Most orbits that would make the extra cost of a smallsat launcher acceptable, would be too much for a space tug to get to from another orbit IMO. Space tugs could be better used as mission extention vehicles.I do think both will service very small markets, and that seems to me the main reason why they claim that constellations, the only market segment with considerable growth at the moment, would be their main customer. In reality, constellations will not make extensive use of either smallsat launchers or space tugs.
Russia could build a batch of 150 space tugs to be launched into space aboard the Soyuz-2.1a to dock with derelict Soviet-era communications satellites in order to deorbit those satellites.
Another example of space tug domination...https://twitter.com/GoToImpulse/status/1747646045549744318
Who will win this war in the future?
This could potentially be devastating for ULA. They love to talk about high energy, but if you have a reusable LV optimised for LEO (hard to make a reusable LV for high energy without refuelling) and cheap tugs, you basically take all of the argument out of ULA's talking points - the exception being an expendable high energy LV can deliver a payload to GEO quicker than a tug can dock. I don't know how necessary that would be though, that is, to get a sat to GEO asap. Obviously, depots will be needed to make this architecture work at low(er) cost.
Quote from: chopsticks on 01/18/2024 05:44 pmThis could potentially be devastating for ULA. They love to talk about high energy, but if you have a reusable LV optimised for LEO (hard to make a reusable LV for high energy without refuelling) and cheap tugs, you basically take all of the argument out of ULA's talking points - the exception being an expendable high energy LV can deliver a payload to GEO quicker than a tug can dock. I don't know how necessary that would be though, that is, to get a sat to GEO asap. Obviously, depots will be needed to make this architecture work at low(er) cost.If you have a super-cheap two-stage fully reusable superheavy that can put (say) 200 tonne into LEO, then its payload can be a 100-tonne expendable kick stage with a 100-tonne actual payload. I think this beats Vulcan Centaur, except for the minor fact that it does not exist. Think of it as a one-off "tug".But this is completely off-topic for this thread. This thread is supposed to be about using a tug to allow one rideshare to hit multiple orbits to compete with multiple small launchers.
1. https://www.impulsespace.com/helios states Helios is compatible with Falcon 9, Falcon Heavy, Starship, Terran R, New Glenn, and Vulcan. They give payload masses for only Falcon 9 reusable and Terran R reusable, which suggests those are the vehicles they're guessing are the best fit. Looks like they can almost double Falcon 9 ASDS performance to high energy orbits, e.g. they give 6 tonnes to TLI whereas extrapolating NASA ELV figures gives ~3.55 tonnes for just Falcon.2. They mention that F9 reusable with Helios can get 4 tonnes to GEO. For some reason my back of the envelope calculations suggest they should do better than this, around 5 tonnes to GEO, not sure what I'm missing. They appear to have rounded payloads to multiples of 0.5 tonnes, which could explain a portion of this discrepancy but not all. They apparently like 300 km LEO, which is 4231 m/s from GEO assuming 28.5 degree inclination. Assume F9 ASDS can get 17.5 tonnes to that orbit. Assume Helios is 13.5 tonnes dry mass so with a 4 tonne payload the staging occurs in LEO. Assume dry mass of 0.1*13.5 tonnes. One can then calculate the specific impulse as 4231 / ( ln ((4 + 13.5) / (4 + 0.1*13.5)) * 9.81) = 364 seconds. That dry mass and specific impulse are both a lot worse than I'd expect for staged combustion methalox, which their website says they're using. For example Raptor is also staged combustion methalox and is supposed to have 382 s specific impulse. Wikipedia says Starship has a dry/wet mass ratio around 100/1300, which is better than the 0.1 I assumed and Starship pays huge reuse penalties! So something I don't understand is hurting Helios's performance.