How much work will this take once it reaches orbit, to make it usable?
Does the four engine Ixion Wet Station configuration indicate that Centaur V will have four RL-10s?
Yes, to maintain the same thrust to weight ratio as the current Centaur, the Centaur V will need 3 or 4 RL-10's. (Which makes me curious how ULA will make that affordable - unless they switch to BE-3)
Quote from: Lars-J on 12/09/2017 07:10 pmYes, to maintain the same thrust to weight ratio as the current Centaur, the Centaur V will need 3 or 4 RL-10's. (Which makes me curious how ULA will make that affordable - unless they switch to BE-3)Presumably they would be the same improved version Aerojet is bidding for ACES (most of the existing stockpile has been burned through or will be by the time Vulcan debuts, and its not clear that the tooling still exists to produce the legacy engines). 3d printing and other manufacturing modernizations helps a lot. Plus more engines produced allows some economy of scale to appear. IMO comparisons to the relatively high cost of legacy RL10 are not relevant given the significant redesign.
Centaur upper stages won’t be around forever: ULA is already deep into the development of its next-generation Vulcan rocket. Initially, the Vulcan will use the Centaur as its upper stage. But eventually, ULA will switch over to a new type of refuelable upper-stage rocket known as the Advanced Cryogenic Evolved Stage, or ACES.The coming transition doesn’t faze Manber. “ACES may be a little better as an outpost than the Centaur,” he said. Spent stages from NASA’s heavy-lift Space Launch System, which is currently under development, could conceivably be converted as well.
NanoRacks lays out vision for turning rockets into space outposts, starting with Independence-1:https://www.geekwire.com/2018/nanoracks-lays-vision-turning-rockets-outposts-starting-independence-1/Starposts Website:https://www.starposts.space/
QuoteCentaur upper stages won’t be around forever: ULA is already deep into the development of its next-generation Vulcan rocket. Initially, the Vulcan will use the Centaur as its upper stage. But eventually, ULA will switch over to a new type of refuelable upper-stage rocket known as the Advanced Cryogenic Evolved Stage, or ACES.The coming transition doesn’t faze Manber. “ACES may be a little better as an outpost than the Centaur,” he said. Spent stages from NASA’s heavy-lift Space Launch System, which is currently under development, could conceivably be converted as well.
Quote from: e of pi on 04/10/2018 05:54 pmQuoteCentaur upper stages won’t be around forever: ULA is already deep into the development of its next-generation Vulcan rocket. Initially, the Vulcan will use the Centaur as its upper stage. But eventually, ULA will switch over to a new type of refuelable upper-stage rocket known as the Advanced Cryogenic Evolved Stage, or ACES.The coming transition doesn’t faze Manber. “ACES may be a little better as an outpost than the Centaur,” he said. Spent stages from NASA’s heavy-lift Space Launch System, which is currently under development, could conceivably be converted as well.In most cases, there is the tradeoff between the free centaur volume to the robotic automated system and other complexities. It seems that there's not much to gain in an LEO mission compared to a dedicated mission.You spend a fortune on the robotic system, to end up with a sub optimal module and lower LV payload. There are these cases in which this concept could benefit:1. Exploration missions in which the exploration upper stage is converted into habitat. In this case the upper stage is going to be in the same escape route with the payload so there is a big advantage to using it.2. An ACES with auxiliary fuel tanks which could be used after the main tank is breached. In this case the propulsion and other systems can be used.3. If there is planty of unused LV performance.4. If the robotic system can be reused over other modules, or is an integral part of the outpost.This concept seems great in a high launch cost environment. The recent and future decline in launch costs makes it less attractive.Fully reusable LVs may put it to rest.
The benefits of a split dry/wet station (with integral multiple NDS/CBM's) is that of not requiring additional outfitting flights or modules for immediate use, so it is different from the Bigelow in filling the inflatable. Also, it is possible to compose a station from multiple units while still retaining multiple port access (failure/operations scheduling) with the minimum number of launches.Both Bigelow and Ixion concepts suit LEO stations in different ways. The Bigelow allows for continuity with the ISS without as much of a retreat from capability, due to a) ISS contents being able to be transferred to fill the larger Bigelow all at once (forestalling the need to launch as much payload from Earth's gravity well) and b) greater power from a larger solar array, based on a single ULA launch.The Ixion concept allows for less dependence on multiple launches completing an operational ISS follow-on, with less space for continuity of ISS content, less power, and less functional space overall. Also, if you need to transfer less (or none) to the ISS, and do not need to be accessible from high latitude low energy launch vehicles, you can locate at a lower inclination (constrains also any earth observations as well) to preserve delta-v as an access/staging point.Neither of these are well suited for the DSG for various reasons, although the Ixion concept as a short lived LLO "frozen" orbit station as a logistical support function for multiple reusable landers is an interesting "one shot" station concept as an alternative to current plans.(A lunar station architecture does best as closer and more a means of lander support/turnover, but as props are a significant part of this and not human occupancy (ISRU will take considerable time/resources to bootstrap), it remains unclear why you'd want a hab and not a refillable depot (best not combined for safety, although the Ixion concept would allow that also quite well). While a station architecture for solar system access would likely be more about long term minimal hab of sparse duration with the means to assemble propulsion and high impulse propellants for the next few decades, leading to a distant lander support of an entirely different kind.)Bigelow has found few customers over a decade, so the limited number of prospects for HSF stations of any kind makes it hard to project much of a business beyond that of LEO/lunar. And a follow-on commercial station doesn't look secure based on the cost to reach/support it - while a nation (or nations) can "special case" an infrequently visited, highly underused station (due to costs and frequency of visits), a commercial station likely would need at a minimum monthly visits with much more equipment turnover, larger power and long term commitments from "anchor tenants" to break even - something that the ISS has never had the chance for.Also, to "industrialize" space you'd need a means to allow for higher risk missions than ISS, at a minimum for manufacturing and pharmaceutical uses - how do you factor that in to any stakeholder's budgetary horizons, and once you've done that, how do you know your station concept fits those requirements? The benefit of having the ISS right now is as a means to test much of this. Yet that has yet to happen, beyond the inflatable test (BEAM) we've seen. If you're looking to see what comes next, look to trials at the ISS of new collateral, don't look at station concepts yet because its that new collateral that will drive any commercial station concepts forward. As to nationally funded ones, I'm afraid Paul Spudis is right in suggesting that such are delaying tactics for funding expensive lunar missions. If necessary to have, perhaps the best ones are the smallest ones as they are the shortest diversion.Note that Musk is developing a large lander in BFS next. If you want to land on anything, you develop landers. Then you develop the means to get them there (like BFR). If it takes refueing, then its tankers and/or depots (e.g. BFS tanker). If you need them pre-positioned with resources and/or hab redundancy/repair capability, then we're back to some kind of vehicle/SC for that purpose, thus things like this concept in this thread. Seems rather obvious, apart from the politics and wishful thinking.My impression of BO's "gradatim" approach is like with SX a slowly accumulating capability aggregate that is vertically structured off of what they have already, expanding out from footholds they intend on establishing. The kinds of compromised footholds that a nation or perhaps an industrial consortium might consider won't be interesting to either SX or BO, more likely is the reverse case on selling incremental capacity back to nations/consortium's. Thus Ixion/Bigelow aren't interesting in the bootstrap role, too little and to constrained.
In most cases, there is the tradeoff between the free centaur volume to the robotic automated system and other complexities. It seems that there's not much to gain in an LEO mission compared to a dedicated mission.You spend a fortune on the robotic system, to end up with a sub optimal module and lower LV payload.
2- I was also thinking about Outpost as a polar-LLO refueling base for reusable landers. There was some genuine interest at the Gateway Science workshop in the ability to do multi-landing science and exploration missions that could be enabled by a suitably well-placed depot (I think polar-LLO is a much better place for lander mission support than NRO/DRO/EML-x). Getting multiple samples back from a much wider range of sites for instance, or employing leave-behind kits for things like heat flux and seismology experiments (IIRC something like that was on the decadal survey or the list of potential future New Frontiers missions).