What is Tea Monster?
Quote from: Russel on 06/29/2015 12:08 amWhat is Tea Monster?Not so much what as who -- one of our fellow posters.
As I think I said before, I don't think you can get away with hovering that close. Even with the micro gravity that would require quite a number of Kg (equivalent) of thrust continually. What would be nice is being close to an L point and dropping an anchor. Of course if you had the crew fly down with an MMU they could take a few Km of tether and attach it to something.
......I have issues with SEP because of the economics of having massive and expensive vehicles which engage in long mission cycles and the longer the mission cycles the fewer times the investment can be recovered by reuse. This is why I have serious issues with using SEP to get all the way to Mars, and I still do. A suitable SEP tug in the order of 500KW to 1MW isn't going to cost $100M. Its going to cost many times more. And the development isn't going to be cheap either. But I think the technology can be gotten to the point where assembly is largely automated. So its in the right ballpark. And we're talking in the order of 6 months or so to raise a 50 tonne payload from Low Earth Orbit to High Earth Orbit. So reuse 20 times is a possibility. This is not the case for SEP to Mars involving years-long cycles will never see the investment returned. ... ...
Quote from: Russel on 06/29/2015 04:01 pm......I have issues with SEP because of the economics of having massive and expensive vehicles which engage in long mission cycles and the longer the mission cycles the fewer times the investment can be recovered by reuse. This is why I have serious issues with using SEP to get all the way to Mars, and I still do. A suitable SEP tug in the order of 500KW to 1MW isn't going to cost $100M. Its going to cost many times more. And the development isn't going to be cheap either. But I think the technology can be gotten to the point where assembly is largely automated. So its in the right ballpark. And we're talking in the order of 6 months or so to raise a 50 tonne payload from Low Earth Orbit to High Earth Orbit. So reuse 20 times is a possibility. This is not the case for SEP to Mars involving years-long cycles will never see the investment returned. ... ...I recently posted on the MCT speculation thread the idea that SpaceX, who are considering SEP in their for their architecture, are also considering an all-propellant option. IMHO the reason for a non-SEP option would be to avoid the high development cost for SEP that you have pointed out. Have you ever considered an all-propellant option?One way that SpaceX could avoid SEP is by having the MCT cargo/tanker do double duty. In this scenario BFR is a stage one booster and MCT (both passenger or cargo versions) would be a second stage to reach LEO using their own propulsion units. A propellant depot in LEO would receive MCT tankers to accumulate fuel and oxidizer in the depot storage tanks.My idea was that one of the tankers could serve double-duty as a booster for a Mars-bound MCT. A fully-fuelred MCT would attach to a fully-fueled MCT-tanker at the LEO depot. The MCT-tanker would boost both units from LEO to HEO. After separation the Mars-bound MCT would then initiate the TMI burn for a fast transit to Mars and the tanker would return to depot or to Earth for propellant refill.Are there instances where vehicles in your architecture could serve double-duty in a non-SEP option?