I would love to see a solid costing of the cost of a SEP spacecraft. Leaving aside the launch costs, just the spacecraft. If it comes down to a few tens of millions and it can automatically deployed I might have a use for one. But if its hundreds of millions or more.. then.. What did the JPL people think the actual spacecraft would cost? And how were they proposing to have it automatically deploy?
I would also like to see people come up with a 'minimal space junk' mission. And yes Im only half joking.
But if its hundreds of millions or more.. then..
But as soon as your using SEP and your returning vehicle is not being destroyed but rather capturing to high Earth orbit the logic of sending a FRESH retrieval capsule up from Earth is inescapable.
Overall I find the mixing of SEP and Chem in this architecture to be very poor, the SEP is underpowered as it reflects zero improvement on ARM which is ridiculously conservative. The Chem stages don't make use of oberth effects and are big and bulky. This proposal is almost Zubrin like in it's rejection of tech development, even the technologies already under development by NASA right now like HIAD. Did their sand charts assume NASA's tech development budget gets zeroed out and all the money dumped into their program?
Lastly the presenters make the absurd claim that "by being specific with out plan our international partners can see themselves IN the plan and will come on board", which would makes sense if your specifics weren't composed of ALL AMERICAN VEHICLES. After taking out the sole launch vehicle SLS, Orion, and ARM derived SEP theirs not much left for anyone else to do. The habitat module is the only part I could see ESA or Roscosmos doing, the chemical kick-stages are grunt-work that no ones would be interested in. Lastly the landers, everyone knows JPL would produce that, they have ALL the Mars EDL experience and this is unequivocally the most dangerous part of the mission. None of our partners would want the PR risk that would entail. Lastly the crew size of 4 is too small to include enough international astronauts to make the mission attractive, no nation will contribute if their nationals don't get a ticket, on the FIRST flight.
Well if you look at some of these elements as placeholders then things change a bit.For example ESA's work on 4 grid staged ion thrusters indicates a 250Kw thruster as small as 20cm in diameter could be possible with bother efficiency and lower beam divergence than current designs. http://www.esa.int/gsp/ACT/pro/projects/ds4g_overview.html
But the point I keep trying to make is that if $500 million buys you one SEP or instead lofts 500 tonnes of chemical booster, which do you think is more usefull?
But using (and keeping an Orion is a minimal risk design.No 2nd capsule needed. No rendezvous in HEO. No (probable) new capsule design.
Well if you look at some of these elements as placeholders then things change a bit.For example ESA's work on 4 grid staged ion thrusters indicates a 250Kw thruster as small as 20cm in diameter could be possible with bother efficiency and lower beam divergence than current designs. http://www.esa.int/gsp/ACT/pro/projects/ds4g_overview.htmlLikewise ESA is already supply the Orion service module. A 4 person crew should be enough to make at least member a European. However to do so the authors are correct that you have to be specific about what the US would be looking for from its partners. IE the shape, size and mass of the "hole" in the architecture that needs filling. That way the partner does not get stuck with effectively an unlimited commitment to make their systems fit a moving target.
The mission author only 'gaps' are complete non-starters for any other allied space-programs.A crew of 4 gets used up real fast when you try to include Japan and Canada.
Quote from: Russel on 07/06/2015 10:27 pmBut the point I keep trying to make is that if $500 million buys you one SEP or instead lofts 500 tonnes of chemical booster, which do you think is more usefull?WAAA??? First off chemical booster stages are not FREE they have a cost to manufacture as well even if the propellent in them is cheap, second what is this awesome $1000 per kg launch vehicle, it sure ain't SLS.
Quote from: Impaler on 07/06/2015 11:46 pmQuote from: Russel on 07/06/2015 10:27 pmBut the point I keep trying to make is that if $500 million buys you one SEP or instead lofts 500 tonnes of chemical booster, which do you think is more usefull?WAAA??? First off chemical booster stages are not FREE they have a cost to manufacture as well even if the propellent in them is cheap, second what is this awesome $1000 per kg launch vehicle, it sure ain't SLS.What is a chemical upper stage but a tin can with a modest engine strapped on. We're talking a few million dollars worth.The awesome $1000/Kg is where SpaceX is heading and will probably reach it or get close. Yes it sure aint SLS.Now given that's going to become reality, or something somewhere close to it, I'll ask again. A single SEP, or hundreds of tonnes of loaded chemical boosters.Choose.
1) What is a chemical upper stage but a tin can with a modest engine strapped on. We're talking a few million dollars worth.2) The awesome $1000/Kg is where SpaceX is heading and will probably reach it or get close. Yes it sure aint SLS.3) Now given that's going to become reality, or something somewhere close to it, I'll ask again. A single SEP, or hundreds of tonnes of loaded chemical boosters.Choose.
The awesome $1000/Kg is where SpaceX is heading and will probably reach it or get close. Yes it sure aint SLS.
Quote from: Russel on 07/07/2015 02:10 pm1) What is a chemical upper stage but a tin can with a modest engine strapped on. We're talking a few million dollars worth.2) The awesome $1000/Kg is where SpaceX is heading and will probably reach it or get close. Yes it sure aint SLS.3) Now given that's going to become reality, or something somewhere close to it, I'll ask again. A single SEP, or hundreds of tonnes of loaded chemical boosters.Choose.1) What the heck kind of upper stage are you talking about?2) Where SpaceX is heading. IMO this $1000/kg is a long way off. SpaceX is currently at ~$4700/kg with Falcon 9. They expect to be at $2200/kg with Falcon Heavy with an annual flight rate of four Falcon Heavy launches a year. Nearly halving that to $1000/kg is going to take a lot of effort, luck, money, time, and probably all of those combined. QuoteThe awesome $1000/Kg is where SpaceX is heading and will probably reach it or get close. Yes it sure aint SLS."Where SpaceX is trying to head"3) Given that's going to become a reality? Is there something you know that I don't?BTW, I totally agree with you that chemical stages should be used instead of SEP. I just think your reasoning for supporting chemical stages over SEP is flawed.