Quote from: MikeAtkinson on 01/21/2015 07:59 pmThird requirement is there are not other better things that the SpaceX engineers can be working on. That is the opportunity cost.I'd say this is it. SpaceX will move as quick as they can to achieve the ultimate goal ("enabling people to live on other planets") given the human resources they have while making just enough money to cover the expenses.
Third requirement is there are not other better things that the SpaceX engineers can be working on. That is the opportunity cost.
In your recent MIT talk, you mentioned that you didn't think 2nd stage recovery was possible for the Falcon 9. This is due to low fuel efficiency of kerosene fuel, and the high velocities needed for many payloads (high orbits like Geostationary orbit). However, you also said that full reusability would be possible for the Mars Colonial Transporter launch vehicle.What have you learned from flights of Falcon 9 that taught youa) that reuse of its second stage won't be possible; andb) what you'll need to do differently with MCT to reuse its second stage.
Actually, we could make the 2nd stage of Falcon reusable and still have significant payload on Falcon Heavy, but I think our engineering resources are better spent moving on to the Mars system.MCT will have meaningfully higher specific impulse engines: 380 vs 345 vac Isp. For those unfamiliar, in the rocket world, that is a super gigantic difference for stages of roughly equivalent mass ratio (mass full to mass empty).
Quote from: jzjzjzj on 01/21/2015 10:43 pmQuote from: MikeAtkinson on 01/21/2015 07:59 pmThird requirement is there are not other better things that the SpaceX engineers can be working on. That is the opportunity cost.I'd say this is it. SpaceX will move as quick as they can to achieve the ultimate goal ("enabling people to live on other planets") given the human resources they have while making just enough money to cover the expenses.If I were on the board of SpaceX and they were trying to only make just enough money to cover expenses while going after another goal, I'd vote to fire management. The first goal is to make as much as possible doing everything they are doing. If any activity isn't to ultimately be as profitable as possible in their line of business, the shouldn't be doing it. That's business 101. The ultimate goal of any business is to make money. If they are going to enable people to live on other planets they'd better make money at it and each step of the way or they won't get too far.
Quote from: /u/ElonMuskOfficial[..] I think our engineering resources are better spent moving on to the Mars system.
[..] I think our engineering resources are better spent moving on to the Mars system.
So for now focusing on the Falcon US for reuse would actually take them away from a means to increasing their profits. ( They don't have tunnel vision , focusing on just one thing. )
The only way I see it happening is if some major demand shows up for LEO. It would be easiest to get an second stage that only does LEO and not GEO.
2) What technology would be needed to enable cost-effective reuse?
Elon Musk has stated that F9 second stage reusability was not expected -- but with qualifiers that GTO/high energy orbits were too challenging.
I don't expect the Falcon 9 to have a reusable upper stage, just because the - with a kerosene-based system, the specific impulse isn't really high enough to do that, and a lot of the missions we do for commercial satellite deployment are geostationary missions. So, we're really going very far out. These are high delta-velocity missions, so to try to get something back from that is really difficult. But, with the next generation of vehicles...
These are F9/FH questions and not about the MCT.
So the two questions are:1) What would justify reconsideration of the expendible second F9 stage 'decision'?2) What technology would be needed to enable cost-effective reuse?
My perspective:QuoteA reusable second stage that returns the fairing and dispenser would make lots of sense when there are so many identical launches. The fairing could open on one side as done on STS, or hinge back fully and then re-close. Expendible fairings, dispensers, second stages launched week after week will be prohibitively expensive -- and the fuel to de-orbit all of this hardware (with the exception of the fairing as currently used) will need to be in the mass budget anyway.Note: This same argument could be made for a reusable tanker second stage...
A reusable second stage that returns the fairing and dispenser would make lots of sense when there are so many identical launches. The fairing could open on one side as done on STS, or hinge back fully and then re-close. Expendible fairings, dispensers, second stages launched week after week will be prohibitively expensive -- and the fuel to de-orbit all of this hardware (with the exception of the fairing as currently used) will need to be in the mass budget anyway.Note: This same argument could be made for a reusable tanker second stage...
From Elon's reddit AMA:Quote from: /u/MarsColony_in10years In your recent MIT talk, you mentioned that you didn't think 2nd stage recovery was possible for the Falcon 9. This is due to low fuel efficiency of kerosene fuel, and the high velocities needed for many payloads (high orbits like Geostationary orbit). However, you also said that full reusability would be possible for the Mars Colonial Transporter launch vehicle.What have you learned from flights of Falcon 9 that taught youa) that reuse of its second stage won't be possible; andb) what you'll need to do differently with MCT to reuse its second stage.Quote from: /u/ElonMuskOfficialActually, we could make the 2nd stage of Falcon reusable and still have significant payload on Falcon Heavy, but I think our engineering resources are better spent moving on to the Mars system.MCT will have meaningfully higher specific impulse engines: 380 vs 345 vac Isp. For those unfamiliar, in the rocket world, that is a super gigantic difference for stages of roughly equivalent mass ratio (mass full to mass empty).
Is there any way to flip the question around? Instead of asking how to recover 100 M1DVacs from orbit, ask what could be done with 100 M1DVacs that are already in orbit?
If I were on the board of SpaceX and they were trying to only make just enough money to cover expenses while going after another goal, I'd vote to fire management. The first goal is to make as much as possible doing everything they are doing. If any activity isn't to ultimately be as profitable as possible in their line of business, the shouldn't be doing it. That's business 101. The ultimate goal of any business is to make money. If they are going to enable people to live on other planets they'd better make money at it and each step of the way or they won't get too far.
Quote from: AJW on 01/22/2015 04:35 pmIs there any way to flip the question around? Instead of asking how to recover 100 M1DVacs from orbit, ask what could be done with 100 M1DVacs that are already in orbit?100 times the orbital debris problem you had BEFORE you launched (and then kept) all that "junk" in orbit? Seriously, without an on-orbit infrastructure to "salvage" and repurpose the "resources" then it IS simply "junk" and having the stuff up there does no good. You'd still need to recover, recycle/refurbish the equipment "up-there" in order to use it and you also STILL have the problem of kerolox propellant not being all that efficent to use in the first place.Elon mentiones orbital propellant depots, but seems focused more on "Mars-Direct" type operations than orbital assembly, space docks and building up the kind of infrastructure and opertations that would use ONE M1DVac let alone 100 Randy
Quote from: RanulfC on 01/22/2015 05:55 pmQuote from: AJW on 01/22/2015 04:35 pmIs there any way to flip the question around? Instead of asking how to recover 100 M1DVacs from orbit, ask what could be done with 100 M1DVacs that are already in orbit?100 times the orbital debris problem you had BEFORE you launched (and then kept) all that "junk" in orbit? Seriously, without an on-orbit infrastructure to "salvage" and repurpose the "resources" then it IS simply "junk" and having the stuff up there does no good. You'd still need to recover, recycle/refurbish the equipment "up-there" in order to use it and you also STILL have the problem of kerolox propellant not being all that efficent to use in the first place.Elon mentiones orbital propellant depots, but seems focused more on "Mars-Direct" type operations than orbital assembly, space docks and building up the kind of infrastructure and opertations that would use ONE M1DVac let alone 100 RandyClearly there's a market for tugs that can harvest all that junk from wherever it may be and collect it in one place for safe keeping. Or in one place... for feeding into the maws of an on-orbit recycler. Not this year. Not this decade. But someday.
I'm glad you're not on the board, I guess. The maximum profit for SpaceX **over the lifetime of the company** is not necessarily given by the same strategy that gives the maximum profit **this quarter** .... I think Elon is playing a long game. If SpaceX is a dominant player in a transport market that sees thousands or even hundreds of thousands millions of metric tonnes moving between Earth and Mars, that is going to be huge. Far more profit than we can dream of. If you also include being a dominant solar system ISP, and a dominant mars surface transport provider, and a dominant supplier of refined raw materials on mars.... the mind boggles. Musk could be the worlds first trillionaire.As long as they make enough money to keep the wheels turning, they're fine. Maximizing profit NOW is ... not the silicon valley way. That's OldSpace thinking.Rant over.
Rant over.
Quote from: pathfinder_01 on 01/22/2015 04:45 amThe only way I see it happening is if some major demand shows up for LEO. It would be easiest to get an second stage that only does LEO and not GEO.Isn't a 4025 short-lived satellite constellation a 'major demand?'
Quote from: AncientU on 01/22/2015 03:18 pmQuote from: pathfinder_01 on 01/22/2015 04:45 amThe only way I see it happening is if some major demand shows up for LEO. It would be easiest to get an second stage that only does LEO and not GEO.Isn't a 4025 short-lived satellite constellation a 'major demand?'Depends on how many launches that is. They are planned to be small satellites. If they are they could tag along on other flights of disposable 2nd stages.