This is the only way we'll reach the stars
Look above ^
The Dragon space capsule built by SpaceX, the American private space company bankrolled and directed by famous PayPal nerdwealth tycoon Elon Musk, launched successfully from Cape Canaveral today. The Dragon capsule launches from Cape Canaveral atop a Falcon 9 rocket. Credit: NASA TV Don't need no NASA launch controller The …
Leave it to commercial enterprise to get it done; they see the riches in the asteroids, so they have the motivation. As much childhood nostalgia as I feel for NASA, they're an overburdened monolith these days and a relic of the 1970s, and the sheer size of the organisation as well as its political ties mean that it will only ever be able to move slowly, if at all. Corporations may be in it for the profit, but at this stage, I say as long as we get out there, who really cares? We can argue about the delicate science of it once we actually start reaching other planets and stars. Perhaps some sort of public-private partnership (that term used in the correct context!) to allow for scientific exploration while the corporations rape the asteroids for minerals.
...is being commercialized! Corporations in the Vacuum!! Yikes! Marx warned about this - or was it Philip K Dick? ...I disremember. He can only put boosters together (Musk, not Dick) so cheaply due to thousands of third world children hammering soup cans flat at 50 pence (.77 $) a day. The filthy CAPITALIST is probably even making a PROFIT !! Next thing you know he'll be mining asteroids!
Where's Lucky Starr when you need him? (If you don't get that one then you're too damn young - go find your pacifier.)
Will the Ceres Titanium Mine pay taxes to the merikan gummint? Will it hell!
But the socio-economic impact of this, much less the impending carbon footprint, cannot be adequately evaluated until ManFromMars checks in.
The fact that both stages use the same propellants offers a *very* interesting possibility if there is a failure in some stages of the flight, provided the design is suitably equipped.
Prior to 2nd stage separation a series of tests is run on the 2nd stage. If any of them fails the system attempts to protect the payload.
1)Stage 1 throttles down to a minimum to conserve fuel
2)Propellant is routed from Stage 2 tanks into stage 1 to continue feeding the stage 1 engines
Eventually Stage 1 thrust (even at its lowest setting) exceeds thrust. At this point the stage 1 engines are shut down and the remaining propellants exhausted.
Provided everything works out the Falcon acts as the mother of all crumple zones. Close to the final crash Dragon could fire its thrusters as an escape engine or continue to ride it down *without* separation and without firing its main engine (both separation and main engine *have* to work in this maneuver and would be very difficult to test on the day)
Scary as hell to experience but the payload (cargo or passengers) lives to launch another day.
I also welcome this development. Congratulations to all at SpaceX. Let us hope OSC starts to move towards an actual launch as well.
There's so much wrong with that scenario I hardly know where to start.
Firstly: At stage speraration, the vehicle is flying nearly horizontally at about mach 6 and has next to no fuel left so there's little scope for throttling down.
Secondly: There's no fuel lines going between the two stages and any attempts to add them in would add a lot of complexity and weight to the vehicle and would requre massive re-design work to allow for the knock-on effects of those additions.
Thirdly: Even if there were fuel lines connecting the two stages, how do you propose that a rocket going horizontally at mach 6 (almost certainly over the ocean as well) turns its arse around to face the gound and slows itself down to a nice guided landing?
My original post was a *very* brief summary of a longer post made some time ago on another thread. This version gave just the outlines of the suggestion.
*suitably* equipped means "modified", as in not the design as it exists now but with some *relatively* minor modifications (with most of the heavier bits on the first stage. On the 2nd stage 1Kg of extra mass nearly equals a 1Kg *loss* of payload. On 1st stages it's something like removing 16Kg to get 1Kg of payload increase. You're already running control signals into the inter-stage area anyway. How heavy can a couple of low pressure valves (<3bar gauge IIRC 1 cryogenic) and some equally low pressure piping be?
"Firstly: At stage separation, the vehicle is flying nearly horizontally"
I'd hope so.
" at about mach 6"
AFAIK most 2 stage liquid fuel launchers split the delta v *evenly* between the 2 stages. it should be at least M11 to M12.
" and has next to no fuel left so there's little scope for throttling down."
I think you're confusing fuel left and the ability to to *slow* down or the ability to *throttle* down. That's a feature of the engine design. The Falcon 1st stage Merlin engines don't seem to throttle but the 2nd stage vacuum ones can do so down to 60%. shutting down, suggesting its an engine mod (I'd suspect SpaceX can turn a Merlin vacuum engine back to a 1st stage engine *almost* as quickly.
"how do you propose that a rocket going horizontally at mach 6 (almost certainly over the ocean as well) turns its arse around to face the ground"
The same way it got into that attitude in the first place. Using thrust vectoring. It was *always* doubtful you could kill the horizontal velocity it had built up. In my original post the fallback plan was to rotate it so the engines would forward on the axis of travel. It's a 3 point turn in space or a long jumper shifting from body first to legs first for the landing depending on what analogy you prefer. When even the *lowest* thrust level exceeds the total rocket mass its time to shut off the engines and continue to let the tanks drain. BTW probably the *hairiest* moment will be at the top of the 3 point turn which I estimate will be the point of maximum risk of starvation of propellant tot he engines.
" and slows itself down to a nice guided landing?"
This is *not* a landing. It's an *abort*. I guess the phrase "mother of all crumple zones" was not specific enough. It's a controlled crash.
I fully expect the *whole* of the 2 stages to concertina (remarkably evenly if they do so like the nose down crash test that Armadillo Aerospace did of their capsule some time back), absorbing the *massive* kinetic energy of the vehicle. The Falcon is a *total* write off. But the payload, IE the load that *pays* is unharmed and can be prepared for a 2nd launch, although any humans will *probably* need some new suit liners. The phrase "Express elevator to Hell, going down" would sum up my view of it pretty well.
You may still be unclear why I proposed this.
SpaceX have talked about using their main capsule motor in a special escape mode in the event of failure (otherwise it serves like the main engine on the Apollo service module) but a serious failure puts the reliability of *all* components on a vehicle that are not *already* running in doubt, like the main motor and the separation explosive bolts and the parachute deployment.
This idea only uses components that are either *already* running (admittedly in a complex and novel way), components that can be tested *repeatedly* before flight (latching solenoid rather than explosive actuated valves for example) and the physics of the operating vehicle itself.
Customers don't *give* a stuff how their payload gets *into* orbit. Only that it gets to the *right* orbit on *time*.
A provider who could say "We didn't put your payload up, but we did not destroy it and it's in good enough condition to launch at the next window" would have a *significant* advantage over one who said "Hey its a rocket, y'know. The best ones got a 1 in 50 chance of failing anyway. Better luck next time. Come see us again when the insurance coughs up or you got some more money."
Just to be clear this would not even be *tried* without massive CFD and FEA simulation.
Yes intact abort on a rocket *sounds* insane, but nothing I know absolutely *forbids* it from working, either on Falcon or any other launcher with common fueled stages (which lets out Ariane and IIRC the Indian designs but might still include some of the FSU types).
I'll try and address most of your counter points in order. You say the modifications for interstage pipework would be minor. Have you considered the fact that the pipework would have to run on the outside of the vehicle as the engine gets in the way of having the pipes run inboard? Have you considered what effect this would have on the vehicles centre of mass or aerodynamic profile? How would you sort out pumping fuel from one tank to the other once the pressure between the first and second stage tanks equalizes? How do make sure all tanks are fully purged of fuel before impact? (you'd better hope they are or you'll have a very large explosion) What effect are these changes going to have on the structural integrity of the tank and the vehicle as a whole?
Still think these are minor changes?
You say the stack would be going at mach 12 rather than mach 6. I've tried looking this up without much success so I'll assume you're correct on this one. Either way it's still going chuffing fast, horizontally. Any significant manouveres like this 3 point turn you talk about are going to subject the vehicle to lateral stresses it was not designed to stand up to. Rockets are built to be as light as possible remember.
Even if it could do this, it's still moving in the same direction at the same speed, just now pointing the wrong way. How do you control a rocket pointing arse first? Your aerodynamic profile is all different, the main engines and any manouvering thrusters are all pointing the wrong way, aerodynamic heating becomes are real problem as it decends back through the atmosphere (even at mach 6, let alone mach 12) and any shielding on the vehicle is at the front and now pointed the wrong way. These are not simple problems to solve.
I know I refered to this arrangement as a guided landing rather than an abort but the important word there was "guided". You rocket is over the sea remember? How do you propose to get it back over land? Even if you manage that, how do you get it to land upright and concertina neatly as you describe without some very precise control of speed and direction. All with empty fuel tanks?
My point is not to suggest that these problems are insurmountable, only to highlight issues that going by the content of your previous posts, you appear not to have considered and also to point out that the design changes required to address all these problems would not be "minor" but would actually result in a radically different vehicle from the one that launched to other day.
Let me remind you of my second to last paragraph.
"Just to be clear this would not even be *tried* without massive CFD and FEA simulation."
Which would include aerodynamic and pressure loads along with propellant slosh and mass property changes throughout the flight.
I'll also remind you of my use of the "relatively" as in compared to building a new design.
"Have you considered the fact that the pipework would have to run on the outside of the vehicle as the engine gets in the way of having the pipes run inboard? "
I'm very aware of the effect quite small ducts on the outside of a vehicle (specifically the Saturn V stack) can have on airflow and buffeting.
"How would you sort out pumping fuel from one tank to the other once the pressure between the first and second stage tanks equalizes? "
Pumps are another component to fail. Both propellants exert substantial head even at one g (col height x density x gravity force). Under acceleration they will exert rather more. The problem would be to bleed off enough 1st stage tank pressure to let the 2nd stage fluids in while keeping up 2nd stage tank pressure. The 2 propellant pipes coming down would be matched by the 2 pressurization pipes going up to expel contents from stage 2 to stage 1.
"How do make sure all tanks are fully purged of fuel before impact?"
Depends what's done at present. LOX tanks are problematical as they are pressurized by warmed O2. Ideally I'd like to vent the LOX tanks on engine shut down and purge them out to atmosphere before impact while maintaining enough differential pressure for structural integrity. Note with the base slowing faster than the body there should still be enough pressure head to keep emptying the tanks.
The safe option (IE it's working *already* on S1 when a situation needing payload protection arises) is to increase the size of the fuel pressurisation system to cope with *all* tanks. Once again a Kg of stuff on S1 is roughly a 0.1Kg loss of payload on S2. Note at this point we're looking at roughly 2 heavy lumps linked by a set of tubes kept stiff by their differental pressure wrt to the outside air.
"Any significant manouveres like this 3 point turn you talk about are going to subject the vehicle to lateral stresses it was not designed to stand up to."
Like pretty much every other launch vehicle Falcon goes from Vertical takeoff to horizontal flight by pivoting its engines. It's a gradual process. the abort mode would reverse this process and then aim to mitigate some of the horizontal velocity it's built up through using up some (ideally all) of the remaining propellant. Simulation would be needed to find out how far over in reverse you could push it and how much velocity could be canceled. As for stresses high altitude winds can top 90Knots around the Cape
"Even if it could do this, it's still moving in the same direction at the same speed, just now pointing the wrong way. How do you control a rocket pointing arse first?"
Providing it's still firing pretty much the same way. The point of this is to kill as much as possible of its horizontal velocity.
" Your aerodynamic profile is all different, "
Quite true. A large part of it is in fact being generated by the exhaust plume of the Merlin engines
"the main engines and any manouvering thrusters are all pointing the wrong way,"
The main engines are pointed in *exactly* the direction needed to counter velocity. The draco thrusters *may* be usable as they are around the circumference of the capsule (but I'm not sure if they shrouded during launch).
aerodynamic heating becomes are real problem as it decends back through the atmosphere (even at mach 6, let alone mach 12) and any shielding on the vehicle is at the front and now pointed the wrong way. These are not simple problems to solve.
Depends on when and at what altitude you start the turn and the turn rate. Separating 2 vehicles at M12 is routine (for rocket stages) but AFAIK the last time it was tried with an aircraft was during the SR71/D21 drone tests. Aircraft crashed, 1 crew dead, 1 severely injured (not sure if he died later). Outside air pressure makes a hell of a difference to how serious this is.
"You rocket is over the sea remember? How do you propose to get it back over land? "
That's another assumption on your part. The objective is to protect the payload. Depending on where on the launch trajectory the abort happens (which would depend on what orbit the payload is being delivered to) it would either go down in the sea or look to get some cross range nearer to a land site. As the location this would happen at (the pre separation S2 test sequence would happen at a known point of flight leading to a known point when the process would start) it would be possible to make backup recovery arrangements.
"Even if you manage that, how do you get it to land upright"
A presumption you keep on making. sure I'd *love* it to be Thunderbird 1 returning to base. Not going to happen. The bulk of the velocity is at or near the horizontal. Dissipating that is the *whole* point of this maneuver.
"and concertina neatly as you describe "
I'm a realist. If it crumpled enough to dissipate all kinetic energy to leave the capsule at rest with no one on board more than a bit shook up I'd be ecstatic.
"without some very precise control of speed and direction."
Speed at this point is going to be over a range resulting in completely crumpled on both stages to mostly crumpled on S1, bit dented on S2 etc.
I think you're referring attitude, which is what direction the vehicle is pointing in locally. Unless some attempt has been made to shift the track to land this process does not change the
direction the vehicle was moving at all. The objective is protect the payload by *canceling* (as much as possible) the vehicles *desire* to move in that direction.
"All with empty fuel tanks?"
Capsule landings have been surprisingly accurate. For a vehicle which stops maneuvering at around 190 000 ft and which is then dragged wherever there parachutes took them the Gemini series managed to go down to 0.9nm. Gemini's actual lift/drag ratio was IIRC about 0.25 (rubbish by aircraft standards). Steering a whole stack would be challenging.
No one has AFAIK ever tried intact abort on a TSTO. Perhaps it does present too many problems to do without *radical* re-design of the vehicle. But the new generation of common propellant TSTO's suggested that it might be worth a go and I believe making it work would give the first company to do so a *significant* business advantage.
I'm not a professional rocket engineer and would not describe myself as anything but an interested amateur, although I have met a few who do it for a living. The suggestion was an extrapolation of what I feel *should* be possible (note that 2nd to last paragraph again).
Thank you for your observations and opinions. It is always good to hear another PoV.
Apparently it's splashed down right on target, and supposedly 100% success, according to SpaceX & NASA-TV.
And what competitors? I don't see anybody else that's flown anything other than some powerpoint slides. Orbital are the only ones I see being anywhere close to bending metal.
Let's hear it for the first successful commercial spacecraft re-entry!
If you include competitors who would contract for NASA if asked, but not a comercial objective: 1)Roscosmos' Progress 2) ESA's ATV 3)JAXA's HTV
Then the commercial: 4) SpaceX's Dragon
Three of those have already been to the ISS. SpaceX is still a long way off, but it is closing fast.
"If you include competitors who would contract for NASA if asked, but not a comercial objective: 1)Roscosmos' Progress 2) ESA's ATV 3)JAXA's HTV"
Quite true. But you miss the objective of the Commercial Orbital Transportation Services contract and its follow on planed contract for crewed transfer.
A local capsule
on a local launcher
made by local people
for launching local payloads
Mine will be the one with "Royston Vaizey. Locals welcome"
"And what competitors? I don't see anybody else that's flown anything other than some powerpoint slides. Orbital are the only ones I see being anywhere close to bending metal."
Orbital did get the remainder of the cash (c$190m IIRC) when the Rocketplane-Kistler bid failed to secure external funding. They are the other official entry for the COTS programme (SpaceX is not a hobby shop. It's in it for the money).
However OSC they are now asking for $312m for a "risk reduction" flight on top of their current fudning. IIRC the Spacex award was c$250m total. But then by then they had launched 4 Falcon 1's and 1 had already made orbit.
OSC have updated their web site (check elreg for a link) but they are still a long way from even first launch. However they have poured a *lot* of concrete.