Nicely done, nicely done. Reminds me a bit of the early DC-X flights, this link: http://www.youtube.com/watch?v=wv9n9Casp1o is DC-X flight #8 which I expect GrassHopper to do at some point as well (this was 1995 btw, imagine the computers they had on DC-X vs what they have on Grasshopper!)
Blue Origin is a bit ahead here in terms of take off and landing. But it has the challenge of not benefiting from a paid launch contract like SpaceX currently has.
What I find particularly interesting is that either the Dragon or the Blue Origin craft already have the delta-V to land an return to orbit from the moon, if they can get there. The thing that will break that wide open is on-orbit refueling. The game changes in a particularly compelling way when you can launch "gas cans" to orbit and refuel existing craft that are already in orbit. Not only does that extend the life of satellites but it enables Multi-launch configurations. United Launch Associates gave a pretty compelling talk about how they would meet some of those challenges in their long duration vehicle paper: http://www.ulalaunch.com/site/docs/publications/Integrated%2...
a little bird told me the air force is looking at contractors for on-orbit refueling as we speak.. so it's only 5+ years + all of the absurd delays that are inevitable away!!
Would on-orbit refueling work with cryo? I imagine the fuel/oxidizer would boil away too fast for that to work well, unless you sent everything up at once perhaps.
The ULA guys are talking about keeping cryo fuels in depots. They have some thoughts about hydrogen boil off (which they use in their internal combustion engine (H2 + O2) to both do station keeping and temperature management.
I have not seen proposals for on-orbit cryo fuel transfer. But I'm sure they are out there.
SpaceX's grasshopper is significantly larger than either the DC-X or Blue Origin's current test vehicle (it's a full-scale version of a Falcon 9 first stage). SpaceX has several different launch permits for grasshopper testing, right now they're operating under the first one, later they'll test at higher altitudes and with greater horizontal speeds.
It is a shame that NASA and congress didn't decide to go the DC-X scale up route back in the '90s instead of heading down the X-33/VentureStar rabbit hole.
Totally agree with this, both the DC-X comment and the size discrepancy. I have heard it argued that getting the avionics working and the throttle controlled engines are the 'hard' problems, once you get past that scaling is 'just engineering'. That any progress is being made is great.
Have they announced a timeline for actually implementing the grasshopper tech for real launch purposes?!
When that happens, spacex will have won the race to space. No other company would be able to match their launch price, given how high the cost of "disposable" rockets these days..
Not a timeline. However, there have been some reports recently that the first Falcon 9 v1.1 flight (currently scheduled for this June) will attempt to flip the first stage around after separation, relight one of its engines, and use it to slow down before landing on the ocean. IF this can be demonstrated successfully, it links up with the Grasshopper work very nicely. So, a more aggressive schedule than I would have expected just a few days ago.
Given that they already have thrust vectoring, isn't "grasshopper" basically just the software? IOW, this is a full "grasshopper" attempt for the first stage, and the only difference from ideal is that it will land on water.
Relighting / staging while the first stage motor is running at "idle" or something like that will be interesting.
For a relight, you need some propellant at the feed pipes to restart, though if you have small enough aero forces, you could just vent some stuff to accelerate the rocket forward slightly so you can start ingesting liquid again, instead of the pressurant gas and can then proceed with relight.
Then again, since the empty rocket's bottom end is heavy, it could orient itself the right way aerodynamically anyway (acceleration vector pointing the way of the nose) so the liquids go towards the engine end.
If it comes like a dart and not tumbling (which presents its own problems), such a big stage has lots of mass per frontal area and it will come in quite fast.
Interesting aerodynamic problems. I wonder if we might see some maneuverable mini fins or wings at some point.
You won't find a bigger supporter of SpaceX, and no one wants Grasshopper to be doing operational flights tomorrow more than I do. But it will take 10 years, minimum.
Keep in mind no one has successfully done powered vertical landing from orbit. It's never been done. (Well, not from Earth orbit anyway. The LEM landed vertically from lunar orbit.) SpaceX is getting a taste of how hard this is by trying to recover their first stages using parachutes - their every attempt to do so has failed.
If they could focus the bulk of their engineering workforce on this problem they might be able to do it faster. But they have to massively scale up production to meet the orders they've taken, they have to keep their reliability up, they are constantly working on performance upgrades for Falcon 9's engines, and they have to get Falcon Heavy going to crack the DoD market. Oh, and there's this little thing called Dragon and NASA's Commercial Crew program. Something about launching those living sacks of meat and bones we call people tends to hold your focus pretty intensely.
They don't have to do powered descent from orbit for this to be worthwhile. Just doing powered descent for the recovery of the first stage would be a huge win.
I'm sure they'll start with just the first stage, but you can't just do a powered descent - that would leave it in the middle of the Atlantic ocean. It has to be a return-to-launch-site maneuver and landing, which is what you see in the video linked to above. At the point where the vehicle does a 180-degree turn (referred to as a "death swoop" by rlv enthusiasts), it's going Mach 6 and is 1000 miles downrange. That's hard.
Bezos, or his handlers anyway, can be pretty outrageous with this kind of stuff. Water landings of VTVL's have been talked about since the 1960's by various people. It would be pretty ridiculous if he was granted the patent for it.
Not really. There are some savings, but they are not super-great. Plus, we do not yet know whether this works and if what the timeline is. This is hard!
What SpaceX is doing is totally awesome but – for the foreseeable future – a risky business.
> But a fully reusable rocket could change the equation dramatically. Musk illustrated the point by citing SpaceX's Falcon 9, which costs between $50 million to $60 million per launch in its current configuration.
> "But the cost of the fuel and oxygen and so forth is only about $200,000," Musk said."So obviously, if we can reuse the rocket, say, a thousand times, then that would make the capital cost of the rocket for launch only about $50,000."
The goal is to have a vehicle that can land on another planet and return to the surface of Earth in working condition with the only requirement as add fuel.
One hindering factor is the problem of having enough fuel to make the return trip.
There needs to be a better technology to harvest the massive amounts of energy wasted when decelerating from 30k mph to 1 thousand mph during re-entry. Convert the heat to a usable fuel. So we store the fuel needed for re-entry in the velocity of the craft.
A heat to fuel converter. If we could be 100% efficient at this, we would land with just as much fuel as we left to get into orbit.
> There needs to be a better technology to harvest the massive amounts of energy wasted when decelerating from 30k mph to 1 thousand mph during re-entry.
Or, in the case of of Mars, we can focus on in-situ resource utilization [1]. Zubrin's Mars Direct [2] is built around this, and there are some immense fuel savings to be had [3].
At least some Merlin engines have vectorable turbopump exhaust. That's used for roll control on Falcon 9 upper stages. Could imagine it working here, too.
Basically, a small amount of fuel and oxidizer are bled off into a gas generator and used to power the turbines that feed the fuel and oxidizer into the rocket engine.
Not to be missed is the fuel path of this (and other) liquid fuel rocket engine designs:
The cryogenic fuel is piped about the "outer surface" of the rocket's nozzle and combustion chamber such that these essential structures doesn't melt away under the pressure and heat.
I do find that a brave integration -- using fuel as a coolant.
Not an engineer in this field, but I'd imagine using fuel flow as coolant makes for a lighter-weight engine overall, even as it might complicate control system software, and might place narrower limits on, or complicate stability control of the engine's net available (throttable) range of power.
Just speculating here, but perhaps a single engine's power range limitation becomes another reason (along with graceful system degradation, without mission loss, under single engine loss) for SpaceX's multiple engine designs for their larger rockets? Switch off additional engines as rocket weight decreases (due to fuel and oxidizer usage) during descent? Doubtless there is a great difference in total mass between take-off weight and landing weight, so it would seem to require a lot less fuel & oxidizer to land it than to lift it to orbit.
Also wondering about ablative heat-shield placement and arrangement for re-entry, first and second stage.
I don't understand all your questions but here's some.
The fuel is used as coolant since it's a better coolant than the oxidizer for a range of reasons. One of them is that hot oxygen is very corrosive. Also, because of that a small oxygen leak from the coolant passage to the chamber tends to grow larger with catastrophic consequences. With kerosene the problem is coking.
Yes it's more complicated to design a regenerative cooled engine, but existing materials can't take the heat. Some maneuvering thrusters are heat sink designs. Some engines are ablative, with things like evaporating carbon taking the energy.
Yes it only needs one engine for landing vs nine for fully laden takeoff.
Blue Origin is a bit ahead here in terms of take off and landing. But it has the challenge of not benefiting from a paid launch contract like SpaceX currently has.
What I find particularly interesting is that either the Dragon or the Blue Origin craft already have the delta-V to land an return to orbit from the moon, if they can get there. The thing that will break that wide open is on-orbit refueling. The game changes in a particularly compelling way when you can launch "gas cans" to orbit and refuel existing craft that are already in orbit. Not only does that extend the life of satellites but it enables Multi-launch configurations. United Launch Associates gave a pretty compelling talk about how they would meet some of those challenges in their long duration vehicle paper: http://www.ulalaunch.com/site/docs/publications/Integrated%2...
Exciting times, 20 years late but still.