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SpaceX’s Autonomous ‘Grasshopper’ Rocket Makes Milestone Flight

75 points by sk2code 14y ago

andrewflnr 14y ago
Does anyone know what the little vent/flare thing is on the side of the engine?
- lavezza 14y ago
  It is the exhaust of the gas generator. You can see a good view of it here: http://www.spacex.com/press.php?page=37 http://www.spacex.com/press.php?page=37 You can read about the Gas-Generator Cycle for rockets here: http://en.wikipedia.org/wiki/Gas-generator_cycle_%28rocket%29 http://en.wikipedia.org/wiki/Gas-generator_cycle_%28rocket%2... 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.
  - EEGuy 14y ago
    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.
    - Gravityloss 14y ago
      Actually, they use the kerosene for cooling, not the oxygen.
      - EEGuy 14y ago
        Thank you Gravityloss for your correction. 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.
        Gravityloss 14y ago
        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.
jacques_chester 14y ago
Reminds me of the Armadillo Aerospace designs -- relying on fast dynamic control systems instead of more "stable" rocket configurations.
- deleted 14y ago
  [deleted]
ChuckMcM 14y ago
Nicely done, nicely done. Reminds me a bit of the early DC-X flights, this link: http://www.youtube.com/watch?v=wv9n9Casp1o 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%20Vehicle%20Propulsion%20and%20Power%20System%20for%20Long%20Duration%20Cyrogenic%20Spaceflight%202011.pdf http://www.ulalaunch.com/site/docs/publications/Integrated%2... Exciting times, 20 years late but still.
- terramars 14y ago
  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!!
- InclinedPlane 14y ago
  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.
  - ChuckMcM 14y ago
purplelobster 14y ago
I didn't see the mannequin at first, but that gives a good sense of scale. Does it keep balanced with some sort of thrusters? I can't see any.
- flyt 14y ago
  The center engine is on a gimbal.
ricw 14y ago
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..
- adastra 14y ago
  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.
  - simonh 14y ago
    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.
    - adastra 14y ago
      The first stage isn't going at orbital velocity of course, but the second stage is. The SpaceX announcement for Grasshopper refers to both: http://www.space.com/13140-spacex-private-reusable-rocket-elon-musk.html http://www.space.com/13140-spacex-private-reusable-rocket-el... 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.
otibom 14y ago
Can someone explain how they control for roll ?
- dasmoth 14y ago
  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.
Shivetya 14y ago
Is it worthwhile to get more back than just the motor assembly? As in, is the tank structure really worth saving?
- maeon3 14y ago
  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.
  - homeomorphic 14y ago
    > 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]. [1] https://en.wikipedia.org/wiki/In-situ_resource_utilization https://en.wikipedia.org/wiki/In-situ_resource_utilization [2] https://en.wikipedia.org/wiki/Mars_Direct https://en.wikipedia.org/wiki/Mars_Direct [3] Zubrin, Robert. The case for Mars. Free Press, 1996.
- gus_massa 14y ago
  Extracted from a comment of <someperson>: https://news.ycombinator.com/item?id=4752611 https://news.ycombinator.com/item?id=4752611 > 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." Direct link: http://www.space.com/13140-spacex-private-reusable-rocket-elon-musk.html http://www.space.com/13140-spacex-private-reusable-rocket-el...

75 points by sk2code 14y ago

andrewflnr 14y ago

Does anyone know what the little vent/flare thing is on the side of the engine?

lavezza 14y ago
It is the exhaust of the gas generator. You can see a good view of it here: http://www.spacex.com/press.php?page=37 http://www.spacex.com/press.php?page=37 You can read about the Gas-Generator Cycle for rockets here: http://en.wikipedia.org/wiki/Gas-generator_cycle_%28rocket%29 http://en.wikipedia.org/wiki/Gas-generator_cycle_%28rocket%2... 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.
- EEGuy 14y ago
  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.
  - Gravityloss 14y ago
    Actually, they use the kerosene for cooling, not the oxygen.
    - EEGuy 14y ago
      Thank you Gravityloss for your correction. 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.
      - Gravityloss 14y ago
        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.

jacques_chester 14y ago

Reminds me of the Armadillo Aerospace designs -- relying on fast dynamic control systems instead of more "stable" rocket configurations.

deleted 14y ago
[deleted]

ChuckMcM 14y ago

Nicely done, nicely done. Reminds me a bit of the early DC-X flights, this link: http://www.youtube.com/watch?v=wv9n9Casp1o 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%20Vehicle%20Propulsion%20and%20Power%20System%20for%20Long%20Duration%20Cyrogenic%20Spaceflight%202011.pdf http://www.ulalaunch.com/site/docs/publications/Integrated%2... Exciting times, 20 years late but still.

terramars 14y ago
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!!
InclinedPlane 14y ago
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.
- ChuckMcM 14y ago

purplelobster 14y ago

I didn't see the mannequin at first, but that gives a good sense of scale. Does it keep balanced with some sort of thrusters? I can't see any.

flyt 14y ago
The center engine is on a gimbal.

ricw 14y ago

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..

adastra 14y ago
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.
- simonh 14y ago
  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.
  - adastra 14y ago
    The first stage isn't going at orbital velocity of course, but the second stage is. The SpaceX announcement for Grasshopper refers to both: http://www.space.com/13140-spacex-private-reusable-rocket-elon-musk.html http://www.space.com/13140-spacex-private-reusable-rocket-el... 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.

otibom 14y ago

Can someone explain how they control for roll ?

dasmoth 14y ago
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.

Shivetya 14y ago

Is it worthwhile to get more back than just the motor assembly? As in, is the tank structure really worth saving?

maeon3 14y ago
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.
- homeomorphic 14y ago
  > 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]. [1] https://en.wikipedia.org/wiki/In-situ_resource_utilization https://en.wikipedia.org/wiki/In-situ_resource_utilization [2] https://en.wikipedia.org/wiki/Mars_Direct https://en.wikipedia.org/wiki/Mars_Direct [3] Zubrin, Robert. The case for Mars. Free Press, 1996.
gus_massa 14y ago
Extracted from a comment of <someperson>: https://news.ycombinator.com/item?id=4752611 https://news.ycombinator.com/item?id=4752611 > 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." Direct link: http://www.space.com/13140-spacex-private-reusable-rocket-elon-musk.html http://www.space.com/13140-spacex-private-reusable-rocket-el...