SpaceX Soft Lands Falcon 9 Rocket First Stage
spacex.com
spacex.com
That "solid surface" will presumably be a barge. Very exciting stuff.
Edit: The "loss of hull integrity" also answers a common question of "why not use parachutes". Even if they could land the stage softly enough with a reasonable amount of parachutes, the stage has trouble surviving tipping over in the ocean after landing. It needs to land and remain upright, but using parachutes you will often get some lateral velocity that would cause a tip-over. They need more control than parachutes can provide (and that's all ignoring the problems of salt water).
I get nerd chills from the level of precision needed to bring a launch vehicle from hypersonic->subsonic speeds to a target that size, and land to reuse the vehicle.
http://www.boschrexroth-us.com/country_units/america/united_...
It's used at sea for winches, but I'm sure platforms can compensate just as well with the proper force actuators and motion reference units.
Another is to use a semi-submersible rig. What that means is that you fill the bottom half or 2/3 of the vessel with water making it much heavier. That changes the way it rides in the waves and can dampen the effects that a wave has substantially.
http://en.wikipedia.org/wiki/Semi-submersible
Oil rigs are really only for drilling, not for getting the oil out of the ground and into whatever container there is. So that means they move around all the time. Like every couple of weeks.
What you're thinking of is called a jack up rig. They go in water up to a few hundred feet deep. Nothing over 1000 feet for sure. That's because the entire truss has to come out of the water when the barge is being moved from one location to the other.
They get very little wave loading due to having semi-submersible hulls, much like an oil rig.
My typical answer to this is to mention Mars and the very thin atmosphere. There's no point in SpaceX developing technology that they can't use on Mars.
I'm wondering why the next water landing has a low probability of success?
> However, our next couple launches are for very high velocity geostationary satellite missions, which don’t allow enough residual propellant for landing.
Based on the press release they plan on using Falcon Heavy for this type of launch in the future but it sounds like that project isn't ready for primetime yet.
And then the next statement, I assume, refers to the next launches where they can attempt a landing.
EDIT: my assumption is confirmed here http://en.wikipedia.org/wiki/List_of_Falcon_9_launches
Next up are flights 11 and 12, which can't be landed.
Then 13 has the "low probability of success".
Last year, SpaceX attempted a first stage water landing, but was not successful. Their two most recent successes on this front had at least two hardware differences from that old attempt: landing legs and heavier duty RCS thrusters. However, due to some combination of manufacturing and launch scheduling, an old core without these improvements, similar to their attempt last year, will be flying on flight 13.
Parachute landings mean you have a recovery zone, you need a recovery team, you need to find the rocket and bring it back. Whether landing in the ocean or land with a parachute there's a high probability of significant damage from impact and/or seawater intrusion. So now you have a huge amount of effort just to get the rocket back, then you have to clean it up. And the parachute landing likely means much lower chance of being able to fly even one additional flight, let alone many, unless you develop some sort of cushioning system like airbags, in which case you have to add that complexity, cost, and weight to the system. And all of that is aside from having to repack the parachutes for every flight.
SpaceX is planning powered landings for the same reasons that commercial airlines do powered landings. It's safer, it's more controllable, it's a smoother operational experience. It just makes sense.
Soyuz uses a 'suicide burn' that releases a ton of delta-V in a short amount of time.
From the video, it seems that Falcon uses a progressive burn as it approaches. They also mention that they can restart it up to 3 times in atmosphere.
But it seems that answer is aerodynamic control by partially (and differentially) extending the LEGS. Which appears brilliantly smart and should work. Same hardware, zero additional weight or cost, additional function.
They are restarting main engine twice. First time is for trajectory correction I assume.
But even so, it certainly shows success. Can't wait to see 'em get a stage back. That'll be amazing.
1) Atmospheric conditions are right for it (flying a subzero steel device through clouds with moisture in them, same problem that airplanes have)
2) The burning of the cryo-propellants lead to additional ice formation (as they burn they expand from liquid to gas and pull heat out of the tanks/body)
3) "snow" which is a variation on #2 which is that ice crystals that are forming on the rocket as it burns propellant in ascent the camera is accelerating away from them, but in descent the crystals are coming towards the camera.
Either way its an 'easy' fix, whether you heat the cover, add a wiper (ala nascar) or change the position.
I have a feeling someone is working there right now to come up with a quick and dirty deicing system - considering how disappointing this video is. The fluid system the Cirrus SR22 uses comes to mind.
I'm assuming that they only need the video from when they get close to landing so the lens cap can be ejected once the rocket is low enough in the atmosphere that icing is not a problem.
sources:
Be nice to have one solid, the other dashed or dotted.
You probably should always do that, as you won't know where your chart will be used (printed in black and white, very lossily converted to JPEG, whatever)
In this case it doesn't matter, as it's obvious which line is which.
Put another way, scrapping a shuttle mission saved less than 90 million.
PS: It was also horribly compromised based on Airforce requirements yet never flew a single Airforce mission.
For comparison compare the matence cycle a low mileage 0 to 10 year old car vs a low mileage 15 to 30 year old car.
See: Feynman's Appendix F. Specifically his criticism of the Shuttle reliability numbers quoted by NASA management and how they differed from the reliability numbers quoted by NASA engineers.
The shuttles flew a few DoD missions, including I believe at least one for the Air Force (a DSCS satellite during STS-51-J I believe? Maybe others, which DoD mission was for who isn't nicely broken down anywhere that I can find. It looks like most were for the NRO).
However none of the Shuttles ever flew a polar orbit mission; an ability that the Air Force demanded but never used. The large cross-range capabilities of the shuttle (necessitating such large wings) was for polar orbit missions, so those massive wings were dead weight caused by the Air Force.
The airforce had two mission profiles outside NASA's goals. Polar orbits AND capturing Russian satilites. Neither of those missions types where ever flown. The Airforce ended up having a huge impact on the design including much larger cargo bay etc but it was those two mission profiles that really fucked up the design.
If NASA had gotten it's way the shuttle would have been more reliable and cost less than 1/3 as much per mission at the cost of significantly lowered cargo capasity. Intact both shuttle disasters can be traced back to these compromises.
That ship was almost exclusively designed for millitary use. It was speculated that they planned to carry nuclear weapons up in the cargo bay.
You're better off putting those weapons on surface-based ICBMs. It'll take a little longer to get to target than the idea case in orbit, but you can launch all of them at a small area at once if you need to. They're a lot easier to maintain and decommission on the ground too - worth considering, since I think we'd all rather not ever have to use the things.
It's probably better/more stabilizing to do what we did, which is to deploy lots of SSBNs - just okay at first strike, great at second strike since it's almost impossible to destroy them all at once. You're less likely to want to pull the trigger on your own first strike when you know you have a nearly unstoppable second strike capability. The enemy nation is less likely to make a first strike if they believe they can't stop your second strike.
Problem is that some actions that help prevent your opponent from obtaining first strike move you closer to first strike.
For example, having nuclear missiles in submarines makes it very hard for your opponent to take out most of your nuclear weapons in a first strike, but it also gives you the capability to fire from closer range, giving the opponent less time to launch their missiles before your missiles take them out.
This would be similar, as there would be less time between launch and impact.
Space is already militarized, and out of the entire population of HN you were the only one to complain about my comment. I didn't get a single downvote.
https://www.youtube.com/watch?v=d3oSS_FP-cA&src_vid=ZWSMoE3A...
So, first, we now know the US space shuttle was the outcome of some bureaucratic processes in the US (NASA wants a new program to replace Apollo, the Air Force accidentally ends up in a super good negotiating position, Nixon does not want to be responsible for ending manned flight but also doesn't want to pay for a trip to Mars), so in the end it didn't end up a very sensible design. But the Soviets did _not_ known this, and assumed there must be some secret rational reason for building it:
> As TsNIIMash [Central Scientific Research Institute of Machine Building] director Yuriy Mozzhorin later said: "[The Space Shuttle] was introduced as a national program, aimed at 60 launches per year ... All this was very unusual: the mass they had been putting into orbit with their expendable rockets hadn't even reached 150 tons per year, and now they were planning to launch 1,770 tons per year. Nothing was being returned from space, and now they were planning to bring down 820 tons per year. This was not simple a program to develop some space system ... to lower transportation costs (they promised they would lower those costs tenfold, but the studies done at our institute showed that in actual fact there would be no cost savings at all). It clearly had a focused military goal".
So what might this secret military goal be? Apparently the Soviet speculations was that either it might be part of some nuclear fractional-orbit bombardment system, or it might be part of a plan to launch lots of laser weapons into orbit. In any case, we can't have a space shuttle gap, so:
> "[Central Committe Secretary for Defense Matters, Dmitri] Ustinov had made the following argument: if our scientists and engineers do not see and specific use of this technology now, we should not forget that the Americans are very pragmatic and very smart. Since they have invested a tremendous amount of money in such a project, they can obviously see some useful scenario which is still unseen from Soviet eyes. The Soviet Union should therefore develop such a technology so that it won't be taken by suprise in the future".
Let's build it now, and see what it is good for later! And then the Americans started speculating about what the secret military purpose of the Soviet shuttle might be! :D
At peak, in the 70s, there were about 140 launches per year.
So, since SpaceX is moving to a reusable vehicle, this graph could easily change slope in the future.
Anyone know when flight 14 is scheduled?
Flight 15 is scheduled to launch November 2014.
I am not a naysayer. I am very enthusiastic about what SpaceX does. Especially the reusability. But i just want to remind that they never stick to their schedule (that's generally hard to do in the rocket business), and their current schedule for the rest of 2014 looks in a way it will be almost certainly broken even if slightest issues arise.
Flying back the opposite direction is no good because you are fighting the rotation of the Earth and are paying with extra fuel to carry the fuel needed to go back, besides coastlines are always the most densely settled areas of any country.
I can't imagine that the economics will work out, but perhaps someone else has genuine numbers to prove me wrong.
http://www.faa.gov/about/office_org/headquarters_offices/ast...
In the case of the Saturn V, the first stage (S-IC) sequence completed after 2 minutes 41 seconds, at an altitude of 42 miles (68 km) a speed of 6,164 miles per hour (9920 kph). It continued ascending ballistically to an altitude of 68 miles (109 kilometers), ultimately landing 340 mi (550 km) downrange.
EVERYTHING.
When you throw away the entire rocket every flight you throw away tens of millions of dollars in hardware. If you can recover and re-fly stages you can get away with a lot of compromises elsewhere. Especially since the first stage, for SpaceX anyway, represents 3/4 of the hardware cost of the launch vehicle.
Even reusing the first stage once means cutting the overall hardware cost of a flight by nearly 1/3. For SpaceX that translates to about $20 million per flight in savings. And that's from one and only one reuse flight of the first stage. In comparison the fuel is nothing. In comparison even a massive payload hit is acceptable. As long as the payload reduction is less than the cost reduction, everything is golden, and the rest is profit margin. For 2 reuses (3 total flights) the hardware cost per launch drops to 1/2 of current costs. For 5 or more uses per first stage the cost drops below 40%.
SpaceX's launches are already cheaper than the competition, dropping below 1/2 of their current cost floor makes it impossible for the competition to keep up and would enable them to own the launch market.
My comment above wasn't shooting down the concept of reuse, but showing that the lateral range of the stage 1 Saturn V booster was pretty significant. To re-land at Kennedy, you'd likely have to:
1. Change the launch trajectory to gain more initial vertical range.
2. (Possibly) reduce the first stage size to decrease its range. This means increasing comparatively the 2nd and 3rd stage sizes.
3. Use of strap-on boosters (themselves independently recoverable) which would reduce the mass of the remaining recoverable stage 1, and hence the momentum that would have to be re-vectored to KSC.
And while reusability is good, it's a bit like Amdhal's Law: your initial gains are the biggest, and likely you're going to see a cost function something like:
(fixed booster cost + reusability engineering cost) / reuses +
additional fuel cost + refurbishment costs + launch risk
Which doesn't say that the exercise is futile. Only that past 3-4 reuses you're gaining little for what's likely a large additional expense, or phrased differently, there's a minimum cost if you want to go to space today.
It's still not inevitable that such things will happen with reusability automatically. Most likely the first reusables have high maintenance. But they can be improved.
But risk in general is also a function of use and operational time. This has been borne out in many contexts, including both space flight and aviation. Systems degrade in nondeterministic ways over time, increasing failure risk. Even very minor variations in design -- a few mm of protrusion in a fuel-oil heat exchanger in the Boeing 777, implicated in the British Airways 38 Heathrow crash, given a specific set of circumstances in in-flight ambient temperatures and engine throttle settings resulting in ice-induced fuel starvation -- can have profound impacts.
https://en.wikipedia.org/wiki/British_Airways_Flight_38
It'll be interesting to see how re-use, risk, and cost play out with Space-X.
But the extra weight is a concern, it limits payload to orbit. Try flying the first stage back to the launchpad in Kerbal Space Program while delivering a useful payload to orbit! It's instructive. KSP really develops your intuition for rocketry, everyone commenting in this thread ought to buy a copy.
[1] http://www.spacex.com/news/2014/07/22/spacex-soft-lands-falc...
edit - and for the same reason there are also things that would work in KSP that would fail in the real world.
Do you have an example for that?
> edit - and for the same reason there are also things that would work in KSP that would fail in the real world.
That's what I wanted to say with 'the opposite doesn't hold true'.
Not really applicable to this discussion, but one instance which is highly applicable is that you can't control two ships in KSP at once. If your lower stage needed to do a powered land which an upper stage was still accelerating into orbit, you couldn't replicate that in ksp.
.. Unless your name is Scott Manley ;-). But yes, good point about Lagrangian points [1]. I wasn't aware that KSP is only a two-body-simulation - interesting how the game can hide that with its sphere of influence implementation.
[1]http://forum.kerbalspaceprogram.com/threads/18623-Lagrange-p...
Also, my point with the logic is that when looking at the differences between physics in KSP and the real world, we are dealing with overlapping, rather than nesting sets.
First time I've seen this, thanks. You certainly have a point that feasible designs in KSP vs. real world aren't completely nested. When I was arguing about KSP being an upper limit, I didn't really think about the SSTO case - at least the stock simulation certainly doesn't hold up to be able do any kind of feasibility check for horizontally launched vehicles.
8 Rockomax 48-7S (little orange engine, stuck on with 8 small cube struts) + 1 Rockomax X200-32 Fuel Tank (the large gray tank, one size below the big orange tank) will put a capsule in orbit around Kerbin pretty easily. No such luck in real life.
Typically KSP engines have worse performance than real engines, but Kerbin is pretty small.
That's what I meant by 'the opposite is not necessarily true'. My argument was that if something does not work in KSP, it probably won't work in real life (which was refuted by another commenter because of missing Lagrange points). IMO it still holds true for basic rocket designs and their capabilities for LEO / GEO. To my knowledge, all real world rocket designs have been replicated in-game (albeit with much lower complexity of course) and demonstrated to work.
The first video explains the modifications to the game, mainly more realistic aerodynamics, realistic fuels and engine capabilities, a realistic planet and launch site. The second video is him actually performing the mission.
There are a few differences between what he did and what we now know is actually planned, but it's still pretty damn close and demonstrates the feasibility of the concept in a pretty intuitive fashion.
[1] scare quotes because I know its never easy to land and California or Nevada east of Vandenberg for minimal delta-v requirements.
Interestingly SpacePort America (http://spaceportamerica.com/) has a similar problem, although if you look (https://www.google.com/maps/place/Spaceport+America/@33.0125...) you will see there isn't much east of it.
As for cost, fuel is cheap, it's one of the cheapest things in the whole operation. Think about the fact that every commercial airliner has the capability to make an unpowered landing and to save fuel doing so, why don't they? Because operational complexity adds cost much more than using up fuel does. By the same token, the greatest costs in orbital launch come from throwing away the hardware after every flight and operational complexity. If using extra fuel enables them to more easily reuse the stages and get more launches out of them as well as reduce overall operational complexity, then it makes economic sense.
They intend to do a return to launch site--at least eventually. There will be several intermediate steps to prove the system. If it proves unworkable, always landing on a barge is better than not, I guess.
RTLS will certainly require a good deal of margin (by rocketry standards), but first stages usually have some margin already, and SpaceX will have a nice range of options once the F9H comes on line so that they don't have to fly a rocket "fully loaded" except for certain extra-large payloads.
I imagine they can also optimize most flight profiles for RTLS, by sending the first stage more than usually straight up--which is close to the case anyway. Lateral velocity is mostly the job of the second stage.
While it's never been done before, it's not an unheard-of concept. One of the potential evolutions for the STS was "fly-back boosters".
Barnaby Wainfan patented an interesting alternative: after staging, re-enter, then do a burn and fly ballistically back to launch site. This kills the horizontal speed with air resistance instead of propulsion, potentially saving fuel. You have to regain the altitude though.
But mad props to SpaceX for working towards recycling their boosters.
Has SpaceX really cracked that problem? What portion of flights on this smaller rocket can do it? It says some missions won't have enough fuel left over.
Will the Falcon 9 Heavy be able to do all or almost all missions with a landing and full recovery at the end? How much fuel will Heavy have left on average after a return? Theoretically it would not wait until the last possible second to start slowing, and therefore use up almost all of the fuel in order to give the descent a larger margin of error and also reduce the possibility of damage, I assume.
Numbers are not yet known for the 2nd stage retrieval or Falcon Heavy. One could probably assume a similar number for the first stage but possibly a bit less given the Falcon Heavy's higher thrust/weight ratio.
(I didn't know that)
The second stage will need a re-entry heat shield, but otherwise can land like the first. Tricky part is getting enough margin in the second stage for the landing fuel and legs and heat shield. Usually the top stage is the one you optimize most heavily. So plausible, but tricky.
Good news is that the second stage is much cheaper than the first, at least on the F9. Eight fewer engines, for one.
Edit: Found the original copy on the Web Archive http://web.archive.org/web/20110615000000*/http://www.spacex...
An enormous amount of inertia to overcome so 30% doesn't sound so unlikely.
1. Alter the path so the parabolic arc goes back to the launch site.
2. Braking burn during descent to minimize atmospheric stress.
3. Landing burn (AKA "suicide burn") to slow the vehicle enough for the landing legs to absorb the impact.
Though it's not quite that simple. Based on the trajectory of last week's launch, they're actually going to use a much steeper trajectory during the first stage launch. The result is that the first stage uses significantly less propellant to make that first burn (since its downrange velocity is much smaller), but it cuts into the payload capacity quite a bit by forcing the second stage to do more work.
Even if I were an expert, the starting point is asking the question, and if I made claims about the answer, someone would come along and say it is still unknown as to whether they can do that.
It should be framed as a question because it is an open question. That's the way technology works. You don't really know you can do something until you do it.
So this question is an attempt to inform you and others of the correct context for discussion. Of course it failed.
However, once the F9 v1.1 has been thoroughly tested in the reusable configuration they will stop offering the expendable option. Every flight will have the first stage flyback for reuse, and only payloads which allow that flight profile will be flown, leaving more than enough fuel margin to allow return and some contingency.
Larger payloads will simply be flown on the Falcon Heavy, which will reuse the lower stage cores from day one. Even if that means no cross-feed and a massive hit to the payload capacity the Falcon Heavy should still be able to loft payloads larger than the Delta IV Heavy and with reusability it should be able to do so at less than the current cost of the F9.
That's expendable launch (at reusable prices!) every 5-10+ launches per vehicle.
Edit: oops. This was supposed to be a reply to the comment below about launches from Vandenberg being mostly to the south.
Is the rocket currently aimed "at the Atlantic", or are they operating with the precision they need to land back where they took off from: and in that case, do they have a camera pointing at the landing point from a ship?
We won't be getting it for awhile. But I think maybe in about a year or 2 we will get to see the video.
Rockets have to withstand a lot of different types of forces (axial, all sorts of vibrational, probably hoop type stresses), but massive lateral shocks aren't really one of them.
I don't know about that: https://twitter.com/elonmusk/status/488718649515986944
Even with minimal fuel, the tanks are still highly pressurized, a loss in hull integrity would result is a rapid depressurization of those tanks. It may not have been a fiery explosion, but I would bet it made a hell of a bang.