SpaceX Soft Lands Falcon 9 Rocket First Stage

http://www.spacex.com/news/2014/07/22/spacex-soft-lands-falcon-9-rocket-first-stage

by cryptoz • 12 years ago

561 188 12 years ago

jccooper5• 12 years ago

Better video from the first landing, despite the data corruption, than this one, due to the ice fouling. Wonder why this one got iced? Clouds?

But even so, it certainly shows success. Can't wait to see 'em get a stage back. That'll be amazing.

avenueevergreen2• 12 years ago

I speculate that this one iced up because the vehicle flew a much higher trajectory than the previous vehicle, as visually noticed from the launch webcast. This meant that the first stage spent more time higher in the atmosphere.

fortepianissimo• 12 years ago

For all the rocket science, why can't they get a lens that deices itself?

jccooper5• 12 years ago

They will. It's not been seen to be a problem before, so they went with the simplest solution. In rockets, every ounce counts. Now they know it happens (at least sometimes) in this very novel flight regime, they'll do something about it--the linked post even says so explicitly.

ChuckMcM3• 12 years ago

I was wondering that as well. Three possibilities come to mind;

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.

mmaunder• 12 years ago

Icing is caused by supercooled raindrops freezing on the airframe. In this case the spacecraft came from a very high altitude so I'd expect the airframe to already be very cold and even if droplets aren't supercooled, they might just freeze on the cold surface of the lens. Pireps (pilot reports) are available globally where pilots report icing conditions they encounter. I suspect the SpaceX engineers anticipated this possibility and decided that they didn't want to add the extra weight and complexity of a heating or deicing system to the lens.

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.

infogulch• 12 years ago

I think some kind of disposable multi-layered lens cover that peels off automatically would work well. Pretty cheap, and easily replaceable. Effective against more than just ice.

Crito8• 12 years ago

The video is pretty cool, but make sure to read the rest of the page. Most exciting of all is this last note: "We will attempt our next water landing on flight 13 of Falcon 9, but with a low probability of success. Flights 14 and 15 will attempt to land on a solid surface with an improved probability of success."

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).

toomuchtodo5• 12 years ago

That "solid surface" will presumably be a barge. Very exciting stuff.

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.

OrwellianChild• 12 years ago

I'm impressed with the barge concept if only from the wave action the'd have to compensate for. Anyone know wave amplitude in the area they'd be landing in? That's a flat surface that's coming up to meet you or dipping away, making for a pretty heavy drop...

cryptoz• 12 years ago

common question of "why not use parachutes"

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.

ceejayoz5• 12 years ago

Moon landings, too. While Musk has his sight set on Mars, I can't imagine he'd turn down the opportunity to beat NASA to a lunar return.

grecy3• 12 years ago

"We will attempt our next water landing on flight 13 of Falcon 9, but with a low probability of success."

I'm wondering why the next water landing has a low probability of success?

andrewtbham2• 12 years ago

probably because it's another water landing

ceejayoz5• 12 years ago

Might be the flight path or payload limitations.

davidrhunt• 12 years ago

I believe it is because of this:

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.

The_Double• 12 years ago

Flight 13 will be a flight to ISS on a core without landing legs and other modifications for landing. Apparently, they swapped cores earlier, and now they have a rocket left without legs.

avenueevergreen2• 12 years ago

This is not confirmed by SpaceX, but has been floating around the internet as the suspected reason.

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.

washedup5• 12 years ago

It's not about the rocket tipping over. The use of parachutes would require the loss of landing accruacy. They want to be able to guide the first stage to a specific location (like a launch pad), and parachutes would not allow them to do this.

Crito8• 12 years ago

It all factors in. SpaceX has performed grasshopper tests on windy days that would be a problem for a parachute landing. There is also the issue that parachutes sufficient to slow down the stage to a soft land-landing would be far too heavy.

InclinedPlane6• 12 years ago

Powered landings mean precise, highly controlled landings. You land exactly where you want with minimum damage to the vehicle and you go out and put the stage on a truck so you can bring it inside and begin processing it for reuse in a matter of hours.

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.

jccooper5• 12 years ago

Parachutes also hit a lot harder. Powered landing you can touch down with ~0m/s. Parachutes you'd get something like 10 m/s (~22mph.) Not necessarily nice on your equipment.

fixermark• 12 years ago

Not particularly nice on your astronauts / cosmonauts / 赵里昱 either, though they have training, preparation, and (according to an interview with Cmdr. Hadfield awhile ago) specially-poured per-backside crash seats to ameliorate it somewhat.

Crito8• 12 years ago

Yup. The Soyuz landing capsule uses solid fuel retro-rockets at the very last second to slow down, but even then it is apparently a rather unpleasant bump.

andrewtbham2• 12 years ago

Flights 14 and 15 will attempt to land on a solid surface with an improved probability of success.

Anyone know when flight 14 is scheduled?

washedup5• 12 years ago

It is scheduled for October 2014: http://en.wikipedia.org/wiki/List_of_Falcon_9_launches

Flight 15 is scheduled to launch November 2014.

anovikov4• 12 years ago

Almost no chance these will fly this year. We will only see 3 more launches this year IMO, and 2 will not attempt stage rescue, 1 will attempt on water as the previous ones. So wait till 2015...

HarryHirsch2• 12 years ago

Where do you find a solid surface to land on except in Russia and China? You would like to fly across water or at least unpopulated areas in case a problem develops during flight and range safety needs to go for self-destruct. The USA, Europe, India and Japan all do that, because no one wants a re-run of the Long March desaster in 1996.

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.

washedup5• 12 years ago

SpaceX owns some land in southern Texas. It seems that the initial idea is to have a spaceport in Brownsville, TX, and use Cape Canaveral, FL, as the landing location. In the mean time, they can practice by using floating platforms in the Atlantic.

http://www.faa.gov/about/office_org/headquarters_offices/ast...

seanflyon4• 12 years ago

If you can deliver a payload and recover and fully reuse the rocket then your costs drop by an order of magnitude. I can't imagine that the economics won't work out.

Nogwater• 12 years ago

I'm pretty sure they're planning to fly the first stage back to the launch site (Cape Canaveral in most cases for now). It wouldn't return to the same tower, but somewhere at the Cape.

krschultz• 12 years ago

I think they're talking about a barge or floating platform of some sort out in the Atlantic, at least for the initial tests.

greglindahl3• 12 years ago

SpaceX has said that they want to fly the booster back to the launch pad from the first announcement of their reusability plans. Yes, the rocket launches with 30% extra fuel - Falcon 9 v1.1's first stage was made bigger to accommodate that need. Fuel is a small cost relative to everything else.

ChuckMcM3• 12 years ago

If they launch from their Vandenberg launch complex they can "easily"[1] land in the high deserts of California or Nevada. Although I believe the plan is to return to the existing pad. And in answer to the expense question, 9 merlin engines are pretty pricey compared to just fuel costs.

[1] scare quotes because I know its never easy to land and California or Nevada east of Vandenberg for minimal delta-v requirements.

InclinedPlane6• 12 years ago

You just fly back to the launch area. It's immanently feasible to fly that route and always have a buffer of assurance that the rocket's trajectory will not head towards populated areas. If, for whatever reason, that changes then they press a button, the rocket zips apart and falls in pieces into the Atlantic ocean.

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.

jccooper5• 12 years ago

I would suspect SpaceX has the numbers. I don't think they're just guessing that what they want to do will work. Rocket engineers are big on numbers.

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".

smackfu2• 12 years ago

Keep in mind they have a very aggressive flight schedule planned, with basically 3 weeks between launches. August 4, August 25, Sept 12. Possible, but not probable. And if those are delayed, then the later ones are too.

crb• 12 years ago

Will there be a video of the landing, as seen from Earth?

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?

dba7dba• 12 years ago

Probably no video from the earth.

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.

lefrancaiz• 12 years ago

Why does the rocket tipping over cause a loss of hull integrity? Does that mean that it actually exploded, just from going horizontal?

geetee• 12 years ago

Think belly flops on a rocket scale.

icegreentea• 12 years ago

Probably not exploded, just that the lateral stresses that the rocket is designed for.

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.

mbell• 12 years ago

Probably not exploded

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.

bashinator• 12 years ago

I think it just meant that because it was wholly immersed in water, it's not worth refurbishing.

rspeed6• 12 years ago

Compare the amount of force it takes to crush an aluminum can from the sides vs. from the top and bottom. A rocket is the same basic shape and material.

nickhalfasleep• 12 years ago

"it fell over, as planned"... great attribution of the fundamental nature of gravity.

But mad props to SpaceX for working towards recycling their boosters.

m_mueller8• 12 years ago

I had a laugh at that as well. Idiocracy seems near if things like that need to be mentioned in press releases.

elements• 12 years ago

The shuttle SRBs floated vertically after splashdown, so I don't know why someone would be dumb for thinking the Falcon 9 booster might do the same.

axman6• 12 years ago

"This was a COMPLETE failure! It FELL OVER! THEY'RE JUST TRYING TO SAY IT WAS SUPPOSED TO DO THAT AFTERWARDS! SELL ALL SpaceX STOCK PEOPLE!" We've all seen this sort of crap to one degree or another. Sadly a lot of it right here on HN.

larrydag2• 12 years ago

I've been super impressed with how efficient SpaceX is in getting launches into orbit. I did a visual comparison to the Space Shuttle program. It looks like SpaceX will overtake the Space Shuttle launch efficiency by the end of the year.

http://snag.gy/wUTD7.jpg

sources:

http://en.wikipedia.org/wiki/List_of_space_shuttle_missions

http://en.wikipedia.org/wiki/List_of_Falcon_9_launches

bellerocky• 12 years ago

The space shuttle launches are manned missions. I don't think it's a fair comparison.

larrydag2• 12 years ago

good point. I was considering the comparison as resupply missions and (future) re-usability of the vehicle.

tnorthcutt• 12 years ago

That graph might be a little more intuitive if you swapped the axes, FWIW.

hughes• 12 years ago

Definitely. Also choose colours that aren't almost identical.

ghshephard• 12 years ago

It would be a lot more intuitive. Even knowing exactly what was being described and how - It still is difficult for me to understand a graph in which Time is on the Y-axis. I considered for a few moment that I was actually being trolled with that graph.

pothibo• 12 years ago

Telecoms and the market for satellites has only recently boomed. You cannot compare the two programs in such a way.

ceejayoz5• 12 years ago

The limiting factor of the Shuttle wasn't low demand for its services, I don't think.

sitkack8• 12 years ago

Are you taking into account inflation adjusted cost?

rsynnott• 12 years ago

Shuttle was alway fairly low-frequency, far below its design goals, so possibly not a great comparison. Here's 2014 in space launches: http://en.wikipedia.org/wiki/2014_in_spaceflight

At peak, in the 70s, there were about 140 launches per year.

smackfu2• 12 years ago

An expendable vehicle should be inherently more efficient in launching frequency than a reusable one. The reusable one is fundamentally limited by the number of reusable vehicles you have on hand and the time it takes to turn each around. The expendable one is only limited by the speed of your manufacturing.

So, since SpaceX is moving to a reusable vehicle, this graph could easily change slope in the future.

ilaksh2• 12 years ago

The hardest part is not running out of fuel on the way down. Old-school science fiction often assumed something like nuclear power where that wouldn't be a concern. Seems like for many years most people haven't even attempted this full recovery/landing thing because of fuel and weight issues.

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.

jpgvm2• 12 years ago

Until now most information out of SpaceX has suggested it needs roughly 30% propellant left in the first stage of Falcon 9 to attempt a retrieval.

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.

grecy3• 12 years ago

Is SpaceX's long term plan to also have 2nd stage retrieval?

(I didn't know that)

kashkhan• 12 years ago

30% sounds a bit extreme, especially since it is unloaded. I think they could probably do with 5% or less since the vehicle is unloaded (all the propellant is burnt out) and burns for only a few seconds for soft landing, with most of the braking from peak velocity provided by aero braking.

m_mueller8• 12 years ago

From what I've read they need 30% additional fuel at launch (as in a 30% bigger first stage) - that's different than needing 30% left in the rocket after separation. The reason being that to have X [kg] of fuel at Y [m] altitude you'll need (1 + Z(Y)) * X [kg] of fuel at launch, with Z being some function of Y. My gut tells me they'll need 15-20% max for retrieval, the 30% + is just to get it up there. Source: Play KSP.

jessriedel• 12 years ago

I'm sure that all this information is publicly available. There's nothing wrong with asking these question in a forum, but you probably shouldn't suggest that it's some big unknown and you should probably acknowledge that you're asking people to do research for you.

ilaksh2• 12 years ago

Far as I know, the answer to this question is by far the most relevant in the entire thread.

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.

InclinedPlane6• 12 years ago

Right now there is a bit of a slight impedance mismatch between attempted reusability and the commercial launch offering of the full expendable Falcon 9 capability. On the plus side the dual role nature of the Falcon 9 v1.1 means they can take advantage of expendable launches with sufficient margin to test the reusability features, on the minus side it means that when there isn't that margin they don't get free test flights.

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.

someperson• 12 years ago

Don't forget you can do an expendable configuration on the final launch before 'retirement'.

That's expendable launch (at reusable prices!) every 5-10+ launches per vehicle.

russell• 12 years ago

I did see a launch north over my town, about 80 miles north of Vandenberg. It looked like the path was over the ocean all the way. The first stage was still burning, so it was pretty spectacular.

Edit: oops. This was supposed to be a reply to the comment below about launches from Vandenberg being mostly to the south.

sargun• 12 years ago

I'm curious as to why SpaceX, or their competitors haven't utilize Sky Cranes, a la Mars Science Laboratory: http://en.wikipedia.org/wiki/Mars_Science_Laboratory#Sky_cra... - basically, it seems to be a powered parachute.

mmcnickle• 12 years ago

The sky crane solves a very particular set of problems with landing a (relatively) small, functional rover on Mars. It's not really a general solution to returning a large payload intact to Earth.

danielweber• 12 years ago

The sky crane will probably never be used again. It was an engineering marvel but the requirements that brought it into being were a management nightmare. (Requirements to not use any carbon-based propellant directly on the surface of Mars, which probably got violated anyway because you can still see blast marks from the sky crane where MSL landed.) And it was only useful for one very particular mass window -- much lighter and it wouldn't be useful, much heavier and it couldn't work.

JulianMorrison• 12 years ago

The main difference between a sky crane and a soft-landing rocket stage is whether the braking/hovering engines are inside the thing landed (SpaceX) or outside and discarded after landing (sky crane). Since SpaceX is doing their best to not discard things, a sky crane is the opposite of what they want.

anovikov4• 12 years ago

What i don't understand is how are they going to solve the problem of landing precision. The stage is passive from the retroburn (just after the stage separation) for the several hundreds seconds it is flying back, and large part of that trajectory is in atmosphere, and stage has a high sail factor: it is big and, being almost empty, lightweight. So it might be dragged by wind too far from the landing site to compensate in hover mode which is i assume only 100-200 meters or so, even if original entry trajectory is perfect. Ballistic missile warheads for example, accumulate about 100 meters or error due to this factor despite they are much smaller/have higher density and fly several times as fast. A an additional short mid-flight engine burn to compensate may be a solution but so far i haven't heard of that. Anyone has an idea?

ceejayoz5• 12 years ago

Ballistic missile warheads aren't slowing down for a soft landing. Try landing a helicopter at Mach 1 and see how accurate it is compared to a normal landing.

Symmetry• 12 years ago

I believe that's what the new grid fins they've been testing out on the Grasshopper are for. Those are there to let the rocket steer even at the speeds it comes in at.

http://en.wikipedia.org/wiki/Grid_fin

toomuchtodo5• 12 years ago

They are! And they work well at both subsonic and supersonic speeds, just not transonic speeds.

TrainedMonkey• 12 years ago

"This test confirms that the Falcon 9 booster is able consistently to reenter from space at hypersonic velocity, restart main engines twice, deploy landing legs and touch down at near zero velocity."

They are restarting main engine twice. First time is for trajectory correction I assume.

Jacky800• 12 years ago

I wish there is someone in the medical domain equivalent to Elon Musk.

mtm• 12 years ago

Elizabeth Holmes is taking a stab at it: http://seattletimes.com/html/businesstechnology/2024121844_v...

SpaceX Soft Lands Falcon 9 Rocket First Stage

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