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SpaceX Testing Landing Legs On Next Falcon9 Rocket

Unknown Lamer posted about 10 months ago | from the crazy-enough-to-work dept.

Space 73

astroengine writes with news of SpaceX's next step in experimenting with vertical landings for rocket stages. From the article: "Space Exploration Technologies is installing landing legs on its next Falcon 9 rocket, part of an ongoing quest to develop boosters that fly themselves back to the launch site for reuse. For the upcoming demonstration, scheduled for March 16, the Falcon 9's first stage will splash down, as usual, in the ocean after liftoff from Cape Canaveral Air Force Station in Florida. This time, however, SpaceX hopes to cushion the rocket's destructive impact into the Atlantic Ocean by restarting the Falcon 9's engine and extending landing legs that will be attached to the booster's aft section. The goal is a soft touchdown on the water." The test is scheduled for their ISS resupply mission on March 16th 2014 (the mission also features the launch of the crowdfunded KickSat nano nanosatellites) .

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nano nanosatellites? (5, Funny)

Anonymous Coward | about 10 months ago | (#46329357)

Did Mork write the summary?

Re:nano nanosatellites? (1)

Immerman (2627577) | about 10 months ago | (#46330403)

I was about to say the same. And you got it in the first post no less!

Scooped by the upstarts again! (-1, Offtopic)

Anonymous Coward | about 10 months ago | (#46329425)

SoylentNews [soylentnews.org] had this story last week.

Re:Scooped by the upstarts again! (0, Offtopic)

Bruce Perens (3872) | about 10 months ago | (#46331095)

I wrote this up a day before that at http://technocrat.net/d/2014/2/20/6 [technocrat.net] . I've known about it for a month or so, I don't know why nobody else was excited until now.

Re:Scooped by the upstarts again! (-1, Offtopic)

cheesybagel (670288) | about 10 months ago | (#46332109)

I won't post on your site because you don't allow anonymous posts and I have better stuff to do than create yet another login. Anyway:

The commenter 'Lars' is wrong. The Russians use solid retrorockets on Soyuz [youtube.com] before landing. You can still survive a Soyuz capsule landing with them firing, with only the parachutes, but the results aren't pleasant.

Re:Scooped by the upstarts again! (0)

fuzzywig (208937) | about 10 months ago | (#46332747)

The only news about this is that they've just started attaching the legs, as you can see here [twitter.com] . Looking forward to seeing how well they work.

Re:Scooped by the upstarts again! (0)

Teancum (67324) | about 10 months ago | (#46332957)

For those who have been following the development of SpaceX, this shouldn't even be news other than the specific announcement that they really will be doing this on the very next flight.

Then again, if you knew about this.... why didn't you submit a link to Slashdot yourself?

SpaceX (4, Interesting)

beltsbear (2489652) | about 10 months ago | (#46329495)

Recovering the first stage (not this time but maybe this year) will make a huge difference in cost. Saving the 9 engines on the first stage alone is huge.

Much more detail here:
http://www.nasaspaceflight.com... [nasaspaceflight.com]

Re:SpaceX (5, Interesting)

cbhacking (979169) | about 10 months ago | (#46329587)

There will probably be a lot of reconditioning needed anyhow, but yeah, the cost saving could be enormous. The fuel is pretty cheap, really; what makes rocket launches expensive is the need to build an entire new rocket every time. Even the so-called reusable Space Shuttle had a ton (actually, many tons) of parts that were discarded with every launch and had to be built anew for the next one. If SpaceX can actually make the Falcon 9 reusable, it could reduce launch costs by at least an order of magnitude. I think their actual goal is to hit *two* orders of magnitude, and they have a much better ides of costs and feasibility than I do...

Re:SpaceX (4, Interesting)

strack (1051390) | about 10 months ago | (#46329959)

Are you sure about that reconditioning? your comparing it to the space shuttle engine, that needed to be torn down, inspected, and rebuilt after every flight. But that was because it was built to razor thin engineering tolerances. The merlin engine is quite a bit more durable.

Re:SpaceX (4, Interesting)

cbhacking (979169) | about 10 months ago | (#46330021)

Perhaps "recertification" would be a better word. They will need to do a lot of inspection and probably at the very least unmount and closely examine many of the parts, but it's possible they will be able to re-use them without any actual modification. That would be phenomenal, in terms of cost savings. If the average life expectancy of a rocket engine could be raised even to two launches, the costs would come way down.

Re:SpaceX (0)

Anonymous Coward | about 10 months ago | (#46330677)

From what I can tell they are just prototyping the tech on the Falcon 9. It's going to mitigate some costs, those Merlins have so many sensors SpaceX knows just what's going on without having to do full tear downs. But it's the upcoming Raptor engines that this tech is really aimed at. Raptor is being designed from the ground up to be as simple a design as possible with so much telemetry SpaceX will be fully aware of what engines need to be pulled even before it hits the ground, as well as any other problems.

Re:SpaceX (1)

Electricity Likes Me (1098643) | about 10 months ago | (#46330893)

Well the engines which hit the ocean I doubt are ever going to fly again - once seawater gets into anything mechanical and high performance, the best decision you can make is to scrap it. This sounds more like it's a test of whether the soft touchdown will work, in a way which will not explode so much if it doesn't (like as would happen with a hard impact on land).

Re:SpaceX (2)

strack (1051390) | about 10 months ago | (#46331685)

Elon Musk has stated in the past that "a little seawater" wouldnt harm the engines.

Re:SpaceX (2)

cheesybagel (670288) | about 10 months ago | (#46332127)

The salt water is less of a problem than the impact. Truax tested firing rockets underwater. It works fine if you chose the materials adequately.

Re:SpaceX (1)

Delwin (599872) | about 10 months ago | (#46334335)

The intent (not with the Falcon but with later rockets) is for it not to splash down at all but land vertically back on a launch pad. You can then use a crane to put a new second stage on it, bolt it all back together, refuel and relaunch. ... that's the goal at least. We're still a long way from that.

Re:SpaceX (2)

strack (1051390) | about 10 months ago | (#46331749)

Thats adorable. "a whole 2 launches!". Meanwhile the grasshopper VTVL test rocket did 7 jumps, while using a merlin D engine. This isnt your daddys shuttle main engine.

Re:SpaceX (1)

cbhacking (979169) | about 10 months ago | (#46341075)

You kind of missed the point of my post, didn't you?

I never stated, or even implied, that 2 launches was the goal. Nor did I claim or imply that it's all they would be able to achieve. I merely pointed out that even a single re-use would cut costs dramatically (probably by a factor of 1/3 to just shy of 1/2, the rocket being the majority cost of each flight). SpaceX are, obviously, going for far more than a twice-usable rocket. With that said, some parts probably will need to be downchecked and replaced after each flight. Probably not half the components, though, and it's quite likely that most of them will be reusable without anything worse than some inspection and maybe a little cleaning.

I have no idea what the average life expectancy of the parts will come out to be (or how many of them will be later able to be returned to service for lower cost than rebuilding them, which is probably significant), but hey, baby steps. When they use the same rocket for its second orbital launch, it will be a great day for space travel. When they do it for the 20th launch, it will still be amazing but at that point the marginal value of one more launch has gone way down compared to the marginal value of that second launch.

It will be interesting to see, over the next couple decades, how reusable rocketry failure rates shake out. Do they increase steadily over time and number of launches, the way one might expect? Or does a rocket that manages one complete liftoff and recovery without failure have a better chance of making it to twenty than one right off the factory floor has of making it to two? Is there a point where fatigue will make it more economical to replace the rocket anyhow, rather than continually recertifying it, or will it be cheaper to just keep going, making small repairs as needed and upgrades as appropriate, and only manufacture complete new rockets to meet increased capacity demands?

Any way you look at it, this is going to be an exciting era for space travel.

Re:SpaceX (1)

DerekLyons (302214) | about 10 months ago | (#46331967)

Are you sure about that reconditioning? your comparing it to the space shuttle engine, that needed to be torn down, inspected, and rebuilt after every flight.

Only in the early years of the program. As they gained experience, the maintenance requirements were reduced. By the early 90's, the were removing the engines for borescoping after each flight, but only rebuilding them every fifth or sixth flight. By the late 90's they were removing them every fifth or sixth flight for borescoping and only rebuilding them every ninth or tenth flight.

Re:SpaceX (1)

beltsbear (2489652) | about 10 months ago | (#46330045)

I think the goal is to make it so they just need to test them if certain landing conditions are met. That will take a bit. First they need to inspect a few sets after they land and make sure they match expectations. Then after that with engine out capability they should just be able to test them in the end without rebuilding much at all.

Re:SpaceX (1)

Immerman (2627577) | about 10 months ago | (#46330447)

I don't think two orders of magnitude is possible - IIRC the cost of fuel is generally at least a few percent of the entire cost of a launch. Assuming 95% of the current cost of is the cost of the rocket you could get perfect reuse and still only get twice one order of magnitude improvement (aka 20x cheaper) Two orders of magnitude would require that you get it down below 1% of the current cost, which would require much cheaper fuel as well.

Re:SpaceX (1)

cbhacking (979169) | about 10 months ago | (#46330785)

A factor of 20-30 reduction is my guess for where it's likely to wind up in a best-case situation as well, at least with rocketry as we currently implement it. The crazy and wonderful thing is that other changes will potentially make a big difference in the future. For example, if the world ever collectively gets over its brick-shitting with regard to nuclear power, there are conceptual designs for rockets where the energy comes from nuclear sources (such as uranium-hexafluoride gas contained in a quartz "lightbulb") and the only expendables that the rocket needs to carry are the reaction mass. Turns out water, or any of a number of fairly cheap gases, make excellent reaction mass (and because this design would have a ridiculously high specific impulse - basically "fuel economy" for rockets - you wouldn't need very much reaction mass either). Thus, we could reach a point where the consumables on every launch were a trivial fraction of a percent of the cost of the rocket. At that point, costs could drop even further than under the best case of the "fuel is 3-5% of the cost of every launch" assumption.

BUT, that's only if we manage to make rockets reusable, so we can amortize the costs of launching them over a large number of launches. We can start work on that today, with propulsion systems that have changed little in decades, and maybe use those savings to fund R&D into the next generation of rocket propusion, one that has even lower per-launch costs...

Re:SpaceX (1)

Immerman (2627577) | about 10 months ago | (#46330949)

True enough, though I for one hope the brick-shitting continues until we've got some serious experience with nuclear rocketry elsewhere - lunar launches perhaps. Once we get to the point that the fuel is a major portion of the cost to orbit then other things start being worth consideration - tumbling skyhooks for example, which if used for the return trip as well can act as a momentum bank to completely eliminate 90+% of the energy cost necessary to reach orbit. (and which can easily be made with existing materials - theoretically)

Re:SpaceX (2)

Confusador (1783468) | about 10 months ago | (#46331297)

According to Musk, the fuel cost of a F9 1.1 is ~$300,000, or about 0.5% of the system cost.

Re:SpaceX (1)

Teancum (67324) | about 10 months ago | (#46333149)

I like to use this analogy in terms of the fuel costs for rockets: The catering budget to feed the press corps at a Shuttle launch cost more than the fuel being used to launch the rocket.

Even with your figure of about $300k, I would argue that SpaceX spends a comparable amount for public relations + press kits on each flight of the Falcon 9. It really is in the statistical noise level in terms of costs of the launch.

Re:SpaceX (1)

queazocotal (915608) | about 10 months ago | (#46332879)

http://www.spacex.com/falcon9 [spacex.com]
500 tons of rocket.
Let's say it's all fuel (90%+ is).

It's RP1/LOX.
You need 2.5:1 liquid oxygen to RP1.

1980s NASA was paying $.08/kg for LOX. Let's say $.20 now.
And $.20 per kg for RP1 - at most 100% over spot oil price.
$1/kg is reasonable.

Making the average cost per launch for 150 tons of RP1 and 350 tons of LOX about $150K+$70K = $220K.
The quoted price is $56M - or the fuel cost is under half a percent.

Re:SpaceX (2)

Teancum (67324) | about 10 months ago | (#46333243)

I don't think two orders of magnitude is possible

If you want to see what the actual guy who designed the Falcon 9 thinks of the reduction of launch costs, I'd suggest at least reading some of his thoughts [space.com] before pulling up random numbers of your own.

The long term goal of SpaceX is to start selling Falcon 9 flights for about $20-$30 million with a reusable 1st stage and if they can get the 2nd stage to become reusable they want to get it down to about $5 million per flight... with a hoped-for goal to drop that down to perhaps as low as $1 million. In other conversations, Elon Musk has suggested he might even get the cost of a round-trip flight to Mars down to about $500k per person.

In other words, the two orders of magnitude is what SpaceX is trying for and they have rocket scientists who have crunched the numbers to see if it is possible. That is certainly not something calculated on the back of a bar napkin but somebody who is building these rockets and has put something into space.

Re:SpaceX (1)

Immerman (2627577) | about 10 months ago | (#46334289)

I stand corrected.

Whoa, a half-million to Mars and back? Now *that* would change things. That's not much more than it currently costs to get a person to orbit, and not even a rounding error on the current cost to get person to the Moon and back.

Re:SpaceX (2)

Teancum (67324) | about 10 months ago | (#46333107)

At the moment what SpaceX would really love to do is simply recover the Merlin engines, tear them apart and find out what worked and what didn't work in terms of sending stuff into orbit. All of the previous launches had those engines completely fall apart or sink into the deep ocean in a state that is unrecoverable, so this kind of engineering analysis has been impossible. Even if the engines land in the water, a soft landing recovery in the ocean is going to produce some very valuable information that can significantly help with the engine development.

Re:SpaceX (1)

DerekLyons (302214) | about 10 months ago | (#46330469)

Recovering the first stage (not this time but maybe this year) will make a huge difference in cost. Saving the 9 engines on the first stage alone is huge.

Maybe, maybe not. The recovery infrastructure and labor isn't free, nor is the refurbishment infrastructure and labor. In theory the cost difference should be huge, in practice... we don't know. Nobody has ever refurbished and reflown liquid engines that have been dunked in salt water. AFAIK, we don't even have enough hard data to make a proper evaluation.

If I were SpaceX, the first thing I would have done is tossed an engine in the water, recovered it, and studied it. Landing legs and cushioned landing are sexy and the whole process is very impressive on paper to the less well educated space fanboy (I.E. 99% of them)... but engine refurbishment is the key to the whole process.

Re:SpaceX (1)

cb88 (1410145) | about 10 months ago | (#46330733)

If their goal was to just land in the water that would make alot of sense... except they eventually intend to land on the ground which might possibly be cheaper since no retrieval from the ocean would be required and they don't have to worry about salt water corrosion.

I'm not sure why you get the impression that that soft touchdown in saltwater is the goal... it isn't it is just a safety precaution at this point.

Re:SpaceX (2)

ColaMan (37550) | about 10 months ago | (#46330781)

If I were SpaceX, the first thing I would have done is tossed an engine in the water, recovered it, and studied it. Landing legs and cushioned landing are sexy and the whole process is very impressive on paper to the less well educated space fanboy (I.E. 99% of them)... but engine refurbishment is the key to the whole process.

Well, the goal is to eventually land them on, er, land so that they don't get dunked. Then you end up with 9 engines and a first stage in fairly good nick with 5 minutes of flight time on it.

I don't know of their timeline, but I'd expect a couple of sucessful water landings, then it'll be time to land somewhere on terra firma. Or a big-ass barge, that might do the job.

Re:SpaceX (1)

DerekLyons (302214) | about 10 months ago | (#46331977)

Then you end up with 9 engines and a first stage in fairly good nick with 5 minutes of flight time on it.

Given that they've recovered precisely zero engines after flight... that's something of an assumption.

Re:SpaceX (1)

rmdingler (1955220) | about 10 months ago | (#46332975)

Not yet, but certainly getting the space program out of exclusively governmental hands is a good first step toward cost reduction techniques like this.

Rocket science has a successful legacy breeding technology that crosses over well. In the 60's, the Minuteman II's use of quad nand gate ICs reduced their cost to the point they could be used in commercial gadgets.

A space vehicle becomes much more practical when it can land, refuel, and planet hop.

Re:SpaceX (2)

NoImNotNineVolt (832851) | about 10 months ago | (#46333409)

I'm pretty sure they've recovered the engine from the Grasshopper test vehicle after each of its seven flights.

Re:SpaceX (1)

inhuman_4 (1294516) | about 10 months ago | (#46333463)

There isn't really anything new going on here, its just never been put togther like this before.

While NASA prefers water landings, the Soviets landed all of their equipment on the ground. So returning things to the ground isn't really that exciting. Additionally there were landing people (who are much more fragile than mechanical parts) from orbit rather than just high in the atmosphere.

And while reusable engines didn't work out that great for the Space Shuttle for various reasons. Lots of rocket engines have been used over and over on test stands on the ground. Rocket engines that can be reused isn't new tech either.

Re:SpaceX (1)

Teancum (67324) | about 10 months ago | (#46333581)

Then you end up with 9 engines and a first stage in fairly good nick with 5 minutes of flight time on it.

Given that they've recovered precisely zero engines after flight... that's something of an assumption.

I think the goal of this particular flight is to recover the engines of the 1st stage after the flight. I think that count is going to go up by a few by the end of next month. The goal is to do land recovery of the rocket eventually though, and to keep the service crew which refurbishes the rocket down to a minimum. As to if SpaceX will be able to accomplish that goal is certainly something to be skeptical about though.

This will be really cool to watch (1)

brentonboy (1067468) | about 10 months ago | (#46329519)

Given the attention to video that SpaceX has given to their other activities, there's a good chance we'll get to see a video of this thing splashing down, depending on how precisely they can land it.

Re:This will be really cool to watch (4, Insightful)

cbhacking (979169) | about 10 months ago | (#46329665)

I look forward to is as well. Assuming it performs like the Grasshopper test platforms (which it really should, given that Grasshopper is basically just a Falcon 9 first-stage itself), they can bring it down, upright, to an accuracy of a few feet. Of course, that was from a much lower altitude than first-stage separation occurs at, and it probably won't have the fuel for braking thrust all the way down, but I still wouldn't be *that* surprised if they manage to make the incredible thing hover for a second before splashing. After all, without the upper stages and with the fuel mostly gone, the first stage is pretty lightweight... not a lot of inertia they need to counteract.

The other amazing thing about all this is that it's pure experimentation. There's no risk, aside from costs, if something goes wrong with this experiment. The payload will continue on up to the ISS regardless of what the first stage does post-separation. By using a wet landing, they avoid the risk of damaging anything on the ground. This is a chance to purely try things out, and it costs almost nothing more than the launch (which NASA is paying for) already would. A fantastic opportunity to try their models in the real world!

Re:This will be really cool to watch (1)

macson_g (1551397) | about 10 months ago | (#46332015)

The other amazing thing about all this is that it's pure experimentation. There's no risk, aside from costs, if something goes wrong with this experiment. [...]

Well, not entirely. First: they add extra fuel for the braking burn (or reduce amount of fuel available for ascent). Second: the legs will change the aerodynamic, and maybe other characteristics of the fuselage.

They did a braking burn before, so I assume 1. is already tested, but I wouldn't say that there is no risk.

And that's why it's so exiting!

Re:This will be really cool to watch (1)

Teancum (67324) | about 10 months ago | (#46333897)

There is reserve fuel that will be available if there is something like a RUD event with the engines or some other problem on the assent, so it is perfectly valid to be burning that reserve fuel supply upon descent. The main problem is that the recovery system eats into the payload part of the rocket equation (legs have mass), thus the efficiency and Isp suffer from the perspective of the rocket as a whole.

Previous recovery systems have eaten so much of the payload that you essentially got a thimble into orbit. The trick and the challenge is to put in a recovery system and still have enough useful payload mass available to put meaningful payloads into space.

Re:This will be really cool to watch (1)

Immerman (2627577) | about 10 months ago | (#46330463)

Indeed, and I'm looking forward to it. Finally we're approaching the towering inverted candles able to set down gently upon alien worlds that were so iconic in golden-age science fiction.

Re:This will be really cool to watch (1)

cbhacking (979169) | about 10 months ago | (#46330793)

True that. Watch the Grasshopper test flights. It's like science fiction come to life!

Re:This will be really cool to watch (1)

Richard_at_work (517087) | about 10 months ago | (#46333089)

Science Fiction came to life when the DC-X Delta Clipper which did everything the Grasshopper did, just 21 years ago.

http://en.wikipedia.org/wiki/M... [wikipedia.org]

Re:This will be really cool to watch (0)

Anonymous Coward | about 10 months ago | (#46338717)

How dare you disrupt services at the church of Musk like this! with your dirty facts

Re:This will be really cool to watch (1)

captainClassLoader (240591) | about 10 months ago | (#46334913)

Speaking of cool to watch, I compete in dog agility, and the last show, a couple of weeks ago, was a couple of miles from Space X's range in Texas. They had two engine tests during the weekend, and even from that distance the noise rattled the arena we were in like an earthquake. A bunch of us would go running outside to watch the enormous cream colored clouds from the tests fill the sky near the horizon. BTW, some dogs totally freaked at the noise (and the sight of their nerd handlers bolting outdoors to see if they were launching Grasshopper didn't help their confidence much, either.) My pups didn't care, fortunately.

"Back to the launch site"? (1)

Michael Woodhams (112247) | about 10 months ago | (#46329795)

How does this work? The rocket will have gone far down range before the first stage separates.

* First stage reverses direction and comes back. Very fuel expensive, I'd be amazed if they're planning this.
* First stage does one 'orbit' (technically it would still be 'sub-orbital') and returns to launch site from opposite direction. Requires that the stage has sufficient energy, and requires some cross-range maneuvering unless you launch from the equator.
* Summary is incorrect, and stage landing site is not the launch site.

In any case, you really want your landing site to be in the middle of nowhere because some failure modes will result in a high energy impact.

Re:"Back to the launch site"? (0)

TheSync (5291) | about 10 months ago | (#46330183)

First stage reverses direction and comes back. Very fuel expensive, I'd be amazed if they're planning this.

I suspect parachute braking with fuel only used in the last few feet.

Re:"Back to the launch site"? (2)

Isca (550291) | about 10 months ago | (#46330321)

Once you've used up 80% of your fuel plus you have dropped the weight of the upper stages and the fuel/payload for them it's relatively light. Especially compared with how much thrust you can output. That 20% fuel is enough to dramatically change your direction and still leave enough fuel to steer yourself and land in an upright position.

Re:"Back to the launch site"? (1)

Michael Woodhams (112247) | about 10 months ago | (#46330887)

A parachute doesn't solve the problem of your stage being hundreds of km downrange from the launch site. A parachute can help in any of my three proposed scenarios. (I think you'd need to jettison the parachute and drop for a bit before firing the rockets, because I don't think you want to try to land while attached to or entangled in a chute. This is what Curiosity did on Mars.)

Re:"Back to the launch site"? (1)

HornWumpus (783565) | about 10 months ago | (#46330575)

Barge landing? Would have to take a lot of heat, but that's just engineering.

Re:"Back to the launch site"? (1)

Michael Woodhams (112247) | about 10 months ago | (#46330833)

Nice idea, but they are landing something that looks like a pencil on its end. They need somewhere rock solid to put it down.

Re:"Back to the launch site"? (1)

HornWumpus (783565) | about 10 months ago | (#46330969)

Bottom stage only. A stubby pencil.

Barges go pretty large. Ballast the thing and it should be pretty stable in good weather.

Re:"Back to the launch site"? (1)

nojayuk (567177) | about 10 months ago | (#46332369)

I suggested Elon buys a second-hand aircraft carrier and uses that. It would solidify his James-Bond supervillain status and piss off Larry Ellison no end as a bonus.

Re:"Back to the launch site"? (4, Informative)

bledri (1283728) | about 10 months ago | (#46330923)

How does this work? The rocket will have gone far down range before the first stage separates.

* First stage reverses direction and comes back. Very fuel expensive, I'd be amazed if they're planning this.

That's exactly what they intend to do. They refer to it as "boost back." Fuel is cheap compared to the price of a rocket. Right now they are working on a fully reusable first stage and a capsule that lands under propulsive power. After that they'll work on the second stage returning (it can just complete an orbit instead of boosting back. Here's an animation they put out to show the concept. [youtube.com]

Here's an article explaining the current status of the effort [nasaspaceflight.com] and what they hope to achieve with this test.

Re:"Back to the launch site"? (1)

Michael Woodhams (112247) | about 10 months ago | (#46331395)

OK, so I'm officially amazed.

Fuel is cheap when it is sitting in a tank on the ground. Fuel at 100 km altitude and 5km/s speed is a very different story. Fuel which you keep in stage I for 'boost back' is fuel you aren't using to put your payload into orbit, meaning you have lower maximum payload.

Re:"Back to the launch site"? (2)

ColaMan (37550) | about 10 months ago | (#46331909)

It seems that the quantity of fuel required to fly an nearly empty 1st stage is negligable. That is, the amount that they normally leave behind as reserve in case of issues getting to orbit is enough for the 1st stage to land with - you basically just fall/parachute as far as you dare and then fire the engines at the last second to steady/cushion the landing.

Re:"Back to the launch site"? (1)

cheesybagel (670288) | about 10 months ago | (#46332139)

Of course you are going to have less payload with a reusable rocket. The whole idea is that the launch cost per kg will be lower and you use more launches to get the same mass up. Or build a bigger launch vehicle. The problem is if you get zero or negative payload in the process...

Re:"Back to the launch site"? (1)

Michael Woodhams (112247) | about 10 months ago | (#46332599)

I'm not comparing non-reusable rocket to reusable rocket. I'm comparing reusable rocket which returns to launch pad with reusable rocket which lands downrange of launch pad.

The Merlin 1D engine is critical to this. (1)

Anonymous Coward | about 10 months ago | (#46332167)

The improvements in the Merlin 1D give Space-X a higher payload fraction in the Falcon9 v1.1 or extra fuel they can use for reusing the first stage.

Re:"Back to the launch site"? (0)

Anonymous Coward | about 10 months ago | (#46332335)

Yes, the cost is significantly reduced payload/orbital height. That much is obvious. But if you reduce cost per flight by a magnitude or more, does it matter? Also ISS is on pretty low orbit, so its not that much of a problem. The barrier on space tech is cost of launch, not so much raw tonnage. Falcon 9 can currently deliver 13 tons to LEO, that's a lot, cutting that capability for lower price might very well be worth it. Falcon 9 heavy is planned for 53 Tons to LEO, so there is even more you can play with. In comparison Dragon capsule has dry mass 4200kg, and payload up to 3310kg so for Falcon 9 + Dragon, you can get away with half the Falcon 9 payload to LEO. If that means full re-usability and cost reduction in magnitudes - you are golden.

In my book any development that aims to make spaceflight cheaper is worth the effort

Re:"Back to the launch site"? (2)

tp1024 (2409684) | about 10 months ago | (#46332455)

Well, they want to sacrify about 20-30% payload (out of about 16 tons) to do the flyback. They also separate the first stage at Mach 6, or 1.8 km/s. But that's after leaving most of the atmosphere behind and overcoming a lot of the gravity losses during launch. So the actual energy budget is better than it seems to be. Still, the second stage has to do more work than it normally would - some 6km/s are left. About 5/6th of the second stage, including payload, must be fuel. But the engine weighs less than 700kg and tanks for kerosine and LOX only have about 2-3% of the mass of the fuel they contain. So, there is plenty left for the payload.

All of which makes the whole thing a lot more feasible with a lot less fuel than you'd ordinarily assume.

Re:"Back to the launch site"? (0)

Anonymous Coward | about 10 months ago | (#46330943)

"the entire first stage rotates 180 degrees via Reaction Control System (RCS) thrusters, and then reignites three of its nine engines to “boost back” the near-empty stage back to the launch site." (http://www.nasaspaceflight.com/2012/01/spacex-testing-reusable-falcon-9-technology-this-year/)

Reverses direction and boost back is 100% correct. From multiple sources including this video simulation from SpaceX: http://www.youtube.com/watch?v=sSF81yjVbJE&feature=related

Re:"Back to the launch site"? (0)

Anonymous Coward | about 10 months ago | (#46331317)

SpaceX has been looking at opening a launch facility in Brownsville, TX, and recovering first stages at Kennedy. I don't know of any actual plan they have to land at the original launch site, which would indeed be very fuel-intense.

Re:"Back to the launch site"? (1)

Michael Woodhams (112247) | about 10 months ago | (#46331423)

Other replies I have (above) say they do indeed intend to land back at the actual launch site.

Maybe the 'boost back' is just while they're developing the system, and 'land at Kennedy' is the long term plan.

Landing in the dark (0)

Anonymous Coward | about 10 months ago | (#46330961)

Sadly, the upcoming COTS launch is late at night. Probably not much video coverage of the soft landing.

Re:Landing in the dark (1)

tp1024 (2409684) | about 10 months ago | (#46332465)

Rumor has it, that they'll have one heck of a torchlight at the landing spot.

Landing legs... water landing... (1)

NoImNotNineVolt (832851) | about 10 months ago | (#46333633)

I've watched the grasshopper videos countless times, but let me get this straight.

This time, the landing legs will supposedly be actuated. They'll fold out just before "landing". I don't think they've done this before, or at least it didn't look like it from the videos. Cool.

This time, they'll be "landing" on water instead of the launchpad. I wouldn't call it landing if it's not on land; they'll be ditching into the ocean. This makes sense, as this is a real mission for a paying customer, not some engineering demo, and any failures (even ones that don't actually impact their customer's mission) would bring lots of bad publicity. Setting the bar low is prudent.

Now, this is all awesome stuff, but I can't help but wonder... What good are landing legs when you're landing in the ocean?

Seriously. Are the legs gonna have flotation devices attached? Is the rocket going to bob around in the ocean, upright, balancing on these landing legs as the waves roll by? I understand the reasoning behind doing a soft landing in the ocean. I just don't understand what the landing legs are for.

Re:Landing legs... water landing... (1)

bledri (1283728) | about 10 months ago | (#46334869)

This time, the landing legs will supposedly be actuated. They'll fold out just before "landing". I don't think they've done this before, or at least it didn't look like it from the videos. Cool. ...

Now, this is all awesome stuff, but I can't help but wonder... What good are landing legs when you're landing in the ocean?

... I just don't understand what the landing legs are for.

They are doing this to collect data with the goal of eventually boosting back and landing near the launch pad for rapid reuse. The legs actually do help, they reduce aerodynamically induced spin and the terminal velocity. But mostly this is a test so they can gain confidence to return to land.

Re:Landing legs... water landing... (1)

Cytotoxic (245301) | about 10 months ago | (#46335285)

On the last test the stage began to spin too rapidly and the engine shut down because the fuel was slung out of reach of the fuel intake. This time they will have the legs attached which helps with stability on the way down. The water part is just for safety - if you lose control during a landing in the middle of the ocean you crash in the middle of the ocean. Losing control on the way back to Canaveral and crashing into Cocoa Beach would be bad.

Re:Landing legs... water landing... (1)

tibit (1762298) | about 10 months ago | (#46335701)

They could probably sell the scrap to collectors and recover a good chunk of the material costs at least :)

Re:Landing legs... water landing... (0)

Anonymous Coward | about 10 months ago | (#46336125)

The legs are there to see if the legs work. This is a test of the legs: whether they open, and what effect they have (aerodynamic and countless other factors) on launch and flight.

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