SpaceX Testing Landing Legs On Next Falcon9 Rocket

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) .

Comments

nano nanosatellites?

[Anonymous Coward]

Did Mork write the summary?

SpaceX

[beltsbear]

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...

Re:SpaceX

[cbhacking]

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

[strack]

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

[cbhacking]

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

[ColaMan]

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

[Confusador]

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

Re:SpaceX

[strack]

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

Re:SpaceX

[strack]

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

[cheesybagel]

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

[Teancum]

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

[Teancum]

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 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

[NoImNotNineVolt]

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

Re:This will be really cool to watch

[cbhacking]

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:"Back to the launch site"?

[Isca]

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"?

[bledri]

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.

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

Re:"Back to the launch site"?

[ColaMan]

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"?

[tp1024]

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.