Commercial spaceflight venture SpaceX has been talking for a while now about reusing every part of its space launch system, from the optionally manned Dragon capsule (which is already reusable) to the rocket stages that it discards on its way to orbit. Via a new animation, the private space enterprise is showing exactly how this would happen, not via splashdown and recovery at sea like you might be thinking, but by vertically landing back at the launch site under their own power.
Right up front, let's just note that we're a bit skeptical. The scheme calls for the rocket stages to basically fly themselves back to the launchpad--using a series of small external jets to orient themselves--and then touch down gently using their main engines to provide enough reverse thrust to counter the effects of gravity. Even if the seriously delicate choreography required to guide a huge, falling, cylindrical rocket stage back to the launch site could be worked out, it seems like each stage would have to carry quite a bit of extra fuel to provide enough reverse thrust to gently set down at their point of origin.
That being said, we're having a bit of trouble thinking of something SpaceX (and PayPal, and Tesla Motors) founder Elon Musk has put his money and mind behind that hasn't enjoyed at least to some degree of success. And it's probably safe to say that we're not the only ones who have thought of aforementioned issues. But until we see it happen, let's just say we're guarded but enthusiastic about the idea.
We're enthusiastic because if SpaceX can figure this out, they could drastically cut the cost of getting to orbit. And SpaceX isn't even planning on stopping there. The company is determined to create a reusable system that can eventually launch regular manned missions to Mars.
That's far out on the horizon. But in the nearer term, as New Scientist's One Per Cent blog points out, a reusable rocket immediately brings the benefit of flight testing to the realm of space rocketry--that is, you can fly a rocket once or twice before you put people or expensive payloads aboard. That means SpaceX isn't just setting a course for cheaper space access, but for safer space launches as well.
Parachutes not an option? Seems like that would cut the need for extra fuel drastically.
Without chutes!? This looks dangerous - in case if any of landing engines would stop working, whole crew would burn in atmosphere. Or even if one of the engines will work not 100% correct - unpredictable things can happen...
Parachutes add more weight than the rocket fuel needed and are of no use until speed is reduced to a few hundred mph.
Given the area of bearing it should be very sensitive to winds
@Nikarus & RettaH_daM
Parachutes may be added along with the design as a redundancy and/or countermeasure to ensure a safe landing. Besides, this would definitely reduce cost and increase operational speed if you didn't have to stack every rocket component everytime you want to have a flight. They're trying to make spaceflight somewhere near the operational expedience of all other vehicular modes of transportation (i.e. planes, trains, and automobiles). Doing so allows you to get more operational efficiency and longevity out of your devices, not to mention expedite the processes in putting together larger space based projects, like say, an interplanetary vessel. They could build one faster with quick launch vehicle turn arounds.
Yes I agree with you, actually my main concern here is that they don't use parachutes on capsule with humans.
By the way, similar technology is used on Curiosity's descent stage. I suppose they shared some experience. Guys from NASA said that they done a lot of tests and it is safer than it looks. Lets hope so...
Safety is a general concern. But, the safest thing to do is nothing at all.
SpaceX is out of this world! Mega Cheers!
The vertical landing technique is not new - the McDonnell Douglas DX-X did it in the 1990's. With modern computers, precision GPS, miniature radar and LIDAR sensors, laser rangefinders, highly throttle-able and gimbaled rocket engines and such it's easier than it looks.
Smaller demonstrators from Armadillo Aerospace & Masten Space Systems have also done it, and Blue Origin (owner: Amazon's Jeff Bezos), one of SpaceX's fellow Commercial Crew Development competitors, has also demonstrated the tech though not yet from orbit.
SpaceX itself plans on using the SuperDraco launch abort thrusters being developed for the Dragon spaceship for vertical landings as shown at the end of the video. The NASA milestone for testing this 'DragonRider' system is May 2012, with SuperDraco thruster tests starting very soon.
At any rate: the FAA has already granted SpaceX permits to begin testing of their concept at their McGregor, Texas test site under the project name of Grasshopper.
The Grasshopper program starts soon and is anticipated to run 3 years.
"Without chutes!? This looks dangerous - in case if any of landing engines would stop working, whole crew would burn in atmosphere. Or even if one of the engines will work not 100% correct - unpredictable things can happen..."
The Dragon will still have parachutes as a backup. It has 3, but only needs 1 to make a safe landing. Redundancy is a good thing.
As for burning up; its PICA-X heat shield is an upgrade of NASA's PICA system, and it was developed in conjunction with NASA's Ames Laboratory. It can handle re-entering from deep space (Mars etc.) at 30,000 mph, nearly 2x the velocity of an orbital re-entry.
The DragonRider system uses 8 SuperDraco thrusters mounted in pairs 90 degrees apart, but each is individually controlled. The fuels are hypergolic, they ignite on contact, and they are moved by gas pressure from cylinders so pumps aren't required - just valves.
There is no need to fire DragonRider all the way down because as it falls after re-entry it soon reaches 'terminal velocity,' a speed that's a function of gravity, air resistance, the diameter & shape of the object and its mass. For Dragon this is around 250 mph, so it can free fall like a skydiver until the thrusters are needed for the landing. If they don't light (gas cylinder leaks etc.) the parachutes can be deployed.
To make a landing the thrusters only need to run at 20-25 percent thrust because 100% is only needed for high-G launch aborts, so if one fails its partner can simply be throttled up. It's logical to presume that if both in a pair fail the pair opposite it could be throttled down to minimize sliding sideways and the other 4 throttled up. Steering is by thrust differential.
The odds of all of these failures to happen in one flight are miniscule. If the Space Shuttle had 1/4 of the safety systems being designed into the crew Dragon.....
I don't understand the advantage of using this system to recover the stages of the launcher.The extra weight only takes away payload capacity from the launch vehicle.A significantly bigger rocket would be required to lift a given payload,which increases costs.
Thank you for the info! Looks much safer to me now.
But still I don't understand - if it got parachutes then why not to use them - wouldn't it be cheaper?
@Nikarus...not necessarily, it would need to be transported back to the launch facility, a huge logistics operation, especially from an ocean landing, cheers
I think parachutes are a great and proven idea. It could also be they simply wish the challenge of a controlled soft upright landing and so this is their new goal.
Creating new challenges and achieving new goals is how we develop new technology and bring future opportunities. But, I do like the way you think.;)
See life in all it's beautiful colors, and
from different perspectives too!
Landing using the DragonRider burns up about 1,200 kg of unused launch abort fuels, which also happen to be highly toxic: mono-methane hydrazine and nitrogen tetroxide. These are commonly used thruster fuels (Shuttle, Soyuz, most satellites etc.) because they're both reliable and store well in space, though alternatives are being sought. Burning them up makes ground handling after the flight much safer.
Parachutes are not 100% safe either - the lines can tangle or break, canopies can tear etc. Both the Russians and US have lost returning spacecraft from parachute failures. Thrusters that use self-starting fuels are potentially more reliable, plus it adds yet another layer of redundancy & safety.
<b>As to stage recovery:</b> by the time the first stage separates 90+% of it's mass, expended fuel, is gone. From there a small amount of thruster fuel flips it over, then it lites 3 of its 9 engines just long enough to bring it about - which is easier than it looks because of the mass reduction. Then it free-falls at its terminal velocity (tail-down because that's where the center of mass is) and deploys it's landing gear. Once near the ground it lites a single engine, gimbaling it to steer, and lands. This minimizes the burn time, and therefore the fuel needed.
The second stage is different - it goes to orbit, so after it deploys its payloads it then orbits and re-enters over a target area, just as Dragon would. It doesn't use the main engine to land because it's too light. Instead most analysts I've read think it'll use SuperDraco's like Dragon.
Yes, this takes more fuel but the beauty of the Falcon 9 is that the structure is monocoque - the tanks are the fuselage - and made up of 3.66 meter diameter rings with common bulkheads defining the tankage volumes. As such, if they need 10% more fuel to pull it off they can just stretch the whole rocket by adding more rings. The MVAC second stage uses the same basic structure but with fewer rings, a different engine mount (1 instead of 9) etc.
This kind of commonality both reduces costs and speeds development, evidence of which is that due to a large increase in thrust for the imminent next-gen Merlin-1D engine it will use more fuel. Solution: stretch the rocket.
Another interesting tidbit is how SpaceX is making rocket engines a mass production item instead of hand built low production items. Normally a block of metal would be precision machined, then slowly plated to form the thrust chamber and exhaust throat. Starting with the Merlin-1D they changed the tune: they're using explosive hydroforming. Put a mold and alloy cylinder into a thick, cement-like liquid then set off a shaped explosive charge in the middle. <b>POOF!</i>
They're already test-firing them in Texas.
Just how far down range will the first stage be when it's job is done? Wouldn't it have to land in Africa? Would it make a complete orbit around the earth? That's the only flaw I can think of.
A non-recoverable Falcon 9 first stage splashes down about 980 miles downrange and isn't going fast enough to go into orbit. Accelerating to orbital velocities is the job of the MVAC second stage.
If it turns and decelerates shortly after MECO (main engine cut off) this distance would be much reduced. From then it's a matter of how much residual fuel there is. If not much it could land on a prepositioned converted oil platform or barge akin to what SeaLaunch uses to fire off Russian Zenits. If a lot then it could be put on a ballistic course back to Florids OR pushed further to land on or just off the African coast.
Of course all those speculations presume a Florida launch, which is not guaranteed since SpaceX is looking to build their own commercial spaceport. Candidate locations include Texas, Puerto Rico, Hawaii and a few others.
I love how all the long comments ignored Newbeak5.
"I don't understand the advantage of using this system to recover the stages of the launcher.The extra weight only takes away payload capacity from the launch vehicle.A significantly bigger rocket would be required to lift a given payload,which increases costs."
My thoughts exactly. Double check which one is costlier, fuel, or rockets. Not to mention comparing danger vs. other touchdown methods.
I love how you ignored my previous comment.
"Safety is a general concern. But, the safest thing to do is nothing at all."
This concept is based on not just increased safety and reduced cost (which is neither here nor there). It's about increasing operational efficiency and speed. It takes a lot of time to stack a rocket and prep it for launch. A rocket that could "restack" on or near the pad without the need for the pieces to be apprehended by helicopters and freighters would tremendously increase turn around on space operations. You could send more than one flight up at a time in a shorter period. Space construction could be reduced from a decade to a quarter of a decade. More than just NASA centered experimentation can be conducted at any given moment. It's a small but significant step to simplifying spaceflight to the level of commercial and general aviation. We can't work towards a future of personally owned space vehicles if we don't start somewhere outrageously complex from current standards.