Space

SpaceX's next booster stage will attempt to propulsively land on a floating platform

SpaceX's next booster stage wi...
During the upcoming ISS resupply mission, SpaceX will attempt to propulsively land the booster stage of a Falcon 9 rocket on a floating platform in the Atlantic Ocean
During the upcoming ISS resupply mission, SpaceX will attempt to propulsively land the booster stage of a Falcon 9 rocket on a floating platform in the Atlantic Ocean
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During the upcoming ISS resupply mission, SpaceX will attempt to propulsively land the booster stage of a Falcon 9 rocket on a floating platform in the Atlantic Ocean
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During the upcoming ISS resupply mission, SpaceX will attempt to propulsively land the booster stage of a Falcon 9 rocket on a floating platform in the Atlantic Ocean
The second stage recovery will have to wait for SpaceX's next generation of rockets (Photo: SpaceX)
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The second stage recovery will have to wait for SpaceX's next generation of rockets (Photo: SpaceX)
The next ISS cargo resupply mission is scheduled for December 9th, 2014 (Photo: SpaceX)
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The next ISS cargo resupply mission is scheduled for December 9th, 2014 (Photo: SpaceX)
If successful, SpaceX will eventually move to landing its booster stage on land for easier refurbishment and reuse (Photo: SpaceX)
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If successful, SpaceX will eventually move to landing its booster stage on land for easier refurbishment and reuse (Photo: SpaceX)
The latest version of the Falcon 9 rocket is 60 percent more massive, containing enough fuel to attempt a soft landing on most mission profiles (Photo: SpaceX)
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The latest version of the Falcon 9 rocket is 60 percent more massive, containing enough fuel to attempt a soft landing on most mission profiles (Photo: SpaceX)
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Yesterday at MIT's AeroAstro Centennial Symposium, SpaceX CEO Elon Musk said his company will make a first attempt to land the booster stage of its Falcon 9 rocket on a floating platform during the upcoming ISS resupply mission. If the attempt is successful, the company plans to refurbish and reuse the booster stage, making spaceflight history and paving the way for a significant reduction in the cost of access to space.

Achieving a practical, largely reusable spacecraft has been the holy grail of spaceflight for the past few decades, and for very good reasons. Propellant only makes up a tiny percentage (in the case of a Falcon 9 rocket, about 0.3 percent) of the cost of the craft, so being able to reuse all the hardware for multiple flights could potentially slash the cost of spaceflight by a factor of 10 or more.

NASA has been keeping a close eye on SpaceX's progress on the rocket reusability front, partly to investigate how the space agency might be able to land very heavy payloads on the surface of Mars in the coming years. As SpaceX was contracted to resupply the International Space Station, the space agency had a front seat as it witnessed the first stage of the Falcon 9 rocket attempt several boost-backs through the atmosphere leading to, so far, two successful soft landings in water – during the third and fourth ISS resupply missions, respectively.

Now, SpaceX and Tesla CEO Elon Musk has said that, on the fifth resupply mission planned for December 9th, the reusable rocket program is ready to go one step further: instead of a soft water landing, the first stage will attempt for the first time to propulsively land on a floating platform in the middle of the Atlantic Ocean.

"Before we boost back to the launch site and try to land there, we need to show that we can land with precision over and over again," said Musk. "So for the upcoming launch we've got a chance of landing on a floating platform. We have a huge platform that is being constructed at a shipyard in Louisiana right now which is 300 feet long by 170 feet wide (90 by 50 meters)."

The latest version of the Falcon 9 rocket is 60 percent more massive, containing enough fuel to attempt a soft landing on most mission profiles (Photo: SpaceX)
The latest version of the Falcon 9 rocket is 60 percent more massive, containing enough fuel to attempt a soft landing on most mission profiles (Photo: SpaceX)

That might seem like a massive target when you consider that the goal for SpaceX is to propulsively land "with the accuracy of a helicopter," but there's a number of adverse factors. First of all, the legspan of the rocket is quite large, at 60 feet (18 m). Secondly, the platform will be out in the Atlantic Ocean, well out of harm's way should anything not go to plan, and therefore it won't be anchored to the seafloor. Instead, several motors will try and keep it level and at specific GPS coordinates, waiting for the stage to land at that precise spot a few minutes after launch.

"If we land on that [platform], I think we'll be able to refly that booster," Musk continued. "It's probably not more of a 50 percent chance of landing it on the platform [on the first try], but there's a lot of launches that will occur over the next year, at least a dozen, so I think it's quite likely, probably 80 or 90 percent likely, that one of those flights will be able to land and refly."

All Falcon 9 booster stages come with the hardware allowing them to attempt a soft splashdown, but this isn't always possible depending on the payload of the rocket. For instance, launching a satellite in geostationary orbit requires a larger amount of propellant to be drawn from the booster stage, not leaving enough in the tanks to attempt a landing.

In his talk, Musk also gave more insights into the advantages of propulsive landing as opposed to the more familiar approach of recovering hardware with a parachute-driven soft landing in the ocean. As it turns out, the landing legs equipped in the reusable version of the Falcon 9 also double as giant body flaps that are able to generate a large amount of drag as the stage travels through the atmosphere, cutting terminal velocity – and therefore the propellant needed to boost back to a soft landing – in half.

If successful, SpaceX will eventually move to landing its booster stage on land for easier refurbishment and reuse (Photo: SpaceX)
If successful, SpaceX will eventually move to landing its booster stage on land for easier refurbishment and reuse (Photo: SpaceX)

Introduced in September last year, the latest iteration of the Falcon 9 rocket is approximately 60 percent heavier than the initial expendable version, with the bigger tanks in the first stage containing the extra fuel needed for powered landing.

But, while SpaceX might finally be closing in on reusing the booster stage (which reportedly accounts for about 70 percent of the cost of the rocket), building a reusable second stage won't be nearly as easy as storing more propellant in the second stage of the Falcon 9. In fact, Musk said yesterday, the second stage in the Falcon family will never be reusable, due to the low specific impulse of the engine and the fact that the mission profile often involves launching satellites in geostationary orbit, which is way too far for an easy boost-back.

So, for a reusable second stage from SpaceX, we will have to wait for the next generation of rockets.

"With the next generation of vehicles, which is a methane-oxygen system in which the propellants are cooled to close to their freezing temperatures to increase the density, we can definitely do full reusability," said Musk. "We're talking about a much bigger vehicle, and we're also going to be upgrading to a full-flow staged combustion. That system is intended to be a fully reusable transportation system all the way to Mars and back."

Musk said that we could start seeing the first test flights for that system as early as five or six years from now.

Source: MIT

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7 comments
Darin Selby
There STILL is no forethought to the environmental repercussions, or the detrimental effects from burning "hypergolic rocket propellants", and how that affects all living things!
Burning these propellants create INCREDIBLE amounts of toxic emissions with every firing of these rockets!
This reusable spacecraft technology doesn't even bother using the energy-saving method of PARACHUTING, or even GLIDING back to Earth, as the Space Shuttle did! Instead it uses RAW ROCKET POWER to muscle its way back down to Earth, all the while spewing 800 pounds of toxic emissions during its re-entry and landing phase.
The hypergolic propellant would have to be something like 80% of Dragon's mass. And I've read that it carries 800 POUNDS of hypergolic propellant.
Although hypergolic propellants tend to be difficult to handle because of their EXTREME toxicity and/or corrosiveness, they can typically be stored as liquids at room temperature and hypergolic engines are easy to ignite reliably and repeatedly.
In contemporary usage, the terms "hypergol" or "hypergolic propellant" usually mean the most common such propellant combination, dinitrogen tetroxide plus hydrazine and/or its relatives monomethyl hydrazine and unsymmetrical dimethylhydrazine. These chemicals, stored in the SpaceX Dragon V2 payload capsule, are EXTREMELY toxic to all living things.
Derek Howe
I can't wait to watch that footage, its going to be awesome!
Robert Walther
Not nearly as toxic as no space travel at all.
Kaido Tiigisoon
Dear Darin.
The combustion products for MON and MMH are nitrogen, water vapor and carbon dioxide. If any of those are "extremely toxic" then you should drop dead right now because that's the mixture You're breathing (plus some oxygen and trace amounts of other gases).
Yes, both MMH and N2O4 are both extremely toxic, but in case of Draco engine only relatively small amounts are used. First stage of the Falcon 9 (the main subject of the article) burns petroleum in oxygen - both relatively harmless.
Embur
Re: @Darin Selby. Dear Darin, did you just read the same article that I did?
Regarding your comments re: "Parachuting or Gliding". If you had read the article you would have read that the landing legs, "double as giant body flaps that are able to generate a large amount of drag as the stage travels through the atmosphere, cutting terminal velocity – and therefore the propellant needed to boost back to a soft landing – in half". Not exactly RAW ROCKET POWER is it? And you need to keep in mind that this isn't a tiny crew capsule that can float gently back to earth under a couple of 'chutes, this is a first stage over 50 metres long. Parachutes big enough to soft land this rocket would be so big they would blot out the sun...
Regarding your comments re: "The detrimental effects from burning "hypergolic rocket propellants", and how that affects all living things!" The main engines of the Falcon 9 burn a LOX/ RP-1 mix, not any form of hypergolic fuel. RP-1 is basically highly refined kerosine, so during its re-entry the exhaust would be much the same as that of a commercial jet aircraft. The Dragon on the other hand does use hypergolic propellant, it uses N2O4 / MMH because as you yourself pointed out, "hypergolic engines are easy to ignite reliably and repeatedly." It's a very good thing when your engines and manouvering thrusters fire reliably and repeatedly when you're at an altitude of more than 100 km, and your speed is measured in mach numbers. As for 800 pounds of "fuel" being 80% of Dragons mass, not even close on either count. Dragon carries (according to wikipedia) up to 1,388 kg (3,060 lbs) of propellant, and masses 4,200 kg (9,300 lb) dry. So the propellant actually makes up about 25% of Dragons total mass, and most of that propellant will be burnt... in space.
I hope you respond to this post, because I would actually like to know the "environmental repercussions, or the detrimental effects from burning "hypergolic rocket propellants", and how that affects all living things". I'm not a scientist or a chemist, but i'm willing to bet the effects of a relative handful of rocket launches are much, much smaller than the effects of the 1,100,000,000 cars currently on the worlds roads.
And, yes.The footage will be awesome!
habakak
'...or even GLIDING back to Earth, as the Space Shuttle did...'
Darren, the Space Shuttle program was an immense failure (off course it had successes, but look at the cost). It cost $500 million per launch. With over 100 launches, that's over $50 billion. Enough to eat up NASA's full annual budget for a 4 or 5 years. We are trying to make space flight cheaper, not more expensive. Too expensive = not sustainable. Gliding home might look cool, but it's not realistic at this point.
The environment will be fine. There are many many more things that you and I partake in every day that is much more destructive to the environment than launching a few rockets every week somewhere on earth.
Slowburn
@ habakak The shuttle was incredibly poorly designed. From choosing the wrong fuel for surface to LEO flight Through the decision to make a hybrid design encompassing both NASA and Air Force requirements. The LH forced the external tank which killed both Challenger and Columbia. STS also required far to much maintenance between flights a trait they shared with another Rockwell design the B-1 bomber.