SpaceX Clips Dragon’s Wings After Investigation

When the SpaceX Dragon spacecraft reached orbit for the first time in 2010, it was a historic achievement. But to qualify for NASA’s Commercial Orbital Transportation Services (COTS) program, the capsule also needed to demonstrate that it could return safely to Earth. Its predecessor, the Space Shuttle, had wings that let it glide home and land like a plane. But in returning to the classic capsule design of earlier spacecraft, SpaceX was forced to rely on a technique not used by American spacecraft since the 1970s: parachutes and an ocean splashdown.

The Dragon’s descent under parachute, splashdown, and subsequent successful recovery paved the way for SpaceX to begin a series of resupply missions to the International Space Station that continue to this day. But not everyone at SpaceX was satisfied with their 21st century spacecraft having to perform such an anachronistic landing. At a post-mission press conference, CEO Elon Musk told those in attendance that eventually the Dragon would be able to make a pinpoint touchdown using thrusters and deployable landing gear:

The architecture that you observed today is obviously similar to what was employed in the Apollo era, but the next generation Dragon, the Crew Dragon, we’re actually going to be aiming for a propulsive landing with gear. We’ll still have the parachutes as a backup, but it’s going to be a precision landing, you could literally land on something the size of a helipad propulsively with gear, refuel, and take off again.

But just shy of a decade later, the violent explosion of the first space worthy Crew Dragon has become the final nail in the coffin for Elon’s dream of manned space capsules landing like helicopters. In truth, the future of this particular capability was already looking quite dim given NASA’s preference for a more pragmatic approach to returning their astronauts from space. But Crew Dragon design changes slated to be implemented in light of findings made during the accident report will all but completely remove the possibility of Dragon ever performing a propulsive landing.

Risk Versus Reward

On paper, the ability for Crew Dragon to propulsively make a soft landing essentially anywhere on Earth is a huge advantage for NASA. For example, consider a scenario where there is a medical emergency aboard the Space Station; Crew Dragon offered not only a gentler touchdown than slamming into the ocean under parachutes, but it could be directed to land the injured crew member in a more convenient location. Instead of dropping an astronaut in the middle of a heart attack miles off the coast, they could potentially be brought down in the Nevada desert and taken to the hospital in an ambulance.

SpaceX concept art of propulsive landing

Even in more mundane scenarios, a soft landing is less stressful for a crew that will already be in a weakened state due to their long stay in orbit. It’s also better for delicate scientific payloads which are being returned from the Station. Being able to land the Crew Dragon back at Kennedy Space Center would also give NASA the ability to quickly access time-sensitive experiments, one of the many capabilities the agency lost with the retirement of the Space Shuttle. The advantages of a soft landing are so great that one of SpaceX’s competitors in the COTS program, Sierra Nevada Corporation, positioned the ability to resume Shuttle-like landings as the keystone element of their Dream Chaser spaceplane proposal.

But despite the many advantages of soft landing an orbital spacecraft, the Dream Chaser didn’t get selected to continue with the COTS program, and Elon Musk eventually admitted the capability for Crew Dragon had been put on the back burner. When asked about it at the 2017 International Space Station Research and Development conference, he said the concept worked on a technical level, but that it had run afoul of NASA’s culture of safety:

Dragon 2 is capable of landing propulsively. Technically, it still is. Although you’d have to land it on some pretty soft landing pad because we’ve deleted the little legs that pop out of the heat shield. But it’s technically still capable of doing it. The reason we decided not to pursue that heavily is it would have taken a tremendous amount of effort to quality that for safety, particularly for crew transport…It could be something that we bring back later, but it doesn’t seem like the right way to apply resources right now.

The message was clear. NASA had already lost a Space Shuttle due to an overly complex heat shield, and didn’t want to take any unnecessary risks with their new commercial partners. It might not be ideal, but the ocean splashdown is a simple and reliable way of getting humans back home safely; a logical choice for companies that are building their first generation of manned spacecraft.

For Emergency Use Only

Saying that the Crew Dragon could technically perform a propulsive landing on a “pretty soft landing pad” might sound like a joke, but with Elon Musk, you should never rule anything out. SpaceX already built a net-equipped ship to catch the Falcon 9’s falling payload fairing, and it stands to reason the same concept could be used with Dragon. It might seem like an unnecessary extravagance just to keep propulsive landings on the table, but it’s important to remember that the SuperDraco landing engines also double as the spacecraft’s Launch Escape System (LES). So no matter what, the engines and all their associated mass are permanently part of the spacecraft.

SuperDraco engines firing during 2015 LES test

Unfortunately, this complex dual-function system has now become something of a liability. SpaceX believes the explosion in April was not due to a fault in the SuperDraco engines themselves, but in a leaky one-way check valve. Put simply, the propellants leaked into a part of the system in which they were never designed to be. When the propellant tanks were pressurized in preparation of firing the engines, the foreign liquids caused the plumbing to rupture. The resulting release of the highly energetic hypergolic hydrazine and nitrogen tetroxide propellants used in the SuperDraco tore the spacecraft to pieces almost instantaneously.

In other words, the event uncovered a serious flaw in the SuperDraco propellant delivery system. If this had happened in 2017, SpaceX would perhaps have taken the time to redesign the system. But it’s 2019, and the Crew Dragon is already considerably behind schedule. NASA and the White House are eager to get astronauts launched from American soil again, and there’s no time to make such extensive changes to the spacecraft.

To remedy the problem to NASA’s satisfaction in the least amount of time possible, SpaceX has decided to replace the valves in question with burst discs. As the name implies, these are one-time-use devices that literally burst when the pressure behind them is high enough. This will solve the problem of propellants leaking where they aren’t supposed to be, but it will also fundamentally change how the engines can be used.

Replacing the valves with single-use burst discs means the SuperDraco engines cannot be fired until they are actually needed, and when they are activated, they’ll likely be run until the propellant tanks are dry. In short, the switch to burst discs means the SuperDraco engines are much closer to the traditional “one and done” abort systems than SpaceX originally envisioned.

Onwards and Upwards

The abandoned “Red Dragon” concept

The decision to walk back on a feature that had been publicly touted for nearly a decade was undoubtedly a difficult one for SpaceX. But the pressure to get the Crew Dragon up and running with baseline functionality is simply too great. NASA needs SpaceX to start running regular crew rotation missions to the International Space Station, and if that means a return to Apollo-era ocean landings, so be it. The agency has gone so long without the Shuttle at this point that they’ve largely come to terms with losing its precision soft landing capability.

On the other hand, SpaceX had themselves been cooling on the idea in recent years, and this situation may be the out they needed to finally bring this chapter of Dragon’s development to a close. There was a time when SpaceX saw propulsive landings on Earth as a precursor to landing the Dragon on Mars. But with SpaceX’s future plans for the Red Planet now focused on their massive Starship, refining the capability on the Dragon doesn’t offer much in the way of useful data for the company.

When pressed for further comment during his Q&A at the ISS R&D Conference on how the removing Crew Dragon’s landing gear would affect its ability to eventually land on Mars, the mercurial Elon hinted that plans had already changed behind the scenes at SpaceX:

There was time when I thought that the Dragon approach to landing on Mars, where you’ve got a base heat shield and side mounted thrusters, would be the right way to land on Mars. But now I’m pretty confident that that is not the right way, and there’s a far better approach. That’s what the next generation of SpaceX rockets and spacecraft are going to do. So the difficulty of qualifying Dragon for propulsive landing, and the fact that, from a technology evolution standpoint, it was no longer in line with what we’re confident was the optimal way to land on Mars. That’s why we’re not pursuing it.

120 thoughts on “SpaceX Clips Dragon’s Wings After Investigation

  1. Shouldn’t NASA reconsider their choice then, parhaps the Dream Chaser could fulfill the original promise?

    Or perhaps Space X knew all along but included it anyway in order to win? There are lots of companies that will under bid another to get the contract and then have to ‘adjust’ afterward.

    1. Sierra Nevada Corporation actually appealed the decision saying they felt their bid offered a compelling value, especially since both selections (SpaceX and Boeing) were doing traditional capsules. Long story short, the resulting inquiry revealed NASA had doubts about Sierra Nevada being able to deliver on promised goals.

      It’s worth noting that they are now working on a cargo version of Dream Chaser, which would allow for the return of sensitive equipment/experiments. Since it’s not being made for humans, it will be easier and cheaper to get that version up and running. So long term, NASA might get some of that functionality back.

        1. I’d love to see the Dream Chaser fly. It’s an interesting spacecraft with a long and fascinating history. But that said, I do have my doubts that Sierra Nevada will ever complete it.

          NASA made the safe call by going with the two more established players, and even then, they’ve had plenty of trouble keeping to the established timeline.

    2. SpaceX would have included vertical landing if NASA had allowed them to test it on cargo flights. The cost of developing it without piggy-backing on flights that NASA had paid for was too high, given that they were developing a new ship to replace Dragon and Falcon. NASA wanted their return cargo back and didn’t wish to risk it on these tests. Given the recent explosion in the system to be tested, the risk NASA avoided was real.

        1. You don’t need a resistable valve for propulsive landings, the burst disc fix would be fine for that purpose. What you need a reusable valve for is an abort followed by a propulsive landing … Or a Mars orbit insertion burn, followed by a landing burn.

          1. You don’t need a reusable valve in those scenarios either.
            All of them would keep the Super Draco system pressurized once it was armed, and the valve in question now a burst disc simply separates the helium plumbing from the propellant tank while the system is depressuruzed, it doesn’t replace the throttle valves that actually controls the engines firing

            The only scenario where it needs to be reusable is for ground testing hot firing it before launch..

          2. There was never an abort followed by a propulsive landing scenario. If Dragon has to abort, the Super Draco propellent will be entirely consumed by the abort, and the landing mode is parachute to water.

        2. Nothing.
          The Super Draco system would never be armed and pressurized at the ISS.
          The only time it gets armed is if there is a launch abort, in which case it lands immediately, or if they doing a propulsive landing in which case it would land within minutes of being activated.
          So it would never be able to cause a problem anywhere near the ISS

    3. Crew Dragon not propulsively landing has ZERO to do with the test stand explosion, which was caused by a leaky valve. SpaceX removed propulsive landings 2 years ago when NASA decided ~10 test flights would be necessary – making it too expensive to continue certification.

      Now that the leaky valve investigation is winding down an In-Flight Abort test is on the manifest, and NASA is looking for a first crewed flight date.

      1. Indeed. The decision to use burst discs just aligns the hardware with it’s intended use. The leaky valves were a holdover from older designs that no longer made any sense. Like the human appendix. The real question is why nobody took the initiative to make the change before the explosion.

        Maybe, if Starship becomes a boondoggle, SpaceX will reconsider and add the capability back in some future revision. Just look how many changes Soyuz made over 50 years.

        Space Shuttle also added and lost stuff. Columbia launched in 1981 with ejector seats for example.

        1. Texas, that’s incorrect.
          The check valves are to allow preflight ground testing like they do for Falcon 9,it has nothing to do with propulsive landing.
          By changing to the burst disc, it will now have to be replaced after ground testing of the abort system, until they re-engineer it to a different valve style that nasa will certify.

          In either a abort or landing scenario, once the system pressurizes, it stays pressurized until its on the ground, so it doesn’t need a check valve once helium starts flowing.

    4. It would take just as long, if not longer to man rate DreamChaser at this point. Remember, it does not even have a man rated launch vehicle, nor an escape system, nor has it flown in space for a second as of yet.

      1. And Dream Chaser’s (crewed version) test-glide milestone wasn’t accomplished until more than a year after it’s contract deadline – a key reason why it was downselected from the program.

    5. I developed a propulsion system that will make orbital launches with a single spacecraft, 5 or 6 times in a single day, more than possible. It is called a Centrifugal Propeller, and I have a working proof-of-concept prototype. I took it to my nation’s capital, Ottawa, in June 2018, and met with 2 government officials. One of these fellows is a smart guy with 4 degrees, 2 of which are in engineering and physics. During the meeting, and after viewing the prototype and the principle behind it, he kept repeating, “You are going to win the Nobel Prize.” It is nice to have a credentialed person acknowledge what I have accomplished, but it has been extremely difficult to get the attention of Elon Musk or Jeff Bezos. The Centrifugal Propeller will continually accelerate in space so a trip to Mars will be little more than a day-trip. That will make all of the money that Musk and Bezos are spending on rockets, a total waste. I am not sure what it is going to take to get their attention. Attempts to contact them or their immediate staff have gone ignored.

        1. Nice plagerism there dude. That design was published in the antigravity book years ago. It works fine in a friction environment like lying on its side on ice but it makes a pitiful amount of movement for the power input to it. In vacuum it just shakes up and down producing zero thrust. The apparent thrust on low friction is a swimming effect of the slightly higher speed surge swing versus the smoother return swing. Prove you can lift a single sheet of paper with it and maybe you can brag.

          1. You are totally wrong. My Centrifugal Propeller provides constant thrust by redirecting the reaction of centrifugal force, at a right angle to the plain of the centrifuge. It is NOTHING like the device that you are describing.

        1. Centrifugal propellers are detailed with diagrams and explanations in “The AntiGravity Book” 1980s gathering of ideas for how humans might have already built our own flying saucers. It sounds convincing in theory but does not work in practice. The primary version has a powered center with a hole allowing a rod to slide back and forth through it as it is contained with a ring shaped bounding guide like an off-center ring. This has the effect of sliding the rod wide in one direction and tight in the other as it is rotated by the powered center. Such a movement creates a throw in one direction and a soft retreat in the reverse direction. It can be demonstrated on ice to move a battery powered electric spinner slowly in a direction but exerts zero force if hung from a fish scale pointed up.

          1. Check out the proof-of-concept prototype demonstration on YouTube. Search Centrifugal Propeller 1.8. I challenge anyone on the planet to prove me wrong. It works, I proved it.

  2. SpaceX is irrevocably on a path to a much larger craft called “BFR” or the more family-friendly “Starship”. This is intended to have all of the features that Falcon and Dragon are not getting. They developed a staged-combustion full-flow engine to fly it. This is more powerful than other engines, and around twice as complicated, as there is a fuel-rich and an oxidizer-rich pre-combustion stage, each with its own turbopump. This recently flew on the hopper prototype in Boca Chica, Texas. However, it avoids pumping fuel and oxidizer on the same shaft, as all conventional liquid-fueled rockets do today, which requires a lot of the seal between them.

    This was the first flight of that sort of engine not to end in explosion since 1969, when the Russian N1, their answer to the Saturn V, failed 23 seconds after lift-off, causing one of the largest non-nuclear explosions in history.

    Despite this entire project looking far-fetched and being carried out in an unconventional way (construction of major components outdoors, a low-fidelity prototype that could have been a water tower, but flew), they have made tremendous progress. SpaceX and Musk make very ambitious bets, and carry them out, which appears to have been missing from other space efforts.

      1. By coincidence, I just today spent 45 minutes more than I ever anticipated, learning about “staged-combustion full-flow” rocket engines (and how it differs from the other types) over at youtube.

        It’s a very interesting comparison of Space X’s new Raptor engine to a bunch of others, with very educational engine flow animations:

        (Title of the video is “Is SpaceX’s Raptor engine the king of rocket engines?” @ Everyday Astronaut)

        I do love the fact that one can just spend an evening random-clicking yt recommendations and find treasures of information like that, without even knowing that you wanted to learn about it :)

    1. for return to space station, don’t you think it would be funny if the spaceship has more internal volume than the space station? big rocket to take up a station crew. crew dragon has a purpose.

      1. Starship launch to the ISS will cost less than Falcon 9/Crew Dragon launch, and have incredible payload capabilities at the same time. No contest.
        Crew Dragon was just cheaper to build than Starship, and fit the NASA contract.

      1. Cisco used the acronym years ago when they were developing their GSR 12000 platform (Big F-ing Router). Some of the developers showed up at the Cisco Networkers conference sporting temporary stick-on BFR tattoos. :D

      1. The difference with the Shuttle was that its only escape option was gliding away, and only in certain portions of the launch.
        Unlike the Shuttle, Starship has its own engines that it can use to escape from a booster failure.

        And yes, you will say, but what if Starship itself fails?
        But that’s like saying, what if the Shuttle itself fails? Or what if Starliner fails?

        Yes, Starship has more fuel than the others on board, but all it takes to kill the crew is one small failure on any of them , and while the fireball may be bigger, the survivability is the same.
        In addition, being autonomous and reusable, Starship can be tested unmanned to ensure reliability, unlike any other system.

  3. SX isn’t interested in spending the money to land Crew Dragon on land anymore because it doesn’t make any sense and would be a giant waste of their money. BFR is the long term future not Falcon and Dragon. BFR will land propulsively This article waa also a waste if my time.

  4. The author is wrong on a key point.
    The check valve being replaced by a burst disc doesn’t prevent propulsive landings the only thing it prevents is ground testing of the engines before each flight.
    You can’t test, refuel, and fly, because the disc would have to be replaced.

    But in either an abort scenario, or a propulsive landing, you are going to activate the system near the ground, and within a few minutes you will be on the ground.

    The burst disc seperates the helium pressurization system from the propellant tanks, but once the tanks are pressurized they can stay pressurized, because there are still throttle valves between the propellant tanks and the Super Draco engines.

    So this change doesn’t limit the usage capabilities of the Super Dracos, only the pre flight testing. And it later could be replaced by an actuated valve to allow ground testing again, the burst disc is just the fast and easy to certify replacement with no other system modifications needed.

    The whole tone of the article is off as well, as if SpaceX and Elon aren’t constantly iterating designs as they get experience with a particular design and move beyond it.
    Like Falcon 1 got canned, then Falcon 5 got canceled and Falcon 9 was made, as the most powerful rocket using that design, with Falcon Heavy to push it a little further, but now Elon doesn’t want to do any more work on them, because they have reached their maximum potential, and he’s investing all the resources into Starship, because it will be able to do everything better. Faster cheaper more payload cooler and better
    So if doing more work to get Crew Dragon able to land propulsivly takes away from Starship, he would have lost interest in doing it.

    So, I don’t think that this is a major glitch in the plan, and landings are still just as possible with the burst disc because they still have throttle valves, and the burst disc can later be changed out for another valve to allow pre flight testing again, and Elon hopes to replace Crew Dragon entirely with Starship within a few years, so this isn’t really a major setback for SpaceX.

    1. Except a propulsive landing isn’t a single burn, it’s several separate burns. It would have worked exactly the same as how the first stage lands. At the absolute least, they needed to do a high altitude burn to verify all the engines are working and course correct. Then another course correction a few seconds before final burn.

      With no check valves, the only way to safely use the SuperDracos is now to burn them until the tanks are dry so no hypergolics can travel back through the pressurization system and combine. That means its all or nothing deal.

      Yeah they could in theory go back and add redesigned valves, but that’s where the rest of it comes in. They aren’t that worried about it anymore since Starship is where their future plans are. So they put a bandaid on Crew Dragon and keep things moving.

      I wonder if you actually read the whole thing or just stopped around the middle, because it seems like your comment states the same thing as how the piece ends: that Dragon is no longer the primary goal.

      1. Did they replace the valves with burst discs or did they add burst discs downstream of the valves? If it’s the second then a controlled powered landing would still be possible. If it’s the first then they have the liquid fuel equivalent of a solid fuel rocket.

        Pressurize the tanks high enough to pop the burst discs then the hypergolic fuel and oxidizer meet in the engine and it burns until it’s all gone. Great for an emergency escape system.

        1. Everything I’ve seen says they are replacing the faulty valves with the discs, but I suppose nobody outside of SpaceX could really say 100%. Not until official report comes from NASA, which to my knowledge it hasn’t yet. Until then, probably best to consider all this conjecture.

          With everything taken as a whole though, replacement seems the most likely. SpaceX already knew propulsive landings were basically dead, so why screw around with keeping the leaky valves on the ship if they’re never going to use the things anyway. Just added weight/complication/cost.

          1. Shoddy valves, It was SpaceX during a news conference that said that they were replacing the check valves with burst discs so it’s a pretty reliable source lol

            And they were still using them, because that’s what makes simple ground testing possible.
            With the burst discs they have to disassemble and replace the discs after preflight testing.
            NASA apparently signed off on that process but they may change to a different valve later, since they like to be able to test easily without further disassembly.

        2. Gregg, there is a valve at the helium tank, check valves where the helium lines connect to the propellant tanks, and throttle valves between the propellant tanks and the engine.
          The check valves, now replaced with burst discs, were only to keep the propellant out of the helium pipes when the system was disarmed.
          Once it is armed, they don’t serve a purpose since the helium will always be a higher pressure.
          But the throttle valves are still there downstream of the propellant tanks so no impact on being able to do controlled landing burns.

      2. The check valves were needed to prevent propellant from going from the propellant tanks back into the unpressurized helium lines.
        There is a valve at the helium tank, long pipes taking a twisted path to the propellant tanks, a check valve at the propellant tanks, and then throttle valves between the propellant tanks and the engines.
        Once the helium valve is turned on, the pressurization lines are at a higher pressure than the propellant, so no propellant will get back up into the helium lines.

        And once the system is activated and pressurized, it will stay pressurized until it lands and is safed, either for abort or for propulsive landing.

        The throttle valve is what controls the engines for maneuvering, the fuel system stays pressurized.

        In order for propellant to mix, it would have to travel upstream a long distance through 2 long and twisty pipes, and then back feed through 2 pressure regulator valves, and finally to the manifold at the helium tank.
        That’s not going to happen!

        What did happen is that a small amount flowed back through a check valve and pooled in a low spot in the piping, and then when the system was pressurized rapidly, it was driven at extreme force down the pipe, like water hammer burst the check valve, and under the high pressure and temperature of the impact reacted with the titanium in the valve causing the explosion. It wasn’t propellants mixing that caused it, and as long as the system is pressurized, the helium prevents the back flow.

        And yes, I saw that the conclusion was implied that Starship was the new focus, but the rest of the article and the click bait headline made it sound like the testing setbacks were limiting SpaceX like they were losing features, and that’s what I said that the tone of the article was not looking at the reality of Elon always wanting to advance further, often orphaning plans in the process.

        1. Except if the engines are off, in which case the pressures will equalize and the propellant can again flow backwards through the helium lines – hence the check valves to prevent back flow.

          Now they have to run the tanks empty when they fire the engine, otherwise they’d risk the fuel mixing at some later time.

          1. There was never a danger of the fuel mixing, it would have to go through several valves and a lot of pipe to mix.
            The problem was a slug of propellant accumulating in a bend in the pipe, and then when the sudden blast of helium hit the line, it turned that liquid into a bullet, smashing the check valve open, and causing an explosion with the titanium valve from the impact.

            This scenario would not happen in the few minutes that the system could be active in a flight scenario.
            And if it was a concern, they could pulse the engines every few seconds to keep the propellant out of the helium pipes.

          2. OK then, put the high pressure HeIium vaIve right behind the check-vaIve, making any Ieakage triviaIIy small.
            Beef up the supply line and the check valve, and make the valve out of entirely unreactive composite.
            Test the heck out of the thing with heat, time, overpressure, and so forth.

    2. I think your missing the point though.

      The fact that they can’t be tested means anything else is moot. SpaceX would never trust untested engines as the primary landing system. That’s just not the way they operate.

      So if burst discs mean you can’t test the full up system, as it would be at the moment of landing, then it’s no good.

      1. The quick fix that NASA would sign off on to get it flying again safely was the burst disc but I am pretty sure that SpaceX is looking at an upgrade to the system, possibly as simple as another controlled valve at the inlet to the propellant tanks that would stay sealed except when the helium valve was opened. This would guarantee no leakage, and allow hot fire testing.
        So yes if they ever wanted to try landing again they would do something different than the burst disc but only because of preflight testing capabilities

  5. Is it just me, or does all this seem moot? ‘Land, refuel, take-off’ is nowhere near the realm of safe-for-humans. Shouldn’t they inspect/repair heatshields after [and before!] EVERY trip? Nevermind darn-near every other system. And, somehow, suddenly, we can afford so much fuel to launch into space, *without* huge disposable gas-tanks, and *still* carry enough fuel to land? Something fishy ’bout all this.

    1. I mean…you just described an airplane. We’ve been doing pretty well with those so far.

      As for fuel, that’s pennies compared to the cost of the rocket. F9 runs in oxygen and kerosene, full tank of both costs something like 300K for a 60 million flight.

    2. Airlines land, refuel and take off all the time, and all the pilots do is walk around and kick the tires between flights. That is the goal for Starship.
      Yes, they will inspect any heat shielding that it has after every flight, but it will be designed so that it doesn’t take months to inspect like the Shuttle,, and won’t need repair under normal circumstances.
      The shuttle used an aluminum skin and structure, so any heat leakage would cause catastrophic failure because the aluminum just falls apart..Starship will be stainless steel, so it may warp or melt in worst case scenario, but only where the damage is, and they won’t have crew or fuel directly on the other side. So much more robust design, and being a simple shape, much less complicated heat shielding design.

      The Starship booster is about the same diameter as the Shuttle external tank, and about 50 feet longer.
      It will have more fuel, and more power, than the shuttle did.
      And then Starship will be sitting on top of it, instead of on the side like the shuttle.
      And unlike the shuttle, Starship has a lot of fuel on board itself.
      The shuttle only used fuel from the external tank and had none on board.
      So when you look at the total fuel on board the full stack its considerably more than shuttle had.
      This is possible because the Raptor engines are more powerful and efficient with the ffsc design.

      As far as fuel for landing, it will take very little fuel for the booster to land, because most of its weight will be gone as fuel is burned on ascent so it just needs enough to run 1 or 3 out of the 31 engines and only for a few seconds.

      1. Actually, the shuttle did have a bit of fuel on-board. That was needed for the Orbital Maneuvering System (OMS). Remember that, when the external tank was detached, it fell back into the ocean. The shuttle needed the OMS system to circularize the orbit to keep it aloft.

        1. Dave, the shuttle main engines used hydrogen for fuel. The shuttle had no hydrogen tanks on board, all the fuel came from the external tank.
          The OMS system was just a normal hypergolic maneuvering thruster system.

          My comparison is that Starship has its own on board fuel supply to run its main engines, and is the upper stage of the rocket.
          This was in context of explaining why Starship would have enough fuel to launch and then land again, because it has a lot more fuel than the shuttle did.

          1. “The shuttle had no hydrogen tanks on board”

            Then how did they run their hydrogen fuel cells for electrical power while in orbit, after detaching the external tank? The fuel cells also provided drinking water as their exhaust product. If they didn’t have hydrogen tanks on board, they would have been thirsty and in the dark.

      2. The shuttle did not have an aluminum skin. It had an aluminum and titanium structure (titanium for thrust structure around engines and hardpoint mounts). The shuttle’s skin was reinforced carbon-carbon for all leading edges, thermal tiles on the bottom, and thermal felt blankets (Nomex) on the bottom. Any aluminum on the outside would have melted away very fast at the beginning of reentry (like the internal structure of Columbia did).

        1. I stand corrected, but still correct ;)
          I must have been remembering the description of the aluminum structure being cut by any plasma that got past the tiles and was thinking that the skin was also aluminum.
          But the end result is the same, stainless steel will hold up to damaged tiles much better than carbon fiber or aluminum, and with a less intense reentry profile designed to minimize heating, it’s not as close to the edge of survivability.

        2. Ok, yes, I forgot that it has some small spherical hydrogen tanks below the deck to run the fuel cells.
          So let me rephrase this…
          The Shuttle had no on board fuel tanks connected to the SSMEs, and definitely not enough to even get one to start up!

          My point was still accurate that the shuttle had no fuel on board except for maneuvering thrusters, and all the fuel for the main engines was from the external tank.

    3. space shuttle had a lot of structural mass to enable the cross-range re-entry capabilities of those wings. also shuttle had the largest payload aside from the eelv. so… that’s why it needed that ridiculous tank. now it’s just crew and their systems. no record breaking cargo hold in the back. much more efficient and reliable.

      i am curious, on reliability front, if crew dragon has fail-safe baliistic mode like soyuz. it should. it looks like a nicer design than sozyuz. i hope they tell us what that mission profile is like if it’s a thing.

  6. The entire article could be replaced by single sentence. “Musk makes pragmatic business decision and focuses development resources on SLS” ( Starship Launch System ;-). The rest of it was overly negative fluff trying to make something out of nothing…

  7. This event has no bearing on whether SpaceX was going to land Dragon 2 propulsively in the future. The plans were already taken off the table for the time being. If they were revived for some reason, there’s no reason they couldn’t make additional changes to the system.

  8. I think part of the problem with a powered-landing Dragon is that the rocket nozzles are located on the base of the capsule, which is close to where the people are. Which means fuel close to where the people are. This was the biggest flaw in the space shuttle. As an aside, I think the author of this article mischaracterizes the situation by blaming the Columbia accident on an overly complex heat shield; that was only one factor in the accident and not the most serious one by far. If the rockets for powered descent were above the capsule (like a launch abort system) it would be safer.

    1. … it’s a rocket. The fuel is *always* right beside the crew, no matter what. Rockets are 90% fuel, 8-9% structural mass, and 1 to 2% payload (people, cargo, capsule, food, air, etc). There is no way to keep the 90% fuel away from the 2% payload.

    2. John Wolter, all capsules and craft have rocket fuel under the astronauts..
      Or on the wall of the capsule next to them , etc
      A. There is no other place to put it, and B. They need it there to get the CG correct..
      So SpaceX isn’t doing anything any different from any of the other companies as far as fuel location.

      1. That’s patently false.

        Orion has the abort motors away from the capsule in a tower, Starliner has them in the service module. Nobody has ever been foolish enough to put abort system INSIDE the craft before, it has always either pushed or pulled, then separated once it had burned out.

        The only reason Crew Dragon has engines inside the capsule itself is because they were supposed to be used for landings. Now that those landings aren’t happening, it’s an unnecessary risk.

        1. The original comment was talking about fuel next to the people, not abort engines, as was my accurate reply.

          They all have hypergolic fuel for the control thrusters in the capsule, wherever the abort motors are.

          And Blue Origin actually has a solid rocket motor inside the capsule it looks like a coffee table sticking up between the seats lol

  9. The entire space ship thing for passengers is totally moote.
    Once underground tunnels advance in technology to vacuum and g force matching gravity, the Boring Co.

  10. I think the explosion of the Crew Dragon was a fabrication requested/demanded by NASA to allow SLS a chance to catch up. That bs movie they provided, the recent admonishment by the government to SpaceX about the cheap excuse, The firing of of the military commander in charge of the SLS and the recent reduction in their timelines all point to a faked explosion.

  11. The tension between SpaceX and NASA will only increase over time. The eventual outcome is not difficult to foresee, SpaceX will dominate interplanetary crewed travel and colonisation.

  12. When they start landing *every* booster, they can move on to crew or cargo capsule landings. THey are learning a lot, doing well, but they need to crawl before they walk.

    1. If I recall correctly, they actually have landed every booster which had a mission profile they felt was safe for landing (after the initial group of failures). The failures were the extreme downrange stretches (like Falcon Heavy center cores) that wouldn’t be tried with humans, and a single malfunction-caused water landing which would’ve been dizzying but survivable for people.

      Landing a booster that only goes up for a couple minutes is very different from landing from orbit after months in space and facing totally different re-entry conditions, though. Booster landings, Dragon landings and Starship landings are all totally different animals. To develop capability for crew landings, the only similar thing you can test it on is cargo landings… and NASA didn’t want their valuable cargo to be subject to testing, hence SpaceX gave up on propulsive Dragon landings.

    2. They kind of already are landing every booster. They lose a few droneship landings on the missions where they don’t have any extra energy to spare. None of those are seen as mission critical, and they do not have redundant backups that would be in place for manned missions. And people seem to forget that: 1) manned propulsive landings date back to the Apollo program, because not all space bodies have the luxury of an atmosphere to break your fall. 2) Parachutes can and will also fail sometimes.

    3. They already do. The only ones they haven’t been recovering are the ones that don’t have the spare propellant.

      But even then, they are starting to reschedule those missions for Falcon Heavy so they don’t have to sacrifice a rocket.

  13. Has SpaceX considered parachutes to slow descent and then thruster rockets to hit the landing pad. The advantage is a slower approach to the ground without adding much weight to the capsule. They already seem to be able to slow the capsule with rockets. This would just slow the total descent speed before rockets cushioned the final approach.

      1. No reason why it shouldn’t allow landing. Once the engines are primed the burst disks are no longer necessary, so you can re-fire the engines even after an escape burn.

  14. The problem I see with these plans is, once you’re locked on to them, you tend to close your thinking towards other options. If mid air refueling is a routine procedure, I don’t see why a system for “catching” the returning capsule cannot be developed. If the rate of decent of the capsule is sufficiently decreased via chutes, a VTOL aircraft should be able to capture a tether of some sort to take it where it needs to go, be that a waiting aircraft carrier, or another location. Think of a trailing chute, with a single line with arresting hooks. Think outside of the box.

    1. Wardell, yes, catching a fairing with a helicopter is definitely possible, it’s not a hard technical challenge, just some decent piloting and a good GPS system.
      However, you would have to have 2 fully crewed helicopters and ships far out to sea for every launch, and you aren’t talking about an R44 helicopter, you are needing large heavy lift helicopters because the fairings are very large and heavy.

      And while this might be simple in a test on a nice calm afternoon, there is no way that this can be done at night, or in clouds or fog or heavy rain or stormy or windy weather. If the sea is very rough it’s not even safe to take off or land the helicopter, much less try to maneuver close to a parachute, with the grapple line wildly swinging around in the wind, and then once you capture the fairing it is spinning around under you as you fight the wind.

      Yes, it could be done, and the military lands in all weather conditions, but no one would take the risk to crew to fly in that kind of condition for a commercial project. And the costs of having extremely expensive helicopters and highly paid pilots constantly sitting around hoping for good weather would not make it economically viable.

      The catcher ships can operate under any normal weather conditions, any time of day, and are a lot cheaper to operate than a helicopter fleet, and if they get the targeting algorithms right,, it should become reliable.

      1. Inertia can be solved for by either having the helicopter descend matching the rate of descent of the fairing, or use a tension limiting winch that pays out cable with a brake keeping maximum tension on it.

        I mean Electron is planning on using a helicopter to catch their rocket! A fairing should be a piece of cake.

        But again since it can only be done in good weather, I don’t think it’s a good option for SpaceX.

  15. The article includes tons of baseless authorial speculation like “The decision to walk back on a feature that had been publicly touted for nearly a decade was undoubtedly a difficult one for SpaceX.” In fact NASA had made it clear that they were never going to approve a propulsive landing for Astronauts which had made the idea of having an optional “land” landing totally useless and SpaceX had simply decided to leave more advanced features to the Starship which it envisions completely replacing the function of Crew Dragon within just a few years as well as making all other spaceflight technology totally obsolete.

    You may or may not think that’s insane… perhaps its as insane as SpaceX thinking they could massively reduce launch costs by developing reusable boosters for the Falcon 9…

    1. If you actually bothered to look up Elon’s Q&A at the ISS conference where the quotes are pulled from, you’d know his immediate response to the person asking if they had canceled propulsive landings was saying how hard a decision it was for them to walk away from the plan.

  16. Alright, put the high-pressure He valve right behind the check-valve, making any leakage trivially small.
    Beef up the supply line (against the higher pressure) and the check valve, and make the valve out of entirely unreactive composite.
    Test the heII out of the thing with heat, time, overpressure, and the like.

  17. NASA’s problem wasn’t the heat shield being “complex”, it was not putting the shuttle on top of the booster stack. Both shuttle losses were because the shuttle was next to the two solid fuel boosters and next to a cryogenic fuel tank. The O-rings failed on Challenger’s last flight, piercing the main fuel tank. Columbia was damaged by ice and insulation falling off the main fuel tank at supersonic speeds. Other shuttles experienced some minor damage, but Columbia’s was too extensive for it to survive reentry.

  18. “NASA and the White House are eager to get astronauts launched from American soil again, and there’s no time to make such extensive changes to the spacecraft.”

    Why? is the Earth in eminent doom? Is there a comet coming that will wipe out civilization?
    Chillax, slow down and do things right. Not to mention Stop pissing away our tax dollars by rushing things.
    Hey NASA, if it was your own money you were spending you know you would slow it down.

    1. We are basically paying for the entire Russian space program with what they charge us for rides to the ISS, on ancient technology.

      And with only a single option to space, when it can’t fly, no one can go up.
      Recently Soyuz had an in flight abort, and was grounded for a while while they investigated, and if it had taken any longer to resolve, they would have had to abandon the ISS.

      So the rush is to get back to being able to launch our own astronauts, on better designed rockets, without them having to learn Russian, from American soil, without having to pay ridiculously large amounts to an enemy nation.

      And yes, the longer it takes, the more money is wasted on Soyuz launches.

        1. Let’s see, nuclear missiles pointed at each other, submarines off the coast,, tarrifs, cyber warfare, US troops being sent to discourage Russian troops from attacking our allies, election meddling, etc.
          They certainly are not our allies, and with the whole missile and cyber warfare thing I think they are still at least borderline enemies, or could return to being active enemies at a moments notice.

  19. The appendix is apparently a reservoir for good gut bacterial (had C-diff Lately?). Check valves are commonly known to not work (ask an experienced engineer) and nobody in their right mind puts common plumbing in a fuel+oxidizer system, let alone a hyperbolic one. (Learned that last one the hard then expensive way.) Most engineers don’t like common wall tanks or seals between delivery channels.

    1. Explosion had nothing to do with hypergolic fuel mixing or shared plumbing.
      Small amount of propellant seeped past check valve after multiple ground cycles of testing and refueling and accumulated in Bend in helium pipe. When helium was turned on, slug of propellant was accelerated down the tube, striking the check valve at high velocity, causing it to burst open from the water hammer effect. The velocity of impact was high enough to cause an explosive reaction between the propellant and the titanium check valve parts, triggering the initial explosion.
      No fuels mixed until after the propellant/titanium explosion which then damaged the propellant tanks

  20. The thing is a bomb , the shuttle was obsoleted because the capsule system is many times more safe ,
    a capsule with rocket fuel aboard and the heat of t re-entry present an un-necessary risk to the
    passengers .Ditch the Super Draco fireworks package , adapt the escape tower from another capsule or design a new one that drops off so the vehicle returns with no fuel ; the safest configuration possible .

    1. Wrong answer because of wrong assumptions!
      All the capsules ever have had rocket fuel on board.
      They all have some sort of thrusters, and have the fuel for them
      And yes, Crew Dragon has bigger tanks than most, but you are just as dead if 1iter of hypergolic fuel blows up under your butt as 10 liters, so not really a noticeable difference in safety!

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