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It's too bad NASA didn't let SpaceX test propulsive landing with the cargo Dragons. Without that, SpaceX scrapped the feature from the Dragon program as a whole

• mzkply 7y ago
  They would still have had to work on parachutes because a Pad Abort uses up all the propellant... leading to a parachute landing just off the beach at the Cape.
• apendleton 7y ago
  They didn't scrap it exactly, they just relegated its function to use as an emergency propulsive abort system. But the Dragon 2 still has the super dracos... and one of them exploded, causing the loss of a test vehicle, a few months ago, which has resulted in timeline setbacks to the program. It doesn't seem like reliability has been a walk in the park there either.
  • waiseristy 7y ago
    The super draco didn't explode fyi, it was the fueling system.
    • wolfram74 7y ago
      An interesting distinction, like saying "the engine didn't explode, the gas tank did" but one wouldn't be there except for the other. I suppose for properly fixing the problem it's important to say one vs the other, but in general conversation it could come off as a pedantic?
      • waiseristy 7y ago
        Well, yes. Pedantic as it may be, the fueling systems seem to be a recurring theme for SpaceX, not their motors. Remember Amos-6?
        • Klathmon 7y ago
          Both failures may have had something to do with "fuel", but they aren't in any way related. The Crew Dragon abort test anomaly was caused by a problematic valve leaking oxidizer "backwards" into the helium tubes which are used to pressurize the system right before ignition. The second they pressurized, it sent a huge amount of oxidizer into the engine where there should have only been helium at the time which caused the explosion. The AMOS-6 anomaly was caused by LOX pooling and working it's way into the liner of a COPV inside the LOX tank. The LOX got into the fibers, and a small amount of friction ignited the oxygen and caused the "boom". They may seem similar in that they are both related to the oxidizers getting somewhere they shouldn't and igniting, but a rocket is pretty much just a tube of carefully controlled fuel and oxidizer and a nozzle to shoot it out. Of course most problems are probably going to result in fuel or oxidizer getting somewhere it shouldn't, and when that happens they are going to explode. For laypeople the exact reason why the fuel and oxidizer mixed at the wrong time isn't really important, but don't fall into the trap of thinking that the 2 are related.
          • waiseristy 7y ago
            So at this point who is being the pedantic one? Lol!
            • Klathmon 7y ago
              It's not being pedantic if you are correcting the conclusion. You mentioned that fueling system issues have been a recurring theme in failures, and I just wanted to point out that it's not really correct. Even though the 2 failures looked somewhat similar from the outside, they actually had basically nothing in common.
• mitchty 7y ago
  Wouldn't dragon need the rockets to land on Mars? Parachutes aren't gonna do jack in Mars atmosphere. I thought that was the bigger reason for the retro rockets.
  • waiseristy 7y ago
    SpaceX has no plans to send Dragon to mars
    • gpm 7y ago
      SpaceX had plans to send Dragon to mars, that were cancelled at about the same time propulsive landing was cancelled for commercial crew. It's likely that cancelling it for commercial crew also cancelled the mars plans.
      • waiseristy 7y ago
        I think they cancelled it because it was a hair brained scheme from the get go. You need a lot of juice to not only land on mars, but then to propulse back off of it.
        • rst 7y ago
          Red Dragon was always going to be one way, as a lander for some notional science payload. It was still a bit harebrained because it wasn't clear how to deploy that payload, whether rover or other, through the hatch. (I think I once saw a slide that had a subsurface drill deployed from inside the capsule by drilling through the heat shield.)
        • lightedman 7y ago
          If propulsive landing was a harebrained scheme, we'd have never had the lunar landings.
          • vkou 7y ago
            It takes ~3,000 m/s of dV to slow down, and do a powered landing on the Moon. It takes takes ~6.400 m/s of dV to slow down, and do a powered landing on Mars. Thanks to the tyranny of the rocket equation, it takes ~5x more fuel to do a powered landing on Mars, than it does on the Moon. For the entire mission. That's five Saturn V rockets, if you want to get a similar payload to Mars and back. Shaving most of the dV requirements of the 'land on Mars' leg of the journey will reduce that requirement, from ~5x to ~2x.
• the_duke 7y ago
  If I remember correctly, SpaceX totally could have gone for propulsive landing, but opted not to because certification would have been a lot more work.
  • stetrain 7y ago
    I think it basically came down to NASA not wanting them to test it on NASA flights. SpaceX would have had to do their own launches and landings to verify the propulsive landing system, but they wanted to test it out on "production" cargo missions they were already doing for NASA.
• hyperion2010 7y ago
  It seems like the minimal possible complexity of a sheet of fabric is always going to be higher than the minimal complexity of an engine simply because the physics of cloth are much harder to simulate accurate so you will never be able to find all the edge cases. Yes engines are initially more complex to build, but their minimum complexity once they are well understood should be lower -- even with the code needed to run them. You can't exact attach a debugger to the universe.