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You make some useful points about the challenges. However, NASA will never do a purely propulsive landing of such a craft? Is it really inconceivable that ove

You make some useful points about the challenges. However, NASA will never do a purely propulsive landing of such a craft? Is it really inconceivable that over time it could become, and be demonstrated to be, at least equally safe to using parachutes?

sandworm101 11y ago
Never isn't from a policy but a physics standpoint. If the chutes are already there, then it makes sense to use them. They are lighter/cheaper than hauling a full backup rocket system. From what I've seen, it looks like SpaceX plans on using the rockets to cushion a landing already under chutes, like the russians do today. That allows for much smaller chutes and faster landing. If the rockets fail then the landing with be rough but still survivable, with the re-usability of the craft being written off. The propulsive landing of booster stages makes sense only because you already have giant engine/fuel reserves, which aren't going to orbit. And since there are no humans around you don't need any sort of abort option. Also, if you are going to have a potentially rough landing, would you rather do so sitting 6" from a box containing a parachute, or 6" from a tank of rocket fuel?
- tempestn 11y ago
  > Also, if you are going to have a potentially rough landing, would you rather do so sitting 6" from a box containing a parachute, or 6" from a tank of rocket fuel? The former, of course. I agree that a propulsive landing wouldn't be likely any time in the near future. But if it could eventually be shown to be safe (and therefore the quote above doesn't apply), I don't necessarily agree that it would be more expensive. You wouldn't need large engines or a lot of fuel, as the capsule wouldn't be very heavy. Yes, it would definitely still be more expensive than parachutes in terms of equipment and weight. However, it would mean you could land right back at your facility, rather than splashing down in the ocean and dealing with retrieval. When we're looking into the future of reusable, commodity space travel, that would be a significant advantage.
  - sandworm101 11y ago
    Why would a parachute not land at the home facility? Some, parafoils, can be flow and landed on runways like a glider. Nasa has been working on this concept for years. The X38 one was massive overkill, a full glider, but the concept of a chute directing the craft to a very specific touchdown point is well within today's tech. http://spaceflight.nasa.gov/history/station/x38/parafoil.html http://spaceflight.nasa.gov/history/station/x38/parafoil.htm...

sandworm101 11y ago

Never isn't from a policy but a physics standpoint. If the chutes are already there, then it makes sense to use them. They are lighter/cheaper than hauling a full backup rocket system. From what I've seen, it looks like SpaceX plans on using the rockets to cushion a landing already under chutes, like the russians do today. That allows for much smaller chutes and faster landing. If the rockets fail then the landing with be rough but still survivable, with the re-usability of the craft being written off. The propulsive landing of booster stages makes sense only because you already have giant engine/fuel reserves, which aren't going to orbit. And since there are no humans around you don't need any sort of abort option. Also, if you are going to have a potentially rough landing, would you rather do so sitting 6" from a box containing a parachute, or 6" from a tank of rocket fuel?

tempestn 11y ago
> Also, if you are going to have a potentially rough landing, would you rather do so sitting 6" from a box containing a parachute, or 6" from a tank of rocket fuel? The former, of course. I agree that a propulsive landing wouldn't be likely any time in the near future. But if it could eventually be shown to be safe (and therefore the quote above doesn't apply), I don't necessarily agree that it would be more expensive. You wouldn't need large engines or a lot of fuel, as the capsule wouldn't be very heavy. Yes, it would definitely still be more expensive than parachutes in terms of equipment and weight. However, it would mean you could land right back at your facility, rather than splashing down in the ocean and dealing with retrieval. When we're looking into the future of reusable, commodity space travel, that would be a significant advantage.
- sandworm101 11y ago
  Why would a parachute not land at the home facility? Some, parafoils, can be flow and landed on runways like a glider. Nasa has been working on this concept for years. The X38 one was massive overkill, a full glider, but the concept of a chute directing the craft to a very specific touchdown point is well within today's tech. http://spaceflight.nasa.gov/history/station/x38/parafoil.html http://spaceflight.nasa.gov/history/station/x38/parafoil.htm...