8 ms·

SpaceX successfully tests parachute for bringing astronauts back [video]

221 points by salmonet 11y ago

krschultz 11y ago
This was pretty low risk considering that they have been landing the cargo Dragon capsule under parachute for a few years now. The crew Dragon capsule probably has slightly different weight & balance characteristics but the system hasn't changed that much.
- JshWright 11y ago
  There are a few changes with this parachute system. Notably, it uses 4 chutes, rather than 3 (which is the number used by the current cargo Dragon, and how many the Crew Dragon test article used for the pad abort). All in all though, you're right, this was mostly just a checkbox that needed to get checked off.
  - ChuckMcM 11y ago
    Josh, do you know if is there anywhere that confirms the 204s ISP number for the superdraco thrusters? And what the fuel mass is for that? EDIT: yes its a typo, I mean 240s
    - delibes 11y ago
      The citation for the wikipedia page (240s ISP) gives an exhaust velocity of 2,300m/s : https://en.wikipedia.org/wiki/SuperDraco#cite_note-DragonFlyEAI201403-4 https://en.wikipedia.org/wiki/SuperDraco#cite_note-DragonFly... - page 12 of the PDF. So taking a rough 2300/9.8 gives about 235s
      - irrelative 11y ago
        FWIW, Isp is measured in seconds and by multiplying it times gravity, you get the exhaust velocity. I believe this was done to more easily compare rocket efficiency regardless of units of gravity. It looks like you're doing this calculation: Isp * Gravity / Gravity If you're trying to predict the hover duration, that will depend on the delta V of the vehicle. Then, a hover duration would be: Delta v / Gravity Not sure what the expected delta V is for the Dragon though.
      - ChuckMcM 11y ago
        Yes I read that (and the spaceflight insider article (http://www.spaceflightinsider.com/organizations/space-exploration-technologies/spacexs-superdraco-engine/ http://www.spaceflightinsider.com/organizations/space-explor...), all numbers that are derived by third parties. So while I do not doubt that the numbers for that vehicle and that test are accurate, I keep hoping to find actual data from SpaceX on the performance of the production rocket slated for use in the production Dragon Module. I understand that SpaceX plays this information close to its vest given the competition with Boeing for Commercial Crew and perhaps Blue Origin should SpaceX ever decide to sell rockets for sub orbital tourist jaunts[1]. Anyway I'm just interested in more official specs so that I can have more confidence in my understanding of their capabilities. [1] If you think about it, they have all the hardware, an F9r with a Dragon Crew mounted on top, they boost up to 100km, separate, the Dragon gets a nice ballistic arc for that weightless feeling and then both the booster and the capsule go back and land back at the pad for re-use.
    - JshWright 11y ago
      I don't know of any source for that. Is 204s a typo of 240s? 204s would be awfully low for a Hydrazine engine (though I suppose it's possible they care a lot more about the TWR and have optimized for that).
      - ansible 11y ago
        Even an Isp of 240 is not all that high. This page: http://www.astronautix.com/props/n2o4mmh.htm http://www.astronautix.com/props/n2o4mmh.htm Lists a bunch of engines that have Isp values in the 300 range. SpaceX tends to optimize for total operational cost, rather than performance, so I wouldn't be surprised by the tradeoffs they've made to create a reliable and reusable system.
lmm 11y ago
Needs [video] tag.
douche 11y ago
I will never be able to look at a video of a space flight again without thinking of how it would be achieved in Kerbal Space program. Four Mk2R Radial Mount Parachutes, I think...
- jewel 11y ago
  If anyone here hasn't played Kerbal Space program, try out the demo. It's less of a game and more of a space rocket simulator, with a real physics engine. I learned a lot by playing it. I'm not in any way affiliated with the game, but can say with certainty that the overlap of HN readers and people who would enjoy the game is very high.
  - kincardine 11y ago
    It's also less of a simulator and more of a total brain takeover. When I first started playing all I could think about (as I was trying to get work done) were trans-munar injections and free-return trajectories.
    - stuxnet79 11y ago
      I bought the game but still haven't played it yet. How much of a timesink is it? Could it be enjoyed in 30min to an hour playing sessions?
      - Buttons840 11y ago
        Yes, you can leave the game in almost any state and then pick up where you left off later. The only exception is suborbital flights, but getting to orbit takes 3 to 5 minutes max.
        douche 11y ago
        For the first couple hours, you're going to be reverting to launch/construction every five minutes anyway when you mess up and crash or realize you didn't build your rocket correctly to do what you want to do.
ChuckMcM 11y ago
The more interesting test for me was the hover tests (https://www.youtube.com/watch?v=07Pm8ZY0XJI https://www.youtube.com/watch?v=07Pm8ZY0XJI) I keep doing back of the envelope calculations to see if a Dragon2 has enough fuel capacity to land and return from the lunar surface. Granted there is limited ability to leave and re-enter the capsule but it would make for an interesting capability. If I recall correctly the "land on land" scenario for dragon has it using parachutes most of the way down, then doing a drop and land at the end.
- JshWright 11y ago
  Far more important than the parachutes is the atmosphere. Even without parachutes, the atmosphere is responsible for almost all of the deceleration the capsule experiences. The atmosphere takes it from orbital velocity (~30,000 m/s EDIT: ~8,000m/s (km/h->m/s conversion fail)) and slows it down to the terminal velocity of the capsule (~100 m/s). The capsule only has to take care of that last bit from terminal velocity down to 0 m/s. On the moon, there is no atmosphere, so the capsule would have to handle all the deceleration from lunar orbital velocity (~2,000 m/s) to 0. So, in ballpark figures, you're looking at 20 times more 'delta V' (change in velocity) that the capsule would have to accomplish in order to land on the moon. It takes _way_ more fuel to manage that.
  - baq 11y ago
    if you replaced the dragon's trunk with a booster, it should be enough. i'm pretty sure it's not feasible, but in KSP world totally would work.
    - sathackr 11y ago
      obligatory https://xkcd.com/1244/ https://xkcd.com/1244/
    - zardo 11y ago
      I doubt Falcon Heavy could throw enough mass to make it work. Dragon is just a poor vehicle to send to the moon. It should work for landing a few tons on Mars though (one way).
novlean11 11y ago
SpaceX with their reusable stuff is definitely changing the whole space industry. We might have an option to fly out there in our life time without being a millionaires.
- stuxnet79 11y ago
  Yes, I just finished Elon Musk's biography and it seems the objective is to get the price down to between $500,000 to a million for getting a single person to Mars. Extremely ambitious, but if it does happen, I will sell my house plus whatever hard assets I will own at the time and take my trip one-way to Mars.
  - JoeAltmaier 11y ago
    I'll be on that trip too!
  - jernfrost 11y ago
    I thought a lot about that too. A lot of people think that seems nuts of course to move to such a barren hostile world. But there is a certain appeal to do something advances human civilization. On earth you are just one small cog on the big wheel. You don't matter that much to the well being of earth civilization. But on Mars every single colonist would matter a lot for the future of that colony. Even if one dies earlier on Mars, it would seem better to live a short life with purpose than a long without purpose.
    - meric 11y ago
      What about Antarctica? Sure it's not a different planet, but you will be doing things that advance human civilisation and every person on Antarctica matters. EDIT: There's a lot of scientific research going on down there. [1] In Antarctica you can participate in research that can reduce the possibility of such a catastrophe in the first place. [1] https://en.wikipedia.org/wiki/Research_stations_in_Antarctica https://en.wikipedia.org/wiki/Research_stations_in_Antarctic...
      - 11y ago
rglover 11y ago
Slow, steady progress is a beautiful thing.
- karanbhangui 11y ago
  I have a document I keep notes in for major life lessons or principles for myself. I've added your perfect quote under the principle for mastering the value of time and compounding: https://www.dropbox.com/s/4hdwbj0igcyivcd/Screenshot%202016-01-29%2000.37.59.png?dl=0 https://www.dropbox.com/s/4hdwbj0igcyivcd/Screenshot%202016-...
  - rglover 11y ago
    Ha! That's awesome, thanks for the inclusion :)
vecter 11y ago
I'd appreciate it if someone could explain to me how dangerous it is to use multiple parachutes instead of one. It sounds like it provides more reliability in case the one parachute fails, but it also seems there would be a risk of the parachutes becoming entangled. I personally have no understanding of the engineering or a sense of those risks.
sopooneo 11y ago
Why do the parachutes chords angle to the side in the air? It seems like after a little while in constant wind, it would end up hanging vertically, while falling at an angle.
- WatchDog 11y ago
  One side of the chord is shorter than the other.
- lobster_johnson 11y ago
  Good, relevant discussion here: https://m.reddit.com/r/askscience/comments/3xs6mg/how_do_large_triple_parachutes_like_those_used_on/ https://m.reddit.com/r/askscience/comments/3xs6mg/how_do_lar...
backtoyoujim 11y ago
who owns washington post and spacex?
- Ankaios 11y ago
  The Post is owned by SpaceX's competitor, Jeff Bezos.
Tharkun 11y ago
Youtube link: https://www.youtube.com/watch?v=4PG438XSarg https://www.youtube.com/watch?v=4PG438XSarg

221 points by salmonet 11y ago

This was pretty low risk considering that they have been landing the cargo Dragon capsule under parachute for a few years now. The crew Dragon capsule probably has slightly different weight & balance characteristics but the system hasn't changed that much.

JshWright 11y ago
There are a few changes with this parachute system. Notably, it uses 4 chutes, rather than 3 (which is the number used by the current cargo Dragon, and how many the Crew Dragon test article used for the pad abort). All in all though, you're right, this was mostly just a checkbox that needed to get checked off.
- ChuckMcM 11y ago
  Josh, do you know if is there anywhere that confirms the 204s ISP number for the superdraco thrusters? And what the fuel mass is for that? EDIT: yes its a typo, I mean 240s
  - delibes 11y ago
    The citation for the wikipedia page (240s ISP) gives an exhaust velocity of 2,300m/s : https://en.wikipedia.org/wiki/SuperDraco#cite_note-DragonFlyEAI201403-4 https://en.wikipedia.org/wiki/SuperDraco#cite_note-DragonFly... - page 12 of the PDF. So taking a rough 2300/9.8 gives about 235s
    - irrelative 11y ago
      FWIW, Isp is measured in seconds and by multiplying it times gravity, you get the exhaust velocity. I believe this was done to more easily compare rocket efficiency regardless of units of gravity. It looks like you're doing this calculation: Isp * Gravity / Gravity If you're trying to predict the hover duration, that will depend on the delta V of the vehicle. Then, a hover duration would be: Delta v / Gravity Not sure what the expected delta V is for the Dragon though.
    - ChuckMcM 11y ago
      Yes I read that (and the spaceflight insider article (http://www.spaceflightinsider.com/organizations/space-exploration-technologies/spacexs-superdraco-engine/ http://www.spaceflightinsider.com/organizations/space-explor...), all numbers that are derived by third parties. So while I do not doubt that the numbers for that vehicle and that test are accurate, I keep hoping to find actual data from SpaceX on the performance of the production rocket slated for use in the production Dragon Module. I understand that SpaceX plays this information close to its vest given the competition with Boeing for Commercial Crew and perhaps Blue Origin should SpaceX ever decide to sell rockets for sub orbital tourist jaunts[1]. Anyway I'm just interested in more official specs so that I can have more confidence in my understanding of their capabilities. [1] If you think about it, they have all the hardware, an F9r with a Dragon Crew mounted on top, they boost up to 100km, separate, the Dragon gets a nice ballistic arc for that weightless feeling and then both the booster and the capsule go back and land back at the pad for re-use.
  - JshWright 11y ago
    I don't know of any source for that. Is 204s a typo of 240s? 204s would be awfully low for a Hydrazine engine (though I suppose it's possible they care a lot more about the TWR and have optimized for that).
    - ansible 11y ago
      Even an Isp of 240 is not all that high. This page: http://www.astronautix.com/props/n2o4mmh.htm http://www.astronautix.com/props/n2o4mmh.htm Lists a bunch of engines that have Isp values in the 300 range. SpaceX tends to optimize for total operational cost, rather than performance, so I wouldn't be surprised by the tradeoffs they've made to create a reliable and reusable system.

lmm 11y ago

Needs [video] tag.

douche 11y ago

I will never be able to look at a video of a space flight again without thinking of how it would be achieved in Kerbal Space program. Four Mk2R Radial Mount Parachutes, I think...

jewel 11y ago
If anyone here hasn't played Kerbal Space program, try out the demo. It's less of a game and more of a space rocket simulator, with a real physics engine. I learned a lot by playing it. I'm not in any way affiliated with the game, but can say with certainty that the overlap of HN readers and people who would enjoy the game is very high.
- kincardine 11y ago
  It's also less of a simulator and more of a total brain takeover. When I first started playing all I could think about (as I was trying to get work done) were trans-munar injections and free-return trajectories.
  - stuxnet79 11y ago
    I bought the game but still haven't played it yet. How much of a timesink is it? Could it be enjoyed in 30min to an hour playing sessions?
    - Buttons840 11y ago
      Yes, you can leave the game in almost any state and then pick up where you left off later. The only exception is suborbital flights, but getting to orbit takes 3 to 5 minutes max.
      - douche 11y ago
        For the first couple hours, you're going to be reverting to launch/construction every five minutes anyway when you mess up and crash or realize you didn't build your rocket correctly to do what you want to do.

ChuckMcM 11y ago

The more interesting test for me was the hover tests (https://www.youtube.com/watch?v=07Pm8ZY0XJI https://www.youtube.com/watch?v=07Pm8ZY0XJI) I keep doing back of the envelope calculations to see if a Dragon2 has enough fuel capacity to land and return from the lunar surface. Granted there is limited ability to leave and re-enter the capsule but it would make for an interesting capability. If I recall correctly the "land on land" scenario for dragon has it using parachutes most of the way down, then doing a drop and land at the end.

JshWright 11y ago
Far more important than the parachutes is the atmosphere. Even without parachutes, the atmosphere is responsible for almost all of the deceleration the capsule experiences. The atmosphere takes it from orbital velocity (~30,000 m/s EDIT: ~8,000m/s (km/h->m/s conversion fail)) and slows it down to the terminal velocity of the capsule (~100 m/s). The capsule only has to take care of that last bit from terminal velocity down to 0 m/s. On the moon, there is no atmosphere, so the capsule would have to handle all the deceleration from lunar orbital velocity (~2,000 m/s) to 0. So, in ballpark figures, you're looking at 20 times more 'delta V' (change in velocity) that the capsule would have to accomplish in order to land on the moon. It takes _way_ more fuel to manage that.
- baq 11y ago
  if you replaced the dragon's trunk with a booster, it should be enough. i'm pretty sure it's not feasible, but in KSP world totally would work.
  - sathackr 11y ago
    obligatory https://xkcd.com/1244/ https://xkcd.com/1244/
  - zardo 11y ago
    I doubt Falcon Heavy could throw enough mass to make it work. Dragon is just a poor vehicle to send to the moon. It should work for landing a few tons on Mars though (one way).

novlean11 11y ago

SpaceX with their reusable stuff is definitely changing the whole space industry. We might have an option to fly out there in our life time without being a millionaires.

stuxnet79 11y ago
Yes, I just finished Elon Musk's biography and it seems the objective is to get the price down to between $500,000 to a million for getting a single person to Mars. Extremely ambitious, but if it does happen, I will sell my house plus whatever hard assets I will own at the time and take my trip one-way to Mars.
- JoeAltmaier 11y ago
  I'll be on that trip too!
- jernfrost 11y ago
  I thought a lot about that too. A lot of people think that seems nuts of course to move to such a barren hostile world. But there is a certain appeal to do something advances human civilization. On earth you are just one small cog on the big wheel. You don't matter that much to the well being of earth civilization. But on Mars every single colonist would matter a lot for the future of that colony. Even if one dies earlier on Mars, it would seem better to live a short life with purpose than a long without purpose.
  - meric 11y ago
    What about Antarctica? Sure it's not a different planet, but you will be doing things that advance human civilisation and every person on Antarctica matters. EDIT: There's a lot of scientific research going on down there. [1] In Antarctica you can participate in research that can reduce the possibility of such a catastrophe in the first place. [1] https://en.wikipedia.org/wiki/Research_stations_in_Antarctica https://en.wikipedia.org/wiki/Research_stations_in_Antarctic...
    - 11y ago

rglover 11y ago

Slow, steady progress is a beautiful thing.

karanbhangui 11y ago
I have a document I keep notes in for major life lessons or principles for myself. I've added your perfect quote under the principle for mastering the value of time and compounding: https://www.dropbox.com/s/4hdwbj0igcyivcd/Screenshot%202016-01-29%2000.37.59.png?dl=0 https://www.dropbox.com/s/4hdwbj0igcyivcd/Screenshot%202016-...
- rglover 11y ago
  Ha! That's awesome, thanks for the inclusion :)

vecter 11y ago

I'd appreciate it if someone could explain to me how dangerous it is to use multiple parachutes instead of one. It sounds like it provides more reliability in case the one parachute fails, but it also seems there would be a risk of the parachutes becoming entangled. I personally have no understanding of the engineering or a sense of those risks.

sopooneo 11y ago

Why do the parachutes chords angle to the side in the air? It seems like after a little while in constant wind, it would end up hanging vertically, while falling at an angle.

WatchDog 11y ago
One side of the chord is shorter than the other.
lobster_johnson 11y ago
Good, relevant discussion here: https://m.reddit.com/r/askscience/comments/3xs6mg/how_do_large_triple_parachutes_like_those_used_on/ https://m.reddit.com/r/askscience/comments/3xs6mg/how_do_lar...

backtoyoujim 11y ago

who owns washington post and spacex?

Ankaios 11y ago
The Post is owned by SpaceX's competitor, Jeff Bezos.

Tharkun 11y ago

Youtube link: https://www.youtube.com/watch?v=4PG438XSarg https://www.youtube.com/watch?v=4PG438XSarg