6 ms·

SpaceX’s Pad Abort Test

162 points by ggonweb 11y ago

ghayes 11y ago
At the Kennedy Space Center, NASA had an interesting abort procedure for astronauts still on the ground at the launch site: an underground Rubber Room which astronauts could slide down into. [0] https://scriptunasimages.wordpress.com/2012/11/23/inside-nasas-rubber-room/ https://scriptunasimages.wordpress.com/2012/11/23/inside-nas... [1] http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20110012275.pdf http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/2011001...
greglindahl 11y ago
And to contrast this with the Orion capsule abort system: Crew Dragon's abort thrusters will eventually used for landing, while Orion's (much heavier) abort system is jettisoned 120 seconds into flight. See https://en.wikipedia.org/wiki/Orion_%28spacecraft%29#Launch_Abort_System_.28LAS.29 https://en.wikipedia.org/wiki/Orion_%28spacecraft%29#Launch_... and https://en.wikipedia.org/wiki/Orion_abort_modes https://en.wikipedia.org/wiki/Orion_abort_modes
- anovikov 11y ago
  Even if they are not used for landing, main thing is that they use same fuel tanks as those used by Draco thrusters for orbital propulsion and deorbit, so no weight is wasted (weight of the Super Draco engines themselves is not that big). Overall payload loss for the abort system is about same as if using the escape tower (ca. 800kg if i do my math right), but escape burn is possible throughout the ascent, not just in the first 3 minutes, and there is no additional safety risk from it (if escape tower failed to separate, astronauts will be doomed, here there is no such risk).
donpdonp 11y ago
Thanks for this post. It makes clear this 'pad abort test' is really a test of the amazing SuperDracos which could constitute their own launch system! SuperDracos are partially 3D metal printed and can fire months after being fueled. http://en.wikipedia.org/wiki/SuperDraco http://en.wikipedia.org/wiki/SuperDraco
- greglindahl 11y ago
  Not just partly: from that Wikipedia article: "It was announced in May 2014 that the flight-qualified version of the SuperDraco engine is fully printed, and is the first fully printed rocket engine. In particular, the engine combustion chamber is printed of Inconel, an alloy of nickel and iron, using a process of direct metal laser sintering, and operates at a chamber pressure 6,900 kilopascals (1,000 psi) at a very high temperature. The engines are contained in a printed protective nacelle to prevent fault propagation in the event of an engine failure."
- rst 11y ago
  The SuperDracos have already been through a full-duration simulation of the abort profile at SpaceX's test facility in Texas. It's more a test of system integration: that the guidance system is able to command them correctly, that nothing about the abort profile screws up parachute deployment, etc.
- donpdonp 11y ago
  Wow what a ride! The capsule 'rocketed' off the pad, using only the superdraco thrust.
zachrose 11y ago
> Crew Dragon will accelerate from 0 to nearly 100 mph in one second. The entire test is less than two minutes long, with Dragon traveling over one mile in the first 20 seconds alone. That sounds totally insane, and yet at 4.5 g's was what the Apollo crews experienced on a successful launch.
- karcass 11y ago
  And 7 g's on re-entry ...
- karcass 11y ago
  And 7 g's on re-entry ...
- azernik 11y ago
  If my mental math comes out correct, that's 25 m/s in one second, so assuming straight against gravity, that's a bit over 3g for one second. Not too bad, considering how extreme of a situation is involved.
  - mikeash 11y ago
    100MPH is about 45m/s, not 25. Fighting gravity, that's 55m/s^s acceleration, or 5.5g. Still fairly mild, considering. The Soyuz launch escape system, for example, subjects its occupants to 14-17g for five seconds. Incidentally this is the only LES that's seen actual use, when it saved a crew from an exploding rocket in 1983.
    - azernik 11y ago
      You are very correct.
    - demallien 11y ago
      Whilst it is true that there has only been one launch abort so far, if the Shuttle had a launch abort system it would have saved the seven astronauts aboard. Just mentioning this in case someone mistakes your post as arguing that launch abort systems are rarely useful.
burd691 11y ago
I know SpaceX is looking to make space flight more like commercial flight. Given that commercial airliners don't have anything like this in their design, shouldn't the goal be to get space flight to the same failure rate as commercial flight? Thus eliminating the need for an abort system?
- cyrus_ 11y ago
  Once they are that reliable, I'm sure SpaceX could consider removing the abort system to save on weight. Though I assume that the SuperDracos are designed to also be used in space / on Mars.
  - greglindahl 11y ago
    And for landing back on Earth, just not initially: http://www.spacex.com/news/2014/05/30/dragon-v2-spacexs-next-generation-manned-spacecraft http://www.spacex.com/news/2014/05/30/dragon-v2-spacexs-next...
- JshWright 11y ago
  These thrusters would be there anyway. The fact that they can be used as the abort mechanism is just a bonus (a well planned and engineered bonus...)
- jpk 11y ago
  The NASA Commercial Crew program's requirements include a line item for "assured crew return in the event of an emergency."[0] Which means any of the CCDev proposals that use the traditional rocket launch approach for the first stage need an abort mechanism that can carry the crew module away from the rest of the vehicle. So arguably you're right, but they have to develop abort capability per the NASA spec. [0] http://en.wikipedia.org/wiki/Commercial_Crew_Development#Requirements http://en.wikipedia.org/wiki/Commercial_Crew_Development#Req...
- mikeash 11y ago
  Airliners can't really explode, since they pull in oxidizer from the air rather than storing it on board. Since a fire will spread relatively slowly (relative to a rocket whose oxidizer and fuel decide to make friends all at once), the function of getting the squishy meat payload away from the fire can be accomplished through simpler means, in this case with inflatable slides and the squishy meat payload's own locomotive appendages. That is to say, airliners do have an equivalent system in the form of their evacuation slides, it just looks quite different because airliners operate quite differently.
jonlucc 11y ago
> Buster the Dummy already works for a great show you may have heard of called MythBusters. Our dummy prefers to remain anonymous for the time being. I'd love to know what the SpaceX test dummy's name is, but for now I'm going to assume it's Edison.
- ISL 11y ago
  My prior has a prominence near "Elon".
- demallien 11y ago
  I'm betting on Chuck (as in Yaeger)
- eps 11y ago
  Unlike MythBusters, SpaceX is likely to have more than one dummy and, unlike Nasa^H^H^H^HESA they tend not to make cutesy circus out of their projects, e.g. avoid things like "Oh, hai, Twitter, I'm the Rosetta probe! Yuppie!" So I suspect dummies will remain anonymous.
  - karlshea 11y ago
    I don't think you're the target demo for the cutesy circus events. Unlike SpaceX, NASA needs all the public exposure and goodwill it can get, which is what the Twitter accounts are for. There are plenty of data and science-heavy websites for the non-casual user.
    - eps 11y ago
      That's exactly my point. SpaceX doesn't need to name the dummies, nor judging by their history they would want to.
      - lotsofmangos 11y ago
        Just Read The Instructions Of Course I Still Love You
smegel 11y ago
SpaceX's first manned flight is going to be a momentous occasion.
Animats 11y ago
Mercury escape tower used when booster loses control, 1961.[1] Unmanned launch with a dummy. [1] https://www.youtube.com/watch?v=Vp9BnBDKa0s https://www.youtube.com/watch?v=Vp9BnBDKa0s
- bjwbell 11y ago
  54 years ago!! Makes you think. What amazing feats of engineering. The abort capsule was even picked up by helicopter. Themselves relatively new at the time.
- hcrisp 11y ago
  Apollo's launch escape system was tested using a rocket called Little Joe II, which started spiraling unexpectedly due to a gyro problem causing the rocket to fail. Fortunately the escape system worked as intended. [1] https://youtu.be/AqeJzItldSQ https://youtu.be/AqeJzItldSQ
  - ceejayoz 11y ago
    I wonder how many of those observing realized it wasn't part of the scheduled test. What a lucky disaster!
- vermontdevil 11y ago
  It was also used with live people in a Soyuz rocket. Google up Vladimir Titov and there's a video of this. He attributed to the designer of LES for saving his and his compatriot's life.
klum 11y ago
Nice explanation of what's going on. I've always thought there was an opportunity for much more of this kind of thing during the previous launches--explaining the process to those of us who really have no idea.
smoyer 11y ago
As a general comment, I love watching SpaceX (for several reasons). The almost monthly stream of announcements, flights and "firsts" reminds me of watching the Apollo program progress as a young child. Then I was limited to seeing what NASA happened to put on television since I couldn't read for the early parts of the program. I'm finding reading briefs like this much more exciting as an engineer.
simonh 11y ago
I know the SuperDraco's are designed to eventually enable a soft-landing back on Earth. In this case they are only being used for the abort, and the landing will be by Parachute, presumably the powered landing approach isn't ready for testing yet. I understand the initial manned launches will use parachutes for landing as well. What I'm wondering is, will they eventually carry enough fuel to both be able to do an abort, and then do a powered landing, if required? I assume so, since at that point the only cost in terms of weight to be able to do the abort as well as the landing would be the weight of the fuel for the abort itself. Also if the capsule will be capable of an abort at any stage in the ascent, what preparations will be in place to allow for capsule recovery? Presumably it could come down anywhere along the line of flight, up to the point at which it achieves orbit. That could include the middle of Africa, and maybe even the Indian Ocean. Imagine a second stage engine failure. None of these are criticisms of the system, it's fantastic engineering and potentially a huge win over current options. Excuse me while I got and watch Gravity again (while switching off the part of my brain that knows from KSP how orbital rendezvous work).
- snops 11y ago
  >What I'm wondering is, will they eventually carry enough fuel to both be able to do an abort, and then do a powered landing, if required? Even if it could, its important to note that the abort system would only be used when something has gone drastically wrong, potentially an explosion, which means you can't garuntee Dragon will be undamaged. In that case, would you trust a complex powered landing, or a simpler parachute landing where you have triple redundancy? In addition, SpaceX launch on the coast and the rocket flies over the sea, so an abort may end up with a sea landing. I haven't seen any concepts from SpaceX showing a powered dragon landing at sea, and it would presumably require a pretty calm sea state, while parachutes would work in any weather. You could see similar problems with a powered landing on unfamiliar land, for instance trying to "land" on a tree canopy.
  - jessriedel 11y ago
    Why would parachutes work better at sea? Just like a rocket, the parachute stops providing useful upwards force as soon as the capsule touches water/ground. The only thing I can think of is that it is probably easier to add landing air bags to a capsule descending by parachute than by rocket, but that's really only useful on land.

162 points by ggonweb 11y ago

At the Kennedy Space Center, NASA had an interesting abort procedure for astronauts still on the ground at the launch site: an underground Rubber Room which astronauts could slide down into. [0] https://scriptunasimages.wordpress.com/2012/11/23/inside-nasas-rubber-room/ https://scriptunasimages.wordpress.com/2012/11/23/inside-nas... [1] http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20110012275.pdf http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/2011001...

greglindahl 11y ago

And to contrast this with the Orion capsule abort system: Crew Dragon's abort thrusters will eventually used for landing, while Orion's (much heavier) abort system is jettisoned 120 seconds into flight. See https://en.wikipedia.org/wiki/Orion_%28spacecraft%29#Launch_Abort_System_.28LAS.29 https://en.wikipedia.org/wiki/Orion_%28spacecraft%29#Launch_... and https://en.wikipedia.org/wiki/Orion_abort_modes https://en.wikipedia.org/wiki/Orion_abort_modes

anovikov 11y ago
Even if they are not used for landing, main thing is that they use same fuel tanks as those used by Draco thrusters for orbital propulsion and deorbit, so no weight is wasted (weight of the Super Draco engines themselves is not that big). Overall payload loss for the abort system is about same as if using the escape tower (ca. 800kg if i do my math right), but escape burn is possible throughout the ascent, not just in the first 3 minutes, and there is no additional safety risk from it (if escape tower failed to separate, astronauts will be doomed, here there is no such risk).

donpdonp 11y ago

Thanks for this post. It makes clear this 'pad abort test' is really a test of the amazing SuperDracos which could constitute their own launch system! SuperDracos are partially 3D metal printed and can fire months after being fueled. http://en.wikipedia.org/wiki/SuperDraco http://en.wikipedia.org/wiki/SuperDraco

greglindahl 11y ago
Not just partly: from that Wikipedia article: "It was announced in May 2014 that the flight-qualified version of the SuperDraco engine is fully printed, and is the first fully printed rocket engine. In particular, the engine combustion chamber is printed of Inconel, an alloy of nickel and iron, using a process of direct metal laser sintering, and operates at a chamber pressure 6,900 kilopascals (1,000 psi) at a very high temperature. The engines are contained in a printed protective nacelle to prevent fault propagation in the event of an engine failure."
rst 11y ago
The SuperDracos have already been through a full-duration simulation of the abort profile at SpaceX's test facility in Texas. It's more a test of system integration: that the guidance system is able to command them correctly, that nothing about the abort profile screws up parachute deployment, etc.
donpdonp 11y ago
Wow what a ride! The capsule 'rocketed' off the pad, using only the superdraco thrust.

zachrose 11y ago

> Crew Dragon will accelerate from 0 to nearly 100 mph in one second. The entire test is less than two minutes long, with Dragon traveling over one mile in the first 20 seconds alone. That sounds totally insane, and yet at 4.5 g's was what the Apollo crews experienced on a successful launch.

karcass 11y ago
And 7 g's on re-entry ...
karcass 11y ago
And 7 g's on re-entry ...
azernik 11y ago
If my mental math comes out correct, that's 25 m/s in one second, so assuming straight against gravity, that's a bit over 3g for one second. Not too bad, considering how extreme of a situation is involved.
- mikeash 11y ago
  100MPH is about 45m/s, not 25. Fighting gravity, that's 55m/s^s acceleration, or 5.5g. Still fairly mild, considering. The Soyuz launch escape system, for example, subjects its occupants to 14-17g for five seconds. Incidentally this is the only LES that's seen actual use, when it saved a crew from an exploding rocket in 1983.
  - azernik 11y ago
    You are very correct.
  - demallien 11y ago
    Whilst it is true that there has only been one launch abort so far, if the Shuttle had a launch abort system it would have saved the seven astronauts aboard. Just mentioning this in case someone mistakes your post as arguing that launch abort systems are rarely useful.

burd691 11y ago

I know SpaceX is looking to make space flight more like commercial flight. Given that commercial airliners don't have anything like this in their design, shouldn't the goal be to get space flight to the same failure rate as commercial flight? Thus eliminating the need for an abort system?

cyrus_ 11y ago
Once they are that reliable, I'm sure SpaceX could consider removing the abort system to save on weight. Though I assume that the SuperDracos are designed to also be used in space / on Mars.
- greglindahl 11y ago
  And for landing back on Earth, just not initially: http://www.spacex.com/news/2014/05/30/dragon-v2-spacexs-next-generation-manned-spacecraft http://www.spacex.com/news/2014/05/30/dragon-v2-spacexs-next...
JshWright 11y ago
These thrusters would be there anyway. The fact that they can be used as the abort mechanism is just a bonus (a well planned and engineered bonus...)
jpk 11y ago
The NASA Commercial Crew program's requirements include a line item for "assured crew return in the event of an emergency."[0] Which means any of the CCDev proposals that use the traditional rocket launch approach for the first stage need an abort mechanism that can carry the crew module away from the rest of the vehicle. So arguably you're right, but they have to develop abort capability per the NASA spec. [0] http://en.wikipedia.org/wiki/Commercial_Crew_Development#Requirements http://en.wikipedia.org/wiki/Commercial_Crew_Development#Req...
mikeash 11y ago
Airliners can't really explode, since they pull in oxidizer from the air rather than storing it on board. Since a fire will spread relatively slowly (relative to a rocket whose oxidizer and fuel decide to make friends all at once), the function of getting the squishy meat payload away from the fire can be accomplished through simpler means, in this case with inflatable slides and the squishy meat payload's own locomotive appendages. That is to say, airliners do have an equivalent system in the form of their evacuation slides, it just looks quite different because airliners operate quite differently.

jonlucc 11y ago

> Buster the Dummy already works for a great show you may have heard of called MythBusters. Our dummy prefers to remain anonymous for the time being. I'd love to know what the SpaceX test dummy's name is, but for now I'm going to assume it's Edison.

ISL 11y ago
My prior has a prominence near "Elon".
demallien 11y ago
I'm betting on Chuck (as in Yaeger)
eps 11y ago
Unlike MythBusters, SpaceX is likely to have more than one dummy and, unlike Nasa^H^H^H^HESA they tend not to make cutesy circus out of their projects, e.g. avoid things like "Oh, hai, Twitter, I'm the Rosetta probe! Yuppie!" So I suspect dummies will remain anonymous.
- karlshea 11y ago
  I don't think you're the target demo for the cutesy circus events. Unlike SpaceX, NASA needs all the public exposure and goodwill it can get, which is what the Twitter accounts are for. There are plenty of data and science-heavy websites for the non-casual user.
  - eps 11y ago
    That's exactly my point. SpaceX doesn't need to name the dummies, nor judging by their history they would want to.
    - lotsofmangos 11y ago
      Just Read The Instructions Of Course I Still Love You

smegel 11y ago

SpaceX's first manned flight is going to be a momentous occasion.

Animats 11y ago

Mercury escape tower used when booster loses control, 1961.[1] Unmanned launch with a dummy. [1] https://www.youtube.com/watch?v=Vp9BnBDKa0s https://www.youtube.com/watch?v=Vp9BnBDKa0s

bjwbell 11y ago
54 years ago!! Makes you think. What amazing feats of engineering. The abort capsule was even picked up by helicopter. Themselves relatively new at the time.
hcrisp 11y ago
Apollo's launch escape system was tested using a rocket called Little Joe II, which started spiraling unexpectedly due to a gyro problem causing the rocket to fail. Fortunately the escape system worked as intended. [1] https://youtu.be/AqeJzItldSQ https://youtu.be/AqeJzItldSQ
- ceejayoz 11y ago
  I wonder how many of those observing realized it wasn't part of the scheduled test. What a lucky disaster!
vermontdevil 11y ago
It was also used with live people in a Soyuz rocket. Google up Vladimir Titov and there's a video of this. He attributed to the designer of LES for saving his and his compatriot's life.

klum 11y ago

Nice explanation of what's going on. I've always thought there was an opportunity for much more of this kind of thing during the previous launches--explaining the process to those of us who really have no idea.

smoyer 11y ago

As a general comment, I love watching SpaceX (for several reasons). The almost monthly stream of announcements, flights and "firsts" reminds me of watching the Apollo program progress as a young child. Then I was limited to seeing what NASA happened to put on television since I couldn't read for the early parts of the program. I'm finding reading briefs like this much more exciting as an engineer.

simonh 11y ago

I know the SuperDraco's are designed to eventually enable a soft-landing back on Earth. In this case they are only being used for the abort, and the landing will be by Parachute, presumably the powered landing approach isn't ready for testing yet. I understand the initial manned launches will use parachutes for landing as well. What I'm wondering is, will they eventually carry enough fuel to both be able to do an abort, and then do a powered landing, if required? I assume so, since at that point the only cost in terms of weight to be able to do the abort as well as the landing would be the weight of the fuel for the abort itself. Also if the capsule will be capable of an abort at any stage in the ascent, what preparations will be in place to allow for capsule recovery? Presumably it could come down anywhere along the line of flight, up to the point at which it achieves orbit. That could include the middle of Africa, and maybe even the Indian Ocean. Imagine a second stage engine failure. None of these are criticisms of the system, it's fantastic engineering and potentially a huge win over current options. Excuse me while I got and watch Gravity again (while switching off the part of my brain that knows from KSP how orbital rendezvous work).

snops 11y ago
>What I'm wondering is, will they eventually carry enough fuel to both be able to do an abort, and then do a powered landing, if required? Even if it could, its important to note that the abort system would only be used when something has gone drastically wrong, potentially an explosion, which means you can't garuntee Dragon will be undamaged. In that case, would you trust a complex powered landing, or a simpler parachute landing where you have triple redundancy? In addition, SpaceX launch on the coast and the rocket flies over the sea, so an abort may end up with a sea landing. I haven't seen any concepts from SpaceX showing a powered dragon landing at sea, and it would presumably require a pretty calm sea state, while parachutes would work in any weather. You could see similar problems with a powered landing on unfamiliar land, for instance trying to "land" on a tree canopy.
- jessriedel 11y ago
  Why would parachutes work better at sea? Just like a rocket, the parachute stops providing useful upwards force as soon as the capsule touches water/ground. The only thing I can think of is that it is probably easier to add landing air bags to a capsule descending by parachute than by rocket, but that's really only useful on land.