Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Aerospace SpaceX rocket landing attempt

Tags:
  1. Jan 5, 2015 #1
    So SpaceX is going to try to land a rocketship on a boat... That's pretty amazing, if you ask me. Does anyone know of a TV station that will be broadcasting the event live? I know I could watch it here http://www.spacex.com/webcast/ , but it would be nice to be able to see it on the big screen with the whole fam
     
  2. jcsd
  3. Jan 5, 2015 #2

    phinds

    User Avatar
    Gold Member

    Geez ... that IS amazing. Very surprising that they are even going to try it and even more surprising that they put the odds of success at 50% (at best). Still, they know its capabilities a lot better than we do and wouldn't be trying it if there were not at least some reasonably chance of success.

    Seems that landing leads to another problem though ... say it works. THEN what ? How do they get it back onto land?
     
  4. Jan 5, 2015 #3
    Ooh I hadn't thought of that. That whole process might actually be as exciting as the landing (if the landing is actually a success of course). That would be horrible if the landing was successful and they damage the rocket when they are trying to bring it back onto land
     
  5. Jan 6, 2015 #4
    Actually it seems they have accounted for that by recognizing this is a process and that there are bound to be failures along the way, but that also we often learn more from failures than successes. People can say whatever they want to about Elon Musk but I like his cool blend of dreamer and practical "hands on". He sees Problem - Booster stages are where much of the money goes and we throw it away because it is difficult to not throw it away Solution - Find out just how difficult that really is and see what that reveals for a 2nd step and narrow down. The payoff is quite literally astronomical.
     
  6. Jan 6, 2015 #5

    Garth

    User Avatar
    Science Advisor
    Gold Member

    Thanks! That makes me the cleverest man in the world.....
    Garth
     
  7. Jan 16, 2015 #6

    berkeman

    User Avatar

    Staff: Mentor

  8. Jan 17, 2015 #7
    Despite the crash ( or RUD, if you prefer :P ) it appears a simple problem to repair. As anyone could see there was a problem with attitude as it was at nearly a 45 degree angle rather than perpendicular. Apparently a simple hydraulic system or it's controls failed to do it's job at fin guidance. Redundancy caused the engines to attempt to compensate but it was too little, too late. It is praiseworthy that they hit the barge on target. I doubt it will take much to fix this last wrinkle. Overall as experiments go, quite successful as it lends credibility to the idea that it is by no means an insurmountable problem even with present technology.

    Here's the link -> http://www.popularmechanics.com/how-to/blog/spacex-falcon-9-reusable-rocket-failed-landing
     
  9. Jan 17, 2015 #8
    Yeah, and from what I understand they're going to make another landing attempt on the 29th, it seems like the chances of success on this one are wayyyy higher than they were before.

    I might have misread that though and I don't remember where... Can anyone verify that they are in fact going to attempt another landing on the 29th? I know that they do have a launch scheduled for that day....
     
  10. Jan 18, 2015 #9

    mheslep

    User Avatar
    Gold Member

    Musk identified the problem as a 10% shortage of hydraulic fluid. If this was a simply problem to fix, then why wasn't it identified earlier, i.e. add an ample margin of fluid, unless the vehicle mass margin is too tight allow such? If that's the case, then adding more fluid won't be simple.
     
  11. Jan 22, 2015 #10

    cjl

    User Avatar

    They probably thought they did have an ample margin, and more control effort was required than expected. They'll probably just add more for the next flight.
     
  12. Jan 22, 2015 #11

    mheslep

    User Avatar
    Gold Member

    I could see that being the case if the control profile left expectations; that is, PID control degenerated into some kind of bang-bang oscillation. If that's the case, then fluid store is not the fundamental problem.
     
  13. Jan 22, 2015 #12

    cjl

    User Avatar

    It's also possible if their plant or dynamic models were a bit off. It doesn't require a dramatic oscillation to eat into aerospace-style margins.
     
  14. Apr 12, 2015 #13

    mheslep

    User Avatar
    Gold Member

  15. Apr 13, 2015 #14

    mheslep

    User Avatar
    Gold Member

    13 mins 35 34 33 ...
     
  16. Apr 13, 2015 #15

    berkeman

    User Avatar

    Staff: Mentor

  17. Apr 14, 2015 #16

    mfb

    User Avatar
    2017 Award

    Staff: Mentor

    And liftoff!

    The first stage separated, the second stage is firing, they will try to land the first stage again in a few minutes.

    Edit: Second stage engine cutoff and separation.
    Dragon has unfolded its solar arrays.
     
    Last edited: Apr 14, 2015
  18. Apr 14, 2015 #17

    berkeman

    User Avatar

    Staff: Mentor

    Ack, they stopped the live feed and said to check social media for the live landing site action. Facebook is not showing me an obvious live feed. Anybody got a link to a live landing site feed?
     
  19. Apr 14, 2015 #18

    berkeman

    User Avatar

    Staff: Mentor

  20. Apr 14, 2015 #19

    mfb

    User Avatar
    2017 Award

    Staff: Mentor

  21. Apr 14, 2015 #20

    mheslep

    User Avatar
    Gold Member

    Arg. Wind responsible for "excess" velocity? A 10 m/s wind places more than a half ton of force on that cylinder (~3.7mx30m), meaning it might have to come in with a tilt into the wind. I don't recall any indication of wind velocity on those multiple ground landing tests in Texas.

    Barge drift with current/wind? Though barge station keeping is routine.
     
  22. Apr 15, 2015 #21

    mheslep

    User Avatar
    Gold Member

    The vehicle appears to have incurred a ~20deg tilt from vertical with a single vehicle height remaning above the platform. Last moment positioning correction, or wind forcing? I see white caps on the water so there was at least 10 m/s wind on the surface, higher a couple hundred meters up. I can't see how they avoid some maneuvering thrusters (couple hundred N) at the top of the lander if wind is the problem, as gimballing the engine has against the rotational moment of that lander must be too slow? Only minimal thruster fuel required, in the last few hundred meters before landing. I suppose the mass of the thrusters (minimum two?) would be no trivial matter when every kilo of payload means 98 kilos of rocket.

    Descent velocity also seems a bit faster than the Texas tests. Looks like ~30 m/s at 30 m if the video is real time. Descent velocity did zero (apparently) by the time it hit the pad, but that velocity at 30 m also means almost no time to correct lateral velocity - which Musk noted was high. Lateral velocity correction means a vehicle rotation with this scheme, which per above is not quick.

    blob:https%3A//vine.co/b77664ce-5826-4c4f-b694-4fe24a0ac215
     
    Last edited: Apr 15, 2015
  23. Apr 15, 2015 #22

    Astronuc

    User Avatar
    Staff Emeritus
    Science Advisor

  24. Apr 16, 2015 #23

    donpacino

    User Avatar
    Gold Member

  25. Jun 28, 2015 #24

    Dotini

    User Avatar
    Gold Member

    Space X has exploded a few minutes after launch.

    Watching the press conference, I gleaned the following:


    - They have a serious problem. They have 4 months of supplies left on ISS. The crew will be returned when they are down to 45 days.

    - Water and water filtration and provisions are probably the biggest loss to the ISS. And the docking adapter and radio system. Russian Progress and Soyuz flights are pending, as is one from Japan later in the summer.

    - The ISS water processor is reaching its limits.

    - All three commercial vehicles to ISS (Orbital, Progress and Space-X ) were lost in a one year time frame.

    - Stand-down of Musk's rocket until problems are understood.

    - FAA will have oversight of the investigation which will be conducted by Space-X, which operates on an FAA license.

    - Commercial crewed vehicles are paused and under scrutiny, as are budgets. But they want to continue with the concept. Boeing is working on one.

    - The Russian Progress launch which adds crew to the ISS is still on for next month.
     
    Last edited: Jun 28, 2015
  26. Jun 28, 2015 #25

    phinds

    User Avatar
    Gold Member

    Damn !
     
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook