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SpaceX: First stage landed! Satellites in orbit

  1. Dec 21, 2015 #1

    mfb

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    A great launch, everything worked as expected, delivering 11 OrbComm satellites to Earth orbit (they all got deployed in the minutes after reaching orbit). But that was the routine part... although it was the first flight of an improved version of Falcon 9 1.1 ("Full thrust" version).
    The first stage accelerated the second stage to about 1.5 km/s, then separated, turned around, flew back, and landed. It is the first time a rocket stage used for going to orbit has been recovered like that. Certainly a remarkable day in the history of spaceflight.



    helicopter view

    Full launch, landing and satellite deployment video

    Two pictures from the stream (the numbers in the upper right corner are the second stage speed and height).

    falcon1.jpg

    falcon2.jpg


    One satellite gets deployed, the box in the lower middle part of the image:
    falcon3.jpg
     
    Last edited: Dec 24, 2015
  2. jcsd
  3. Dec 21, 2015 #2

    Bystander

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    Finally!
     
  4. Dec 21, 2015 #3
  5. Dec 22, 2015 #4

    mfb

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  6. Dec 22, 2015 #5

    mheslep

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    Aye. First time in history, right, from a full orbital launch?

    e gettyimages-502234980_custom-32a756627383c1e97ae7c4620bdb407694835886-s800-c85.jpg
     
  7. Dec 22, 2015 #6
    The first stage didn't get into orbit, it's purpose is to get the second stage moving at a sufficient velocity and great enough altitude prior to orbit insertion.
    It's impressive engineering though.
    Whether or not it pays off in the end depends on whether the soft landed booster stage is in fact re-usable fairly quickly, or whether the refurbishing costs are not very different to building a new one.
     
  8. Dec 22, 2015 #7

    mfb

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    Using this stage again will certainly be interesting. I didn't see specific plans yet.

    The first stage didn't get into orbit, but at least it reached space due to the target orbit of ~650 km - significantly above the ISS, for example.
     
  9. Dec 22, 2015 #8
    I guess this particular one probably will not be re-used, well not as a whole, maybe parts of it.
    More likely a lot of it will be taken apart and examined very carefully to see how components had performed, potential stress failures identified, and so on that could be improved.
     
  10. Dec 22, 2015 #9

    mheslep

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    I know. I'm drawing a distinction between the Falcon mission which reached orbit and landed the 1st stg, and the recent Amazon funded mission which also landed but was only a suborbital mission.
     
  11. Dec 22, 2015 #10

    mheslep

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    Yes I think I recall from the video that the 1st stage separation occurs at about 10% of the final payload velocity.
     
  12. Dec 22, 2015 #11

    mfb

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    Stage separation happened at 6000 km/h (and 77 km height), satellite deployment at 26000 km/h. That is 23%.
    Full launch video
    Vertical velocity seems to be more than 1km/s at that point. A very steep launch profile, but one that helps to get the first stage back to the launch pad.
     
  13. Dec 22, 2015 #12

    mheslep

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    I've not seen any comment yet on why SpaceX abandoned the barge for landing, or how they gained permission for a landing attempt at the Cape. A demolition charge could not have completely avoided tons of misguided 1st stage raining on the Cape.
     
  14. Dec 23, 2015 #13
    My guess is that a barge is essentially a boat and it can tilt and move unpredictably due to weather and sea conditions.
    Landing on land eliminates the risk that something moves in a weird way that the onboard guidance systems can't cope with.
     
  15. Dec 23, 2015 #14

    mfb

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    The landing platform is also much larger than the barge.
    The previous missions all came very close to the drone ship, I guess the risk of the rocket going completely wrong was not that large. There is also the risk of the launch going wrong, with much more fuel.
     
  16. Dec 23, 2015 #15

    mheslep

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    Sure, and launches fail occasionally on the pad with all that fuel, but none the less on the pad which is secured for that eventuality. Shortly after launch the vehicle is downrange over the Atlantic.

    On more consideration, I imagine that since the 1st stage is also returning from over the ocean the high speed portion of the descent is safe enough, and if there's a deviation from profile in the last ~mile they still have time to destroy it. The Cape is well named; I had opportunity recently to travel down the FL coast close offshore, which is otherwise remarkably straight for hundreds of miles except for the Cape jutting out into the ocean. Its a kind of giant land barge for the FL coast.
     
  17. Dec 23, 2015 #16
    Here is a graphic that I found very interesting to demonstrate the ability of SpaceX
    ATkpdAX.png
     
  18. Dec 23, 2015 #17
    This video is fantastic. I love the timeline at the bottom.
     
  19. Dec 23, 2015 #18
    The ballistic return trajectory is such that it would land in water. Shortly before landing one engine fires and changes the trajectory so it intersects the landing pad.
     
  20. Dec 23, 2015 #19
    Great stuff. I have a good friend who works for SpaceX.
     
  21. Dec 23, 2015 #20

    mheslep

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    Blue Origin-Amazon's Bezos from doesn't agree there's a credit worthy distinction between the Falcon 1st stage and his suborbital flight. The twitter verse didn't take it well.
    jeff-bezos-tweet.png
     
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