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SpaceX Launches Load to ISS, Successfully Tests Falcon 9 Over Water

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  • by WindBourne (631190) on Saturday April 19, 2014 @12:29AM (#46793175) Journal

    Data upload from tracking plane shows first stage landing in Atlantic was good! Flight computers continued transmitting for 8 seconds after reaching the water. Stopped when booster went horizontal. Several boats enroute through heavy seas...

    The issue is NOT whether they they recovered the stage, but whether it landed at slow controlled speeds. Apparently, SpaceX feels that it did 'land' on the water. As such, one or 2 more times with this, and they will be able to put it on land.

    Personally, I think that bringing it all the way back to the cape is a mistake. Instead, they should use one of the old oil rigs that are out there. Clean it up, land it on the rig, and then offload with a crane to a barge and take it back for launc.

  • by wisebabo (638845) on Saturday April 19, 2014 @12:35AM (#46793195) Journal

    The landing of the first stage in the Atlantic (a process that required decelerating it and bringing it to a hover just above the surface of the ocean before letting it fall in), is part of the resupply mission to the ISS. That is, once the first stage boosted its cargo towards the ISS, it then performed this test.

    Too bad that they didn't try to return the first stage to land and then try to land it there but I understand their desire to do things one step at a time (it's safer this way also). I'm curious to know if this first stage had landing gear attached (maybe not because of the additional weight, drag). Also, in the future when they DO try to land it on land, where will they be aiming? If the flight profile of the first stage is mostly vertical then, without much fuel I guess they could return to Florida, otherwise would they be going for a Caribbean island? The Azores or Canary Islands? Africa? I'm sure they've got this figured out, I'm just curious.

    Anyway, if they manage to recover the first stage by soft landing it without dunking it in salt water, it could REALLY drop the costs of space flight, even if they don't manage to reuse the 2nd stage (which they plan to do also). I remember reading that of the $20 million cost of a launch only about $500,000 was due to fuel, so this is a complete game changer. Even if the stage can only be reused a few times it'll make access to low earth orbit (the expensive part of space travel) much cheaper!

    I only hope and pray that it works reliably and that the weight penalty is not too great! I thought they would have to use a lot more fuel to slow down and turn around but I guess they're using air resistance for the braking and the (now almost empty) booster is very light. Pretty unbelievable when you see a 10 story tall rocket turn around and land on a pillar of fire.

  • by beelsebob (529313) on Saturday April 19, 2014 @12:50AM (#46793223)

    No, the plan was to land in the sea, and to have helicopters near by. Only in the future do they plan to do very accurate landings.

  • by wagnerrp (1305589) on Saturday April 19, 2014 @12:54AM (#46793237)

    I remember reading that of the $20 million cost of a launch only about $500,000 was due to fuel, so this is a complete game changer.

    Right idea, but wrong numbers. A Falcon 9 launch, not including the cost of the payload itself, is nearly $60M, while the fuel for it is only a quarter million.

  • by Hadlock (143607) on Saturday April 19, 2014 @01:07AM (#46793273) Homepage Journal

    The rocket (1st stage) when empty needs almost no fuel (about 4% of the total fuel at launch) to return to the launch site and land. The upgraded Falcon v1.1 has 10% more fuel at launch as well as increased cargo capacity (more efficient engines). Hitting a floating barge means you have to have good conditions at the launch site, as well as 400 miles out at sea as well. That dramatically limits your launch capability and exponentially increases your recovery costs.

  • by subreality (157447) on Saturday April 19, 2014 @02:44AM (#46793499)

    RTLS, TAL and AOA all relied on the main engines. If all three SSMEs failed they would have ditched it in the Atlantic. The scenarios aren't really comparable - they had a lot more fuel to work with but also a much heavier vehicle to return.

    RTLS is easier for the Falon 9. After separation the stage 1 assembly is quite light: it has shed the payload, second stage, and most importantly, most of its own fuel; the remainder is about 5% of the original mass. It can therefore make a pretty quick burn to reverse its course.

    They have some real numbers over here: http://forum.nasaspaceflight.c... [nasaspaceflight.com] .

  • by esperto (3521901) on Saturday April 19, 2014 @09:04AM (#46794155)
    " You didn't expect them to stand upright in the water like a buoy did you?" Actually I would, when the booster from the shuttle land on water (here is a video https://www.youtube.com/watch?... [youtube.com]) at first it goes horizontal but a few seconds later they go back straight up, because it is basically an empty cannister with some quite heavy engines on the bottom. IIRC before they start tugging the booster divers have to attach some hoses to pump water into the booster and make them go horizontal.
  • by cjameshuff (624879) on Saturday April 19, 2014 @09:19AM (#46794183) Homepage

    It got up there while carrying a lot more propellant and a whole second stage. The braking burn uses only 3 engines to limit the acceleration and ends with just enough propellant left to stop it when it reaches the ground. On top of this, it gets passive aerodynamic braking the whole way down.

    The mass ratio for the first stage burn, burdened with the second stage and braking propellant, is probably around 4, and a braking burn with equal delta-v would need the same mass ratio, except with no second stage and ending with the rocket empty. The overall first stage mass ratio is around 30, so all else being equal, a return would take around 3/29 = 10% of the propellant on the first stage. But all else is not equal, the returning rocket is mostly empty tanks descending through a thick atmosphere that provides plenty of braking, so the final burn only has to bring it to a halt from terminal velocity, and I omitted the second stage propellant. Overall, 4% sounds quite reasonable.

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