Falcon 9 first stage survives splashdown


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The controlled splashdown of today’s Falcon 9 first stage was apparently so gentle that the stage survived intact and has been photographed floating at sea.

SpaceX says it plans to tow the stage back and try to salvage it. According to Musk, they were testing “a very high retrothrust” during the landing, whatever that means.

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6 comments

  • Kirk

    “Very high retrothrust” refers to the use of three engines instead of one for the landing burn. Talk about hoverslam! This much quicker landing burn leaves very little margin for error, but is more efficient as it avoids twenty-some seconds of gravity losses plus starts at a lower altitude when then stage has been slowed even more by the atmosphere, thus allowing recovery in some cases where the payload and orbit don’t quite allow for recovery via a standard one engine landing burn.

    The only other time they tried this was with the 2016-06-15 launch of Eutelsat 117W B / ABS-2A, and it ended badly, with the booster running out of propellant while still 20 feet or so above the deck of the barge, crashing down, splaying its legs wide and landing on the engine bells, then seeming to pause for a moment before toppling over and exploding. The landing attempt appears at 1:36 of “How Not to Land an Orbital Rocket Booster” https://www.youtube.com/watch?v=bvim4rsNHkQ&t=96

    That was the last landing failure which SpaceX has suffered, and occurred after they had successfully landed a booster four times. They have now had 21 successful booster recoveries (this one doesn’t count) and they have reflown six boosters.

    Humorously, NSF is recording this sea landing as a failed attempt at expending the booster!

  • Is this part of an effort towards full reusability? This approach would leave more propellant in the upper stage so that the upper stage can decelerate from LEO to re-entry and then the same, high-thrust approach could be used by the second stage. Also, might SpaceX have been testing deceleration from orbit of the second stage only to burn up or perhaps succeed in re-entry but not have had enough propellant for the landing burn? Might they have been doing these things without reporting them?

  • Tom

    So, SpaceX sacrificed the booster so they could test a high retro-thrust landing profile without risking damage to their sea-landing barge. Makes sense, but I need more detail as to what benefits this approach has over their current, proven landing profile. If its geared towards minimizing the fuel requirement for the return-to-Earth phase, that’s certainly a big plus for both first and second stage reuse efforts and payload sizing.

    Has anyone heard anything in regard to their progress on fairing recovery?

  • geoffc

    This was a Block 4 core, which like Block 3 they are only flying twice, and it was on its second flight. Storing these things is expensive, so the rest of the Block 3/4 fleet will be expended on their second flights seems to be the plan.

    Just because they are expending a stage does not mean they are not going to test stuff. I love this about SpaceX, they are constantly testing on flights, after the core mission is complete.

    Using OCISLY to land this stage was a problem for two reasons. The three engine burn is potentially dangerous and if they punched a hole in OCISLY it would not be ready for the Falcon Heavy center core next week. Also the cycle time on OCISLY would not favour landing, return to port, drop off the stage, get back out at sea in time for the launch and would cause a delay.

    Might be time to start thinking about another barge for the Atlantic. What a great problem to have!

  • MDN

    I conjecture that this experiment could have been to provide data for possible extraterrestrial purposes at some point, such as landing with a large intact payload (habitat?) On Mars.

    Elon is always thinking ahead.

  • Edward

    Kirk wrote: “Humorously, NSF is recording this sea landing as a failed attempt at expending the booster!

    Well, that is a first. Credit to America, in this second space race. Will there be an investigation into this failure and corrective action taken?

    This reminds me of Douglas Adams’s suggestion for flying: throw yourself at the ground and miss. Perhaps other space agencies and companies can learn from this to create their own reusable rockets, try to expend them and fail.

    [End of sarcasm.]

    geoffc noted: “Storing these things is expensive

    SpaceX may not even have sufficient storage space for all the rockets. They may need more space in the not so distant future, due to their plan for an increased launch cadence. What a logistics problem to have, too many returning rockets and not enough space to hold them. Who knows what they will do with this one; perhaps it is only good as a museum piece.

    geoffc suggested: “Might be time to start thinking about another barge for the Atlantic.

    Hopefully they have been pondering this logistics problem for a couple of years, as they had been hoping to ramp up their launch cadence for these past two years — and doing it successfully for the past year. Recovering from the 2016 pad explosion probably took resources that might have gone into converting another barge into a drone ship, and it certainly delayed the need for another one.

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