4 ms·

The third one landed on a drone in the middle of the ocean. Call me crazy but wouldn't that be a moving object? Insane. All 3 rockets.

jacquesm 8y ago
The drone ship does what it can to be as stationary as possible but the swell will always move the platform to some extent so the ocean landings are a lot more impressive than the land based ones.
- Spinosaurus 8y ago
  Keep in mind that the boosters flip around and initiate a burn to get back over land. As far as i'm aware, the core maintains a primarily ballistic trajectory and thus lands out in the ocean.
  - errantspark 8y ago
    The boostback burn is a hell of a thing too, there was a Space Shuttle contingency plan called RTLS that was essentially the same thing. IIRC one of the commanders described it as "an unholy act of physics". This is quite similar, albeit with much less mass.
    - JshWright 8y ago
      Yeah, the major complication with the STS RTLS option is that the Shuttle had to keep the external fuel tank until after the return burn was completed (since the shuttle itself carried no propellant for the main engines). Scott Manley did a video a few years back explaining how this return profile works (and attempting to fly it in Orbiter) https://www.youtube.com/watch?v=Iwn3kk-q1YU https://www.youtube.com/watch?v=Iwn3kk-q1YU
      - DuskStar 8y ago
        Also (IIRC) you wanted the external tank to have as little remaining propellant in the main tank as possible, to facilitate separation without impacting the tank. Which meant that your burn times didn't really change when aborting, which is not a common feature of spacecraft abort systems to say the least. And there was no way to eject the SRBs early, either. Once those lit, you were in for a ride... The space shuttle had far more black zones in its launch profile than would have been acceptable in the Saturn program, or any manned program since.
        JshWright 8y ago
        Yeah, the tank had to be empty before it could be dropped (so the RTLS profile actually involved continuing away from the launch site for a while in order to burn off all the fuel without overshooting the return).
- ehsankia 8y ago
  I've always been curious as to why that drone is so damn tiny compared to the rocket. Wouldn't make it slightly larger reduce your chances of missing the platform, or are they just that confident about their accuracy?
  - ambicapter 8y ago
    The drone ship is almost the size of a football field.
    - ehsankia 8y ago
      Huh, you're right. It's really hard to get a sense of scale. https://www.teslarati.com/wp-content/uploads/2018/02/OCISLY-and-Roomba-123117-johnabc123.jpeg https://www.teslarati.com/wp-content/uploads/2018/02/OCISLY-...
  - ygra 8y ago
    As someone noted already, the drone ship isn't small. Also, accuracy didn't seem to be a problem in any if the landings, as long as nothing unexpected happened, like fuel running out. Someone ok r/spacex recently compiled a diagram of landing locations: https://i.redd.it/yra4ipgl3ln21.jpg https://i.redd.it/yra4ipgl3ln21.jpg it doesn't look like they need the target to be bigger.
mattrp 8y ago
It’s just a practice round for the startup of regular New York to London service.

jacquesm 8y ago

The drone ship does what it can to be as stationary as possible but the swell will always move the platform to some extent so the ocean landings are a lot more impressive than the land based ones.

Spinosaurus 8y ago
Keep in mind that the boosters flip around and initiate a burn to get back over land. As far as i'm aware, the core maintains a primarily ballistic trajectory and thus lands out in the ocean.
- errantspark 8y ago
  The boostback burn is a hell of a thing too, there was a Space Shuttle contingency plan called RTLS that was essentially the same thing. IIRC one of the commanders described it as "an unholy act of physics". This is quite similar, albeit with much less mass.
  - JshWright 8y ago
    Yeah, the major complication with the STS RTLS option is that the Shuttle had to keep the external fuel tank until after the return burn was completed (since the shuttle itself carried no propellant for the main engines). Scott Manley did a video a few years back explaining how this return profile works (and attempting to fly it in Orbiter) https://www.youtube.com/watch?v=Iwn3kk-q1YU https://www.youtube.com/watch?v=Iwn3kk-q1YU
    - DuskStar 8y ago
      Also (IIRC) you wanted the external tank to have as little remaining propellant in the main tank as possible, to facilitate separation without impacting the tank. Which meant that your burn times didn't really change when aborting, which is not a common feature of spacecraft abort systems to say the least. And there was no way to eject the SRBs early, either. Once those lit, you were in for a ride... The space shuttle had far more black zones in its launch profile than would have been acceptable in the Saturn program, or any manned program since.
      - JshWright 8y ago
        Yeah, the tank had to be empty before it could be dropped (so the RTLS profile actually involved continuing away from the launch site for a while in order to burn off all the fuel without overshooting the return).
ehsankia 8y ago
I've always been curious as to why that drone is so damn tiny compared to the rocket. Wouldn't make it slightly larger reduce your chances of missing the platform, or are they just that confident about their accuracy?
- ambicapter 8y ago
  The drone ship is almost the size of a football field.
  - ehsankia 8y ago
    Huh, you're right. It's really hard to get a sense of scale. https://www.teslarati.com/wp-content/uploads/2018/02/OCISLY-and-Roomba-123117-johnabc123.jpeg https://www.teslarati.com/wp-content/uploads/2018/02/OCISLY-...
- ygra 8y ago
  As someone noted already, the drone ship isn't small. Also, accuracy didn't seem to be a problem in any if the landings, as long as nothing unexpected happened, like fuel running out. Someone ok r/spacex recently compiled a diagram of landing locations: https://i.redd.it/yra4ipgl3ln21.jpg https://i.redd.it/yra4ipgl3ln21.jpg it doesn't look like they need the target to be bigger.

mattrp 8y ago

It’s just a practice round for the startup of regular New York to London service.