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Why land? Fuel makes up a very small percent of the launch cost of a rocket. Landing also allows a much better experience for cargo and crew return, and it make

Why land? Fuel makes up a very small percent of the launch cost of a rocket. Landing also allows a much better experience for cargo and crew return, and it makes it possible to bring equipment to other planets or moons. Why vertical? Vertical landing is much more flexible. You can land on a barge at sea. You can land on the launchpad itself. You can land on a planet or moon with no atmosphere.

nicolapcweek94 10y ago
> You can land on a planet or moon with no atmosphere. IE: Mars, the ultimate SpaceX goal, which has just enough atmosphere to be annoying but not nearly enough to make parachutes work, so they had to find another way to land a big enough payload to transport 100 tons of stuff there
- andars 10y ago
  The first stage will not land on Mars.
  - nicolapcweek94 10y ago
    No it won't, but they're definitely gonna reuse the tech they're developing to land the S1 on Earth to land the MCT on Mars And to land the BFR S1 on Earth, which I'd guess would be a bit too much for parachutes even with Earth's relatively thick atmosphere, if what people have been saying on Reddit is right September 21st can't come soon enough!
  - JshWright 10y ago
    No, but the cool thing is, SpaceX is using their first stage landings to do research that will advance their goals on Mars. In order to land large payloads on Mars, SpaceX is going to have to do something that, up until recently, has never been done before. They're going to have to fire a rocket engine 'backwards' in an atmosphere (albeit a thin one) while travelling at supersonic speeds. This will be necessary in order to slow down enough to actually land (parachutes don't buy you much on Mars). This 'supersonic retropropulsion' is something that has been modeled a lot, but is really hard to actually test. You would need to get a rocket up to supersonic speeds, in the thin upper stages of Earth's atmosphere (where the conditions are close to that of Mars) and have it fire its engines backwards. As luck would have it, that's exactly what the Falcon 9 first stage does during its reentry burn. The data they are collecting now will be invaluable in designing their Mars bound spacecraft. NASA is also very interested in this data: https://www.nasa.gov/press/2014/october/new-commercial-rocket-descent-data-may-help-nasa-with-future-mars-landings/ https://www.nasa.gov/press/2014/october/new-commercial-rocke...
- Retric 10y ago
  All methods of landing on Mars require an aeroshell and parachute sequence, but after that there are three choices https://en.m.wikipedia.org/wiki/Mars_landing https://en.m.wikipedia.org/wiki/Mars_landing The advantage to powered landings is they work well for delicate stuff like people. Or in space X's case they are landing a really light shell and have a really powerful engine already attached.
  - nicolapcweek94 10y ago
    Well, they're landing a really light shell with a really powerful engine for now, on Earth. Mars is gonna be a different story, considering the Red Dragon mission in 2018 (with already existing infrastructure, since the Red Dragon will basically be a Dragon 2 capsule and the S1 for the mission will be a Falcon Heavy) is gonna have the heaviest payload ever landed on mars with a semi-empty Dragon 2, and all the missions after that will probably try to land at least one MCT, which would be heavier of a Dragon 2 by itself, with some cargo... Luckily the MCT will have an even more powerful engine, and Mars's lighter gravity will probably help!
  - phire 10y ago
    I feel like there is a [Citation Needed] for that Wikipedia quote. All existing landers used an aeroshell and parachute sequence, but that doesn't mean it's impossible to land with just Rockets. The aeroshell/parachute method is used because it allows landers to come straight in from a Hoffman transfer orbit, bleed off all that extra speed and land with the least amount of fuel required. But it's way to risky for a manned lander, as the landing date (and location) are locked in months ahead of time with no option for an abort or delay. A manned lander is likely to aerobreak into a stabke Mars parking orbit first. Allowing the crew can check the lander, check the weather at the landing site and detach from a reusable transfer module. From low Mars orbit, they are going much slower and need to disperse much less energy. You could just throw Rockets and fuel at the problem. Or wings might be far more attractive than a parachute for slowing down in the upper atmosphere (though, any wings would have to be massive to actually glide all the way down to the lower atmosphere or land)
    - 10y ago

nicolapcweek94 10y ago

> You can land on a planet or moon with no atmosphere. IE: Mars, the ultimate SpaceX goal, which has just enough atmosphere to be annoying but not nearly enough to make parachutes work, so they had to find another way to land a big enough payload to transport 100 tons of stuff there

andars 10y ago
The first stage will not land on Mars.
- nicolapcweek94 10y ago
  No it won't, but they're definitely gonna reuse the tech they're developing to land the S1 on Earth to land the MCT on Mars And to land the BFR S1 on Earth, which I'd guess would be a bit too much for parachutes even with Earth's relatively thick atmosphere, if what people have been saying on Reddit is right September 21st can't come soon enough!
- JshWright 10y ago
  No, but the cool thing is, SpaceX is using their first stage landings to do research that will advance their goals on Mars. In order to land large payloads on Mars, SpaceX is going to have to do something that, up until recently, has never been done before. They're going to have to fire a rocket engine 'backwards' in an atmosphere (albeit a thin one) while travelling at supersonic speeds. This will be necessary in order to slow down enough to actually land (parachutes don't buy you much on Mars). This 'supersonic retropropulsion' is something that has been modeled a lot, but is really hard to actually test. You would need to get a rocket up to supersonic speeds, in the thin upper stages of Earth's atmosphere (where the conditions are close to that of Mars) and have it fire its engines backwards. As luck would have it, that's exactly what the Falcon 9 first stage does during its reentry burn. The data they are collecting now will be invaluable in designing their Mars bound spacecraft. NASA is also very interested in this data: https://www.nasa.gov/press/2014/october/new-commercial-rocket-descent-data-may-help-nasa-with-future-mars-landings/ https://www.nasa.gov/press/2014/october/new-commercial-rocke...
Retric 10y ago
All methods of landing on Mars require an aeroshell and parachute sequence, but after that there are three choices https://en.m.wikipedia.org/wiki/Mars_landing https://en.m.wikipedia.org/wiki/Mars_landing The advantage to powered landings is they work well for delicate stuff like people. Or in space X's case they are landing a really light shell and have a really powerful engine already attached.
- nicolapcweek94 10y ago
  Well, they're landing a really light shell with a really powerful engine for now, on Earth. Mars is gonna be a different story, considering the Red Dragon mission in 2018 (with already existing infrastructure, since the Red Dragon will basically be a Dragon 2 capsule and the S1 for the mission will be a Falcon Heavy) is gonna have the heaviest payload ever landed on mars with a semi-empty Dragon 2, and all the missions after that will probably try to land at least one MCT, which would be heavier of a Dragon 2 by itself, with some cargo... Luckily the MCT will have an even more powerful engine, and Mars's lighter gravity will probably help!
- phire 10y ago
  I feel like there is a [Citation Needed] for that Wikipedia quote. All existing landers used an aeroshell and parachute sequence, but that doesn't mean it's impossible to land with just Rockets. The aeroshell/parachute method is used because it allows landers to come straight in from a Hoffman transfer orbit, bleed off all that extra speed and land with the least amount of fuel required. But it's way to risky for a manned lander, as the landing date (and location) are locked in months ahead of time with no option for an abort or delay. A manned lander is likely to aerobreak into a stabke Mars parking orbit first. Allowing the crew can check the lander, check the weather at the landing site and detach from a reusable transfer module. From low Mars orbit, they are going much slower and need to disperse much less energy. You could just throw Rockets and fuel at the problem. Or wings might be far more attractive than a parachute for slowing down in the upper atmosphere (though, any wings would have to be massive to actually glide all the way down to the lower atmosphere or land)
  - 10y ago