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It take 2 to 3 days to reach the ISS from the ground. Getting to orbit is only 8min of that. The rest is a slow approach of the station. If you want to deliver

It take 2 to 3 days to reach the ISS from the ground. Getting to orbit is only 8min of that. The rest is a slow approach of the station. If you want to deliver cargo or people to a specific orbit and a specific place, say the ISS, you're not gonna be able to turnover a SSTO in a day. Even a week might not be enough for a quick return trip to and from the ISS. All this time your expensive ground to orbit capacity is idle. A first stage can launch a second stage into orbit and return to launch site in less than 15min. How fast you can turn it around for relaunch is an engineering challenge, but there's no fundamental reason you couldn't do it in a day or even in an hour.

mandevil 6y ago
Note that two day approaches are not a real requirement, it's a choice that is made for operational flexibility. On Gemini 11 all the way back in 1966 NASA demonstrated docking a mere 94 minutes after launch (essentially one orbit). However, the launch window for that flight was two seconds, which is ... not ideal. By planning for a several day approach you give yourself a several hour launch window, which is much more workable. There is another reason for the leisurely approach for manned spacecraft. Studies have shown that something like 75% of spacefarers suffer from Space Acclimatization Sickness, generally lasting 1-3 days before your body gets used to zero-gee and you are fine. A leisurely approach lets an astronaut deal with that phase NOT in the shared space station that spends decades in outer space, but in the capsule which will be coming back down in a few months. SAS is a major limitation on space tourism, incidentally. You'll notice that there are very few plans between 15 minute suborbital hops and two weeks in space: that's because if even trained, physically fit astronauts take 1-3 days to adapt to space, no one is sure what a person who is not as trained will do, and if the word of mouth is "I went into space for three days and felt sick the entire time" that's not a good customer experience.
- rbanffy 6y ago
  I guess that by the time we get to serious space tourism, we'll have a rotating station with centrifugal gravity.
  - dmd 6y ago
    But then you can no longer look out the window without puking.
    - rbanffy 6y ago
      For that you take the elevator to the observatory.

mandevil 6y ago

Note that two day approaches are not a real requirement, it's a choice that is made for operational flexibility. On Gemini 11 all the way back in 1966 NASA demonstrated docking a mere 94 minutes after launch (essentially one orbit). However, the launch window for that flight was two seconds, which is ... not ideal. By planning for a several day approach you give yourself a several hour launch window, which is much more workable. There is another reason for the leisurely approach for manned spacecraft. Studies have shown that something like 75% of spacefarers suffer from Space Acclimatization Sickness, generally lasting 1-3 days before your body gets used to zero-gee and you are fine. A leisurely approach lets an astronaut deal with that phase NOT in the shared space station that spends decades in outer space, but in the capsule which will be coming back down in a few months. SAS is a major limitation on space tourism, incidentally. You'll notice that there are very few plans between 15 minute suborbital hops and two weeks in space: that's because if even trained, physically fit astronauts take 1-3 days to adapt to space, no one is sure what a person who is not as trained will do, and if the word of mouth is "I went into space for three days and felt sick the entire time" that's not a good customer experience.

rbanffy 6y ago
I guess that by the time we get to serious space tourism, we'll have a rotating station with centrifugal gravity.
- dmd 6y ago
  But then you can no longer look out the window without puking.
  - rbanffy 6y ago
    For that you take the elevator to the observatory.