So why RTLS? Why wouldn't NASA just fill the trunk with 5 tonnes of extra stuff for the ISS? Surely there must be lots of NASA folks with stuff they'd like to bolt on to the ISS exterior if only they could get it there. Among other things, you could put 3 BEAM modules in the trunk and have quite a bit of spare payload. If there were propellant tanks in the trunk, and if you had Dragon on the right ISS port, you could reboost the entire ISS.
Barber landing is 15% lower.
Quote from: envy887 on 07/23/2016 02:23 am Barber landing is 15% lower.Don't get Elon mad again. It's a "drone ship," not a barber.
And no, the Dragon can't reboost the ISS, its thrusters point in the wrong direction. And there isn't going to be propellant tanks in the trunkc.
Is there some reason Orbital gets paid over 2x more per amount of upmass?
Johnny,Thank you for the pointer to the NASA audit report. That was enlightening.If I understand correctly, NASA let two commercial resupply contracts.Orbital: 8 missions, 18.6 tonnes up, 18.6 tonnes trash, $1.9B, $102,000/kgSpaceX: 12 missions, 35.4 tonnes up, X tonnes down, $1.6B, $45,000/kgIs there some reason Orbital gets paid over 2x more per amount of upmass?
What Jim said, plus:Dragon is volumetrically limited, not mass limited. Even if they wanted to put more payload in, there's no room.Same goes for the trunk, especially since it has to be unloaded remotely. Can't exactly squeeze stuff in there.RTLS is only 30% lower payload than expendable, per Musk. Barber landing is 15% lower. For the coming upgrades, that's 16t RTLS and 19t to a barge landing.
Quote from: envy887 on 07/23/2016 02:23 amWhat Jim said, plus:Dragon is volumetrically limited, not mass limited. Even if they wanted to put more payload in, there's no room.Same goes for the trunk, especially since it has to be unloaded remotely. Can't exactly squeeze stuff in there.RTLS is only 30% lower payload than expendable, per Musk. Barber landing is 15% lower. For the coming upgrades, that's 16t RTLS and 19t to a barge landing.On the other hand, 15% for a GEO mission is value that they traded for reusability. Even without any extra payloads, the satellite lifted could have extra energy to get to its slot quicker (meaning revenue sooner, or an extended life once in place). Some vendors value this above all else, and may go to Arianespace/ILS (or even ULA) regardless of reduced launch prices for Falcon 9.
Quote from: Jim on 07/23/2016 01:30 amAnd no, the Dragon can't reboost the ISS, its thrusters point in the wrong direction. And there isn't going to be propellant tanks in the trunkc.Out of curiosity: why not? Is there anything preventing the trunk from carrying a propellant tank + a thruster that *isn't* pointed in the wrong direction?
Quote from: skybum on 07/23/2016 09:01 pmQuote from: Jim on 07/23/2016 01:30 amAnd no, the Dragon can't reboost the ISS, its thrusters point in the wrong direction. And there isn't going to be propellant tanks in the trunkc.Out of curiosity: why not? Is there anything preventing the trunk from carrying a propellant tank + a thruster that *isn't* pointed in the wrong direction?There is nothing to stop space x doing this but as far as we know they have no plans and they (as far as we know) have not been asked to.It would require significant work and time and these are two things space x have little of these days.
Falcon 9 RTLS can send 12 tonnes into ISS orbit.Falcon 9 Barge landing can sent 17 tonnes into ISS orbit.That's a huge improvement for the work of sending the barge out and back. And they own the barge asset regardless of what they do with it. How much can the barge trip possibly cost? A couple million $? Given that the launch costs >$70m, that's peanuts.
Would SpaceX say no if a vendor was willing to pay a higher price to use the full performance of a F9 in expendable mode?
SpaceX has been using extra margin on the last couple of GTO launches to deliver the satellites to Super-synchronous GTO.