Quote from: vanoord on 03/02/2019 10:15 amQuote from: Alexphysics on 03/02/2019 09:58 amQuote from: hkultala on 03/02/2019 07:03 amWhy barge and not land landing for the first stage?I thought it would have enough performance for coming back to cape canaveral on this kind of payload.This kind of payload? What do you expect with a +12 metric ton spacecraft on top of the rocket? This is the heaviest thing a Falcon 9 has ever launched to ANY orbit. Add that to the "reserving performance" thing and inevitably they have to land on the droneship.Is there not also a belief that the S1 trajectory was lower than usual, so any boostback burn would have to add height as well, increasing propellant requirements?It seems it might have been all a misunderstanding, it was actually a lofted trajectory and in some way even more lofted that some cargo missions. I don't understand very well how NASA would like such trajectory, if Falcon 9 has a bad day and the crew has to abort mid-flight, they will have quite a hard reentry with all the g-forces. Soyuz usually flies a flat trajectory, they usually take about the same time to get to a similar orbit as this Dragon has gone into but if you look back at their failure in October the rocket was still about 50km up at about 2 minutes or so and the apogee after abort never went higher than 100km and the rocket was travelling almost horizontal from the external camera views (not exactly horizontal, but you know, something like 30º or something like that, maybe even less than that). If only this flight could have been in daylight to have some visual reference... but all we have is the telemetry from the webcast. Maybe we could even compare that with the "telemetry" from Roscosmos coverage of the Soyuz launches but I'm not sure about how an abort would be better with a lofted trajectory...
Quote from: Alexphysics on 03/02/2019 09:58 amQuote from: hkultala on 03/02/2019 07:03 amWhy barge and not land landing for the first stage?I thought it would have enough performance for coming back to cape canaveral on this kind of payload.This kind of payload? What do you expect with a +12 metric ton spacecraft on top of the rocket? This is the heaviest thing a Falcon 9 has ever launched to ANY orbit. Add that to the "reserving performance" thing and inevitably they have to land on the droneship.Is there not also a belief that the S1 trajectory was lower than usual, so any boostback burn would have to add height as well, increasing propellant requirements?
Quote from: hkultala on 03/02/2019 07:03 amWhy barge and not land landing for the first stage?I thought it would have enough performance for coming back to cape canaveral on this kind of payload.This kind of payload? What do you expect with a +12 metric ton spacecraft on top of the rocket? This is the heaviest thing a Falcon 9 has ever launched to ANY orbit. Add that to the "reserving performance" thing and inevitably they have to land on the droneship.
Why barge and not land landing for the first stage?I thought it would have enough performance for coming back to cape canaveral on this kind of payload.
So stupid question. Will Dragon2 take this long to reach the ISS when there are crew on board as well? If so, how do they “go to the toilet” during that roughly 24 hour period?
Quote from: M.E.T. on 03/02/2019 02:37 pmSo stupid question. Will Dragon2 take this long to reach the ISS when there are crew on board as well? If so, how do they “go to the toilet” during that roughly 24 hour period?According to this Business Insider article, the Crew Dragon is equipped with a toilet and privacy curtain. Given its other posh comforts (for a spacecraft) this isn't surprising to me. I'm not sure if KSC CC launches could adapt the "fast-track" 6 hour rendezvous method developed by Roscosmos for Soyuz. Doubt it because of the starting inclinations of KSC, while Balkanaur is almost already on that inclination.https://www.businessinsider.com/spacex-crew-dragon-capsule-what-its-like-inside-2018-8
I really wish at one of these many press conferences that someone asked if the D2’s will return to Earth with all of its unused hypergolic propellant onboard, or if it dumps it at some point.
Quote from: thomson on 03/02/2019 01:48 pmAnyone knows how to track SpX-DM1 or how to find out its current orbital parmeters? I'd like to try taking a photo of ISS with a Dragon chasing it up. My understanding is that Dragon should be on similar orbit: with the same inclination, right ascension of the ascending node, just slightly lower apogee and/or perigee to catch up with the ISS.Are the orbital parameters available anywhere? I'd like to observe it tonight and was wondering how far away from ISS the Dragon will be.Dragon is in plane with ISS and catching up from behind in a lower orbit with a higher rev rate. If you can see ISS, you should see Dragon chasing it along the same path a few minutes later.
Anyone knows how to track SpX-DM1 or how to find out its current orbital parmeters? I'd like to try taking a photo of ISS with a Dragon chasing it up. My understanding is that Dragon should be on similar orbit: with the same inclination, right ascension of the ascending node, just slightly lower apogee and/or perigee to catch up with the ISS.Are the orbital parameters available anywhere? I'd like to observe it tonight and was wondering how far away from ISS the Dragon will be.
Quote from: Johnnyhinbos on 03/02/2019 03:02 pmI really wish at one of these many press conferences that someone asked if the D2’s will return to Earth with all of its unused hypergolic propellant onboard, or if it dumps it at some point.Being an (software) engineer, I would prefer to keep the super dracos as options all the way till landing. My bet would be that have the old propulsive landing routines buried in their emergency software decision tree as a last resort if the capsule is in free fall after a certain altitude (turned off once the vehicle is safed.) Complete conjecture on my part with no basis in known facts...
Quote from: envy887 on 03/02/2019 02:09 pmQuote from: thomson on 03/02/2019 01:48 pmAnyone knows how to track SpX-DM1 or how to find out its current orbital parmeters? I'd like to try taking a photo of ISS with a Dragon chasing it up. My understanding is that Dragon should be on similar orbit: with the same inclination, right ascension of the ascending node, just slightly lower apogee and/or perigee to catch up with the ISS.Are the orbital parameters available anywhere? I'd like to observe it tonight and was wondering how far away from ISS the Dragon will be.Dragon is in plane with ISS and catching up from behind in a lower orbit with a higher rev rate. If you can see ISS, you should see Dragon chasing it along the same path a few minutes later. Actually, not exactly. You'll see its path displaced by the distance earth's rotation has carried you in the interval between passes. See http://www.jamesoberg.com/95sep-feelingorbmechanics.pdf
Quote from: Alexphysics on 03/02/2019 10:30 amQuote from: vanoord on 03/02/2019 10:15 amQuote from: Alexphysics on 03/02/2019 09:58 amQuote from: hkultala on 03/02/2019 07:03 amWhy barge and not land landing for the first stage?I thought it would have enough performance for coming back to cape canaveral on this kind of payload.This kind of payload? What do you expect with a +12 metric ton spacecraft on top of the rocket? This is the heaviest thing a Falcon 9 has ever launched to ANY orbit. Add that to the "reserving performance" thing and inevitably they have to land on the droneship.Is there not also a belief that the S1 trajectory was lower than usual, so any boostback burn would have to add height as well, increasing propellant requirements?It seems it might have been all a misunderstanding, it was actually a lofted trajectory and in some way even more lofted that some cargo missions. I don't understand very well how NASA would like such trajectory, if Falcon 9 has a bad day and the crew has to abort mid-flight, they will have quite a hard reentry with all the g-forces. Soyuz usually flies a flat trajectory, they usually take about the same time to get to a similar orbit as this Dragon has gone into but if you look back at their failure in October the rocket was still about 50km up at about 2 minutes or so and the apogee after abort never went higher than 100km and the rocket was travelling almost horizontal from the external camera views (not exactly horizontal, but you know, something like 30º or something like that, maybe even less than that). If only this flight could have been in daylight to have some visual reference... but all we have is the telemetry from the webcast. Maybe we could even compare that with the "telemetry" from Roscosmos coverage of the Soyuz launches but I'm not sure about how an abort would be better with a lofted trajectory... This has been discussed MANY times up-thread.I believe you have this backwards.It is a flatter trajectory, the opposite of loftedThat makes it easier to understand why the ASDS is so far downrange.You could look in the L2 Simulations thread and probably find just what you want or ask OneSpeed for a side-by-side.
Quote from: M.E.T. on 03/02/2019 02:37 pmSo stupid question. Will Dragon2 take this long to reach the ISS when there are crew on board as well? If so, how do they “go to the toilet” during that roughly 24 hour period?If they decide to do it in 24h, they will have more opportunities. For a 6h rendezvous they may have just two or three days a month to do it and for a faster one obviously a less frequency. 24h sounds right for me, it gives you time to take a rest inside Dragon before docking with the ISS. Also the capsule has a toilet, no need to worry about that.
I never noticed up until now that one section of a pipe on an MVac gets red hot during operation. I went back to the Nusantara Satu webcast and it was there as well, it appeared to be a duller red glow, but maybe it's down to the the camera auto exposure.
Quote from: Alexphysics on 03/02/2019 04:06 pmQuote from: M.E.T. on 03/02/2019 02:37 pmSo stupid question. Will Dragon2 take this long to reach the ISS when there are crew on board as well? If so, how do they “go to the toilet” during that roughly 24 hour period?If they decide to do it in 24h, they will have more opportunities. For a 6h rendezvous they may have just two or three days a month to do it and for a faster one obviously a less frequency. 24h sounds right for me, it gives you time to take a rest inside Dragon before docking with the ISS. Also the capsule has a toilet, no need to worry about that.I don’t know about that - depends on what you had for breakfast...Apollo 8
