I completely agree that the future of orbital transport will make the current paradigm of expendable rockets look ridiculously expensive and wasteful. That's already true to a certain extent with F9 vs. everybody else. It will look even more so when SS/SH is flying.
QuoteI completely agree that the future of orbital transport will make the current paradigm of expendable rockets look ridiculously expensive and wasteful. That's already true to a certain extent with F9 vs. everybody else. It will look even more so when SS/SH is flying.That may be true for large rockets with large payloads > 1 Ton. But smallsats that require specific orbits and can't wait for a rideshare that just happens to be close enough to their target orbit will rely on smaller rockets. And these smaller rockets have diminishing returns for re-usability. Especially if they are mass-produced on a large scale in turn driving the manufacturing costs per rocket down. Rocketlab has zero plans for reusing their Electron rocket. Instead they plan to simply mass-produce them to sell them at a competitive price. Sure you can launch hundreds of them at once on a large reusable rocket if you really wanted to, but what if you only wanted to launch a single small satellite in a specific orbit? Expendable small rockets will exist for the same reason expendable plastic bottles do, convenience.
In a near-repeat of the EFT-1 launch, a Delta IV Heavy operating out of SLC-37 would send Orion and its service module into an elliptical orbit with a stable perigee. Orion would separate and validate its systems in this orbit. Immediately after Orion’s systems checked out and orbital inclinations aligned, Falcon Heavy would launch expendable, carrying an unmanned Dragon 2, into the same orbit. However, Dragon 2 would remain mated to the Falcon Heavy upper stage. Expending all three cores of Falcon Heavy would leave 45.3 tonnes of propellant residuals in low Earth orbit, of which 29.9 tonnes would still remain after matching orbits with Orion. The Falcon Heavy upper stage would have the same modifications used in its inaugural test flight to allow extended restart of the Merlin 1D Vacuum engine.Orion would use its own thrusters to match orbits with the other vehicle, then hold position. Dragon 2, with its software updated to allow maneuvering while still attached to the Falcon upper stage, would execute autonomous docking. Although Dragon 2 previously docked while flying free of the upper stage, it is already able to compensate for shifts in the center of mass in order to carry externally-manifested payloads.Once Dragon 2 has firmly mated to the docking adapter on the nose of Orion, the Falcon Heavy upper stage would reorient using cold gas thrusters and then fire at perigee to push both Dragon 2 and Orion onto TLI. The combined stack, with Dragon 2, Orion, and the upper stage, would mass 71.1 tonnes at startup, and the M-1D would provide 1,860 m/s of additional impulse at minimum residual shutdown.From an orbit with the same apogee as EFT-1, this would be enough to commit the stack to a lunar flyby with 80 m/s of margin. Dragon 2, Orion, and the upper stage would separate. The upper stage would be left on a disposal trajectory, while Dragon 2 and Orion would adjust their own paths independently: Dragon 2 to line up for free-return and Orion to orient for injection into the desired lunar orbit.
I watched this as well and thought there was another possibility that Bridenstine hadn't considered. He mentioned that Dragon 2 is the only vehicle that can perform autonomous docking...well, then, why not use Dragon 2?https://medium.com/@davidstarlingm/back-to-the-moon-61a47c60f78dQuoteIn a near-repeat of the EFT-1 launch, a Delta IV Heavy operating out of SLC-37 would send Orion and its service module into an elliptical orbit with a stable perigee. Orion would separate and validate its systems in this orbit. Immediately after Orion’s systems checked out and orbital inclinations aligned, Falcon Heavy would launch expendable, carrying an unmanned Dragon 2, into the same orbit. However, Dragon 2 would remain mated to the Falcon Heavy upper stage. Expending all three cores of Falcon Heavy would leave 45.3 tonnes of propellant residuals in low Earth orbit, of which 29.9 tonnes would still remain after matching orbits with Orion. The Falcon Heavy upper stage would have the same modifications used in its inaugural test flight to allow extended restart of the Merlin 1D Vacuum engine.Orion would use its own thrusters to match orbits with the other vehicle, then hold position. Dragon 2, with its software updated to allow maneuvering while still attached to the Falcon upper stage, would execute autonomous docking. Although Dragon 2 previously docked while flying free of the upper stage, it is already able to compensate for shifts in the center of mass in order to carry externally-manifested payloads.Once Dragon 2 has firmly mated to the docking adapter on the nose of Orion, the Falcon Heavy upper stage would reorient using cold gas thrusters and then fire at perigee to push both Dragon 2 and Orion onto TLI. The combined stack, with Dragon 2, Orion, and the upper stage, would mass 71.1 tonnes at startup, and the M-1D would provide 1,860 m/s of additional impulse at minimum residual shutdown.From an orbit with the same apogee as EFT-1, this would be enough to commit the stack to a lunar flyby with 80 m/s of margin. Dragon 2, Orion, and the upper stage would separate. The upper stage would be left on a disposal trajectory, while Dragon 2 and Orion would adjust their own paths independently: Dragon 2 to line up for free-return and Orion to orient for injection into the desired lunar orbit.
Quote from: sevenperforce on 04/05/2019 01:04 amI watched this as well and thought there was another possibility that Bridenstine hadn't considered. He mentioned that Dragon 2 is the only vehicle that can perform autonomous docking...well, then, why not use Dragon 2?https://medium.com/@davidstarlingm/back-to-the-moon-61a47c60f78dQuoteIn a near-repeat of the EFT-1 launch, a Delta IV Heavy operating out of SLC-37 would send Orion and its service module into an elliptical orbit with a stable perigee. Orion would separate and validate its systems in this orbit. Immediately after Orion’s systems checked out and orbital inclinations aligned, Falcon Heavy would launch expendable, carrying an unmanned Dragon 2, into the same orbit. However, Dragon 2 would remain mated to the Falcon Heavy upper stage. Expending all three cores of Falcon Heavy would leave 45.3 tonnes of propellant residuals in low Earth orbit, of which 29.9 tonnes would still remain after matching orbits with Orion. The Falcon Heavy upper stage would have the same modifications used in its inaugural test flight to allow extended restart of the Merlin 1D Vacuum engine.Orion would use its own thrusters to match orbits with the other vehicle, then hold position. Dragon 2, with its software updated to allow maneuvering while still attached to the Falcon upper stage, would execute autonomous docking. Although Dragon 2 previously docked while flying free of the upper stage, it is already able to compensate for shifts in the center of mass in order to carry externally-manifested payloads.Once Dragon 2 has firmly mated to the docking adapter on the nose of Orion, the Falcon Heavy upper stage would reorient using cold gas thrusters and then fire at perigee to push both Dragon 2 and Orion onto TLI. The combined stack, with Dragon 2, Orion, and the upper stage, would mass 71.1 tonnes at startup, and the M-1D would provide 1,860 m/s of additional impulse at minimum residual shutdown.From an orbit with the same apogee as EFT-1, this would be enough to commit the stack to a lunar flyby with 80 m/s of margin. Dragon 2, Orion, and the upper stage would separate. The upper stage would be left on a disposal trajectory, while Dragon 2 and Orion would adjust their own paths independently: Dragon 2 to line up for free-return and Orion to orient for injection into the desired lunar orbit.Dragon 2 is not the only vehicle which can to autonomous docking*. CST-100 will also be able to. But you need to understand that the * is that Dragon and CST-100 are only certified, programmed, built to dock to ISS. Dragon/CST-100 would need to be re-certified to dock to something as light as Orion, and it's not clear that Orion could have the reflectors for docking. And changing the software to fly Dragon/CST-100 with a stage behind it, would be a massive rework (it may not even be possible given where the thrusters are). Oh and also, it would take all the people currently working commercial crew to stop what they are doing to work on this, to get it done in 1.5 years. Many reasons it's not possible in that timeframe.
Dragon 2 is not the only vehicle which can to autonomous docking*. CST-100 will also be able to. But you need to understand that the * is that Dragon and CST-100 are only certified, programmed, built to dock to ISS. Dragon/CST-100 would need to be re-certified to dock to something as light as Orion, and it's not clear that Orion could have the reflectors for docking. And changing the software to fly Dragon/CST-100 with a stage behind it, would be a massive rework (it may not even be possible given where the thrusters are). Oh and also, it would take all the people currently working commercial crew to stop what they are doing to work on this, to get it done in 1.5 years. Many reasons it's not possible in that timeframe.
Quote from: jarmumd on 04/05/2019 02:20 amQuote from: sevenperforce on 04/05/2019 01:04 amI watched this as well and thought there was another possibility that Bridenstine hadn't considered. He mentioned that Dragon 2 is the only vehicle that can perform autonomous docking...well, then, why not use Dragon 2?https://medium.com/@davidstarlingm/back-to-the-moon-61a47c60f78dQuoteIn a near-repeat of the EFT-1 launch, a Delta IV Heavy operating out of SLC-37 would send Orion and its service module into an elliptical orbit with a stable perigee. Orion would separate and validate its systems in this orbit. Immediately after Orion’s systems checked out and orbital inclinations aligned, Falcon Heavy would launch expendable, carrying an unmanned Dragon 2, into the same orbit. However, Dragon 2 would remain mated to the Falcon Heavy upper stage. Expending all three cores of Falcon Heavy would leave 45.3 tonnes of propellant residuals in low Earth orbit, of which 29.9 tonnes would still remain after matching orbits with Orion. The Falcon Heavy upper stage would have the same modifications used in its inaugural test flight to allow extended restart of the Merlin 1D Vacuum engine.Orion would use its own thrusters to match orbits with the other vehicle, then hold position. Dragon 2, with its software updated to allow maneuvering while still attached to the Falcon upper stage, would execute autonomous docking. Although Dragon 2 previously docked while flying free of the upper stage, it is already able to compensate for shifts in the center of mass in order to carry externally-manifested payloads.Once Dragon 2 has firmly mated to the docking adapter on the nose of Orion, the Falcon Heavy upper stage would reorient using cold gas thrusters and then fire at perigee to push both Dragon 2 and Orion onto TLI. The combined stack, with Dragon 2, Orion, and the upper stage, would mass 71.1 tonnes at startup, and the M-1D would provide 1,860 m/s of additional impulse at minimum residual shutdown.From an orbit with the same apogee as EFT-1, this would be enough to commit the stack to a lunar flyby with 80 m/s of margin. Dragon 2, Orion, and the upper stage would separate. The upper stage would be left on a disposal trajectory, while Dragon 2 and Orion would adjust their own paths independently: Dragon 2 to line up for free-return and Orion to orient for injection into the desired lunar orbit.Dragon 2 is not the only vehicle which can to autonomous docking*. CST-100 will also be able to. But you need to understand that the * is that Dragon and CST-100 are only certified, programmed, built to dock to ISS. Dragon/CST-100 would need to be re-certified to dock to something as light as Orion, and it's not clear that Orion could have the reflectors for docking. And changing the software to fly Dragon/CST-100 with a stage behind it, would be a massive rework (it may not even be possible given where the thrusters are). Oh and also, it would take all the people currently working commercial crew to stop what they are doing to work on this, to get it done in 1.5 years. Many reasons it's not possible in that timeframe.Reflectors don't seem like they would be that hard to install on Orion. Orion can remain attached to the DCSS once it is in its proper orbit to give Dragon 2 more mass to dock with. Also with commercial crew development wrapping up this year, perhaps they will have some time to work out these software configurations with the right incentives.
Dragon 2 can already compensate for shifting CoM since it can externally manifest payloads. That being said, my proposal does not have Dragon 2 "flying" while still attached to the stage. Orion would perform the rendezvous with Dragon and the upper stage; Dragon 2 would only need to perform the approach and docking while Orion held position. The docking ports are androgynous and Orion's can be configured passively to allow Dragon 2 to go active.Not sure about structural loading on the capsule, though.
Quote from: Glorky FCY on 04/05/2019 02:34 pmReflectors don't seem like they would be that hard to install on Orion.Please show me where you think they would go. Also show where they would fit under the LAS.
Reflectors don't seem like they would be that hard to install on Orion.
Quote from: sevenperforce on 04/05/2019 02:57 pmDragon 2 can already compensate for shifting CoM since it can externally manifest payloads. That being said, my proposal does not have Dragon 2 "flying" while still attached to the stage. Orion would perform the rendezvous with Dragon and the upper stage; Dragon 2 would only need to perform the approach and docking while Orion held position. The docking ports are androgynous and Orion's can be configured passively to allow Dragon 2 to go active.Massive difference between a cg shift of 0.5m to ~6m. How is Dragon 2 not "flying" if it's performing the approach and docking? Docking mechanisms are not currently androgynous. Orion (EM-1) was not slated to have a NDS-B1. And Dragon would have to dump it's nose cone.
Dragon 2 can already compensate for shifting CoM since it can externally manifest payloads. That being said, my proposal does not have Dragon 2 "flying" while still attached to the stage. Orion would perform the rendezvous with Dragon and the upper stage; Dragon 2 would only need to perform the approach and docking while Orion held position. The docking ports are androgynous and Orion's can be configured passively to allow Dragon 2 to go active.
Quote from: jarmumd on 04/05/2019 06:22 pmQuote from: Glorky FCY on 04/05/2019 02:34 pmReflectors don't seem like they would be that hard to install on Orion.Please show me where you think they would go. Also show where they would fit under the LAS.Uh...what reflectors are you talking about? They are the size of quarters. They fit completely within the docking nose.Quote from: jarmumd on 04/05/2019 06:25 pmQuote from: sevenperforce on 04/05/2019 02:57 pmDragon 2 can already compensate for shifting CoM since it can externally manifest payloads. That being said, my proposal does not have Dragon 2 "flying" while still attached to the stage. Orion would perform the rendezvous with Dragon and the upper stage; Dragon 2 would only need to perform the approach and docking while Orion held position. The docking ports are androgynous and Orion's can be configured passively to allow Dragon 2 to go active.Massive difference between a cg shift of 0.5m to ~6m. How is Dragon 2 not "flying" if it's performing the approach and docking? Docking mechanisms are not currently androgynous. Orion (EM-1) was not slated to have a NDS-B1. And Dragon would have to dump it's nose cone.Yes, the cg shift of several meters is the big software issue I discussed in the letter.Dragon 2 is not free-flying in the sense that it would not be responsible for adjusting its orbit; that is the area where trying to rework the software would become a bridge too far. Orion does the rendezvous. Dragon 2 merely needs to line up and come in slowly using existing software.Dragon 2's docking mechanism is androgynous. If they needed to update Orion's docking mechanism to an NDS-B1 then that would be the least of anyone's worries. Also, I do not believe Dragon's nose cone would impinge on Orion.