first congratulation for NASA and Spacex for the nicest presentto all the space follower folk. We all dream about moon and mars ... OK, around 2014 the last ATV mission will fly to the station.The only orbit raising possibility for ISS stays the good old Zwezda with refueling via Progress flights.Can the dragon with some extra fueling modifications use the draco thrusters to raise ISS orbit ?If it makes sense , NASA can leave maybe a dedicated dragon ( a used one ) on nadir 2 to be used as backup for Orbit raising.
Quote from: rubtest on 05/28/2012 02:46 amfirst congratulation for NASA and Spacex for the nicest presentto all the space follower folk. We all dream about moon and mars ... OK, around 2014 the last ATV mission will fly to the station.The only orbit raising possibility for ISS stays the good old Zwezda with refueling via Progress flights.Can the dragon with some extra fueling modifications use the draco thrusters to raise ISS orbit ?If it makes sense , NASA can leave maybe a dedicated dragon ( a used one ) on nadir 2 to be used as backup for Orbit raising.Node 2 nadir is a crappy location for reboost, due to the large moment arm.What's wrong with Zvezda/Progress?
Quote from: rubtest on 05/28/2012 02:46 amWhat's wrong with Zvezda/Progress?yes , Nadir 2 is a poor position for massive thrust ( I think also ofthrust contamination residues problem in this port area )Zwezda + Progress are good and reliable, but are also single point of failure for several station essential functions.having a dragon can provide a Backup for orbit changes
What's wrong with Zvezda/Progress?
Quote from: Jorge on 05/28/2012 02:52 amQuote from: rubtest on 05/28/2012 02:46 amfirst congratulation for NASA and Spacex for the nicest presentto all the space follower folk. We all dream about moon and mars ... OK, around 2014 the last ATV mission will fly to the station.The only orbit raising possibility for ISS stays the good old Zwezda with refueling via Progress flights.Can the dragon with some extra fueling modifications use the draco thrusters to raise ISS orbit ?If it makes sense , NASA can leave maybe a dedicated dragon ( a used one ) on nadir 2 to be used as backup for Orbit raising.Node 2 nadir is a crappy location for reboost, due to the large moment arm.What's wrong with Zvezda/Progress?I suppose the notion that Zvezda is aging and progress has and may fail again in the future.
Why couldn't Dragon be modified to attach where Progress does, to do the same kind of boosting using SuperDracos?
Quote from: FinalFrontier on 05/28/2012 02:54 amQuote from: Jorge on 05/28/2012 02:52 amQuote from: rubtest on 05/28/2012 02:46 amfirst congratulation for NASA and Spacex for the nicest presentto all the space follower folk. We all dream about moon and mars ... OK, around 2014 the last ATV mission will fly to the station.The only orbit raising possibility for ISS stays the good old Zwezda with refueling via Progress flights.Can the dragon with some extra fueling modifications use the draco thrusters to raise ISS orbit ?If it makes sense , NASA can leave maybe a dedicated dragon ( a used one ) on nadir 2 to be used as backup for Orbit raising.Node 2 nadir is a crappy location for reboost, due to the large moment arm.What's wrong with Zvezda/Progress?I suppose the notion that Zvezda is aging and progress has and may fail again in the future. Post-shuttle, ISS has been boosted to an orbit that could easily survive a Progress stand-down of at least a year, perhaps much longer. So the failure of an individual Progress is not an issue.
Quote from: Jorge on 05/28/2012 03:06 amQuote from: FinalFrontier on 05/28/2012 02:54 amQuote from: Jorge on 05/28/2012 02:52 amQuote from: rubtest on 05/28/2012 02:46 amfirst congratulation for NASA and Spacex for the nicest presentto all the space follower folk. We all dream about moon and mars ... OK, around 2014 the last ATV mission will fly to the station.The only orbit raising possibility for ISS stays the good old Zwezda with refueling via Progress flights.Can the dragon with some extra fueling modifications use the draco thrusters to raise ISS orbit ?If it makes sense , NASA can leave maybe a dedicated dragon ( a used one ) on nadir 2 to be used as backup for Orbit raising.Node 2 nadir is a crappy location for reboost, due to the large moment arm.What's wrong with Zvezda/Progress?I suppose the notion that Zvezda is aging and progress has and may fail again in the future. Post-shuttle, ISS has been boosted to an orbit that could easily survive a Progress stand-down of at least a year, perhaps much longer. So the failure of an individual Progress is not an issue.True but zvezda is still aging. Without progress what if its engines fail?
I guess that is the argument being put forward here anyway. I did say "the notion is" I don't agree with it myself.
Quote from: FinalFrontier True but zvezda is still aging. Without progress what if its engines fail? I guess that is the argument being put forward here anyway. I did say "the notion is" I don't agree with it myself. I was actually interested to hear if the thrust of the current Draco engines from a dragon can influence at all the orbit of the ISS ?is it at all feasible from the american segment ?
True but zvezda is still aging. Without progress what if its engines fail? I guess that is the argument being put forward here anyway. I did say "the notion is" I don't agree with it myself.
all the Orbit raising vehicles till now were docked to the ZWEZDA port ( Progress , ATV) in the russian segment.
if it is somehow feasible , NASA can prepare a detailed emergency procedure "how to do it" in case of a need, maybe test it once. and have a plan "B" in the hand.
Didn't Bill Gerstenmaier say they don't need much reboost anymore? Maybe I'm misremembering that.. he was probably talking about maneuvering to avoid debris.
Quote from: FinalFrontier on 05/28/2012 03:13 amQuote from: Jorge on 05/28/2012 03:06 amQuote from: FinalFrontier on 05/28/2012 02:54 amQuote from: Jorge on 05/28/2012 02:52 amQuote from: rubtest on 05/28/2012 02:46 amfirst congratulation for NASA and Spacex for the nicest presentto all the space follower folk. We all dream about moon and mars ... OK, around 2014 the last ATV mission will fly to the station.The only orbit raising possibility for ISS stays the good old Zwezda with refueling via Progress flights.Can the dragon with some extra fueling modifications use the draco thrusters to raise ISS orbit ?If it makes sense , NASA can leave maybe a dedicated dragon ( a used one ) on nadir 2 to be used as backup for Orbit raising.Node 2 nadir is a crappy location for reboost, due to the large moment arm.What's wrong with Zvezda/Progress?I suppose the notion that Zvezda is aging and progress has and may fail again in the future. Post-shuttle, ISS has been boosted to an orbit that could easily survive a Progress stand-down of at least a year, perhaps much longer. So the failure of an individual Progress is not an issue.True but zvezda is still aging. Without progress what if its engines fail?That's why Zvezda has two engines. And if Zvezda has a serious propulsion failure upstream of the engines, ISS is doomed anyway since Zvezda is the sole source of CMG desaturation for attitude control. QuoteI guess that is the argument being put forward here anyway. I did say "the notion is" I don't agree with it myself. Fair enough.
Hence, I can see why there would be a desire to have a backup to Zvezda (besides Visiting Vehicles) but that brings up the ICM/USCM ect debates again and is beyond the scope of this thread (as dragon is a visiting vehicle).
Quote from: FinalFrontier on 05/28/2012 04:23 amHence, I can see why there would be a desire to have a backup to Zvezda (besides Visiting Vehicles) but that brings up the ICM/USCM ect debates again and is beyond the scope of this thread (as dragon is a visiting vehicle). Right. You can posit Zvezda to be a vulnerability all you want, but you can't posit Dragon as the solution unless you intend to have one up there all the time.
Quote from: sanman on 05/28/2012 03:07 amWhy couldn't Dragon be modified to attach where Progress does, to do the same kind of boosting using SuperDracos?There is literally no reason to do this. Dragon is designed for use with the U.S. segment modifying it for use with the Russian segment would be totally unnecessary and expensive.
Quote from: FinalFrontier on 05/28/2012 03:12 amQuote from: sanman on 05/28/2012 03:07 amWhy couldn't Dragon be modified to attach where Progress does, to do the same kind of boosting using SuperDracos?There is literally no reason to do this. Dragon is designed for use with the U.S. segment modifying it for use with the Russian segment would be totally unnecessary and expensive. Well, then there should be universal docking point where anything can attach to do a station boost. Then the station can always get boosted in a pinch, if Progress or whatever else has been delayed/suspended/etc.
Quote from: sanman on 05/28/2012 04:36 amQuote from: FinalFrontier on 05/28/2012 03:12 amQuote from: sanman on 05/28/2012 03:07 amWhy couldn't Dragon be modified to attach where Progress does, to do the same kind of boosting using SuperDracos?There is literally no reason to do this. Dragon is designed for use with the U.S. segment modifying it for use with the Russian segment would be totally unnecessary and expensive. Well, then there should be universal docking point where anything can attach to do a station boost. Then the station can always get boosted in a pinch, if Progress or whatever else has been delayed/suspended/etc.Is the price of that module ( think a few hundred million ) worth the expense of " it should be there" for the small, small chance that progress fails, Zvezda is empty / disabled but the space station still intact, and no ATV is docked?Where do you place it?Who builds it?Who launches it?Who pays for it?These are not trivial questions. Reality supersedes " it should be there" or " it would be nice to have" Spacecraft are not legos or a computergame where you can just add a part and it'll magically work. There's physics, economics and politics involved.There should be a Sea Dragon with a VASIMR mars cycler. That way we can get to mars, if other things don't work out. And ponies.
Assuming there was an issue with Zvezda/Progress, another alternative would be to carry a Super Draco and fuel as an external cargo pack inside the Dragon trunk. The booster pack would then need to be moved (by the Canadarm) to a suitable location on the ISS for firing.
Quote from: OneSpeed on 09/11/2015 11:06 pmAssuming there was an issue with Zvezda/Progress, another alternative would be to carry a Super Draco and fuel as an external cargo pack inside the Dragon trunk. The booster pack would then need to be moved (by the Canadarm) to a suitable location on the ISS for firing.not really.A. Why does it have to be a Super Dacro or on a Dragon?B. How is it controlled?c. The only suitable locations are Zvezda aft end and Canadarm can't get there. Or the other end, but that is only for docking.
1. Are there existing nadir hardware mounting points near the ISS centre of gravity (in the US segment?).2. e.g. could existing handrail or shield attachment points and power connectors not be repurposed? 3. Could the thruster not be controlled remotely with a suitable wireless device from the cupola?