Quote from: gwiz on 04/29/2015 04:38 pmQuote from: JimO on 04/29/2015 04:12 pmRevisit the hazard of uncontrolled reentry -- This reentry will be different, the Progress will have tanks practically full of propellant and water, which over the next few days can be expected to freeze. That ought to significantly enhance survivability through boil-off cooling at high temperatures, allowing large quantities of hypergolic propellants to reach the surface in a localized area. Is this a USA-183-type event headed our way?...and you may quote me.Why are the tanks expected to freeze? Progress is designed for a long orbital life, mostly attached to another spacecraft and unable to control its attitude. I would have thought the thermal design of the thing would be aimed at keeping fluids fluid, regardless of attitude.This depends partly on having full electrical power. We don't know right now how much electrical capability is left on-board.
Quote from: JimO on 04/29/2015 04:12 pmRevisit the hazard of uncontrolled reentry -- This reentry will be different, the Progress will have tanks practically full of propellant and water, which over the next few days can be expected to freeze. That ought to significantly enhance survivability through boil-off cooling at high temperatures, allowing large quantities of hypergolic propellants to reach the surface in a localized area. Is this a USA-183-type event headed our way?...and you may quote me.Why are the tanks expected to freeze? Progress is designed for a long orbital life, mostly attached to another spacecraft and unable to control its attitude. I would have thought the thermal design of the thing would be aimed at keeping fluids fluid, regardless of attitude.
Revisit the hazard of uncontrolled reentry -- This reentry will be different, the Progress will have tanks practically full of propellant and water, which over the next few days can be expected to freeze. That ought to significantly enhance survivability through boil-off cooling at high temperatures, allowing large quantities of hypergolic propellants to reach the surface in a localized area. Is this a USA-183-type event headed our way?...and you may quote me.
Quote from: FinalFrontier on 04/29/2015 04:40 pmQuote from: gwiz on 04/29/2015 04:38 pmQuote from: JimO on 04/29/2015 04:12 pmRevisit the hazard of uncontrolled reentry -- This reentry will be different, the Progress will have tanks practically full of propellant and water, which over the next few days can be expected to freeze. That ought to significantly enhance survivability through boil-off cooling at high temperatures, allowing large quantities of hypergolic propellants to reach the surface in a localized area. Is this a USA-183-type event headed our way?...and you may quote me.Why are the tanks expected to freeze? Progress is designed for a long orbital life, mostly attached to another spacecraft and unable to control its attitude. I would have thought the thermal design of the thing would be aimed at keeping fluids fluid, regardless of attitude.This depends partly on having full electrical power. We don't know right now how much electrical capability is left on-board.Does it always have full power when docked to ISS? I'd think the nadir ports would leave it in the shade for much of the time.
Actually, Komarov/Ivanov/Solovyov have said that:(1) TM from 3rd stage was lost some 1.5 sec before scheduled ejection of SC;(2) SC separated more or less on time;(3) SC was found to rotate with the period of 4 seconds;(4) today, manifolds of SC were found to be depressurized which led to cancellation of the mission.No most possible cause was named but they would check issues at the moment of separation.
Quote from: Liss on 04/29/2015 04:43 pmActually, Komarov/Ivanov/Solovyov have said that:(1) TM from 3rd stage was lost some 1.5 sec before scheduled ejection of SC;(2) SC separated more or less on time;(3) SC was found to rotate with the period of 4 seconds;(4) today, manifolds of SC were found to be depressurized which led to cancellation of the mission.No most possible cause was named but they would check issues at the moment of separation.Ouch. So that would mean things depressurized. Not good. Still, seems like contrary to what I thought earlier that the problem was with the 3rd stage after all.
I guess if they can somehow comand the thrusters to fire until fuel depletion could be good, even if not able to control the spin. Less nasty stuff would have a chance to hit the ground.
Quote from: rds100 on 04/29/2015 04:43 pmI guess if they can somehow comand the thrusters to fire until fuel depletion could be good, even if not able to control the spin. Less nasty stuff would have a chance to hit the ground.If they can at least get it to hit the atmosphere broadside instead of front or rear first, it would stand a much better chance of breaking up and burning.
Quote from: FinalFrontier on 04/29/2015 04:19 pmQuote from: Rocket Science on 04/29/2015 04:17 pmCan we get assets in place for an intercept?Like shooting it down?Not 'shoot down' but 'disintegrate' so that there is nothing large and dense enough to likely survive passage through the upper and middle atmosphere.
Quote from: Rocket Science on 04/29/2015 04:17 pmCan we get assets in place for an intercept?Like shooting it down?
Can we get assets in place for an intercept?
Quote from: Ben the Space Brit on 04/29/2015 04:22 pmQuote from: FinalFrontier on 04/29/2015 04:19 pmQuote from: Rocket Science on 04/29/2015 04:17 pmCan we get assets in place for an intercept?Like shooting it down?Not 'shoot down' but 'disintegrate' so that there is nothing large and dense enough to likely survive passage through the upper and middle atmosphere.Yes, I imagine "assets" could be put into place and would likely be able to break up the Progress on its way down. They'd want to hit it from the trailing part of the orbit to minmize the chance of any debris bouncing back up in orbit.Too bad we don't have a few ships equipped with railguns, as those would blow it apart in one shot.
(4) today, manifolds of SC were found to be depressurized which led to cancellation of the mission.
Quote from: Liss on 04/29/2015 04:43 pm(4) today, manifolds of SC were found to be depressurized which led to cancellation of the mission.The implication here is that prop has been lost to space, if the manifolds are depressurized.
Any "intercept" would scatter debris into higher orbits at the same inclination and same plane as ISS. It would endanger ISS.Besides USA-193 took months to plan and position assets, only weeks exist before reentry.
How much do we think is on board? What's the amount at insertion?
I'm unclear on the terminology here - is "manifold" synonymous with "propellant tank" ("bak" in Russian I think) in this usage?
Total propellant (fuel+oxidizer) 1373 kg
I'm not questioning anything but I don't understand. Full tanks of anything getting hot and exploding would seem to reduce the risk of substantial anything getting to the ground. Frozen fuel is what makes this more dangerous than usual?