Is it common aerospace procedure?
AIUI, the majority of the risk comes from MMOD damage to the heatshield causing an entry anomaly. This is roughly proportional to total time on orbit (which is much longer than Shuttle), not crewed time on orbit (which is much shorter than Shuttle).
MMOD damage to the heatshields of vehicles that still have their trunks or service modules attached should be non-existent. Therefore this should not be a factor in calculating LOC numbers.
Quote from: clongton on 07/12/2017 06:41 pmMMOD damage to the heatshields of vehicles that still have their trunks or service modules attached should be non-existent. Therefore this should not be a factor in calculating LOC numbers.That's not what I gather from:https://www.nasaspaceflight.com/2015/05/eft-1-orion-inspections-vital-mmod-information/and https://www.nasaspaceflight.com/2016/08/nasa-mmod-primary-threat-crew-vehicles/Backshell TPS is also at risk. I could be misinterpreting those though.
Quote from: envy887 on 07/12/2017 07:06 pmQuote from: clongton on 07/12/2017 06:41 pmMMOD damage to the heatshields of vehicles that still have their trunks or service modules attached should be non-existent. Therefore this should not be a factor in calculating LOC numbers.That's not what I gather from:https://www.nasaspaceflight.com/2015/05/eft-1-orion-inspections-vital-mmod-information/and https://www.nasaspaceflight.com/2016/08/nasa-mmod-primary-threat-crew-vehicles/Backshell TPS is also at risk. I could be misinterpreting those though.There have been 50 Soyuz missions to ISS and 30 Soyuz missions to Mir. These missions typically last about 5 to 6 months. How many of them were severely damaged by MMOD? AFAIK, none. It doesn't look like ASAP is using any of that data.
Quote from: RonM on 07/12/2017 07:53 pmQuote from: envy887 on 07/12/2017 07:06 pmQuote from: clongton on 07/12/2017 06:41 pmMMOD damage to the heatshields of vehicles that still have their trunks or service modules attached should be non-existent. Therefore this should not be a factor in calculating LOC numbers.That's not what I gather from:https://www.nasaspaceflight.com/2015/05/eft-1-orion-inspections-vital-mmod-information/and https://www.nasaspaceflight.com/2016/08/nasa-mmod-primary-threat-crew-vehicles/Backshell TPS is also at risk. I could be misinterpreting those though.There have been 50 Soyuz missions to ISS and 30 Soyuz missions to Mir. These missions typically last about 5 to 6 months. How many of them were severely damaged by MMOD? AFAIK, none. It doesn't look like ASAP is using any of that data.Just because there hasn't been a loss of a Soyuz from MMOD doesn't mean there is no risk. Also the debris environment around the ISS / LEO in general is worse now than it ever has been, which is a part of the issue. There are MMOD models that output different risk factors depending on assumptions made about the amount and location of debris hazards. For example, fine debris from the Chinese ASAT test is slowly coming closer to Earth, but exactly where it is, how big the particles are, and how fast the orbital decay rate for the debris is a matter of some guesswork. How you model those parameters can change the risk level.
Um, not just no loss of Soyuz (which would require more than just what we might call major MMOD), but no major damage to any Soyuz OR Progress from MMOD EVER. There have been hundreds of flights.Shuttle's black, fragile and exposed heatshield is 400 times the area of the little bit of Dragon's tougher PICA heatshield that is protected by a metal covering but isn't covered by the trunk. Also, you can see at least half of it clearly from at least one window.
Could get trapped and suffocated by the blankets.
Quote“The other provider has placed a value on agility and rapid problem solving with beneficial results. They are also showing signs of evolving to reconcile their approach with the benefits and need for discipline and control.“However, they need to ensure that the evolution reflects an inherent desire to adopt the tenets of systems engineering.”Uh, yeh. I'm glad that SpaceX is never going to adopt the "tenets of systems engineering" while Musk is in charge.
“The other provider has placed a value on agility and rapid problem solving with beneficial results. They are also showing signs of evolving to reconcile their approach with the benefits and need for discipline and control.“However, they need to ensure that the evolution reflects an inherent desire to adopt the tenets of systems engineering.”
Quote from: RedLineTrain on 06/29/2017 12:05 amQuote“The other provider has placed a value on agility and rapid problem solving with beneficial results. They are also showing signs of evolving to reconcile their approach with the benefits and need for discipline and control.“However, they need to ensure that the evolution reflects an inherent desire to adopt the tenets of systems engineering.”Uh, yeh. I'm glad that SpaceX is never going to adopt the "tenets of systems engineering" while Musk is in charge.And that is why they had and will have more failures