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That may be useful for stuff you can afford to lose, but during the same period how many spacecraft have Boeing lost. When a mission takes a decade to plan a b

That may be useful for stuff you can afford to lose, but during the same period how many spacecraft have Boeing lost. When a mission takes a decade to plan a build, you go with the launch vehicle most likely to get you to destination successfully. Fail rates matter immensely. You don't want a launch vehicle iterating on your launch.

swimfar 8y ago
He's probably referring to tests that don't significantly affect the probability of a successful mission. I don't know anything about how Boeing does this. But I can imagine a contractor going another route where they offer to come up with a new technology and then make the customer pay for all of the testing. Why kill two birds with one stone when you can get them to pay for you to throw two stones?
civilitty 8y ago
Whether or not NASA (and by extension Boeing) can afford to lose a mission isn't dependent on how much it costs but on public relations and legislation. Money has diminishing returns when it comes to mission success rates. A common ballpark example I've heard from JPL PMs: you can spend $500 million on one launch with a 95% chance of putting one satellite in orbit - or - you could spend $250 million per launch on two launches, each with a 80% chance of putting up one satellite. The probability of getting at least one satellite in orbit with the latter scenario is ~96%, higher than than the $500mil/launch option, with an 80% chance of saving 25-75% of the budget for the second launch (depending on scheduling and staff retention costs for that mission). The problem with the latter option is that the public is swayed more by the absolute number of failures rather than the percentage, especially since NASA's missions usually draw a lot of global publicity. This kind of public pressure effects legislators and eventually starts changing the "cost-benefit" analysis agencies like NASA do until they're chosing the one launch option every time. The SLS is inseparable as a project from NASA as far as the public is concerned. Even though SpaceX is also heavily funded by NASA historically, Musk's cult of personality has largely saved them from feeling the kind of public pressure NASA has had to deal with in their usual missions. That ability to experiment without PR consequences is invaluable but we'll have to see whether their failure rate is big enough to scare away NASA for manned missions.
- skookumchuck 8y ago
  When a mission is $250m, I wonder how much additional a second identical copy would cost. For example, if $200m of that is R&D, it would only cost $300m for two missions.
  - civilitty 8y ago
    The marginal cost of an identical copy is almost always "just" the cost of assembly and testing - which can be astronomical if the mission is pushing the boundaries of technology like the Mars Science Lab or the NuStar x-ray telescope - but for most missions the major cost is R&D leading up to final assembly. For the majority of missions, that second $250 million goes towards engineering an extra 15% success chance for the satellite itself (success rate of the launch vehicle is known). The first $150 million gets you 80%, the second 250 million gets you an extra 15% with a flat $100 mil for launch. If you budget for two 80% launches, however, $150-200 million gets you two satellites, you spend $125-200 million on launches (you cant wait until your first failure to put money down for the second launch so it's at least a 1.25x multiplier), and $25-100 million on extra staffing costs (you can't risk losing your top PIs/scientists between the first and second launch so you have to pay them the entire time). Ideally, both options would be evaluated independent of popular sentiment. For manned exploration or cutting edge missions like the Mars rovers, we should strive for that 95% single mission success rate. Otherwise we should err towards getting more science done faster and cheaper.
- TangoTrotFox 8y ago
  The numbers are even better than you're throwing out there. Gotta keep in mind two big factors. A lot of the cost in these missions is not just the satellite hardware but the R&D costs. And the second is that launches are insured, so you'd need to compare the relative rate of insurance more than the expected value of fail rate x satellite cost. I have no idea on insurance costs for e.g. SpaceX vs Boeing launches but I'd be quite surprised if they're not extremely comparable. But yeah, I think you're really hitting at the heart of the problem that's going to become even more troublesome once we start putting people on Mars. There are a practically unlimited number of ways for something to go wrong. And even if we do everything we possibly can, we're still playing an odds game with extremely high stakes. A sensationalizing media and an ill informed public creates a nasty mix for issues like this.

swimfar 8y ago

He's probably referring to tests that don't significantly affect the probability of a successful mission. I don't know anything about how Boeing does this. But I can imagine a contractor going another route where they offer to come up with a new technology and then make the customer pay for all of the testing. Why kill two birds with one stone when you can get them to pay for you to throw two stones?

civilitty 8y ago

Whether or not NASA (and by extension Boeing) can afford to lose a mission isn't dependent on how much it costs but on public relations and legislation. Money has diminishing returns when it comes to mission success rates. A common ballpark example I've heard from JPL PMs: you can spend $500 million on one launch with a 95% chance of putting one satellite in orbit - or - you could spend $250 million per launch on two launches, each with a 80% chance of putting up one satellite. The probability of getting at least one satellite in orbit with the latter scenario is ~96%, higher than than the $500mil/launch option, with an 80% chance of saving 25-75% of the budget for the second launch (depending on scheduling and staff retention costs for that mission). The problem with the latter option is that the public is swayed more by the absolute number of failures rather than the percentage, especially since NASA's missions usually draw a lot of global publicity. This kind of public pressure effects legislators and eventually starts changing the "cost-benefit" analysis agencies like NASA do until they're chosing the one launch option every time. The SLS is inseparable as a project from NASA as far as the public is concerned. Even though SpaceX is also heavily funded by NASA historically, Musk's cult of personality has largely saved them from feeling the kind of public pressure NASA has had to deal with in their usual missions. That ability to experiment without PR consequences is invaluable but we'll have to see whether their failure rate is big enough to scare away NASA for manned missions.

skookumchuck 8y ago
When a mission is $250m, I wonder how much additional a second identical copy would cost. For example, if $200m of that is R&D, it would only cost $300m for two missions.
- civilitty 8y ago
  The marginal cost of an identical copy is almost always "just" the cost of assembly and testing - which can be astronomical if the mission is pushing the boundaries of technology like the Mars Science Lab or the NuStar x-ray telescope - but for most missions the major cost is R&D leading up to final assembly. For the majority of missions, that second $250 million goes towards engineering an extra 15% success chance for the satellite itself (success rate of the launch vehicle is known). The first $150 million gets you 80%, the second 250 million gets you an extra 15% with a flat $100 mil for launch. If you budget for two 80% launches, however, $150-200 million gets you two satellites, you spend $125-200 million on launches (you cant wait until your first failure to put money down for the second launch so it's at least a 1.25x multiplier), and $25-100 million on extra staffing costs (you can't risk losing your top PIs/scientists between the first and second launch so you have to pay them the entire time). Ideally, both options would be evaluated independent of popular sentiment. For manned exploration or cutting edge missions like the Mars rovers, we should strive for that 95% single mission success rate. Otherwise we should err towards getting more science done faster and cheaper.
TangoTrotFox 8y ago
The numbers are even better than you're throwing out there. Gotta keep in mind two big factors. A lot of the cost in these missions is not just the satellite hardware but the R&D costs. And the second is that launches are insured, so you'd need to compare the relative rate of insurance more than the expected value of fail rate x satellite cost. I have no idea on insurance costs for e.g. SpaceX vs Boeing launches but I'd be quite surprised if they're not extremely comparable. But yeah, I think you're really hitting at the heart of the problem that's going to become even more troublesome once we start putting people on Mars. There are a practically unlimited number of ways for something to go wrong. And even if we do everything we possibly can, we're still playing an odds game with extremely high stakes. A sensationalizing media and an ill informed public creates a nasty mix for issues like this.