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> They'd rather spend $2b to get a 97% likelihood of a positive outcome, than $1b with an 80% likelihood. I don't know if you picked your numbers out of a hat,

> They'd rather spend $2b to get a 97% likelihood of a positive outcome, than $1b with an 80% likelihood. I don't know if you picked your numbers out of a hat, but napkin statistical analysis (if I'm not mistaken) is that two attempts with an 80% likelihood would have a 96% likelihood of at least one success. That's not quite exactly 97%, but if your numbers are not their actual assessment, it's worth wondering if their bets are the good ones. The thing that skews their monetary needs towards the expensive option with a better likelihood, as I understand it, is that they can't afford the bad PR that comes from failure. But in pure, statistical terms, they might, actually be better off betting less money on projects with less likelihood of success. They would fail more often, but overall, would spend less money for the same amount of success.

maxxxxx 8y ago
"as I understand it, is that they can't afford the bad PR that comes from failure." I think that's the real problem.
ridgeguy 8y ago
NASA tried "faster, better, cheaper". It didn't work out so well. Mars Climate Orbiter, Mars Polar Lander were two missions executed under the FBC regime. They failed, arguably due to underfunding that elevated risks. It's hard to say, because the statics are sparse. I'm personally ok with paying taxes to fund missions at the level of, say, New Horizons (~$700 million over 15 years) or Cassini (>$3B).
- glandium 8y ago
  But the point of a cheaper project that has more likelihood of failure is that you could try again. You can even learn from the previous failure to reduce the likelihood of failure on the second attempt. Plus, since you've done a lot of the development for the first mission, you probably can save a lot of time and money. But that's armchair space exploration engineering. I could be completely wrong in my assumptions. That being said, what is non compressible, though, is the time to get to where we need to go (Mars, Ryugu, or whatever else in space), and having to retry is a set back that can be counted in large number of years.
  - _Tev 8y ago
    Don't forget that every "try again" adds 80-150M to the cost for new launch vehicle. SpaceX is starting to change this, but most of the NASA history / planning was done in context of high launch costs.

maxxxxx 8y ago

"as I understand it, is that they can't afford the bad PR that comes from failure." I think that's the real problem.

ridgeguy 8y ago

NASA tried "faster, better, cheaper". It didn't work out so well. Mars Climate Orbiter, Mars Polar Lander were two missions executed under the FBC regime. They failed, arguably due to underfunding that elevated risks. It's hard to say, because the statics are sparse. I'm personally ok with paying taxes to fund missions at the level of, say, New Horizons (~$700 million over 15 years) or Cassini (>$3B).

glandium 8y ago
But the point of a cheaper project that has more likelihood of failure is that you could try again. You can even learn from the previous failure to reduce the likelihood of failure on the second attempt. Plus, since you've done a lot of the development for the first mission, you probably can save a lot of time and money. But that's armchair space exploration engineering. I could be completely wrong in my assumptions. That being said, what is non compressible, though, is the time to get to where we need to go (Mars, Ryugu, or whatever else in space), and having to retry is a set back that can be counted in large number of years.
- _Tev 8y ago
  Don't forget that every "try again" adds 80-150M to the cost for new launch vehicle. SpaceX is starting to change this, but most of the NASA history / planning was done in context of high launch costs.