Mystic_L t1_ix5k523 wrote
“Exceeding expectations” concerns me when it comes from an engineer; they’ve spent a bizillion man hours working out every detail, checking and rechecking.
It shouldn’t be exceeding expectations if it was going well, it should be going exactly as expected.
quad-ratiC t1_ix5krcl wrote
Spirit, opportunity, and voyager exceeded expectations just to name a few. Nasas expectations tend to be very conservative
Mystic_L t1_ix5l0ou wrote
I’ll give you those, but they exceeded longevity of mission expectations, that’s slightly different than a rocket on its way to a moving target.
Cartz1337 t1_ix5wz7v wrote
Not really… almost every Apollo mission had significant problems of one type or another. Apollo 13 is obviously the most memorable one due to it actually exploding. Here are some details on the rest.
Apollo 1, killed its crew in a fire on the launchpad during preflight testing.
Apollo 6 - unmanned, significant POGO, multiple engine failures in 2nd stage. 3rd stage failed to reignite.
Apollo 8 - Frank Borman was puking most of the way to the moon. The spacecraft itself was the ‘best ever made’ with only 8 minor issues.
Apollo 9 - one member crew was space sick, impacting flight plan
Apollo 11 - nearly missed landing site due to improper tunnel venting, incorrect rendezvous radar setting overloaded computer during landing causing a string of alarms that could have caused an abort.
Apollo 12 - struck by lightning during launch. They weren’t sure if the strike blew the parachute pyros so they didn’t know for the entire flight if they were in a flying coffin. Also they pointed their TV camera at the sun and fried it.
Apollo 13 - boom, failure is not an option etc
Apollo 14 - abort switch contaminated with metal shavings, causing the button to appear pressed intermittently. They had to patch the computer manually to disable the switch. Landing radar failed to lock and had to be rebooted during the landing.
Apollo 15 - crew was so exhausted after returning from the lunar lander that they suffered long term damage to their cardiovascular systems. Mostly due to deficiency of potassium.
Apollo 16 - CSM thrust vectoring failed causing a prolonged delay in the landing while they worked around the issue. Astronaut tripped over the heat transfer experiment on the surface and destroyed it.
And this is just from memory. I don’t think it’s unreasonable for a mission to exceed expectations. There is an expectation of some difficulties, if some things not working as planned. To have only minor issues, issues you anticipated and planned contingencies for or no issues at all would most certainly exceed expectations.
personizzle t1_ix5z31n wrote
"Exceeding expectations" in this case means things like "We expected this part to have maybe 5% variance from nominal, and designed to cover worst-case scenarios within that range, but it was more like 2% from nominal because a bunch of stuff worked extremely well." Not "it went way faster than we expected and we don't know why, might overshoot moon idk."
jadebenn t1_ixaxenm wrote
In this case, (with the recent info from the press conference), SLS performed within 0.3% of projections, and neither it or Orion have had any major issues (fingers crossed!). For the first launch of a fully-integrated launch vehicle and payload, that's super impressive!
mtbdork t1_ix5nsc9 wrote
Ever since the first rovers sent to Mars “disappointed” government officials by not accomplishing their goal of finding life.
Nowadays, NASA has to be much more lamesauce conservative about their goals in order to secure and maintain funding by making politicians happy.
Every estimate was probably made as pessimistically as possible so that anything that was better than “exactly according to these pessimistic plans” was a positive surprise, incentivizing politicians to give them further funding to do what they really want, which is really cool stuff. The quiet part they can’t say out loud…
dasBaums t1_ix5zw0m wrote
Also a good mantra to stay happy in life
ellWatully t1_ix5tdlw wrote
Error bars go in both directions so better than expected performance is not unusual at all. "Better than expected" doesn't mean it's doing something it shouldn't have been able to do. It just means that variability stacked up in a favorable way. You model this stuff to account for uncertainty in all your components so the expected performance already assumes it's not going to be perfect. Frankly, in a complex system like this, it's difficult to even quantify what "perfect" even is because there are infinite dispersions and it's not always obvious what combination of variables is best.
toodroot t1_ix6q2a9 wrote
NASA appears to use standards like "99% likely to achieve its primary science mission". There's no surprise when that means that the thing typically has a lifetime much longer than the primary science mission.
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