NASA Engineering Estimates

In My Humble Opinion (IMHO)
#1

We learned from Scotty on Star Trek that the best way for an engineer on a star ship to be seen as a ‘miracle worker’ is to greatly inflate the estimated time needed to actually accomplish something, such that when one finishes before the expected time it will be a ‘miracle’.

I wonder if NASA does this very thing when they plan/report missions. Case in point, the Mars Ingenuity drone recently completed its 13th flight. The flight was a few hundred meters distance. I saw an article where the author states:
“The mission’s planners don’t know how long the plucky vehicle will last, because it has far out-lived its design lifetime, so they’re just enjoying the ride.”

I don’t mean to take anything away from the amazing achievement of flying a drone on a planet located millions of miles away, but 13 short flights doesn’t sound like very many flights to me. Indeed, some of the flights consisted of little more than getting the rotors to spin and elevating a few meters simply to test components. Inexpensive drones here on earth could log scores of these sorts of short flights before failing. Why such low projections of success and short design lifetimes?

Ingenuity is hardly the only NASA project to do this. Does NASA intentionally set the bar low on mission expectations for funding reasons so they can claim wild successes when things merely go as planned or expected?

#2

One thing is its solar recharged, on small panels on the hull of the craft, and on mars which gets 1/4 the sun then we do, so it takes quite a while to recharge the thing. So it’s not like a home based USB rechargeable, but IIRC takes a few days to do so, and uses some of that power to keep it’s batteries warm at night.

#3

I lack the engineering lingo to meaningfully discuss, but my son has been a quality engineer for a couple of space companies - rockets and satellites. He consistently complains that NASA requires unnecessarily high engineering tolerances - and then objects to paying the resulting costs and bearing the resulting delays.

Like I said, I lack the lingo, but ISTR he speaks as tho NASA requires human flight standards on non-human missions - which GREATLY increases the time/cost.

If he is correct, and NASA does grossly overengineer everything, that might contribute to missions having greater than predicted lifespans.

My suspicion is that NASA does so largely to reduce the risk of failure as much as possible.

#4

No engineer in his right mind gives management an estimated time line based upon best case scenarios, that’s the way to lose your position in a hurry. Always give worst case scenarios and then when pushed explain your reasoning and come to a mutual agreement for anything less. That is, you force management to buy in to the schedule.

For NASA a failure takes years to recover from and the loss comes from taxpayer dollars which you may never get back. Much incentive to be conservative in your approach.

#5

Any mission has a list of tasks that must be accomplished in order to be a success. And a bunch of other, “Gee, this would be great” things that are secondary. The entire mission planning is geared around accomplishing the main list. All those extra drone flights are gravy.

I was slightly involved in a Centaur project around 1966-67 and we had to develop and launch a large nose cone that would hold future satellites. It split into two halves and fell away leaving the satellite ready for orbit insertion. Our whole team was watching from a remote control room at Lewis when it launched. A great cheer went up when the nose cone separated and flew away. Then the damn thing exploded. Silence and tears.

But - we met all our goals and the mission was declared a success. We just didn’t make anything past that point! Here is a bit of background on the Centaur program at Lewis. I’m pretty sure the guy with the jacket in the second photo ended up my branch chief in the 1990s.

#6

Here is a film of one such experiment:

#7

Having been and worked with engineers for more than a quarter of a century, I feel safe saying that engineering isn’t always an exact science. You come up with a solution to a problem and you hope it works as you planned. Any 10 teams of engineers can very well come up with ten equally viable solutions. But stuff happens, requirements may change, designs have to be modified.

You do the best you can to anticipate issues and cover all contingencies. But stuff still can happen. And when what you design has to survive launch, then deploy and work in space where you can’t just tweak and adjust, naturally you’re going to over-engineer the crap out of everything. As a result, if the worst case scenario doesn’t happen, you get some amazing best-case results, especially longevity.

#8

Keep in mind that, while some missions go far beyond what they were designed for, there are also a lot of them that go far shorter than planned. Like, zero length, in a lot of cases: The spacecraft suffers some absolute catastrophic loss before it can even begin to accomplish any of its mission.