[saosebastiao]

I think the explanation is pretty simple.

There is a (very likely) crackpot idea floating around that has gotten a lot of press. This crackpot idea, if it is what is claimed, would have immense value in NASA's primary field of operations and expertise. And this idea has gone through a couple rounds of experimentation where thrust has been measured, but is likely experimental error.

Here is the important part: NASA is investigating this because they are being pressured to investigate this. And they have succeeded in proving the existence of a few sources of experimental error. But not all of them, because there is still some measurement of thrust. And as long as the testing is relatively cheap and the pressure to validate is relatively strong, they will continue to test it. It is entirely likely that not a single physicist at NASA believes this thing works, but they are still getting paid to prove their intuitions as correct.

And I don't buy that testing this is a waste of money. It has already done some good: they've been able to identify and control for sources of measurement error of thrust at the near zero bounded end of thrust magnitude. That experience and capability is still valuable in designing and testing new ion thrusters.

[sanderjd]

> It is entirely likely that not a single physicist at NASA believes this thing works, but they are still getting paid to prove their intuitions as correct.

This, to me, is a key point. I'd rather some of my tax money go toward proving scientific stuff than a lot of the rest of what it goes toward. Maybe there are other scientific pursuits that are more worthy, but an imperfect prioritization of the importance of funding science doesn't seem like it should rate very high on the outrage-o-meter.

[Swannie]

Surely in testing this device, NASA will develop techniques in how to test the efficacy of similar extremely low power propulsion devices?

Or put another way, in testing this device, NASA are refining their ability to conduct a "control" experiment, whilst at the same time debunking some crackpot science that seems to be the subject of discussion every time they talk to senior politicians??