Scientists May Have Figured Out Why So Many Spacecraft Were Failing

In the last 20 years it's been surprisingly common for space probes to end missions early because reaction wheels have failed, moreover there's been a large number of failures associated with a specific supplier - Ithaco. A NASA spin off which developed low cost reaction wheel systems that helped bring the cost down for many space missions.
A new study offers some clues as to what might have been going on and why solar weather might be able to damage mechanical systems.

[NoNameAtAll]

All hail ceramic bearings

When having balls of steel isn't enough

[wheelitzr]

So I will begin with "I am not a rocket scientist" however as an industrial HVAC and commercial equipment service technician I replace bearings all the time and as a matter of fact I am currently covered in grease from a 15 hp electric motor that blew a rear bearing and cost my customer over $2000 to fix. There is this extreamly common thing that happens to electric motors that are being driven off what we call a VFD (variable frequency drive) it allows us to control the speed of a motor but because of how a vfd works and converts the voltage it creates voltage spikes in the rotor that hava no where to go but through the bearings and into the housing, this pits the balls, races and destroys the bearing over just a few months. The thing to keep in mind is that there is a very small amount of contact area from the ball to the race so it doesn't take much to destroy the bearing in a very short period of time. Something as simple as a rotor grounding shaft would have eliminated the bearing failure.

[theCodyReeder]

Ah yes electric arc across a bearing is why you have to be careful to not ground across a bearing when welding.

[HydraulicPressChannel]

You can get same failure mechanism with cheap frequency convert drives on electric motor bearings. The ceramic bearing is good but expensive fix the other solution is install grounding carbon brush but that's needs probably some maintenance over long periods of time so using just ceramic bearings on stuff like that is probably good idea, especially when they are already stupidly expensive :D

[marclowe]

Missed opportunity: "Bearings fail when the friction on them become unbearable."

[edp]

I worked on commercial space communication satellites, and my dad worked on Hubble Space Telescope. Reaction wheels were always acting up. On Hubble some of the reaction wheels have been replaced on servicing missions, the only spacecraft (other than the ISS) that such replacement in orbit is possible. On our commercial satellites, there were usually more than 4 wheels, so there was some redundancy. I always wondered why such a (seemingly) simple device was so troublesome. Your video provides some interesting insight into this issue.

[MattThompsonOnGoogle]

I remember when Bill gave that presentation to all of us former Ithaco Space Systems employees on the fifth anniversary of it's closing. He set up a projector in his barn and after our barn party reunion we all listened very intently. I saw the picture of a CME on the screen, looked back at Jeff Golden, then to Eric Stromswold, and my jaw dropped as they let me know that they agreed.

The ball bearing is basically the gateway for static potential to discharge from a relatively massive rotor (hidden under a relatively thin cover) to a massive dish. Yes, of course it would be subject to ionic buildup, regardless of any Faraday cage of the rotor cover. Remember, the outer bearing cover is attached to the outside of the main cover housing. Essentially, it's all right there waiting to pick up these ionic discharges.

I so miss working at Ithaco. Everyone there worked so hard at making those things work right... Laurie spent so many hours in the inner cleanroom taking so many measurements fir Bill and Eric WHILE ALSO building so many other RWAs. I stick to Torqrods so I didn't know much but I just remember how heartroken we we're when we lost the Iridium contract because of the failures. That was the death of a great company.

[thechieftain]

"the pressure of the sun's light" now that's some awesome physics

[AsbestosMuffins]

you know its also possible they realized this about 10 years ago said "yikes!" and quietly switched to ceramics

[hatman]

Finally, the aerospace industry is catching up to fidget spinner technology.

[raydunakin]

Fascinating! Space is such an extreme environment and there's still so much we don't know yet.

[mydogbrian]

- 🥺 Bombarded with audio all day I like to read the closed captions you provide in your always very informative video presentations. I really apreciate your thoughtful consideration. Keep up the good work. 👍

[hofi]

A friend who is building large CNC machines said it is a huge problem to ground these machines properly because ESD (when machining some matertials) and the currents of the motors are causing these problems with the bearings

[mattcolver]

A good experiment for the X-37A would be to put some reaction wheels in it and run them in space for a year or two then bring them back and take a look at them.

[makarlock]

I absolutely love it that you insist on using the satellite girl figurine every time you talk about the Hayabusa. Maybe next time show a picture of the motorcycle :^)

[treasureplanet]

Most fascinating. I work for a major satellite fleet operator. We've been seeing this exact type of wheel failure in some ~15 year-old spacecraft which were expected to last even longer. I'm going to go back and check the data for correlations. Glad that there seems to be a fix in the newer wheels, even if accidental. Thanks for this one, Scott!!

[fogllama]

And here I thought it was Sun Rust caused by damp and salty photons. Boy, do I feel silly now.

[Anonarchist]

I put ceramic bearings on my fidget spinner and it changed my life.

[tinkmarshino]

Damn Scott.. you always pick the most interesting things to talk about.. Plus you put them to us in a way that this 66 year old fart can actually understand.. or maybe it is just because of my Scottish heritage (Lamont clan) helps me to understand... Well done brother.. carry on...

[Arsagon]

This has to be one of my favourite videos on this channel yet. A nice inside on the engineering problems involved in rockets and space probes but easy enough to be understood by laymans.