Opportunity General Health Options

[Doug M.]

I've been clicking around for a general health status for Opportunity, but haven't been able to find one.


Power -- The solar panels seem to be showing signs of degradation over time but it's not clear how much. NASA reports regularly on power output, tau/opacity and dust levels, but not on the status of the panels themselves. They did clock well over 500 watt-hours as recently as May, so it doesn't look like their performance is a serious issue. As for non-solar power, the radioisotope heaters seem to be fine; they're Pu-238, so they would only have lost about 10% of their power since launch. So the WEB is still toasty.

Motors and joints -- I know we've got one bad wheel motor (which means we spend a lot of time driving backwards) and the bad arm azimuth joint and the separate issue with the arm potentiometer.

Electronics -- There was the flash memory issue earlier this year but I don't know if that was a one-off or a sign of age.

Instruments -- The Mossbauer spectrometer is done because its radioactive cobalt source ran out. MiniTES got dust on its mirror after the big 2007 dust storm and stopped working. AFAICT the other instruments are okay? Pancam, Navcam, Hazcams, and the APXS all seem to be working fine. There was a NASA press release last month that said "Opportunity imaged the Rock Abrasion Tool (RAT) bit to assess remaining bit life", but it didn't say anything about what they saw and I haven't been able to find any more information. Clearly the RAT is still working, at least for now.

What else?


Doug M.

[stevesliva]

"Relatively finite." Are you using inductive reasoning to conclude that Opportunity's lifetime is approaching infinity?

[peter.neaum]

"Relatively finite." Are you using inductive reasoning to conclude that Opportunity's lifetime is approaching infinity?

Imagine the headaches that would cause! ;-)

The article (linked above) shows brushes + friction = resulting in predictable wear / gouging.
That cannot go on forever (!), so the motors, relative to other items on the rover have an end of life date.

My thought was 'what wear is there in a brushless motor?' - which then leads to why didn't they use brushless - which then leads to advantages vs disadvantages etc...

[RoverDriver]

...
My thought was 'what wear is there in a brushless motor?' - which then leads to why didn't they use brushless - which then leads to advantages vs disadvantages etc...

We'll see Curry actuators how they survive there. Although I'm no expert, brushless require a more complex electronics, and if you think that electronics is more robust than mechanical components, think again. Out of 17 actuators we use almost every day, only two have issues) while most of the flash file system (which has no moving parts) have issues, and even Curry had some serious issues with one of the flash gates.

If I had to rebuild MER all over again, I'm not so sure the brushed motors would be the first items on my list.

Paolo

[James Sorenson]

If I had to rebuild MER all over again...

The MER design has proven itself to be solid and reliable. I hope the design could someday be used again, perhaps with some upgraded electronics components and a different set of instruments.

[RoverDriver]

The MER design has proven itself to be solid and reliable. I hope the design could someday be used again, perhaps with some upgraded electronics components and a different set of instruments.

There are two things I would redesign:

1) Move the UHF and HGA to a higher place. So many times I had to negotiate the vehicle attitude with communication requirements!

2) have the solar deck tilted about 20 degrees. No more hunting for high tilt in Wintertime.

3) and of course I would like Google Fiber from Mars.

Paolo