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.

[vjkane]

There are two things I would redesign:

Maybe ultraflex solar panels for more power

This thread isn't totally idle speculation. The Mars community is considering a line of future MER-size rovers to explore the diversity of surface types with past histories of water. With modern instruments, it could be really nice upgrade.

I suspect that a precision landing system would also be high on the list for a future rover line.

Would be nice to have a single general purpose heat source RTG (MMRTG's have 8) to supplement the solar array for survival heating and power during dust storms. Of course, the mission cost just sky rocketed due to the certifications.

[fredk]

In this well-lit image, it appears to be an original equipment plastic cover that is fraying and coming loose.

Not surprizingly sharp-eyed members here spotted this years ago - check out the animation here.

[James Sorenson]

Maybe ultraflex solar panels for more power.

More power maybe, but what about deployed rigidity? A rover going over rocks and pot holes in the road no doubt will put alot of vibrational stress on the bonded cells and structure. Was there ever testing done on this for the MAX-C concept?

[mcaplinger]

Was there ever testing done on this for the MAX-C concept?

As far as I know MAX-C was a series of viewgraphs "designed" by scientists and systems people. Engineers generally come in and make things work only after the mission is selected.

Let's put this speculative discussion somewhere else as it's off-topic for MER. The rover after M2020 will likely resemble MER only in that it will have wheels and drive around.

[mcaplinger]

My thought was 'what wear is there in a brushless motor?'

The bearings and gear teeth still see wear in a brushless motor.

Predicting the lifetime of any mechanical system, or any system at all for that matter, is a bit of a black art.

[hendric]

Looks like some research is being done for low-temp batteries. https://www.nature.com/articles/d41586-018-02631-9

[Explorer1]

The meantime... the newest A.J.S. Rayl update shows that apparently the power situation is so good, the team is attempting to use the excess(!) for more astronomical observations:
http://www.planetary.org/explore/space-top...-extension.html

I am wondering what the issue is with the batteries remaining fully charged; I've heard about this before, but does anyone have more details? Not just asking because I'm a laptop user who wants to preserve my own as much as possible...

[mcaplinger]

I am wondering what the issue is with the batteries remaining fully charged; I've heard about this before, but does anyone have more details?

http://batteryuniversity.com/learn/article...based_batteries

Your battery would last longest if you constantly maintained it at somewhere between 50% and 75% of capacity. Of course you want to discharge it sometimes since otherwise there's not much point in having a battery.