New Mars rover snapshots capture Endeavour crater vistas

Those must be some incredible batteries.

The life-cycles of the batteries is certainly a factor, but the very slow degeneration of the photovoltaic panels that keep the batteries charged was the big surprise.

The slow rate of charge and discharge, and a shallow Depth of Discharge, and the extreme cold all play a factor in prolonging the life of the batteries.

A lithium battery might last for 500 cycles when drained fully each time, but 5000 cycles when only the top 10% is used between recharges, where a "cycle" is the energy of one full discharge. Even then the battery is not completely dead, but will have approximately 60-70% of its capacity remaining.

Similiarily, if the battery is maintained close to full, it will lose 20% a year at 25 degrees Celsius, but only 5% at 0 degrees. If the lithium battery is kept roughly half full, it will age 3-5 times slower.

The short lifetime of batteries in consumer appliances is mostly due to the batteries running much too hot, and the people not knowing how to keep them properly. (Or they just don't care)

The life-cycles of the batteries is certainly a factor, but the very slow degeneration of the photovoltaic panels that keep the batteries charged was the big surprise.

As I understood, it was assumed that the panels would be covered in dust within months or couple years, but as luck would have it there has been enough gusts of wind to periodically sweep the panels clean.

And then there's the fact that the manufacturer may choose to add built-in obsolescence by charging the batteries to a higher cell voltage. It's possible to gain roughly 10-15% more capacity that way, but it dramatically reduces the cycle life of the battery.

A moot point now, but I still can't see why they didn't put dust wipers on the solar collectors. If they knew that would be the limiting factor for the length of the mission, at an extra million $, it seems like a really cheap trade for extended data collection.

its a very fine dust; like talcum powder. which might easily be wiped off if it wer not for charges. Such small particles easily get into the scratches of that once polished surface. While the air is thin, the speeds can be quite dry and gusty on Mars.

lets hope the batteries last here,it looks like the most impressive place yet.that big rock,i wish they would give us a size,looks filled with layers of something.i don't think the wipers issue has to do with bucks as much as weight.there was some talk about a cell phone microphone going along so we could hear mars but got left because of the weight issue.

the thing is: when they go ask for money to fund the project, they need to say that the mission will be short to keep the cost low. Then you build and extremely robust robot and you say you are "surprised" that it lastest so long. Then you go ask for fund a second time to extend the mission.

It's easier to get fund to extend a mission then to get fund to build a new mission.