>Over seven years into its (originally) 90-day mission, the Mars rover Opportunity arrived at the rim of Endeavour Crater.
This is absolutely amazing engineering. I would love to see NASA double down on robotic exploration (and mining) of the solar system for the next decade or two.
Really advance the state of art of robotics, make discoveries that would be extremely difficult and costly for people to do, and get many more missions per/dollar than a manned program could.
The rovers had their power requirements and solar panels designed so that 90 days of mission could pass before getting occluded by martian dust. Once on Mars NASA discovered that occasional whirlwinds, which existence was unknown during mission planing, cleaned the panels back to usable current output levels.
They did consider various options, but nothing met the requirements.
"In short, there were possible methods, but nothing simple and light and certain. And the rover developers didn't have the time, the mass, or the leeway to experiment. Attractive though the idea was, this mission couldn't afford to try it."
NASA released some e-Books the other day. They go in depth into technical topics of space exploration. Perhaps one of the books describes the challenges of wiper blades.
Fans would be a smarter solution. Wiper blades plus dust and dirt = a mess, not necessarily clean solar panels. Engineering something that would be reliable on Mars would be rather difficult, and would add mass and complexity to the rovers, which would take away from the mass needed for other instruments and time needed for testing everything else. Also, dust buildup on the solar panels was only one factor limiting the expected lifetime of the rovers, so instead they chose to balance the engineering of the vehicle and concentrate on hitting the base mission lifetime expectancy.
Something to think about, possibly good or bad. If these rovers hadn't had such longevity, would have had other rovers on Mars in the meantime? If so, would they have been more capable? Or have these rovers represented such tremendously cost effective experiments that we're getting what we would have gotten with other rovers, but saved on launch and opportunity costs (awaiting transit to Mars, possible mission failures, etc.)?
No, there would not have been other rovers on Mars in the meantime. There were no rovers in development between MER (Spirit and Opportunity) and MSL (which is now en route to Mars).
There's a lot riding on MSL landing safely, because there's nothing solid after MSL right now. There used to be a 2018 rover, but it was recently cancelled.
They're certainly trying. The Mars Curiosity rover will be capable of amazing feats. Unfortunately, the JWST has been chewing up a lot of the space science budget at NASA lately, and will continue to do so for a few years.
Another nail in the 'dry Mars' hypothesis. Fascinating stuff of course, it will get really interesting when Curiosity gets there. Looking forward to that!
The "dry Mars" hypothesis has been dead for decades. At this point we have about as much evidence for water on Mars as we have for water on Earth.
The media is always keen on every new "omg, there was once water on Mars" discovery, but we've moved on to trying to figure out the details; where, when, how much, where did it go?
At this point we have about as much evidence for water on Mars as we have for water on Earth
Be careful with language like that. Sloppy journalists might turn that into a "we need to balance both sides of the story" and we'll wind up with people denying the existence of water on Earth.
Mars had water far more recently than it had any substantially different orbit. The sun has been getting brighter over the past four billion years, too, but afaik that isn't enough to stick together a full Martian climate history. There's other stuff going on which we don't fully understand yet.
Opportunity is far more impressive than Voyager. Voyager has basically been sitting in a nice clean vacuum doing nothing for the past thirty-five years, it's no wonder it's still working. Opportunity has been hard-scrabbling around in sandy, dusty environments, heating up in the day and cooling down at night, with dozens of joints and moving parts waving around all day.
I was under the impression the accepted reason for Mars losing water was it being carried off by solar wind due to Mars' lack of a strong magnetic field, that lack in turn being caused by its smaller size making its outer core not remaining molten like Earth's to generate a dynamo current.
This is absolutely amazing engineering. I would love to see NASA double down on robotic exploration (and mining) of the solar system for the next decade or two.
Really advance the state of art of robotics, make discoveries that would be extremely difficult and costly for people to do, and get many more missions per/dollar than a manned program could.