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Mars Opportunity Rover Is In Danger of Dying From a Dust Storm (engadget.com)
According to NASA, the Mars Opportunity rover is currently trying to survive an intensifying dust storm on the red planet. "The storm's atmospheric opacity -- the veil of dust blowing around, which can blot out sunlight -- is now much worse than a 2007 storm that Opportunity weathered," reports NASA. "The previous storm had an opacity level, or tau, somewhere above 5.5; this new storm had an estimated tau of 10.8 as of Sunday morning." Engadget reports: The storm was first detected on Friday June 1st by the Mars Reconnaissance Orbiter, at which point the rover's team was notified because of the weather event's proximity to Opportunity. The rover uses solar panels, so a dust storm could have an extremely negative impact on Opportunity's power levels and its batteries. By Wednesday June 6th, Opportunity was in minimal operations mode because of sharply decreasing power levels. The brave little rover is continuing to weather the storm; it sent a transmission back to Earth Sunday morning, which is a good sign. It means there's still enough charge left in the batteries to communicate with home, despite the fact that the storm is continuing to worsen.
"The brave little rover": https://xkcd.com/695/
I wonder how long it could last in standby if someone hadn't been foolish enough to force it to waste power phoning home just to say "I'm still here." That single transmission could possibly be what killed it.
I'd also like to note that if Opportunity wasn't designed to power down safely (or recover to a working state if someone were foolish enough to not have it power down before completely running out of power) recharge the batteries when there's enough sunlight, then have Opportunity restart, someone needs to loose their engineering degree.
--- Keep the choice with the user..
Since this article doesn't explain it, an optical depth tau value of 10.8 means approximately 0.002% of the sunlight is reaching the rover, compared to 0.4% for the last storm. It's really, really dark out there.
Opportunity and Spirit are not fitted with any mechanism to clear their solar panels. Originally, it was assumed that dust on the panels would be what would end the mission. But winds and whirlwinds were found on the planet, these occasionally blew dust from the panels, and the mission was extended.
The pressing problem is that there won't be enough energy to keep the heaters running, the electronics will cool down to -50C, and either the heaters won't turn back on when the sun returns, or, if they do, the electronics won't work when they defrost.
Prediction for end of Universe #42: Fencepost error in Quantum_bogosort.cpp
0.4% of the sunlight wouldn't have be enough to make the solar panels work. So a greater darkness than that doesn't really make any difference. It might as well be pitch black if the intensity is below 1%.
What is important, then, is how long this dust storm will last.
Prediction for end of Universe #42: Fencepost error in Quantum_bogosort.cpp
"The storm's atmospheric opacity -- the veil of dust blowing around, which can blot out sunlight -- is now much worse than a 2007 storm that Opportunity weathered," reports NASA.
The storms are getting worse ... what do you Martian "deniers" say now, eh???
Considering how the two solar powered rovers (Spirit and Opportunity) that touched down in January 2004 were originally only expected to survive for a few months only to have one finally go out in March of 2010 and the second finally in real peril of going out in June of 2018 it shouldn't be too much of a loss for the second one to finally go out. Both of them spectacularly outperformed what was expected of them and it's probably time for the last of them to quit it with the victory laps. Not that Curiosity, their bigger nuclear-powered older bother, isn't doing well for itself either. It touched down in August 2012 and it's too still going despite an originally planned two year mission length. I'm interested to see if it'll last even longer or if the decay of it's Pu238-dioxide power source will be what keeps it from extending it's mission beyond the original goal by as much as Opportunity has.
"Why should I want to make anything up? Life's bad enough as it is without wanting to invent any more of it."
You know how I can tell that neither of you actually read the article?
The main concern here isn't the dust storm itself. It's the need to keep the rover's heaters operational while maintaining a minimal power level in the batteries.
No sig today...
Seriously, you have to take those claims of "designed for 90 days of operation" with some big grains of salt.... There's no way they'd spend all the money, time and energy on R&D to get something like this put on Mars, when they REALLY only expected it would be used for a few months.
That might be the length of time they NEEDED to complete the original planned research project, so in a worst-case scenario, NASA doesn't have to say they failed. But I'm quite certain this thing was engineered with the hopes it would run for years and years -- as it has done.
...The story reports an optical depth of the dust storm of tau=10.8. This is astoundingly dark. The transmittance of light through the atmosphere is 1/e^tau so that only 1/50,000 (0.002%) of the sunlight is getting through! It is effectively perpetual night there right now....
Note that the e^1/tau factor is for direct beam. What this means is that almost all of the light that gets through to the surface is scattered light.
The tau for a rainy day for earth is very high too. It doesn't mean that the surface is completely dark, it just means that the light that does get through has scattered many times-- you can't see the disk of the sun, but some light does reach the surface.
10.8 is a record for the highest tau measured from the surface of Mars, though.
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