Mars Rover "Spirit" In Danger 222
Riding with Robots writes "Just days after announcing that the Mars Phoenix Lander has met its icy demise, NASA reports that a dust storm has left the rover Spirit on the edge of power failure. During one recent Martian day, the robotic geologist's solar array produced only 89 watt hours of energy, the lowest output by either rover in their nearly five years on Mars. Mission managers are taking steps to protect the hardy, battle-worn spacecraft, but the agency describes Spirit's status as 'vulnerable.'"
Winter? (Score:5, Interesting)
Isn't this just an effect of reduced sunlight during winter? Or is Spirit near the equator / other hemisphere? I know the Phoenix shutdown is at least partly due to seasonal changes
From the Press Release:
"NASA's Phoenix Mars Lander has ceased communications
after operating for more than five months. As anticipated, seasonal
decline in sunshine at the robot's arctic landing site is not
providing enough sunlight for the solar arrays to collect the power
necessary to charge batteries that operate the lander's instruments."
Mars Rovers, Landers, and Orbiters (Score:5, Interesting)
Viking 1 - orbiter + lander - dead and dead (fuel leak, battery)
Viking 2 - orbiter + lander - dead and dead (out of gas, bad software update)
Pathfinder - lander - lost contact in 12 weeks.
Sojourner - rover - lost contact in 12 weeks.
Spirit - rover - critically low power, busted wheel
Opportunity - rover - still roving strong
Phoenix - rover - dead, but we're still listening
Re:It's been a good run (Score:2, Interesting)
Think next time they'll add a cleaning brush attachment for the arm?
Well that was the logest 90 days I can remeber (Score:4, Interesting)
These things had a 90 day life span! Next time I think we should send them in pairs so they can help each other out in a pinch.
Re:Only 89 watt hours of energy (Score:3, Interesting)
Different Hemispheres (Score:5, Interesting)
Spirit and Opportunity, however, are in the southern hemisphere, and it's early spring. Between the dust on Spirit's solar panels and being about 12 degrees further from the equator than Opportunity, things got a little worrisome for Spirit over the winter, but her minimum power levels at that time were over twice the 89 Watt-hours quoted in the article.
Low power is slightly less of a concern now than it was then, because the surface temperature should be higher and so electronics should need less heating, but that huge drop in power is probably more than enough to make up the difference. The other potential positive factor is Spirit's batteries had a decent level of charge when the storm started, so if the storm dissipates quickly they'll probably be in the clear. Trying to maintain 89 W-hr for several months, however, could very easily be fatal, so they're trying to use an absolute minimum of power to keep her out of fault mode.
Spirit actually hadn't moved an inch for several months to save power until a week or two ago. Her team had parked her on a sloped rock face at about a 30 degree angle to square her solar panels to the noon sun over the winter, and because of relatively clear skies, she was even able to take a high resolution panorama [nasa.gov] (link is to an index, not directly to the giant 42 MB image) and do some stationary science. As the sun angle increased, they had just started inching back towards a 20 degree tilt to follow it when the dust storm hit. There's a rather dramatic picture of what that 30 degree tilt [nasa.gov] looks like on the program site.
As of the last report I've seen, the atmosphere is 69% opaque due to suspended dust (although I believe more than 31% of the sunlight diffuses through indirectly), and the dust coating on Spirit's solar panels is only letting through 32% of of the sunlight that actually reaches them. In the past they'd had good luck with winds cleaning the panels off, but that hasn't happened in a while. The team is hoping that the same seasonal weather that brings on these dust storms will generate a few lucky dust devils.
Opportunity, on the other side of the planet meanwhile, has been getting 500-600 Watt-hours and averaging about 50 meters per day of progress towards the huge crater Endeavor, which is 12 km away.
And what nutjob modded the parent as a troll? Sheesh! And to think we probably let that person vote, too.
Re:Mars Rovers, Landers, and Orbiters (Score:1, Interesting)
One interesting little bit of trivia about this joint mission, which was only designed to last for 40 days, is that the Sojourner rover depended on the Pathfinder lander, which carried it down, to relay communications to earth. Pathfinder died first, leaving the poor little Sojourner all on its own, but probably still functional.
In the event of losing contact, the rover was programmed to try to drive back to where it remembered the lander being and circle it, on the assumption a rock or something was blocking the signal. Last year the Mars Reconnaissance Orbiter photographed and clearly identified Pathfinder, but Sojourner is small enough they aren't sure if they spotted it or not. It's probably a little black spec barely visible halfway between the lander and where it was when contact was lost, meaning it died shortly afterwards. It's impossible to be sure, however, and one of the team members has proposed the whimsical but fun idea that it got confused about its position and took off in a straight line across the country-side. It could be over a kilometer away by now.
Go WALL-E...err...I mean Sojourner!
Re:Winter? (Score:3, Interesting)
That's what never made sense to me. Seems like all it would take is a low voltage cutoff circuit that shuts off power to everything as long as the voltage is below a threshold voltage, and then when the power comes back on, it would boot back up. In fact, most modern battery technologies require such safety measures to prevent the battery charge from getting so low that the batteries won't take a charge (or the cells reverse polarity like NiCd batteries have a habit of doing). I guess there's still the issue of whether the batteries will fail to operate if they get too cold....
Re:It's been a good run (Score:4, Interesting)
Here's the things one or both rovers have survived so far:
* Full flash memory
* Non-rotating wheel
* Dusty solar panels
* Stuck in dust dunes
* Two winters (very cold)
* Going down and up steep crater slopes
* A global dust-storm that put power at the edge (about a year ago)
* Broken joint motor
* Power leak
That's nine. If they follow feline conventions, then number 10 will be it.
Re:It's been a good run (Score:1, Interesting)
Not trolling, but NASA is an expert at setting expectations low, then milking things for all they're worth when they keep working 'beyond expectations'.
So, good job, but enough of the 'will only last for 2 months' bullshit already.
Re:Winter? (Score:3, Interesting)
Both of the rovers are near the equator. Its just a build up of dust.
The phoenix lander was near the north pole. It was there checking for ice. The phoenix lander being in the colder region will actually be so cold it will have carbon dioxide freezing onto it. Its unlikely to wake back up in the spring...but possible.
The cool thing with the phoenix lander is it DID find ice and even saw snow.
Re:Options (Score:5, Interesting)
Well, I had read about the fear of issues with dust settling on the solar cells; I figured they should have used the same mechanism that NASCAR uses to clear the lenses of the car-cams. A clear, celluloid cover over the cells, which can be rolled-up off of a spool on either side of the cells, and a brush along the top of the spool. Every time dust collects on the cells, the spool winds out a new clear celluloid cover, the dusty bit is brushed off, and rolled up. Next time, the motor rolls the opposite direction.
Oh well, maybe the next rover will have something like this.