Topic: Mars rovers nearing the end?

[Nemesis]

Link to full article

The first and largest dusty squall has reduced direct sunlight to Mars' surface by nearly 99 percent, an unprecedented threat for the solar-powered rovers. If the storm keeps up and thickens with even more dust, officials fear the rovers' batteries may empty and silence the robotic explorers forever.

"This is a scary storm," said Mark Lemmon, a planetary scientist at Texas A&M University and member of the rover team. "If it gets any worse, we'll enter into some uncharted territory. There's been a lot of discussion about what we're going to do if (the rovers) don't have enough power to run during the day."

The next rovers should be sent out with a whisk broom and jumper cables to reactivate these ones if the storm does take them down. 

[Slider]

They lasted a god long time....must be running Linux

[Nemesis]

"[JPL] needed the tools to be able to develop their mission software on a system from someone with a proven track record," explained Steven Blackman, director of business development for aerospace and defense for the software company Wind River. The Alameda, California-based company developed the VxWorks real-time operating system used in aboard the MER rovers, as well as other NASA and European Space Agency missions.

In addition to VxWorks' reliability, the system allows users to add software patches -- such as a glitch fix or upgrade -- without interruption while a mission is in flight. "We’ve always had that [feature] so you don't have to shut down, reload and restart after every patch," Blackman said, adding that some commercial desktop systems require users to reboot their computers after a patch.

The Earthside controls use a lot of Java.

[Death_Merchant]

The Earthside controls use a lot of Java.

Timezone difference between JPL & Mars Opportunity Site = 10 hrs

Me thinks the real Java in use is by the JPL Opportunity controllers

Lookie here for downloadable kewlness
http://www.giss.nasa.gov/tools/mars24/

[Nemesis]

Link to full article

Mars' globe-engulfing dust storm has died down during the past several weeks, but the two robotic rovers on its surface now face the fallout of dust from the thin atmosphere.

Scientists use the measure "tau" to describe the light blockage, where zero is perfectly clear and light blockage diminishes as the figure increases. Tau grew to greater than 5 during the peak of the dust storm.

"Unless tau goes to 5 for several sols in a row, it looks like she's out of the woods," Lemmon said of the Opportunity rover, which has born the brunt of the dusty assault. Tau is currently around 3.3, he added.

Stifled light can threaten the Mars rovers because their electronics need to stay above -40 degrees Fahrenheit (-40 degrees Celsius)-below that and metal circuits can shrink, snap and claim the rovers' lives.

"Spirit's panels are still cleaner than before the storm, Opportunity's panels are dustier," Lemmon said. He added that mission managers are thinking of ways to minimize accumulating dust, such as tilting the solar panels, but most options seem more risky than simply toughing it out.

They just may last a while longer.  Possibly a great while.  It would be nice if they are still going when the next lander arrives.

[Centurus]

What they should have done was install some kind of a wiper on the rovers, to wipe the panels off every once in a while to ensure that the surfaces of the panels receive as much light as possible.

[Nemesis]

Wipers would have meant removing an instrument.  They were only aimed at 90 days guaranteed, they are on super duper bonus time now.  Superb workmanship.

[Panzergranate]

It amzes me how they manage to drive these things by remote control.

It takes 18 minutes, when Mars is closest to us, for the radio signal from the rovers to reach Earth and another 18 minutes for radio signals to travel the distance back. So if the operator sees the rover is heading for a cliff then it has already happened 18 minutes ago.

Having designed and built robots for various pruposes and also fun, weight is always the problem to overcome. I increases drive motor current consumption, affects steering especially if tracked and increases wear of traction transmission systems.

The NASA Mars Rovers have done extremely well to last so long as they should have had some sort of mechanical failure by now.

Perhaps the solution to the solar panels dust problem would have been to have them rotate through more than 90 degrees to drop the dust off.

[Tus-XC]

nasa has thought of moving rotating the panels already, i think they deemed it to risky... i'm thinking they move to slow and thus they might lose valuable solar energy in an attempt to clean the panels.

[Nemesis]

The moving parts to tilt the panels would also be dust covered.  Moving them would risk the dust jamming them and likely they will avoid such risk as it would end the life of the rover and the current power levels are "adequate".  Its not really broken so trying to fix it is a risk.

As to driving with the long delay you must remember that the speed of these is less than a crawl and is charted out well in advance with local "emergency stop" if anything does not work as programmed.  Small slow moves and many stops makes it practical and effective though very slow.

[Lloyd007]

Spirit and Opportunity are still alive and kicking according to the latest JPL update 

link: http://www.jpl.nasa.gov/missions/mer/

[Panzergranate]

"We took one Mars Rover and fitted ot with Duracell batteries, then we fitted normal Zinc Carbon batteries to another...."