Updates Mars Science Laboratory (Curiosity)

[statickid]

In those terms, curiosity's soft short could be likened (as a human mission analog) to a small air pressure leak in the hull, bleeding out O2.

 

[N_Molson]

In those terms, curiosity's soft short could be likened (as a human mission analog) to a small air pressure leak in the hull, bleeding out O2.

Except that the RTG supplies a constant level of power, that decreases slowly with time but still lasts more than long enough for the intended mission duration and even an extension. So (almost) nothing is really lost, so to say, but the efficiency of the whole system is seriously downgraded.

What I find a bit worrying is that the problem already happened, has repeated, and that the next time the rover could be in deep trouble. It would almost take a small robotic arm equipped with a tiny soldering iron, a pair of pliers and a "first aid electronical kit", and access hatches to critical systems. Now a remote timelapsed repair operation would probably be challenging.

 

[Proximus]

Fingers crossed its problem caused by a non critical system that can be isolated from the RTG.

Otherwise curiosity will have to live with the extra load along with previous other shorts :uhh:

 

[Urwumpe]

Fingers crossed its problem caused by a non critical system that can be isolated from the RTG.

Otherwise curiosity will have to live with the extra load along with previous other shorts :uhh:

Well, its one of those glitches that give old cars individuality. :lol:

---------- Post added at 01:47 PM ---------- Previous post was at 01:46 PM ----------

What I find a bit worrying is that the problem already happened, has repeated, and that the next time the rover could be in deep trouble. It would almost take a small robotic arm equipped with a tiny soldering iron, a pair of pliers and a "first aid electronical kit", and access hatches to critical systems. Now a remote timelapsed repair operation would probably be challenging.

Give the over two general purpose robotic arms (so one arm can also repair the other) and let it repair itself... And land a container with spare parts next to it... :lol:

 

[Izack]

It would almost take a small robotic arm equipped with a tiny soldering iron, a pair of pliers and a "first aid electronical kit", and access hatches to critical systems. Now a remote timelapsed repair operation would probably be challenging.

Which is, unfortunately, the drawback to unmanned vehicles in the old debate. Unmanned vehicles have to operate without maintenance for their entire useful lifetime.

As impressive as Curiosity's electrical system is, I'm worried about these hits to its operability. Hopefully whatever device is failing can be isolated without destroying Curiosity's usefulness.

 

[N_Molson]

Give the over two general purpose robotic arms (so one arm can also repair the other) and let it repair itself... And land a container with spare parts next to it...

Which is, unfortunately, the drawback to unmanned vehicles in the old debate. Unmanned vehicles have to operate without maintenance for their entire useful lifetime.

Or plan a manned repair mission... But someone is going to say it wouldn't be cost-efficient :hmm:

 

[Proximus]

Or plan a manned repair mission... But someone is going to say it wouldn't be cost-efficient :hmm:

:rofl: I mentioned to a friend in work today about MSL's woe's as he has repaired some Teledyne chemical processing equipment in the past. His response was "If the ticket to Mars wasn't so expensive he would happily take at look at Curiosity for you"

 

[orb]

NASA JPL:
Curiosity Resumes Science After Analysis of Voltage Issue

November 25, 2013

Mars Science Laboratory Mission Status Report

NASA's Mars rover Curiosity resumed full science operations on Saturday, Nov. 23.

Activities over the weekend included use of Curiosity's robotic arm to deliver portions of powdered rock to a laboratory inside the rover. The powder has been stored in the arm since the rover collected it by drilling into the target rock "Cumberland" six months ago. Several portions of the powder have already been analyzed. The laboratory has flexibility for examining duplicate samples in different ways.

The decision to resume science activities resulted from the success of work to diagnose the likely root cause of a Nov. 17 change in voltage on the vehicle. The voltage change itself did not affect the rover safety or health. The vehicle's electrical system has a "floating bus" design feature to tolerate a range of voltage differences between the vehicle's chassis -- its mechanical frame -- and the 32-volt power lines that deliver electricity throughout the rover. This protects the rover from electrical shorts.

"We made a list of potential causes, and then determined which we could cross off the list, one by one," said rover electrical engineer Rob Zimmerman of NASA's Jet Propulsion Laboratory, Pasadena, Calif. Science operations were suspended for six days while this analysis took priority.

The likely cause is an internal short in Curiosity's power source, the Multi-Mission Radioisotope Thermoelectric Generator. Due to resiliency in design, this short does not affect operation of the power source or the rover. Similar generators on other spacecraft, including NASA's Cassini at Saturn, have experienced shorts with no loss of capability. Testing of another Multi-Mission Radioisotope Thermoelectric Generator over many years found no loss of capability in the presence of these types of internal shorts.

Following the decision to resume science activities, engineers learned early Nov. 23 that the rover had returned to its pre-Nov. 17 voltage level. This reversal is consistent with their diagnosis of an internal short in the generator on Nov. 17, and the voltage could change again.

The analysis work to determine the cause of the voltage change gained an advantage from an automated response by the rover's onboard software when it detected the voltage change on Nov. 17. The rover stepped up the rate at which it recorded electrical variables, to eight times per second from the usual once per minute, and transmitted that engineering data in its next communication with Earth. "That data was quite helpful," Zimmerman said.

In subsequent days, the rover performed diagnostic activities commanded by the team, such as powering on some backup hardware to rule out the possibility of short circuits in certain sensors.

{...}



The Planetary Society Blog - Ken Herkenhoff: Curiosity update, sols 453-464: Electrical problem causes delays; rover back to work

 

[N_Molson]

OK, so it's more the RTG (rather its heat to electricity conversion devices) that is a bit capricious... If it happens only from time to time and the voltage can be reverted to its initial level, that's not too nasty, provided the components are designed to handle the stress (and it seems it's the case).

 

[Proximus]

Yeah good news that operations have been recommenced :thumbup:
Still a bit worrying its the RTG dropping out intermittently though :blink:

 

[statickid]

Well if the statement has any merit, they said it's not even a real concern now that they've identified it

 

[N_Molson]

Hehehe I imagine the rover randomly sending sparks now...

 

[tl8]

http://www.brickset.com/news/article/?ID=9179
http://blog.lego.cuusoo.com/2013/12/18/lego-nasa-mars-curiosity-rover/

New Lego model.
Out next year ~$30

 

[Hartmann]

The rover wheels seems to have excessive wear in the rough surface of mars.

Its not critical but could cause concern in the future when the rover arrive at the Aeolis mons

They would need to be more careful driving with re-routing if necessary.

http://www.space.com/24049-mars-rover-curiosity-wheel-wear.html

 

[Unstung]

I'm curious about why this thread has been inactive lately. (Haha, very funny.)

Wheel damage on the rover has been considerable, and JPL is looking at a new path to drive Curiosity with smoother terrain.

JPL: "Curiosity Mars Rover Checking Possible Smoother Route"

The team operating NASA's Mars rover Curiosity is considering a path across a small sand dune to reach a favorable route to science destinations.

A favorable route would skirt some terrain with sharp rocks considered more likely to poke holes in the rover's aluminum wheels.

While the team has been assessing ways to reduce wear and tear to the wheels, Curiosity has made progress toward a next site for drilling a rock sample and also toward its long-term destination: geological layers exposed on slopes of Mount Sharp. The rover has driven into a mapping quadrant that includes a candidate site for drilling. Meanwhile, testing on Earth is validating capabilities for drilling into rocks on slopes the rover will likely encounter on Mount Sharp.

Curiosity has driven 865 feet (264.7 meters) since Jan. 1, for a total odometry of 3.04 miles (4.89 kilometers) since its August 2012 landing.

Accumulation of punctures and rips in the wheels accelerated in the fourth quarter of 2013. Among the responses to that development, the team now drives the rover with added precautions, thoroughly checks the condition of Curiosity's wheels frequently, and is evaluating routes and driving methods that could avoid some wheel damage.

A dune about 3 feet (1 meter) high spans the gap between two scarps that might be a gateway to a southwestward route over relatively smooth ground. Curiosity is approaching the site, "Dingo Gap," from the southeast. The team is using images from the rover to assess whether to cross the dune.

[...]

The team still appears to be deciding whether to cross Dingo Gap. JPL wouldn't want Curiosity to get stuck like Opportunity in 2005, after all.

JPL: "NASA Mars Rover's View of Possible Westward Route"

There source of this panorama is here, with a geological explanation of the area.

 

[Keatah]

The wheels are wearing out at a faster than expected rate. Sure, they could have made them far more durable for minimal weight increase. But that's not the intention. The wheels (it has been said) is one of the fail-safe "timers" used to prevent the mission from dragging on and on. Except they're failing sooner than later.

They don't want to end up with a functional rover that's living for 10 years again. Believe it or not, there are plenty people that want Oppy to die asap.

 

[MattBaker]

Sure, they could have made them far more durable for minimal weight increase.

Engineers are engineers, not magicians. They didn't know about the trouble with the wheels until it happened on Mars. That rover went through a year-long process and turned out with this wheels, because they thought they would be appropiate for the task at hand.

And besides: With the new sky crane I wouldn't be so sure if "minimal weight increase" is as unproblematic as you make it seem. I'm sure they had a lot of situations where they were like "Can't we make therovr 50 kilograms lighter? What about 30? Come on, this would really help, 10?"

 

[Keatah]

I'm assuming, and I don't know for certain, but the weight increase wouldn't be that much if you made the "webbing" between the cleats 1 or 2 mils thicker. Half a kilo more? 1 kilo more? That would solve the puncture problem.

The engineers knew this would happen, and it showed up in the testbeds in the mars labs. They were running the wheels with only the skeleton-cleat remaining and some were ovalized and non-symmetrical. Part of the experiment on surface mobility.

And I recall there being a whole writeup on this topic. I don't recall where I got the pdf from. And there's a vid from the mars yard where they're testing the wheels and you can here them popping and puncturing!

But whatever the causes and reasons, the fact is the wheels are degrading faster than predicted and different routes need to be planned.

---------- Post added at 05:21 AM ---------- Previous post was at 05:01 AM ----------

http://www.universetoday.com/107405/rough-red-planet-rocks-rip-rover-curiosity-wheels/
http://www.planetary.org/blogs/emil...101-theres-a-hole-in-the-wheel-dear-liza.html
http://www.unmannedspaceflight.com/index.php?showtopic=7658&st=165

---------- Post added at 05:33 AM ---------- Previous post was at 05:21 AM ----------

http://strategic.mit.edu/docs/SM-48-Baker-B-2012.pdf
https://www.youtube.com/watch?v=za-oAFdBs_Q
https://www.youtube.com/watch?v=nllHgoJ7rZk

 

[Unstung]

The wheels are wearing out at a faster than expected rate. Sure, they could have made them far more durable for minimal weight increase. But that's not the intention. The wheels (it has been said) is one of the fail-safe "timers" used to prevent the mission from dragging on and on. Except they're failing sooner than later.

They don't want to end up with a functional rover that's living for 10 years again. Believe it or not, there are plenty people that want Oppy to die asap.

If this is the case, will the wheel thickness be adjusted, with new data from Curiosity, for the 2020 mission so the rover can last through its prime mission?

 

[Keatah]

It's also known (and stated) that the wheels couldn't be too rigid and strong, they have to bend and act as a [the only] shock absorber on landing.

---------- Post added at 05:49 AM ---------- Previous post was at 05:41 AM ----------

If this is the case, will the wheel thickness be adjusted, with new data from Curiosity, for the 2020 mission so the rover can last through its prime mission?

My guess would be yes.