Mars Rover Spirit Mission Update Thread

[redgryphon]

<font color="yellow">"It's gotten through the worst part, solar energy-wise. "</font><br /><br />When can we expect dust storms? And will the rovers survive them? I remember reading that they could survive a storm at the beginning of the mission, but would that be true after a year on the surface?

 

[centsworth_II]

Having already made it halfway and still alive and kicking, I think we have reason to hope the rovers can double their current lifespan and make it one full martian year of work. <div class="Discussion_UserSignature"> </div>

 

[thechemist]

Spirit had a rather serious problem on Sols 338 and 339, when a rock got clogged inside one of the wheels. Let's hope JPL will find a way to remove the rock. MER forum <div class="Discussion_UserSignature"> <em>I feel better than James Brown.</em> </div>

 

[fangsheath]

This is a good example of the software dealing with a little problem before it becomes a big problem. The rover detects the increased current and stops before the rock gets really wedged in there.<br /><br />Judging from the most recent Hazcam shot, they reversed the wheel spin and the rock dropped out. It may still be in the wheel, though, we should be able to see when they bring the wheels back to translation mode.

 

[fangsheath]

It fell right on the edge of the rim, hopefully it will drop out when they bring the wheels back parallel. If not, a sharp turn to the left letting this wheel drag should do the trick.

 

[fangsheath]

Bringing the wheels back to translation mode didn't clear the rock, so they made a short drive to the left, letting the right rear wheel drag. This rolled the rock out of the wheel a little more and actually pushed it into the soil a bit. I think we're gettin' there.

 

[Leovinus]

I guess they can't get the RAT down there or they would have already done that. <div class="Discussion_UserSignature"> </div>

 

[thechemist]

I don't think they can reach there with the arm, but I am not sure if they would risk damage to the instruments in pushing the rock out with it.<br />I am confident they'll remove it by moving the rover, one way or the other. <div class="Discussion_UserSignature"> <em>I feel better than James Brown.</em> </div>

 

[fangsheath]

They have straightened the front wheels and driven backwards just a tad, trying to push the right rear wheel away from the rock, but it managed to move backward with the rim, although it shifted forward a bit. I think repeating this procedure (hard left turn, straighten, back up) is bound to succeed eventually.

 

[alexblackwell]

Below is an interesting article related to the flash memory anomaly on Spirit shortly after landing:<br /><br />And you think your operating system needs to be reliable<br />A Conversation with Mike Deliman<br /><i>ACM Queue</i> (October 2004)<br /><br />Note that the article has four different sections.

 

[fangsheath]

Now they have brought all the wheels except the right rear back to rotation mode and yawed to the left a little. This oriented the vehicle so that the right rear is more upslope. It also pushed the wheel away from the rock, but the little ****** stayed with it again.<br /><br />Patience and perseverance will win, sooner rather than later I think. Even now a drive straight backwards would probably clear it, but I don't think they'll risk it yet.<br /><br />.

 

[bobvanx]

It looks like the trnch they've made, with all the driving about, is helping to keep the rock in the wheel well.<br /><br />Boy, does my heart go out to the team while they work to clear this up.

 

[fangsheath]

Yep, the right rear is down in a depression which tends to help the rock stay with it when they try to move it away. Orienting the vehicle with that wheel upslope will help to counter this. They have continued to do some back and forth and more left rotation. At most any point I think they could simply drive astern with the front wheels at hard right (turning left if you're facing backward) using all six wheels and clear the rock. But the danger is that with more than 100% slip, the wheel would scoop the rock right up and we would be back at square one.

 

[Leovinus]

I still say that if they can't move, they might as well use the RAT to clear it (if it is reachable, which I don't know). Maybe the RAT is on the other end of the rover -- I'm not sure what wheel we're looking at here. <div class="Discussion_UserSignature"> </div>

 

[bobvanx]

It's a rear wheel, Leo. The arm can't reach it.<br /><br />What they ought to do is think like an animal. What does a legged creature do when it steps in something? It lifts its leg and shakes. I think the rocker-bogey suspension allows for this. Remember way back when, and they lifted the front wheels to turn them and lock them? Maybe that system is all locked down now, or required the support of the lander.<br /><br />Amyway, they could still drive that wheel up onto a bigger rock, and "chatter" it.

 

[bobvanx]

Well, well!<br /><br />maybe they got it!?<br /><br />I lined up three sols' worth of images, see the little fragments on the soil? Is that the corner of the rock in the third frame? The wheel looks free!

 

[earth_bound_misfit]

Thanks for the link Alex, it was a very interesting read. <div class="Discussion_UserSignature"> <p> </p><p> </p><p>----------------------------------------------------------------- </p><p>Wanna see this site looking like the old SDC uplink?</p><p>Go here to see how: <strong>SDC Eye saver </strong>  </p> </div>

 

[fangsheath]

It does appear that we are finally clear of the pest. It's not entirely clear to me what they did, but a significant yaw to the right has been made. Possibly they yawed using power to all the wheels except the right front.<br /><br />In any case, this area has a lot of small, loose rocks. Interesting rocks, but trouble. Onward and upward!

 

[Leovinus]

It looks to me that there is still some object at the 2:00 position of the left wheel in that photo. <div class="Discussion_UserSignature"> </div>

 

[bobvanx]

The team thinks they took care of it.

 

[fangsheath]

The rock is quite definitely out of the wheel now, the vehicle has backed up, yawed right and moved forward again, the right rear has made at least a few complete rotations in the process.<br /><br />Meanwhile, if the recently released map is correct, the rover will continue to make its way up Northwest Spur toward a spot called Larry's Lookout (indicated by the blue dot). The approximate current location of Spirit is indicated by the red dot. I think this will give us a good look at the terrain north of Husband Hill.

 

[silylene old]

I hope in the newest set of rovers being designed, that the wheel designed is "closed" so that rocks cannot lodge within them. <div class="Discussion_UserSignature"> <div class="Discussion_UserSignature" align="center"><em><font color="#0000ff">- - - - - - - - - - - - - - - - - - - - - -</font></em> </div><div class="Discussion_UserSignature" align="center"><font color="#0000ff"><em>I really, really, really miss the "first unread post" function.</em></font> </div> </div>

 

[bobvanx]

I don't know that a closed wheel well is necessary. We've driven miles with this design, and had one incident.<br /><br />However, I bet the wheel designer is wondering why they didn't design the well with a conical shape, having a larger opening and a smaller interior. That way, anything they'd ingest would rotate right back out.

 

[Leovinus]

My guess is that the wheel design is the way it is for either or both of these reasons:<br /><br />1) making it as light as possible<br />2) Stuff was inside the wheel when it was folded up for flight. <div class="Discussion_UserSignature"> </div>

 

[radarredux]

> <i><font color="yellow">I hope in the newest set of rovers being designed, that the wheel designed is "closed" so that rocks cannot lodge within them.</font>/i><br /><br />Anything with wheels will have some risk of debris (including the fine powder/soil on Mars or the Moon) getting in and gumming up the works. I would like to see a future "rover" with legs instead of wheels. Then it can be wrapped in a skin to keep the dust particles out.<br /><br />However, having said that, the current rovers have long outlasted their original planned lifespan. NASA/JPL seem to have a darn good platform. I would prefer to see a future rover with same platform but new sensors. This would keep initial development costs down.</i>