[X] My Assistant

[chris]

Given the problems that Opportunity is having now, what changes should be made to future rovers to mitigate such problems? Sand isn't exactly rare on Mars, and I very much doubt we've seen the biggest dunes.

Some suggestions:

- Directly detect speed so you know when you're not travelling as fast as the wheels are rotating (using something like an optical mouse sensor, as suggested here by Gary).

- Change of wheel design.

- Some deployable mechanism to help back out of a bad spot (extending spikes in the wheels might do it, but it would be complicated). I am also reminded of the railway sleepers that WW1 tanks used, although I'm obviously not suggesting we send a railway sleeper

- Sensors on the wheel or wheel hubs so you can sense you are digging in. Given the amount of iron around, could this be done magnetically?

- Some mechanism for sensing sand traps. Sound springs to mind, but I guess the atmosphere is too thin.

Chris

Edit: Added link to mouse sensor post

[JES]

Extracting Opportunity from its current situation is not terribly difficult. Design modifications in a future craft could easily provide a solution. For instance, if the instrument arm were strong enough to support the load without damaging itself the rover could lift itself out of this situation in the same way a construction backhoe can lift itself and shift position without using its wheels. In future expeditions we will encounter more difficult situations as we take on more challenging terrain. How robust is the instrument arm on the MSL? A robotic arm capable of drilling, lifting rocks etc could certainly serve as a backhoe to extract, lift or even turn a tilted rover upright again.

Another thought….We will always be limited in our exploration by our willingness to take any risk with the craft. The rovers are very valuable and easily damaged. One alternative might be to separate the instrumentation from the mobile unit using a rugged faster vehicle to travel and bring samples back to a stationary instrument platform.

[MizarKey]

...One alternative might be to separate the instrumentation from the mobile unit using a rugged faster vehicle to travel and bring samples back to a stationary instrument platform.

Another alternative would be to send two rovers to the same place, a rugged one to be a reconnaissance vehicle to scout ahead and the other to be loaded with equipment and sensors. Each rover could have a tow system that could be used to join the two to get out of tough spots.

On the 'PR' side it would be really cool to have pictures of the rovers 'in situ'

I love those stilty movies of Pathfinder rolling around.

Eric P / MizarKey

[JES]

...One alternative might be to separate the instrumentation from the mobile unit using a rugged faster vehicle to travel and bring samples back to a stationary instrument platform.

Another alternative would be to send two rovers to the same place, a rugged one to be a reconnaissance vehicle to scout ahead and the other to be loaded with equipment and sensors. Each rover could have a tow system that could be used to join the two to get out of tough spots....


Eric P / MizarKey

I like the idea of multiple vehicles. They would make the entourage more adaptable to changing conditions. Specialized vehichles could scout ahead and take greater risk. Slower, safer science packages could follow where it is safe. All could serve as components for rescue. The entourage could accomplish more than a single vehicle and the group would be more adaptable. Sort of a "Wagon Train" to Mars. More "experienced" readers may recognize this reference from way back in the last millenium.

[RNeuhaus]

...One alternative might be to separate the instrumentation from the mobile unit using a rugged faster vehicle to travel and bring samples back to a stationary instrument platform.

Another alternative would be to send two rovers to the same place, a rugged one to be a reconnaissance vehicle to scout ahead and the other to be loaded with equipment and sensors. Each rover could have a tow system that could be used to join the two to get out of tough spots....


Eric P / MizarKey

I like the idea of multiple vehicles. They would make the entourage more adaptable to changing conditions. Specialized vehichles could scout ahead and take greater risk. Slower, safer science packages could follow where it is safe. All could serve as components for rescue. The entourage could accomplish more than a single vehicle and the group would be more adaptable. Sort of a "Wagon Train" to Mars. More "experienced" readers may recognize this reference from way back in the last millenium.

As a gold rule, always travel with more than 3 vehicles when going in off road (Mars) so that the stuck or in trouble ones will be rescated by one of them. Unless, the vehiclue must be specially designateed to travel almost any sort of terrain such as the ones alike to Caterpillar which is very stable and very capable to climb (greater than 30 degrees) , get down (also higher than 30 degree with very little slipping ), and travel over any kind of sands . I think that the next rovers must not carry any wheels but only bands like ones of Caterpillar. This will avoid to send two rovers at the same time. On the other hand, it is better to send a mini MARS GPS which will help rovers to travel easier and faster on Martian land. This will help to free lots of memory and CPU power from the Rover for another purposes .

Rodolfo

[tty]

As a gold rule, always travel with more than 3 vehicles when going in off road  (Mars) so that the stuck or in trouble ones will be rescated by one of them. Unless, the vehiclue must be specially designateed to travel almost any sort of terrain such as the  ones alike to Caterpillar which is very stable and very capable to climb (greater than 30 degrees)  ,  get down (also higher than 30 degree with very little slipping  ), and travel over any kind of  sands . I think that the next rovers must not carry any wheels but only bands like ones of Caterpillar. This will avoid to send two rovers at the same time.  On the other hand, it is better to send a mini MARS GPS    which will help rovers to travel easier and faster on Martian land. This will help to free lots of memory and CPU power from the Rover for another purposes  .

Rodolfo

Tracked vehicles also have drawbacks (which is the reason most military vehicles are still wheeled)

1. More expensive than wheeled vehicles

2. Tracks wear out quite quickly

3. Require stronger engines because of more friction than wheels

4. Clumsy to steer

5. Less redundancy. If a track fails you are stuck while a multi-wheel (6 or more) vehicle usually can move minus one wheel

tty

[ElkGroveDan]

As a gold rule, always travel with more than 3 vehicles when going in off road  (Mars) so that the stuck or in trouble ones will be rescated by one of them. Unless, the vehiclue must be specially designateed to travel almost any sort of terrain such as the  ones alike to Caterpillar which is very stable and very capable to climb (greater than 30 degrees)  ,  get down (also higher than 30 degree with very little slipping  ), and travel over any kind of  sands . I think that the next rovers must not carry any wheels but only bands like ones of Caterpillar. This will avoid to send two rovers at the same time.  On the other hand, it is better to send a mini MARS GPS    which will help rovers to travel easier and faster on Martian land. This will help to free lots of memory and CPU power from the Rover for another purposes  .

Rodolfo

Tracked vehicles also have drawbacks (which is the reason most military vehicles are still wheeled)

1. More expensive than wheeled vehicles

2. Tracks wear out quite quickly

3. Require stronger engines because of more friction than wheels

4. Clumsy to steer

5. Less redundancy. If a track fails you are stuck while a multi-wheel (6 or more) vehicle usually can move minus one wheel

tty

Tracked vehicles would also be problematic on much of the chaotic terrain we've seen on Mars. The multi-wheeled independant drive/suspension systems on MER and Pathfinder were developed as a response to the conditions witnessed at the Viking and Pathfinder sites, i.e. the need to egress to rock strewn regions. Tracks are fine for a sandy or fine textured region like Meridiani, but would create a problem with the handful of topography conditions we've observed thus far. Certainly the conditions at Gusev also come to mind.

[dvandorn]

Tracked vehicles would also be problematic on much of the chaotic terrain we've seen on Mars.  The multi-wheeled independant drive/suspension systems on MER and Pathfinder were developed as a response to the conditions witnessed at the Viking and Pathfinder sites, i.e. the need to egress to rock strewn regions. Tracks are fine for a sandy or fine textured region like Meridiani, but would create a problem with the handful of topography conditions we've observed thus far.  Certainly the conditions at Gusev also come to mind.

And, let's face it, we have successfully landed probes at five locations on Mars, and four out of those five locations have very, very similar types of terrain -- rock-strewn with windblown dust/sand drifts building up in various places. Only Meridiani has shown a different type of terrain.

Of course, there are a lot of different terrain types on Mars. But I think a lot of the flatter plains units (the places we're most likely to try landing) are going to be rock-strewn. So the rocker-bogey wheel system is probably going to be the best approach for most future rovers.

-the other Doug