Making Mars Rovers Survive

[Kaito]

As we all know, Spirit has had some tough times: http://www.orbiter-forum.com/showthread.php?t=5313

On there, i suggested a way to keep the mars rover's power up:

Hm....Just a thought, for future Rovers: Instead of just depending on the sun, why not have a Module orbiting above the planet, and have it just orbit in a rough line on where the rover is traveling. The module would be a special instrument that collects sunlight and is used to power a high intensity laser. When the rover needs an extra "boost" of energy, the Module would adjust its flight path to flight directly over the rover, then Fire its laser as long as it could (limiting factors would be: Necessary power, the power the module has, the angle, or the weather). This would give the Rover a longer life span in terms of energy, and since it's a high intensity laser, the dust would offer little resistance. Just a thought

There was a mini debate on this topic, read the above link to see it.
So, instead of spamming that post, here's a way we can discuss this, and other ways of keeping the Mars rovers lifespan up.

Following DaveS's last post:

The sun is going to be more powerful than any laser you can come up with. You'd also need utilise some of the solar power to actually power the orbiter so that's less power for that laser of yours! And that orbiter would most likely be so huge it would cost several billion dollars to just design, produce and launch that you could afford several MSL-class rovers.

The MERs from start to launch only cost $420 million a piece. So for the cost of that orbiter you probably could get yourself 4 or 5 MERs.

Well, the sun is more powerful then any laser, true, but the laser is more direct. You can put a match head out in the sun and it wont ignite. You can buy a laser, disable its limiting system (theres a limiting system in the laser pointer to make it safe), and point it at a match head, and it will ignite. That is what I'm talking about: More direct, more powerful.

 

[SpaceCowboy]

I guess it would be worth looking into if you could keep the cost down.

 

[Andy44]

It owuld be much cheaper to just put a dust-removal system on the rover's solar panels. Preferably a device that does not actually involve scraping brushes or wipers in direct contact with the panel's surface.

Such a system would add mass to the rover, but that's a lot easier to deal with than launching a second vehicle (the laser orbiter) and having to design the system so that the laser can actually focus well enough to deliver adequate energy and is actually capable of meeting the aiming requirements. Not to mention, the laser orbiter will only be in view of the rover maybe 2 or 3 times in a Martian day, and at least one of those times it will usually be on the night side of the planet and won't have nay solar energy to convert. And if the laser orbiter fails, you are back to square one.

Still, it would make a cool add-on. Orbiter is nice for "wargaming" such ideas.

 

[James.Denholm]

It's an interesting idea - but what about using microwave energy instead? Have some sort of battery in the module, gathering solar energy, storing it, and when necessary, gives the rover a little boost. It wouldn't be capable of blowing away dust, however there would be no danger of damaging the rover if the aim was a little off.

 

[Andy44]

The microwave orbiter idea has been seen in many real-life speculations and in sci fi stories. It may have potential, some day. But for powering one or two small robotic rovers, it still seems like overkill, especially the cost. Perhaps a larger ground infrastructure on Mars may benefit from such an orbiting power station. It's usually assumed that a human presence on Mars means at least a small nuclear reactor will be needed to ensure a robust power source. But a manned rover which must spend many days away from its base won't benefit from a reactor laying in a pit a few hundred yards form the base; it will have to be battery-powered and could use an occasional recharge from a microwave orbiter.

 

[RisingFury]

There are a number of problems with this proposal...

For one, the orbiter could only provide power for a few minutes before going "out of sight" for the rover. And it couldn't even provide power every orbit.

Second, just aiming the thing would be difficult.

Third, making a laser powerful enough... and efficient enough is expensive and difficult.

And one that actually worries me the most is exactly what you said about lasers igniting a match.
You have to take into account that Mars is cold. If you point a laser to the solar panels, you're providing a huge amount of energy that might heat up the panels to the point where they'd crack. Any less energy and... well, it just wouldn't be enough.



Besides, solar panels getting dusted up is not the only big problem of the rovers. Dust is a problem in general and can cause other party to fail. Which of the rovers lost one of the wheel motors?

The rovers were planned for 3 months, they're 5 years old. It's like planning to have a car for 5 years, but end up driving it for a 100 years... it's bound to fail after a while.

 

[spcefrk]

I'd prefer to see rovers running on fuel taken from the atmosphere as a means of testing Mr. Zubrin's concept.