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NASA's Perseverance rover sends stunning images

bbc.com

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Re: NASA's Perseverance rover sends stunning images

#81

Post by khuey »

AnimalMuppet wrote: post #54
marshmallow_12 wrote: post #52

Earlier quoted context omitted.

a glowing green sandwich covered in red sand. But seriously, this stuff is powering those voyager probes 40 years later. Which makes me ask: why do we have to send there technologies 10 billion miles away to make them work? Why can't my fridge be powered this way?

What's powering Voyager is a plutonium pile. Pretty sure you don't want that in your fridge. 10 billion miles from me? Sure, knock yourself out. 10 feet from me? No way.

The radiation emitted by plutonium 238, which is what's found inside RTGs, is easily shielded by essentially any solid material.

The real reason you don't want an RTG powering your fridge is that it costs on the order of one million dollars per watt.

Re: NASA's Perseverance rover sends stunning images

#82

Post by leijurv »

nitrogen wrote: post #74
AnimalMuppet wrote: post #54

Earlier quoted context omitted.

What's powering Voyager is a plutonium pile. Pretty sure you don't want that in your fridge. 10 billion miles from me? Sure, knock yourself out. 10 feet from me? No way.

AKA "Not In My Back Yard." So the question stands and extends to include this: "why not?"

Nuclear reactors are better and have economies of scale, it doesn't make much sense to everyone have their own.

Re: NASA's Perseverance rover sends stunning images

#83

Post by oso2k »

shkkmo wrote: post #69
marshmallow_12 wrote: post #52

Earlier quoted context omitted.

a glowing green sandwich covered in red sand. But seriously, this stuff is powering those voyager probes 40 years later. Which makes me ask: why do we have to send there technologies 10 billion miles away to make them work? Why can't my fridge be powered this way?

The 8 figure price tag for a RTG makes consumer use uneconomical.

More than likely, 99% of that cost is the container and the apparatus to make use of its energy. [0][1]

[0] https://www.thoughtco.com/what-is-most-expensive-element-606...).

[1] https://www.sciencedirect.com/topics/earth-and-planetary-sci....

Re: NASA's Perseverance rover sends stunning images

#84

Post by btilly »

junon wrote: post #70
ryandvm wrote: post #56

Earlier quoted context omitted.

Are you really asking why we can't power your fridge with plutonium?

Do you have an answer that isn't speculation or something you concluded from a breezy stroll over to Wikipedia? Stop mocking questions. It solves nothing.

Each Mars Rover uses 5 kilograms of plutonium 238. (Plutonium 239 is the one that is used in nuclear bombs.)

Per https://www.wired.com/story/nasas-mars-rover-will-be-powered... we currently have a lab dedicated to producing it, and it makes 3.5 pounds per year.

Per https://www.npr.org/2011/11/08/141931325/the-plutonium-probl... the cost of getting the lab restarted was a bit shy of $100 million. And once running fully it costs millions of dollars to run.

At those cost points it would be cheaper to deliver you a brand new fridge each month for the next 20 years than to deliver you a single fridge using plutonium to run without external electricity for the same 20 years. Not to mention that the plutonium itself is toxic.

Re: NASA's Perseverance rover sends stunning images

#85

Post by ddingus »

nitrogen wrote: post #74
AnimalMuppet wrote: post #54

Earlier quoted context omitted.

What's powering Voyager is a plutonium pile. Pretty sure you don't want that in your fridge. 10 billion miles from me? Sure, knock yourself out. 10 feet from me? No way.

AKA "Not In My Back Yard." So the question stands and extends to include this: "why not?"

Risk?

That is my basic opposition. Happy to be flexible on energy in almost every way. Cost, type, uptime...

But error with nuclear tech tends to endure for a very long time. Fukushima will be raising ocean radiation for a long time, just one example.

These are many lifetime events. Some minor, or recoverable, some profound.

Given we can reasonably run the fridge on solar, and other tech, that risk does not seem to make sense to a lot of people.

Doesn't to me.

Now, that said I am not ideologically opposed. Other tech could very seriously improve risk profile. Maybe it becomes worth it.

Then again, the fridge in my RV can run on a small flame, or a very low current source. And no moving parts!

So, we could make fridges differently too. Make tradeoffs.

Re: NASA's Perseverance rover sends stunning images

#86

Post by rsj_hn »

Clewza313 wrote: post #77
rsj_hn wrote: post #43

Earlier quoted context omitted.

The issue is that 90% of the plastic in the ocean is dumped from 10 rivers in Asia and Africa where the waste disposal system consists of driving a truck up to a river and dumping the trash in. Of the remaining 10%, it comes from Latin American nations that do the same thing. Meanwhile western people see these masses of trash and plastic in the ocean and conclude the rational response is to ban straws in the western…

A lot of those effective waste disposal systems in the West, particularly for recycling, consist of paying Asian and African companies to take away the waste, so it can then be dumped in their countries/oceans or get "recycled" in places like this: https://en.wikipedia.org/wiki/Agbogbloshie

No, that is not a waste disposal system, it's how tech companies and other companies that sell gadgets fool their eco customers into thinking they are "recycling" something that cannot in principle be safely recycled. It is yet another example of going through a kabuki ritual rather than effectively dealing with the problem.

Re: NASA's Perseverance rover sends stunning images

#88

Post by hanniabu »

azernik wrote: post #47
rsj_hn wrote: post #32

Earlier quoted context omitted.

I want to see that little helicopter fly! I scoured the site and as yet can't find any images of it, when I thought they were going to take mutual selfies -- heli of the rover and vice versa.

The helicopter hasn't flown yet - they put it down on the ground, and they're going to run it through a lot of remote checks before flying it. IIRC it's gonna be a month or two before first flight.

I would think with the wind and sand storms that it'd be dangerous leaving it exposed for a month before you even get to use it. Does the rover park on top of it during storms for minimal protection?

Re: NASA's Perseverance rover sends stunning images

#89

Post by oso2k »

burnte wrote: post #76
neolog wrote: post #64

Earlier quoted context omitted.

I'd be interested in a real answer to this if any nuclear engineers are around

RTGs get hot, that's the point of them, actually. Too hot for use in a small area like your fridge. On a space probe or rover on a cold planet, the waste heat is useful in keeping things somewhat warm. On earth, not so much. RTGs are also large, too large to power a fridge given the power draw for a fridge. There were microRTGs used in some pacemakers, but the long term safety concerns were never overcome. The decay…

Many advocate for the use of Thorium instead.

Re: NASA's Perseverance rover sends stunning images

#90

Post by hanniabu »

neolog wrote: post #59
moltar wrote: post #35

Earlier quoted context omitted.

I admire your efforts to clean. But unfortunately it’s pointless. There are entire million and billion population countries that treat oceans as waste baskets, simply because they don’t know better. I’ve talked to fishermen in rural Thailand and they don’t have waste collection. So they take their trash every day and just dump it in the middle of the ocean somewhere. They didn’t understand why that was a problem when…

What could they do with the waste instead, if they don't have collection?

Honestly burning it just might be better. Without doing any calculations my intuitions tell me it would be minuscule on the global scale and the benefit of that garbage not going into the ocean would outweigh the added air pollution.
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