That is so cool :)
NASA's Perseverance rover sends stunning images
71–80 of 365 posts
Re: NASA's Perseverance rover sends stunning images
#72Earlier quoted context omitted.
They use the same kind of compression as the last mission. JP2, I believe. https://en.wikipedia.org/wiki/JPEG_2000 I'm not sure that data compression has progressed that much since Curiosity in 2012 or Insight in 2018. There have been some formats that have improved compression at the expense of large amounts of memory or processing power, but neither of those are abundant on a rad-hardened processor. Neither is elec…
One of the obvious constraints is that for science reasons they transmit each image in a lossless format, so we're up against the limits of what a lossless image compressor can do. If there were a future mission's requirement to send back lossy images first, and CPU power was significant, something like AVIF or JPEG-XL would likely be a candidate. https://netflixtechblog.com/avif-for-next-generation-image-c... ICER a…
AVIF has a lossless mode, which is quite a lot better than PNG for example.
Re: NASA's Perseverance rover sends stunning images
#73Earlier 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?
Are you really asking why we can't power your fridge with plutonium?
Not sure about you, but I was promised fusion-powered DeLoreans by now.
Re: NASA's Perseverance rover sends stunning images
#74Earlier 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.
AKA "Not In My Back Yard."
So the question stands and extends to include this: "why not?"
Re: NASA's Perseverance rover sends stunning images
#75Earlier 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?
I'd be interested in a real answer to this if any nuclear engineers are around
Not a nuclear engineer, but we covered this in my third semester of physics at University. The short answer is there isn't any engineering reason why you can't do this. The "real" reason is that there is liability here that nobody knows how to deal with. If the unit became damaged and its shielding failed it could sit there and kill people who came near it for years (for example).
I got to talk to one of the engineers who worked on KRUSTY[1] a 10kW nuclear reactor. This combined with some batteries for peak load could run pretty much any house for a couple of decades. (they talk about several houses in the article but realistically the peak load of a single house when the oven, refrigerator/freezer compressor, and central AC are running is a bit north of 10kW. I would seriously consider a way off grid ranch house if I could have one of these to power it :-)
[1] https://www.popularmechanics.com/space/moon-mars/a20127140/n...
Re: NASA's Perseverance rover sends stunning images
#76Earlier 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?
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 rate is high enough that you'd need to augment or refuel your house every handful of years. Halflife of 87 years, 25% energy loss in 40ish, 10% loss in just over a decade, etc.
Also, they've got little plutonium pellets in them, which is both expensive and dangerous.
Re: NASA's Perseverance rover sends stunning images
#77Earlier quoted context omitted.
My imagination has a pretty big range for 'rural Thailand', do they have a safe way to dispose of it inland? Subsistence folks, to the extent that it might apply here, get a pass from me.
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
Re: NASA's Perseverance rover sends stunning images
#78Earlier 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.
It's not actually a reactor. The plutonium is just emitting radiation, as plutonium will do, and you harness some of the natural heat energy with thermocouples. There's no explosion risk, although you would certainly need trustworthy shielding.
Re: NASA's Perseverance rover sends stunning images
#79Earlier 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.
Thank you for this! Do you know of a source on the net for a simple timeline of when X will happen?
Re: NASA's Perseverance rover sends stunning images
#80Stupid question, but where is Perseverance's energy source? Answer: Plutonium It powers a Multi-Mission Radioisotope Thermoelectric Generator. The plutonium decays at a few % per year, so that means it should be able to bring Elon a sandwich when he lands. https://mars.nasa.gov/mars2020/spacecraft/rover/electrical-p...
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?
Smoke detectors rely on a circuit powered by atomic fission ionizing the air. It isn't their power source (they still need batteries), but it is a safe way to get continuous electricity.
https://www.nrc.gov/reading-rm/doc-collections/fact-sheets/s...
There's probably a way to get a little more power out of it without being too dangerous. But then we'd have ordinary citizens buying things over-the-counter that could be abused in bulk. And I don't see any hassle being worth an extra free outlet or not replacing batteries.