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Perseverance Rover lands on Mars [video]

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Re: Perseverance Rover lands on Mars [video]

#351

Post by killjoywashere »

danaliv wrote: post #336
killjoywashere wrote: post #325

Earlier quoted context omitted.

Can’t talk to the statute mile, but the nautical mile is sublime: one minute of latitude. The amount of math you can do in your head with a system with so many factors of 2, 3, and 5 is truly amazing.

Also the average of one minute of arc on a great circle route, which was the real handy thing about it at sea.

Yes, meridians (on which latitude is measured) being a special case of great circle routes that happen to pass through the poles. That said, as a practical matter, you are more frequently contemplating a chart of smaller scale than "globe" so you're usually counting up distance between fixes, or distance to next turn in a harbor, or some such thing, where you have a compass in hand and just need to set the compass to the length of a mile. The nearest latitude tick marks are quite handy for that.

Re: Perseverance Rover lands on Mars [video]

#352

Post by perryizgr8 »

I must say that this mission is highly disappointing. No risks, no major progress, no pushing the limits.

What does NASA have to show for a decade of work, since Curiosity landed in 2012? A toy helicopter, a drill that poops pellets. Billions of dollars and millions of man-hours later, this is the only progress.

The truth is NASA has become extremely conservative and slow. Compare this to the moon landing. NASA went from one man in Earth orbit in 1961 to people walking on the moon as a matter of routine in 1969. That is the pace needed for serious technological progress in space.

We must let NASA die, and let others pursue these feats, people who have a real passion for space exploration. If NASA had only a bit of passion, they would have sent men on this mission, based on all the learnings from Curiosity.

Defund NASA.

Re: Perseverance Rover lands on Mars [video]

#353

Post by ssijak »

It is just mind boggling that something so far away is autonomously landing on a another planet in such a complicated manner and reporting back to us. Humans can be amazing, this kind of achievements always make me tear up from joy.

Re: Perseverance Rover lands on Mars [video]

#354

Post by mulmen »

grecy wrote: post #349
mulmen wrote: post #338

Earlier quoted context omitted.

It’s unfortunate that fractional measurements and the base size of units get conflated. Maybe metric users do use fractions and I just don’t hear about it. Is that table one and a quarter meters high?

We use millimetres. That table is 1250mm high. If you're cutting it yourself, a precision of 1mm is finer than your saw blade or pencil line anyway, so it's plenty enough. When I hear anything past about 1/8th of an inch my brain shuts down, and I give up.

My argument is a mm is too fine in that situation. 1/8ths and 1/16ths are ideal when working at those scales.

In reality I use both systems all the time. It’s situational.

> When I hear anything past about 1/8th of an inch my brain shuts down, and I give up.

Realistically, same. 32nds don’t get used outside of some specialty wrenches. 16ths are a practical limit where other scales start to make more sense. Probably millimeters.

Re: Perseverance Rover lands on Mars [video]

#356

Post by bernulli »

mulmen wrote: post #337
bernulli wrote: post #332

Earlier quoted context omitted.

The thing is, though, that you have these conversions even within the imperial system ( https://en.m.wikipedia.org/wiki/Imperial_units#/media/File%3... ) but not within the metric system. My experience with U.S. students is that they are having a much harder time making sense of the imperial system (that they are used to) than doing problems in metric, even though they don’t use it in everyday life.

Ok, so? First off, you linked to a list of english measures which are not used in the US. Nobody uses fathoms or barleycorns. Here is the list of actual US customary units: https://en.m.wikipedia.org/wiki/United_States_customary_unit... Second, none of that is relevant to landing on Mars. The only problem space where metric has an advantage is in converting between meters, kilometers and millimeters. That’s great, an…

Yes I understand. Imperial is awesome because you can divide a foot by exactly 2, 3, 4 , and 6, which of course, is the main problem everyone has every day. Metric on the other hand sucks because none of my measurements will ever be nice round numbers.

The hardware doesn’t think in base 10, but having more than that in imperial makes it better?

Your document lists 12 mass units alone. I rest my case, what could possibly be more logical, convenient, and need less conversion.

If communication was your major goal, then the system that is used by 7.3 billion people on this planet would be your choice.

Re: Perseverance Rover lands on Mars [video]

#357

Post by cdelsolar »

yellowapple wrote: post #323
frabbit wrote: post #308

Earlier quoted context omitted.

What is it about that that excites you so much? Is it the idea that life could originate elsewhere and that there might really be aliens? Or is it the idea that Mars could support some sort of colony? Or the hope of completely novel microbiology?

Yes. Any one of these things would be a massive boon to our understanding of life throughout the solar system and broader universe, right down even to here on Earth. All three of them would arguably mark a new era in Earth's history.

we are very screwed if they find life on Mars. It means life is incredibly common and thus the Great Filter theory is true and we only have a few years left as a species most likely.

Re: Perseverance Rover lands on Mars [video]

#358

Post by mulmen »

bernulli wrote: post #356
mulmen wrote: post #337

Earlier quoted context omitted.

Ok, so? First off, you linked to a list of english measures which are not used in the US. Nobody uses fathoms or barleycorns. Here is the list of actual US customary units: https://en.m.wikipedia.org/wiki/United_States_customary_unit... Second, none of that is relevant to landing on Mars. The only problem space where metric has an advantage is in converting between meters, kilometers and millimeters. That’s great, an…

Yes I understand. Imperial is awesome because you can divide a foot by exactly 2, 3, 4 , and 6, which of course, is the main problem everyone has every day. Metric on the other hand sucks because none of my measurements will ever be nice round numbers. The hardware doesn’t think in base 10, but having more than that in imperial makes it better? Your document lists 12 mass units alone. I rest my case, what could possi…

> Yes I understand. Imperial is awesome because you can divide a foot by exactly 2, 3, 4 , and 6, which of course, is the main problem everyone has every day.

Great, we agree.

> Metric on the other hand sucks because none of my measurements will ever be nice round numbers.

Depends on the situation. Metric units can be useful.

> The hardware doesn’t think in base 10, but having more than that in imperial makes it better?

No, it means neither system has an advantage so just pick one. Or invent a new one that allows better hardware utilization.

> Your document lists 12 mass units alone. I rest my case, what could possibly be more logical, convenient, and need less conversion.

I don’t convert, I just pick the unit that fits the problem.

> If communication was your major goal, then the system that is used by 7.3 billion people on this planet would be your choice.

Yeah I use the metric system all the time. Just like NASA.

Re: Perseverance Rover lands on Mars [video]

#359

Post by mulmen »

lmm wrote: post #350
mulmen wrote: post #337

Earlier quoted context omitted.

Ok, so? First off, you linked to a list of english measures which are not used in the US. Nobody uses fathoms or barleycorns. Here is the list of actual US customary units: https://en.m.wikipedia.org/wiki/United_States_customary_unit... Second, none of that is relevant to landing on Mars. The only problem space where metric has an advantage is in converting between meters, kilometers and millimeters. That’s great, an…

> If I am traveling toward Mars at 47 meters per second it doesn’t help me to know that is also .047km per second. Yes it does. It means you can immediately sanity-check your numbers even if you don't have a good sense of what meters and kilometers are, because you have that base/kilo relationship. > My bike ride is six miles, I’m never going to express that in feet. You can eyeball how fast you're going in feet per…

I’m not sure how that sanity check works, can you explain? Do you mean checking conversion between meters and kilometers? Because sure, that’s easier but you could just do everything in meters instead and not run the risk of crashing a spacecraft because of unnecessary conversions or bad assumptions.

I estimate my bike ride progress in landmarks and time. Not feet per second. Did I get to the boat ramp in 20minutes? Better speed up and get to the park by 30.

Re: Perseverance Rover lands on Mars [video]

#360

Post by Plutoberth »

jb1991 wrote: post #355

I can't find any articles that highlight what that component that "flies away" after the landing is going to do next. Does it just get dumped somewhere? Does it go back into orbit?

It GTFO with its remaining fuel and then crash lands. Going back to orbit would require enormous amounts of fuel.
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