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Perseverance Rover lands on Mars [video]

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Re: Perseverance Rover lands on Mars [video]

#461

Post by unanswered »

randomchars wrote: post #460
unanswered wrote: post #458

Earlier quoted context omitted.

I'm sorry, I honestly don't understand what distinction you're trying to point out. If someone's preferred pronoun is "she", for example, and I refer to her as a "they", then that's the wrong pronoun, isn't it? That's literally the definition of "wrong", at least the definition I understand. The right pronoun is "she" and other pronouns such as "he" and "they" and "it" are, by exclusion, wrong. But it seems like you'…

> Maybe it would help my understand if you could provide a chart relating the pronouns someone chooses with the pronouns other people are then allowed to use? I think this is everything wrong with the world currently. Provide you with a chart, so I can justify using gender neutral pronoun? https://apastyle.apa.org/blog/singular-they This is barely more than a year old, is it already outdated? I am an asshole for dari…

> If a person uses “she” or “he,” do not use “they” instead. Likewise, if a person uses “they,” do not switch to “he” or “she.” Use the pronouns the person uses.

This matches my own understanding; I have no idea why you are referring to this article as if it supports your bizarre crusade to misgender people.

Re: Perseverance Rover lands on Mars [video]

#462

Post by mulmen »

thiht wrote: post #454
mulmen wrote: post #419

Earlier quoted context omitted.

Sure, you can pick even numbers in either scale that are awkward decimals in the other. I just prefer the ten degree bands of the Fahrenheit scale for these ranges.

> I just prefer the ten degree bands of the Fahrenheit scale for these ranges. To the identical 5 degrees range of the Celsius scale ?

It's not really identical though. Like I said, Fahrenheit is higher resolution at these scales so that is an advantage. It doesn't mean everyone should convert to F. Just that both systems have benefits. If I changed my perception of the world to C I wouldn't actually gain anything, personally, in the context of weather and HVAC.

If I need to take measurements while boiling water or making ice then I would probably use C.

Re: Perseverance Rover lands on Mars [video]

#463

Post by randomchars »

unanswered wrote: post #461
randomchars wrote: post #460

Earlier quoted context omitted.

> Maybe it would help my understand if you could provide a chart relating the pronouns someone chooses with the pronouns other people are then allowed to use? I think this is everything wrong with the world currently. Provide you with a chart, so I can justify using gender neutral pronoun? https://apastyle.apa.org/blog/singular-they This is barely more than a year old, is it already outdated? I am an asshole for dari…

> If a person uses “she” or “he,” do not use “they” instead. Likewise, if a person uses “they,” do not switch to “he” or “she.” Use the pronouns the person uses. This matches my own understanding; I have no idea why you are referring to this article as if it supports your bizarre crusade to misgender people.

You are aware that we are talking about the mars rover, right?

The comment that you replied to:

> You can just say "they".

Was a reply to this:

> S/he already did. We just don't know yet.

Which was talking about the mars rover.

Re: Perseverance Rover lands on Mars [video]

#464

Post by detaro »

unanswered wrote: post #378
fckthisguy wrote: post #264

Earlier quoted context omitted.

You can just say "they". (Not trying to be judgy. People just seem to forget about the gender neutral use of "they".)

Why is it acceptable to use the wrong pronoun, such as "they", for someone who chooses the pronoun "she" or "he"?

They are not talking about a specific person, so how is "they" wrong?

Re: Perseverance Rover lands on Mars [video]

#465

Post by mulmen »

bernulli wrote: post #446
mulmen wrote: post #358

Earlier quoted context omitted.

> 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 bett…

>> 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. But one of the systems does have an advantage because it stays in base 10, whereas the other doesn't. >> Your document lists 12 mass units alone. I rest my case, what could possibly be more logical,…

> But one of the systems does have an advantage because it stays in base 10, whereas the other doesn't.

That's a benefit to humans, not to hardware, which was the context in which I was speaking.

> But you can't if you just use the `intuitive unit', and that's the whole problem. How would you measure the amount of liquid fuel in, say, the small tank for an attitude control thruster of some probe? How does that add to the overall mass of the whole probe? Or to the force you then need to accelerate it by a certain amount? And now compared to the whole launcher?

Honestly? I'd probably measure it in volts. That's what the hardware is doing after all. That's my point, it doesn't help the computer to convert to base 10 and do calculations that way. Fuel level is measured in volts using binary. For a human something like grams probably makes more sense so sure, display it in those units. But that's a conversion.

> In which units do you measure everything going on in a small wind tunnel model, and how do you compare that with the real thing?

Again, volts on strain sensors. Maybe analog or maybe binary, in newtons. Again, the hardware doesn't think in units humans prefer. There has to be a conversion that doesn't use simple in-your-head math.

> Under which conditions do you go from fluid ounces to ounces to cups to pints to quarts to gallons (also note that, again, you not only switch units but bases)?

Cups, pints, quarts and gallons are all based on the ounce and powers of two. A gallon is 128oz, a half gallon is 64oz, a quart is 1/2 of a half gallon (or a quarter gallon) or 32oz (also, approximately a liter). A pint is half a quart or 1/8th of a gallon or 16oz, a cup is half a pint or 1/16th of a gallon or 8 oz. These fractional scales are really handy for converting between units in some situations. The unit fits the task at hand or you can trivially double or halve the size of the unit if needed. It's the same fractional scale and math used with the inch.

Re: Perseverance Rover lands on Mars [video]

#466

Post by mulmen »

Cthulhu_ wrote: post #423
mulmen wrote: post #269

Earlier quoted context omitted.

Ever been on an airplane? Altitude was almost certainly measured in kilofeet. As noted in other comments, NASA (like the rest of the United States [1]) does use the metric system. But it doesn’t matter. Nothing about the metric system makes it uniquely suitable to landing on Mars. Or space travel in general. What matters is a consistent standard. Internally NASA could use Armstrongs. Where 1 is the weight or height o…

Quick, how many miles is 26357 feet? With metric it's a matter of shifting the decimal. How much is a sixteenth inch anyways.

Yes, conversion between mm, cm, m and km is easy. What's your point? If something is miles away why do I care about it in terms of feet? How many meters is the sun from here? How many km is 1/3 of an AU? How many seconds does it take light to go a meter in vacuum?

A 16th is half an 8th. Twice as much as a 32nd. AKA 2^4, 2^3 and 2^5, respectively.

Re: Perseverance Rover lands on Mars [video]

#467

Post by peter303 »

tectonic wrote: post #19
tectonic wrote: post #14

You can also watch an EDL visualization in your browser: https://eyes.nasa.gov/apps/mars2020/#/home And read about how it will use Terrain Relative Navigation to find a safe landing spot: https://www.jpl.nasa.gov/news/a-neil-armstrong-for-mars-land... Perseverance is phenomenally complex, its Sample Caching System alone contains 3,000+ parts and two robotic arms. So exited for all the sciencing this nuclear-powered,…

Also, InSight's SEIS seismometer is a true marvel: "We have been able to detect, at about 10 hertz, displacement of the ground of the order of less than 5 picometers…which is a fraction of the size of an atom." — https://eos.org/features/a-modern-manual-for-marsquake-monit...

LIGO puts this shame with 10^11 better sensitivity.

Re: Perseverance Rover lands on Mars [video]

#468

Post by nerfhammer »

tectonic wrote: post #14

You can also watch an EDL visualization in your browser: https://eyes.nasa.gov/apps/mars2020/#/home And read about how it will use Terrain Relative Navigation to find a safe landing spot: https://www.jpl.nasa.gov/news/a-neil-armstrong-for-mars-land... Perseverance is phenomenally complex, its Sample Caching System alone contains 3,000+ parts and two robotic arms. So exited for all the sciencing this nuclear-powered,…

from the author of that software https://twitter.com/mrdoob/status/1362508150507790343

Re: Perseverance Rover lands on Mars [video]

#469

Post by pupdogg »

mikeyouse wrote: post #126
pupdogg wrote: post #51

It took them approx. 4,881 hours from launch to land approx. 127,770,000 miles away. Is it safe to say that the average speed of the mission can be calculated as 436 miles/hour?

I think you dropped a thousands somewhere.. 127.8M miles/4,881hrs = 26,000 mph.[1] But in reality, it obviously didn't fly in a straight line, Looks like it traveled closer to 292 million miles[2], so more like 60,000 mph.[3] [1] - https://www.wolframalpha.com/input/?i=127800000+miles%2F4881... [2] - https://mars.nasa.gov/mars2020/timeline/cruise/ [3] - https://www.wolframalpha.com/input/?i=292526838+miles%2F4881...

You are correct, I did. Thank you. That's just amazing!

Re: Perseverance Rover lands on Mars [video]

#470

Post by zwkrt »

matt-attack wrote: post #449
Sharlin wrote: post #171

Earlier quoted context omitted.

Yes, those are all Earth Receive Time, that is, when they were saying that eg. entry interface is two minutes away, in reality the rover was already sitting on the surface and we were just waiting for the radio signal to get here.

But aren’t those two events essentially simultaneous in the relativistic sense? That is by some definitions of “simultaneous”?

In one sense, light experiences no time during travel, so anytime you are hit by radiation (like from a star) there is frame of reference in which the event was instantaneous.

On the other hand, if you were on Earth and I was in between Earth and Mars, I would receive the data more quickly than you, and I could even watch it whiz by me on its way to you. The thing about relativity is that it’s... relative!

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