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Perseverance Rover lands on Mars [video]

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Re: Perseverance Rover lands on Mars [video]

#341

Post by soheil »

BurningFrog wrote: post #71
jaegerpicker wrote: post #57

Seeing the engineers and scientists celebrating the successful landing was one the best things I've seen in a LONG while. Very live affirming and inspiring to me!

Is part of the joy that they now have secure jobs for years to come?

Most common assumption by outsiders is that they're happy that their many years of effort came to fruition, but I think a big part of is that they will be working on this mission for the foreseeable future as you point out. They get to tell their kids I worked on this mission, it was successful and then we made the rover do X, Y and Z in the next few years.

Re: Perseverance Rover lands on Mars [video]

#343

Post by FredFS456 »

dmix wrote: post #234
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,…

> And read about how it will use Terrain Relative Navigation to find a safe landing spot: So basically TERCOM from cruise missles but used on space crafts? All you need is a radar countour map of the area and it can automate it's way to the endzone. https://en.wikipedia.org/wiki/TERCOM

Perseverance's Terrain Relative Navigation uses a camera system and generates a full 3D position fix, but the idea is similar.

Re: Perseverance Rover lands on Mars [video]

#344

Post by jws »

Azrael3000 wrote: post #55

It's a great achievement with some really interesting work done on the landing algorithms with terrain recognition and it seemed to have worked exceptionally well. Looking forward for the next landing in May of the Chinese rover and all the science these robots will produce. Also, the test of Ingenuity, the helicopter, will be very interesting to watch, that could really pave the way for a different exploration style…

Early starships got me thinking: given the high likelihood of a failed starship landing, and maybe having the ability to send one before fully engineering a payload…

What would you ballast a starship with for the practice missions?

Useful materials which might survive a RUD and aim for someplace near a likely landing zone? If you crash the parts of a milling machine, a lathe, some tooling, some assorted metals stock, and a bunch of assorted wire, well sure you just cleared out a machine shop auction, but maybe there comes a day when an early Mars colony would be thrilled to go clean up your “landing” site.

Re: Perseverance Rover lands on Mars [video]

#345

Post by spaetzleesser »

lmilcin wrote: post #251
spaetzleesser wrote: post #236

Earlier quoted context omitted.

They should make km the default unit and not miles....

Actually, NASA uses metric system internally. Imperial units are probably used for general public convenience.

Considering that one of NASA's roles is to inspire young people to enter STEM I think it would be important to promote metric as much as possible.

Re: Perseverance Rover lands on Mars [video]

#346

Post by spaetzleesser »

mulmen wrote: post #338
sojournerc wrote: post #331

Earlier quoted context omitted.

As an occasional woodworker and carpenter, I can tell you having evenly divisable (inch) measurements makes mental division a whole lot easier. It's just a case of using the right tool for the job.

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?

People often say something is 1 and a half meters long. I don't understand how people can work with inch measurements. How do you divide 7"3/8 by 5? This seems a major pain.

Re: Perseverance Rover lands on Mars [video]

#347

Post by FredFS456 »

soheil wrote: post #342

So where are the images? (not the black and white fisheye)

It will be a while before they get better images downlinked. The radio link is unbelievably slow by modern internet standards[0]. Note that the faster 2 Mbps link is only available when one of the orbiters is overhead (4-6 times/martian day[1]). They also have a lot of work to do checking out the rover systems making sure everything is healthy, etc.

[0] https://mars.nasa.gov/mars2020/spacecraft/rover/communicatio...

[1] https://mars.nasa.gov/mars2020/mission/communications/

Re: Perseverance Rover lands on Mars [video]

#348

Post by sojournerc »

mulmen wrote: post #338
sojournerc wrote: post #331

Earlier quoted context omitted.

As an occasional woodworker and carpenter, I can tell you having evenly divisable (inch) measurements makes mental division a whole lot easier. It's just a case of using the right tool for the job.

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?

There's something just right about 1/16th of an inch. About the same as a millimeter, and easy to do math with... it is weird though 1/8th, centimeter is hard to conceive, for me anyway.

When more precision is needed, so easy to go to the 32nd

Re: Perseverance Rover lands on Mars [video]

#349

Post by grecy »

mulmen wrote: post #338
sojournerc wrote: post #331

Earlier quoted context omitted.

As an occasional woodworker and carpenter, I can tell you having evenly divisable (inch) measurements makes mental division a whole lot easier. It's just a case of using the right tool for the job.

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.

Re: Perseverance Rover lands on Mars [video]

#350

Post by lmm »

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…

> 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 second and have a rough idea of how long your ride is going to take. Or rather you could if you had any idea of how long your ride was in feet. There are lots of little everyday things that just become much easier.

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