iTopSpin

NSTR => Non SpinTop Related => Topic started by: Jeremy McCreary on February 17, 2021, 11:16:37 AM

Title: Perseverance lands on Mars tomorrow!
Post by: Jeremy McCreary on February 17, 2021, 11:16:37 AM
Same bonkers EDL (entry, descent, and landing) sequence used by Curiosity...

https://youtu.be/M4tdMR5HLtg

Took a lot of hutzpah to think that EDL would ever work, but it did last time -- flawlessly! And the entry vehicle at 0:52 looks a lot like our favorite toy.

How to watch...

https://mars.nasa.gov/mars2020/timeline/landing/watch-online/
Title: Re: Perseverance lands on Mars tomorrow!
Post by: ta0 on February 17, 2021, 03:58:44 PM
Thanks for the heads up. I'll try to watch tomorrow at 1:15 PM CST
Title: Re: Perseverance lands on Mars tomorrow!
Post by: Texture on February 17, 2021, 07:24:22 PM
That'll be fun to watch. Thanks for letting us know.
Title: Re: Perseverance lands on Mars tomorrow!
Post by: jim in paris on February 18, 2021, 01:25:44 AM
Wahoo ! 13 000 mph before entry!

Mad!☻

Jim
Title: Re: Perseverance lands on Mars tomorrow!
Post by: ta0 on February 18, 2021, 03:44:58 PM
A few minutes!
Title: Re: Perseverance lands on Mars tomorrow!
Post by: ta0 on February 18, 2021, 03:59:48 PM
Landed successfully!  8)
Title: Re: Perseverance lands on Mars tomorrow!
Post by: Jeremy McCreary on February 18, 2021, 06:19:14 PM
One mission bigwig just said that every time they have a landing, there's a plan and a contingency plan. He then held up the latter and tore it up to great applause in Mission Control. :)

America at its best -- doing the hard things with science and engineering as our guides. Hope the rest of the US government gets back into that habit soon.
Title: Re: Perseverance lands on Mars tomorrow!
Post by: the Earl of Whirl on February 18, 2021, 10:03:47 PM
Yes!  Science is not a four letter word.
Title: Re: Perseverance lands on Mars tomorrow!
Post by: Jeremy McCreary on February 19, 2021, 10:02:19 AM
Excellent comparo of the Mars Science Laboratory and Mars 2020 rovers we call Curiosity and Perseverance, respectively...

https://youtu.be/UEO77UEFGT4

The engineering on both machines is beyond incredible. As for the new stuff, gotta love that sample-handling robotic arm tucked in Perseverance's belly.
Title: Re: Perseverance lands on Mars tomorrow!
Post by: Jeremy McCreary on February 19, 2021, 11:21:04 AM
If we didn't have snow on the ground, I'd celebrate by taking my toy rover for another walk...

https://youtu.be/MobwYuhkSVE

The NASA rocker-bogie mobilty system modeled here schematically turns out to be amazingly effective at any scale. But snow's not its long suit.
Title: Re: Perseverance lands on Mars tomorrow!
Post by: Jeremy McCreary on February 20, 2021, 01:33:52 PM
NASA's getting really good at these animations of how a mission is supposed to go. Perseverance's improbable EDL sequence in its entirety with the actual scenery it will encounter...

https://youtu.be/rzmd7RouGrM

Never gets old. With both Perseverance and Curiosity, EDL went exactly as planned. Boggles the mind.

During Curiosity's 6-month shakedown process, only one function out of thousands failed to meet its performance goals  -- a mast-mounted weather instrument of minor importance that still produced some useful data.

Hoping Perseverance's shakedown goes as smoothly -- only much faster. Ready for this rover to get roving!
Title: Re: Perseverance lands on Mars tomorrow!
Post by: Jeremy McCreary on February 20, 2021, 02:45:33 PM
Sorry to keep posting this stuff, but I can't help myself, as I came down with FPPD (Fulminant Perseverance Perseveration Disorder) on Thursday.

Mars is a place of stark beauty, with evidence of active wind- and fossilized water-driven motion everywhere you look. Stunning 2-part documentary compiled in 4K from scenery shot by the Curiosity, Spirit, and Opportunity rovers...

https://youtu.be/ZEyAs3NWH4A

https://youtu.be/W7FcE7yZl4M

Think private National Park tour on Mars!
Title: Re: Perseverance lands on Mars tomorrow!
Post by: ta0 on February 20, 2021, 03:32:10 PM
Am I the only one who looks at those amazing images and searches for a good spot to spin a top?  ;D ;D ;D

By the way, with lower gravity a top would spin longer before falling. Also it will provide more time in the air to catch the top on a trick. But slower precession will require some adjustments. Texture is young enough that he could try one day ;)

Title: Re: Perseverance lands on Mars tomorrow!
Post by: Jeremy McCreary on February 20, 2021, 06:15:02 PM
Am I the only one who looks at those amazing images and searches for a good spot to spin a top?  ;D ;D ;D

By the way, with lower gravity a top would spin longer before falling. Also it will provide more time in the air to catch the top on a trick. But slower precession will require some adjustments. Texture is young enough that he could try one day ;)

Pretty sure you'd have to pay a big extra baggage fee for Figaro.

Wouldn't it be fun to turn down the gravity in a physically correct top simulator?

Though precession rates and critical speeds would decrease, nutation rates wouldn't change -- at least not directly.

The von Karman aerodynamic braking torque is proportional to air density and the square root of the air's kinematic viscosity. The viscosity is ~100 times larger on Mars than on Earth, while the density is ~100 times smaller.

Net effect: The von Karman torque on Mars would be ~10% that on Earth.

I say we go to Mars ASAP!
Title: Re: Perseverance lands on Mars tomorrow!
Post by: ta0 on February 21, 2021, 01:21:01 AM
The von Karman aerodynamic braking torque is proportional to air density and the square root of the air's kinematic viscosity. The viscosity is ~100 times larger on Mars than on Earth, while the density is ~100 times smaller.

Net effect: The von Karman torque on Mars would be ~10% that on Earth.

This table from Aerodynamics of Mars 2020 Rover Wind Sensors (https://www.intechopen.com/books/mars-exploration-a-step-forward/aerodynamics-of-mars-2020-rover-wind-sensors):

(https://api.intechopen.com/media/chapter/70846/media/Table1.png)

gives the kinematic viscosity 35 times bigger and the density 64 times lower on Mars than the Earth, but the end result is the same: about 10% the von Karman drag torque.
Title: Re: Perseverance lands on Mars tomorrow!
Post by: Jeremy McCreary on February 21, 2021, 01:44:01 AM
Kinematic viscosity measures the rate at which momentum diffuses through a fluid. Wasn't expecting it to be higher on Mars.

It's not very sensitive to pressure, so must have to do with the low mean temperature, the high CO2 content, or both.
Title: Re: Perseverance lands on Mars tomorrow!
Post by: ta0 on February 21, 2021, 09:40:07 AM
I was also very surprised that the kinematic viscosity would be bigger in Mars and that's why I checked.
The dynamic viscosity on Earth is still about two times bigger than on Mars.
Title: Re: Perseverance lands on Mars tomorrow!
Post by: jim in paris on February 21, 2021, 11:57:53 AM
Thanx jeremy for the links
and for tuning us to this fascinating project
Time to read again the trilogy on Mars by kim stanley Robinson

Superb videos  ,
Although there are no Martians ( yet)

Ciao
Jim
Title: Re: Perseverance lands on Mars tomorrow!
Post by: Jeremy McCreary on February 21, 2021, 05:35:35 PM
Superb videos  ,
Although there are no Martians ( yet)

Glad you enjoyed them! As you can see, I'm totally obsessed at this point.

You didn't see Martians because they all moved to Titan when they saw us coming.
Title: Re: Perseverance lands on Mars tomorrow!
Post by: Jeremy McCreary on February 23, 2021, 12:40:39 PM
NASA footage of EDL from onboard cameras...

https://mars.nasa.gov/news/8870/nasas-mars-perseverance-rover-provides-front-row-seat-to-landing-first-audio-recording-of-red-planet/

Can't get a ride like that at Disneyland.
Title: Re: Perseverance lands on Mars tomorrow!
Post by: Jeremy McCreary on April 21, 2021, 12:02:07 PM
NASA had a "Wright Brothers moment" yesterday when its $80M proof-of-concept helicopter Ingenuity successfully lifted off the ground, hovered, and landed on its feet for the first time.

https://youtu.be/wMnOo2zcjXA

For Earthlings, at least, it was the first flight of an aircraft of any kind on anothet planet.

Seems like NASA could launch a spinning top on Mars next time it lands there for a lot less than $80M. It'd have to be made of some kind of unobtainium, of course, cuz that's just how JPL rolls. And there'd have to be some kind of fancy autonomous robotic starter in the belly of the rover. But that would be child's play for them.

Write your congressman!  We could be on the advisory board! And The Earl's "Happiness runs in a circular motion" would be a perfect inscription. Nobody knows that better than NASA.
Title: Re: Perseverance lands on Mars tomorrow!
Post by: the Earl of Whirl on April 21, 2021, 01:50:09 PM
Gotta sing “Happiness Runs in a Circular Motion” tonight at open mic night!!!
Title: Re: Perseverance lands on Mars tomorrow!
Post by: Jeremy McCreary on April 21, 2021, 02:30:30 PM
Gotta sing “Happiness Runs in a Circular Motion” tonight at open mic night!!!

There's a whole song about my favorite top saying??

Gotta hear it!  Please have someone get video!
Title: Re: Perseverance lands on Mars tomorrow!
Post by: Jeremy McCreary on April 22, 2021, 05:38:34 PM
Go NASA! Second Ingenuity test flight also a success...

https://www.nasa.gov/feature/jpl/nasa-s-ingenuity-mars-helicopter-logs-second-successful-flight


Title: Re: Perseverance lands on Mars tomorrow!
Post by: the Earl of Whirl on April 22, 2021, 08:46:29 PM
https://m.youtube.com/watch?v=-cGWTAe3M6U
Title: Re: Perseverance lands on Mars tomorrow!
Post by: Jeremy McCreary on April 23, 2021, 12:06:02 PM
Donovan -- what a blast from my hippie past! You chose your sig well, and now I have a melody for it.
Title: Re: Perseverance lands on Mars tomorrow!
Post by: lincolnrick on April 23, 2021, 12:17:44 PM
Thanks for the video Mike! That took me down a rabbit/memory hole of Donovan songs. I didn't realize how many hits he had and what a unique sound he had for the times. 'Atlantis' is a powerful and beautiful song about the lost continent. Took me a long time to climb out of that history hole. 'Mellow Yellow', 'Hurdy Gurdy Man', 'Sunshine Superman', so many more. If you like folk/rock/psychedelic give Donovan a listen.
Title: Re: Perseverance lands on Mars tomorrow!
Post by: Jeremy McCreary on April 24, 2021, 02:04:21 PM
https://youtu.be/fygbRTfaQ1M
Title: Re: Perseverance lands on Mars tomorrow!
Post by: the Earl of Whirl on April 24, 2021, 10:59:12 PM
He does a good job handling that crowd, doesn’t he?  Even when they go faster and faster and faster and then slow down for the finish, he pulls them all together.  Quite impressive!!!  The cheers at the end show how the group really appreciated it.

Glad to see lincolnrick enjoy some of the good work of Donovan.  He was quite the man there for a long time.  He also did the music for the movie “Brother Sun and Sister Moon.”  You might enjoy looking that up, also.  Our local connection is that he once played at the Canal Street Tavern in downtown Dayton near where the Dayton Dragons play minor league baseball.  His signed picture hangs on the wall there.
Title: Re: Perseverance lands on Mars tomorrow!
Post by: the Earl of Whirl on April 24, 2021, 11:04:21 PM
Sadly, after some research, it looks like the Canal Street Tavern is permanently closed!  Rats!!!
Title: Re: Perseverance lands on Mars tomorrow!
Post by: Jeremy McCreary on April 26, 2021, 10:03:02 PM
Perseverance's Mastcam Z recorded Ingenuity's 3rd test flight, another success. During the horizontal phase, the rotorcraft left the frame for 25 seconds.

https://youtu.be/kNx9hcrUpww

What I want to know is what that sneaky little chopper was up to over there all by itself?

I think it was yucking it up with the Martians they don't want us to know about.