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Curiosity Lands on Mars!
Posted By Alice On August 6, 2012 @ 3:43 am In AstroInfo Article,You Need To Know - but Everyone Else's Already Posted It | 2 Comments
There’s not much I can add to what’s already been said, so I’ll settle for answering a few questions brought up at tonight’s landing watch party and sharing some photos from our party as well as the first shots from Curiosity.
I was inspired by Emily Lakdawalla’s post  about the “cables” used during the Sky Crane Maneuver to bring a sample to tonight’s party. She managed to get her hands on a piece of the cord that had been used during testing. The look and feel were identical to nylon rope, so I stopped by Home Depot to get 7.5 meters of nylon rope. I brought her photo along and bought the closest thing they had. It was pretty darn close: similar diameter, same color, braided (different braid pattern), nylon rope. You can see mine hanging from the ceiling in some of the party pictures below. This is a close-up of the real rope:
Curiosity was lowered 7.5 meters on three of these cords. But is the cord really nylon like the rope I got at Home Depot? Yes. All the NASA websites say “nylon cable” or “nylon cord. ” I can’t tell if they did anything special beyond the style of braiding, but the main material was definitely nylon.
One other difference: my rope was rated to support 194 pounds. NASA’s cords each needed to support at least a third of the rover’s total weight (1 ton), so a single rope needed to support
333 pounds. (Whoops. I’m living in a wishful world of metric.) 1 ton is 2000 lbs, not 1000. So a single rope would need to support 660ish pounds. Then I realized I don’t know if that 1 ton weight is on Mars or on Earth. Which matters quite a bit.
Curiosity weighs 2000 lbs on Earth, 750 lbs on Mars. So each cord will hold about 250 lbs. Still needs to be stronger than my rope.
This rover is powered not by solar panels but by a “Radioisotope Power System .” Basically, nuclear power.
This doesn’t mean there’s a nuclear generator onboard. Rather there’s a small block of plutonium (specifically plutonium-238), which is slowly decaying into uranium-234 and eventually into lead. (Wait, don’t turn away just yet, I’ll explain!) As the plutonium decays it releases a good amount of heat because of that famous equation E=mc2. (I’m not going to give the lecture on radiation, nuclear power, and E=mc2 today, rather I’m going to skip straight to the heat part.)
How does the heat power the rover? There are these awesome devices called thermocouples which, when heated, create electricity. It’s the same effect that makes a plug-in cooler  work, but for the cooler you’re doing the process backwards. You add electricity, and it makes the thermocouple cold on one side and hot on the other. Onboard Curiosity, the plutonium is warming up one side of the thermocouple, which makes electricity flow through the circuit.
That electricity is captured in batteries, and Curiosity runs off the batteries.
The first photos returned were simple low-resolution images from the hazard-avoidance cameras near the wheels of the rover. By low-resolution I mean LOW–way less than a megapixel, a mere 64 pixels by 64 pixels. And the sheer number of people trying to download that image brought NASA’s servers to their knees. (The livestream of the landing didn’t bring the servers down, just that first image …)
First photo-can you tell there’s a wheel there?
(You put your right wheel in, you put your right wheel out, you put your right wheel in and you shake it all about …)
Here are the “high resolution” photos we got a few minutes later (256px square)
Also, my brother, Nils, and husband, Jason, were on hand answering all kinds of Mars and Curiosity questions, and shouting out facts I was forgetting to share. Thanks to you too.
See my nylon cord hanging in the back of this picture?
Here’s where the newest photos will be posted , albeit without explanations.
How Do We Talk to Mars? I was reminded today of an old post of mine about communication with Mars . I was reminded by the BAJILLION hits on it, I’d completely forgotten. It’s still accurate, so check it out.
West Seattle Blog –Tracy came to join us shortly after an evening of fielding UFO calls based on a number of sky lanterns released in south West Seattle. Always a great supporter of all my events, thanks so much!
West Seattle Herald  joined us and got some great shots! Again, thanks for the coverage of this awesome and inspiring moment in engineering history.
Seattle Astronomy ‘s Greg Scheiderer was also there, and got some great coverage.
~ A l i c e !
Article printed from Alice's Astro Info: http://www.alicesastroinfo.com
URL to article: http://www.alicesastroinfo.com/2012/08/curiosity-lands-on-mars/
URLs in this post:
 Emily Lakdawalla’s post: http://www.planetary.org/blogs/emily-lakdawalla/2012/07060700-how-curiosity-land-part-3.html
 All the NASA websites say “nylon cable” or “nylon cord.: http://www.nasa.gov/mission_pages/msl/multimedia/gallery/pia13282.html
 Radioisotope Power System: http://solarsystem.nasa.gov/rps/types.cfm
 plug-in cooler: http://www.coleman.com/Products/8570/thermoelectric-coolers
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 Keith: http://thinkzone.wlonk.com/
 Lego rover Rocker-Bogie: http://www.alicesastroinfo.com/2012/07/mars-rover-rocker-bogie-differential/
 Image: http://www.alicesastroinfo.com/wp-content/uploads/2012/08/2012_08_05-Curiosity-landing-watch-013-untitled.jpg
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 where the newest photos will be posted: http://mars.jpl.nasa.gov/msl/multimedia/raw/
 Curiosity’s home page: http://mars.jpl.nasa.gov/msl/
 old post of mine about communication with Mars: http://www.alicesastroinfo.com/2010/02/communicating-with-mars/
 West Seattle Blog: http://westseattleblog.com/2012/08/crowd-watches-mars-landing-at-the-kenney
 West Seattle Herald: http://www.westseattleherald.com/2012/08/06/news/slideshow-update-mars-rover-curiosity-lands-succe
 Seattle Astronomy: http://www.seattleastronomy.com/blog1/2012/08/touchdown-confirmed-curiosity-lands-safely-on-mars/
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