typodupeerror

## NASA's Juno, Armored Tank Heading For Jupiter185

Posted by CmdrTaco
from the gonna-be-a-bumpy-ride dept.
coondoggie writes "When it comes to ensuring that its upcoming Juno spacecraft can survive its mission, NASA is surrounding the spacecraft's electronic innards with titanium to ward off mission-threatening radiation. Juno's so-called radiation vault weighs about 200 kilograms (500 pounds), has walls that measure about a square meter (nearly 9 square feet) in area, about 1 centimeter (a third of an inch) in thickness, and 18 kilograms (40 pounds) in mass. About the size of an SUV's trunk — encloses Juno's command and data handling box, power and data distribution unit and about 20 other electronic assemblies, according to NASA."
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## NASA's Juno, Armored Tank Heading For Jupiter

• #### Let the fat jokes commence (Score:4, Funny)

on Wednesday July 14, 2010 @12:04PM (#32903038) Homepage
It's not fat, It's thick plated!
• #### Re: (Score:3, Funny)

Your satellite's so fat, they had to launch the earth off of it.

• #### shiny (Score:2, Funny)

by Anonymous Coward

But if you hold it the wrong way it blocks the antenna

• #### Couldn't get past the headline... (Score:2, Funny)

it is just screaming for a pewpewpew tag!

• #### 1.8 g/cm^3? What material is that? (Score:2)

Per the measurements given (18kg/(1m^2 * 1cm)) the vault's density is 1.8 grams per cubic centimeter. This is much less dense than aluminum (or steel or lead obviously) - anyone know what the vault is made from?

-Isaac

• #### Re: (Score:2)

Per the measurements given (18kg/(1m^2 * 1cm)) the vault's density is 1.8 grams per cubic centimeter. This is much less dense than aluminum (or steel or lead obviously) - anyone know what the vault is made from?

The density of extra glossy thick marketing material is about one and a half g/cc, I kid you not. (I'm talking about "junk mail" type paper thats almost but not quite cardboard slathered with glossy ink).

Obviously the device is made out of printed out power point presentations. I've heard NASA is pretty good at making power point presentations, if nothing else...

• #### Re: (Score:2)

Presumably it also has more than one wall.

The summary is horribly written, but it does mention that the vault masses 200 kg (is that including contents?) then later that one wall (?) is 18 kg, which doesn't add up either.

Supposing the 200 kg is correct and we're talking about a cube, then each 1 m^2 wall masses 200 / 6 = 33 1/3 kg, or 3.33 g/cm^3. That's close enough to the density of titanium that I suspect the 200 kg figure is correct and the box just isn't a cube.

• #### Re: (Score:2)

Yeah, the article is horribly written. However as I read it, the titanium box is 500 lbs. Considering that they're launching it on an Atlas 5 which can put 14 tons into GEO this is going to be a really heavy probe.

Hopefully it'll bring back some great science and help us better understand Jupiter and our solar system.
• #### Re: (Score:3, Insightful)

It's made from the journalist's incompetence.

• #### Re: (Score:2)

...anyone know what the vault is made from?

Metal.
Read the summary to find out which metal...it's in there.

• #### Is there an engineer or scientist in the house? (Score:5, Insightful)

on Wednesday July 14, 2010 @12:37PM (#32903610)

"about 200 kilograms (500 pounds), has walls that measure about a square meter (nearly 9 square feet) in area, about 1 centimeter (a third of an inch) in thickness, and 18 kilograms (40 pounds) in mass. About the size of an SUV's trunk "

I notice a few issues in this description, which also appears in the article. Some fact-checking might be in order.

How can a single thing be 200 kg, and also be 18 kg? You would think that a single thing would have only one mass.

Then, of course, a square meter is slightly more than 10 square feet.

How can a single square meter of material be made into all six sides of a box the size of a SUV trunk, without slicing it into thinner sheets. A square meter might make one side of such a box, but not all six. If all six sides of a cube total 1 square meter, each side would be about 40.8 cm square. Of course, the box doesn't have to be a cube, but the sum of the areas of the six sides still cannot exceed the total of the material.

Titanium has density of 4.5 g/cm^3. So a 100x100x1 cm piece of it would be 45 kg, not 18 kg.

• #### Re:Is there an engineer or scientist in the house? (Score:4, Informative)

on Wednesday July 14, 2010 @12:57PM (#32903950) Homepage Journal

Maybe they are estimating badly. Encasing a command module in square plates of titanium, however, would require 6 of those plates (envision a six-sided die). 6*18kg = 108kg. Using your math, 6*45kg = 270kg. The summary estimates 200kg which falls somewhere in between the two back of the envelope calculations.

So my guess is that 200kg refers to the total enclosure that's being created from 6 different components that are estimated in the summary to each weigh 18kg.

It'd be nice if people who submit articles "measured twice and cut once" for the maths they include in their submissions, since this is that place where discussion of the incorrect math will dominate an otherwise interesting conversation about Jupiter exploration.

• #### Re: (Score:2)

Also the comments about Juniper having moons. I would like to think that it was a typo, but it is too conveniently a Google keyword that would raise the page rank.

• #### Re: (Score:2)

I suspect you are essentially correct about the mass of the assembly, as compared to the mass of one side or component. I also thought that, perhaps, the sides might not all be of equal shape, size, or thickness. The shape may have more or fewer than six faces, or even some curves. Even if it is a polygon, it still doesn't have to be regular. Also, if one side will be toward the sun most of the time, that side might be thicker than the others. Similarly, if another side is to be oriented away from the

• #### Re: (Score:2)

The first mass is the whole thing, then the the second mass is just a wall. So in the 200 kg there are probably six 18 kg walls and some stuff inside.
• #### Re: (Score:2)

well, that whole article smacks with errors.

funny enough, he is apparently editing and updating the article live. That and censoring most of the comments that are critical of the writing and suggesting corrections.

• #### Victory Unintentional (Score:2)

Asimov's ZZ-1, ZZ-2, and ZZ-3 now have a companion! Can we call it ZZ-4?

• #### Re: (Score:2)

Asimov's ZZ-1, ZZ-2, and ZZ-3 now have a companion! Can we call it ZZ-4?

I say we call it ZZ Top. :-P

• #### Re: (Score:2)

Damn. beat me to it while I was typing.

Now I'm going to get Redundant mods that's hurt my karma.

• #### Re: (Score:2)

Asimov's ZZ-1, ZZ-2, and ZZ-3 now have a companion! Can we call it ZZ-4?

Let's call it ZZ-Top.

• #### this is the american space program (Score:2)

for those who havent seen it in action. if the math is correct we tend to affirm our intention to have visited the planet. should the math be flagrantly bogus, a press statement is quickly issued to confirm our original intent to send millions of dollars of exotic probe hardware hurtling into the surface of a far away world for science.

if you're a space alien, dont worry. eventually a probe will either land or explode violently on your homeworld. its the intergalactic equivalent of throwing rocks down
• #### Internet undo button (Score:2)

This whole story could use one.
• #### Something new? (Score:2)

Ordinarily, we don't hear about shielding, certainly not about a titanium tank to shield those electrtonics. Crap, they should have welded some A-10 cockpit tubs together...

Is this because NASA is using some COTS electronics on this mission? In the 'old days', we saw hardened electronics being used. Or is it a unique mission requirement, beyond what the old probes did?

• #### Re: (Score:3, Informative)

Is this because NASA is using some COTS electronics on this mission? In the 'old days', we saw hardened electronics being used. Or is it a unique mission requirement, beyond what the old probes did?

From TFA ..

For the 15 months Juno orbits Jupiter, the spacecraft will have to withstand the equivalent of more than 100 million dental X-rays

It's going to see hella radiation, so it needs some pretty beefy shielding. They're also using hardened components developed for Mars missions.

Without its protective shield

• #### Re: (Score:2)

Unique as compared to Pioneer, Voyager, or the Mars Rovers?

• #### Re: (Score:2)

Is this radiation from the solar wind? Or from some other source?
• #### Re: (Score:2)

The radiation around Jupiter comes from various sources, but is essentially due to charged particles trapped in Jupiter's magnetosphere. Some do come from the solar winds, and others from Jupiter itself.

• #### Re: (Score:2)

So it would be the same as being in an orbit near the Van Allen belts where charged particles are trapped?
• #### Re: (Score:3, Informative)

FTFA

"For the 15 months Juno orbits Jupiter, the spacecraft will have to withstand the equivalent of more than 100 million dental X-rays," said Bill McAlpine, Juno's radiation control manager, based at NASA's Jet Propulsion Laboratory in Pasadena, Calif., in a release.

According to NASA Jupiter has sizzling radiation belts surrounding its equatorial region and extend out past one of its moons, Europa, about 650,000 kilometers (400,000 miles) out from the top of Jupiter's clouds. Juniper has 63 moons.

• #### Re: (Score:2)

So it's not the transit, it's the orbiting.

Jupiter sounds like fun.

• #### Re: (Score:2)

Most likely a unique requirement as the article goes in to mention that Jupiter has stronger radiation fields then Mars, a planet supposably known for strong radiation.

• #### Re: (Score:2, Informative)

They are still using hardened electronics, but Jupiter's radiation belts are orders of magnitude more intense than Earth's radiation belts.

The main component to shield against in the Jovian environment are high energy electrons. It turns out that shields made out of higher charge elements are better at shielding electrons per mass. Aluminum is the defacto spacecraft material. You want something higher on the periodic chart than Al (for the best shielding to mass ratio), so they chose Titanium due to
• #### NASA Juno site (Score:2)

The mission site is here: http://www.nasa.gov/mission_pages/juno/spacecraft/index.html [nasa.gov] Includes pictures and better information, including Monday's press release, (which happens to be the source of the ft^3 m^3 units in the linked article): http://www.nasa.gov/mission_pages/juno/news/juno20100712.html [nasa.gov]

Shielding is titanium, as lead wouldn't survive liftoff "too soft to withstand the vibrations of launch" and other materials were "were too difficult to work with".

Cables between electronics are shielded in c

• #### This is America! (Score:3, Funny)

on Wednesday July 14, 2010 @01:05PM (#32904048)
SUV's don't have trunks!

What, expecting a metric system rant?
• #### Too dangerous (Score:2)

If this tank probe thing crashes back to earth, it could reek havoc. What are you going to do then, send some sort of cyborg superman to attach it to a skycrane and detonate a nuclear bomb beside it to destroy it?
• #### Summary bad, but not as bad as you might think (Score:5, Interesting)

on Wednesday July 14, 2010 @01:18PM (#32904210)

The article links to some kind of 'ooh, look at me' article instead of NASA's own page on Juno.

Juno Armored Up to Go to Jupiter [nasa.gov]

Each titanium wall measures nearly a square meter (nearly 9 square feet) in area, about 1 centimeter (a third of an inch) in thickness, and 18 kilograms (40 pounds) in mass.

Not exactly good maths there, so probably a PR piece from a 'journalist'.
9 foot^2 = 0.84 m^2 [google.com]. Could be correct, though I wouldn't use "nearly" for something that far off. And it's impossible to tell if the walls are really 9 foot^2 and they just made a very rough guestimate of the metric equivalent.

1/3 inch = 0.85 cm [google.com]
Again, that could be right. It might be exactly 1/3rd inch and they guestimated that to about 1 cm. But it's still 15% off.

40 lbs = 18.14 kg [google.com]
And then you hit something where the weight is actually correct. But since they've messed up that much on the other two, we now don't know if it's exactly 40 lbs or exactly 18 kg.

Hell, we don't even know if the NASA guys who wrote this are incompetent or not. Well, we know they're incompetent, we even know how much (about 15%).

However, the NASA page seemingly being written by an 8-year-old with a bad understanding of units, doesn't really justify linking to an article that is essentially a copy of NASA's page, and especially not when there is no attribution or links to the original article.

• #### Re: (Score:2)

Not exactly good maths there, so probably a PR piece from a 'journalist'.
9 foot^2 = 0.84 m^2. Could be correct, though I wouldn't use "nearly" for something that far off. And it's impossible to tell if the walls are really 9 foot^2 and they just made a very rough guestimate of the metric equivalent.

Or it was information given by a scientist who was keeping things to one significant digit [wikipedia.org] because anything else really is just wasted text in a such an article especially when none of the measurements come out

• #### Re: (Score:2)

Those are all low-accuracy numbers. Note that 0.8 m^2 could be described as "nearly a square meter" and "nearly 9 square feet". Equally, a third of an inch is "about 1 cm".

• #### Re: (Score:3, Insightful)

Pedantic much? Or did you just miss the fact that the engineers working on the project at NASA, when talking to the reporters/PR people, realized saying, "0.84 meters squared, 0.85 cm thick, and approximately 18.14 kg," wouldn't have told them diddly squat about what the actual dimensions of the hardware This is a NASA mission. Thus, it is going to generate a lot of publicity/press in the United States. Most folk in the United States think in terms of feet and inches. Using numbers like 9 square feet, and o
• #### Aha! (Score:2)

I get it. The linked-to blog post (what is supposed to be TFA) is being supplied as an example of how to break every rule of English grammar, right? Likewise, the summary is an example of how to make a Slashdot summary by copying and pasting the first paragraph of TF"A".

• #### Senate vote on NASA bill tomorrow;Bill Nye on NASA (Score:3, Informative)

on Wednesday July 14, 2010 @03:13PM (#32905742) Journal

On a related note, there's a bill in the Senate which will be voted on tomorrow (Thursday) morning which threatens to reduce the proposed funding for robotic missions (like the one described in the summary), commercial crew, and space technology in favor of building a government-designed heavy-lift rocket instead. The Planetary Society has an update describing the situation and is urging people who care about space exploration to call their Senators immediately:

http://www.planetary.org/blog/article/00002584/ [planetary.org]

More background info on the bill: http://www.spacepolitics.com/2010/07/14/a-quick-review-of-the-senate-nasa-authorization-bill/ [spacepolitics.com]

For the curious, Bill Nye the Science Guy (the new director of the Planetary Society) and Louis Friedman are hosting a webcast/discussion at 5pm ET today about the future direction of NASA:

• #### A modest suggestoin (Score:2)

Wouldn't it be easier just to travel at night?

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