NASA's Juno, Armored Tank Heading For Jupiter

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."

Comments

Let the fat jokes commence

[Widowwolf]

It's not fat, It's thick plated!

Re:Let the fat jokes commence

[StikyPad]

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

shiny

[Anonymous Coward]

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

Couldn't get past the headline...

[vlueboy]

it is just screaming for a pewpewpew tag!

Re:Unit conversions

[Anonymous Coward]

4 Square meters is not a square with 4m sides but with 2m sides so the parent is correct and you buddy are wrong

Re:Unit conversions

[chill]

Close enough for government work.

aka

"Mars Polar Lander"

Re:Unit conversions

[Anonymous Coward]

One square meter is about 10.8 square feet. They got everything right except for the "nearly" part (it should be "over"). Squaring the unit does square the number.

Re:Unit conversions

[Dr Caleb]

I learned many years ago that converting units for the metrically challenged does them no service. They need to learn to convert them themselves, so they can speak to the rest of the world in units we all understand.

Re:Unit conversions

[MyLongNickName]

So one square meter isn't a square with 1 meter sides?

Re:Unit conversions

[blueg3]

In English, the unit m^2 is written (and said) "square meter(s)" and the unit ft^2 is written "square foot [feet]".

So, one square meter is 1 m^2, which is an area 1 m x 1 m = 3.28 ft x 3.28 ft = 10.8 ft^2, which is 10.8 square feet.

There's an acceptable, albeit annoying, construction in English (or at least American English) that's completely different: "3 feet square" refers to an area 3 ft. x 3 ft., which is 9 ft^2.

Re:Unit conversions

[MyLongNickName]

I understand the math. I was being sarcastic, actually. yeah, I know it doesn't communicate well over the internet. The point is that 1 square meter is considerbly more than 9 square feet. The actual article is poorly written. If the topic weren't so terribly interesting, I wouldn't have wasted my time. However, I would have linked directly to NASA's page instead of the hack that wrote the article.

Is there an engineer or scientist in the house?

[natoochtoniket]

"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?

[rwv]

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:Unit conversions

[Meriahven]

[in American English] "3 feet square" refers to an area 3 ft. x 3 ft

I'm no expert in your language on that side of the big wet thing, but in Finglish the phrase would be "3 foot square", modulo hyphens. Which just further proves your point about the construction being annoying, I guess :-)

This is America!

[riskeetee]

SUV's don't have trunks!

What, expecting a metric system rant?

Re:Something new?

[gstoddart]

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, or radiation vault, Juno's brain would get fried on the very first pass near Jupiter

So, yes, it's a unique mission requirement.

Re:Something new?

[Tekfactory]

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.

Summary bad, but not as bad as you might think

[MartinSchou]

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

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. 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
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
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:Summary bad, but not as bad as you might think

[BJ_Covert_Action]

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 one-third of an inch give dimensions that people can visualize easily while reading a press release (I can look at my size 12 foot and say, "Well, it's about three of those long on one side). Using point something something centimeters or meters is just going to make people sit around and say, "Okay, a meter is a bit longer than a yard, what's 85% of a meter? Oh wait, it's square meters we're talking about? Screw this, I'm going to go watch the new Twilight movie instead."

When it comes down to it, if an engineer is going to be bragging about one of their projects to the press, they are going to use some off-the-cuff estimates, "Yeah, it's about a third of an inch thick," rather than the specific dimensions they used in their design because they realize that people don't know, or care, what 0.8495672331 cm looks like. Similarly, the press realizes it needs to report units that can actually help people visualize since the majority of the readers are not going to be sitting their with engineering paper and a ruler trying to do some kind of calculations/estimates with the information. Thus, I would say that both the press, and the engineers, did their job just find by, essentially, saying something along the lines of, "It's about this big, if you want to visualize it."

So all that, "I wouldn't call a 15% discrepancy 'close'" mumbo jumbo you just warbled out is nothing more than you spouting an overly pedantic analysis of a, "Hey look at this cool piece of hardware," article. You need to find yourself a hobby other than posting to slashdot if you have nothing better than that to do with your spare time.

Re:Unit conversions

[PopeRatzo]

A square with 3 foot sides has an area of ( 3 foot x 3 foot ) = 9 square feet. Draw it on a sheet of paper and it will become more apparent. You example is unique in that 1 squared is 1.

Nobody told us there was going to be math.

Is it too late for me to drop this class and take Poly Sci instead?

Re:Unit conversions

[RKBA]

It was a long, long time ago, but if I recall correctly Mars Polar Lander was a "Class C" project (meaning that QA requirements weren't very strict, and it didn't have to pass the much more stringent requirements like dual-fault tolerance, etc., that are enforced for class A and class B projects). The breadboard for the meteorology subsystem was a one hundred dollar 8031 CPU board purchased off the Internet from some company whose name I forget. The project couldn't even afford an In Circuit Emulator for the meteorology subsystem CPU. :-(

Re:1.8 g/cm^3? What material is that?

[IICV]

It's made from the journalist's incompetence.

Re:Unit conversions

[Darth Sdlavrot]

Wow, the British are the weird ones, here! Lets do some exercises:

Exercise 1: What is the area of a triangle with a base of 3m and height of 5m?

Mathematically: (3 * 5) / 2 = 7.5

American: That's 7.5 meters squared

Let me fix this for you:

      That's 7.5 square meters.

British: That's sqrt(7.5) square meters?????

WTF? No, they'd say the same thing we'd say.

Re:Something new?

[celticryan]

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 considerations like material availability and ease of manufacturing while still standing up to being launched into space.

Another possibility for high energy electron shielding is to take aluminum and place a higher charge metal (Tantalum is often used) layer right next to it. The Aluminum is the structural component, but the Tantalum is the shielding component.

Senate vote on NASA bill tomorrow;Bill Nye on NASA

[FleaPlus]

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/

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

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:

http://planetary.org/about/press/releases/2010/0712_Where_Should_We_Go_in_Space_Tell_Bill.html

Re:Unit conversions

[H0p313ss]

So one square meter isn't a square with 1 meter sides?

It is, but two square meters is not a square with 2 meter sides. :)

He he... I'm suddenly reminded of having to teach my wife how fractions actually work. (They are just unresolved division solutions with useful properties...)

There are times in life when I wish I could just forget math and be a Joe Sixpack. Am I the only one who has to resist the temptation to teach cashiers how to optimize change giving to involve the least number of coins?

Re:Unit conversions

[PagosaSam]

Jesus boys and girls! I had to go back reread the summary to remember what the topic was! Hint: it's not metric/english conversion.