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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."
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.
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.
"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.