New Spacecraft Set For Dangerous Jupiter Trip

solaGratia passes along word of the equipping of Juno, the most heavily armored craft ever to be launched to another planet. The launch is scheduled for a year from now. "In a specially filtered cleanroom in Denver, where Juno is being assembled, engineers recently added a unique protective shield around its sensitive electronics. ... 'For the 15 months Juno orbits Jupiter, the spacecraft will have to withstand the equivalent of more than 100 million dental X-rays,' said... Juno's radiation control manager... [The] titanium box — 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. The whole vault weighs about 200 kilograms (500 pounds)."

Re:why?

[QuantumG]

to study the planet's composition, gravity field, magnetic field, and polar magnetosphere. Juno will also search for clues about how Jupiter formed, including whether the planet has a rocky core, the amount of water present within the deep atmosphere, and how the mass is distributed within the planet. Juno will also study Jupiter's deep winds, which can reach speeds of 600 km/h.

http://en.wikipedia.org/wiki/Juno_(spacecraft) [wikipedia.org]

It's uglier than you can imagine.

[jrst]

It's uglier than you can imagine.

IIRC (sorry, it was long ago)... on the Pioneer 10//F 11/G missions Van Allen spec'd the Geiger Tube Telescope for an order-of-magnitude more than expected, and we pegged them. Pioneer suffered significantly--never regained full range on one channel of the IPP (Imaging Photopolarimeter--that thing that made the pretty pictures possible).

We nearly lost the spacecraft due to some spurious crap/commands during periapsis on Pioneer 10/F. Try dealing with an idiot-savant-brain-damaged-two-year-old throwing a tantrum with ~90-minute round-trip light time at 256-1024bps. It's ugly.

The running joke was... If you want to be absolutely certain a spacecraft is sterile, just make a flyby of Jupiter. Jupiter's belts are not to be taken lightly. A seriously understated quote from one post-mission presentation "Closest approach: It’s hot in there!"

It's not just hot, it's a red-hot-poker enema in your electronic guts. That Pioneer 10/11 F/G--the epitome of cheap deep-space exploration--survived those encounters and lived to tell--and did so for many more years still amazes me.

It is a testament to what we can do, and what deep-space exploration is all about. (So allow me a bit of hubris: Suck eggs Voyager... you had a much bigger budget, you got the press, you got your name in a Star Trek movie, but we were there first. Nah nah nah.)

opps, out by a factor on 100.

[oliverthered]

Sorry, the cost of war in Iraq (financially to the US alone) is 100 times that of this mission to Jupiter.

Re:opps, out by a factor on 100.

[stevelinton]

Actually it's 1000 times...

Re:opps, out by a factor on 100.

[tsm_sf]

Poe's law (religious fundamentalism) -- "Without a winking smiley or other blatant display of humour, it is impossible to create a parody of fundamentalism that someone won't mistake for the real thing."

Re:opps, out by a factor on 100.

[MRe_nl]

A common mistake.

I suggest you take some drugs.

Re:It's uglier than you can imagine.

[mbone]

While the depth of the atmosphere also helps in shielding, 14 pounds per square inch (or, ten metric tons per square meter), is not a bad first guess for adequate shielding for most of deep space, although it would not nearly be adequate for Jupiter. (Not every part of the spacecraft would require this, but a shielded "safe room" for solar flares would be a very good idea.) Note that the Jovian / Solar Flare radiation is all charged particles (no X or gamma rays), so it might also be possible to do magnetic shielding.

Re:dangerous?

[mbone]

You are correct that there are no significant tidal forces in a 10 meter spacecraft, but there are certainly solar tides on the Earth - they are about 1/2 the amplitude of the Lunar tides, and the interaction between the two gives rise to the Spring and Neap tides.

Re:dangerous?

[photonic]

Correct me if I am wrong, but I doubt that tidal forces play any role at all for Juno. Tidal forces are caused by the difference of gravity over the extend of an object, which is only significant for planets and moons which have sizes on the order of thousands of kilometers, compared to satellites with a diameter of 10 meters. According to the last formula found here [wikipedia.org], the tidal force is roughly a fraction (diameter / orbit height) of the gravitational force itself. A satellite of 10 meters orbiting at the same height above Jupiter as Io (known for its tidal induces volcanoes), will thus experience just a few millionths of the force experienced by Io.

Re:USD $700 million, that's practically free.

[sjames]

You're only off by THREE ORDERS OF MAGNITUDE!

You must be one of those Hollywood Accountants yourself.

Re:It's uglier than you can imagine.

[DerekLyons]

And the only cost-effective ways to do that are propulsion based on nuclear explosions or a space elevator. One technology people are afraid of, the other is not ready.

One technology people are afraid of, two technologies that are not ready.
 
Seriously, people treat nuclear pulse production as if were a done deal, but there's been damn little actual engineering work accomplished. Exactly none of the equipment has been tested except in the form a non-nuclear (very small) scale model. Huge questions remain about the design of the pusher plate and the shock absorbers, as well as the of pulse unit itself.