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Juno Arrival This Year!


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12 minutes ago, Veeltch said:

How do you even define arrival in this case?

I'm looking forward to cool pics of the jovian moons. Maybe even the rings will be visible from the polar orbit.

Probably when they enter the Jupiter SOI, like in KSP.:P

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1 minute ago, Bill Phil said:

What's weird is that they're using solar panels.

The solar panels are a result of Budget cuts (I'm pretty sure, I'm not sure why you'd want solar panels so far from the sun either)

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5 minutes ago, Spaceception said:

The solar panels are a result of Budget cuts (I'm pretty sure, I'm not sure why you'd want solar panels so far from the sun either)

Probably cheaper than plutonium, yeah.

But I think they're using it because it's only recently become an option. Power requirements for those probes aren't huge, and solar panels have been getting more efficient. Salyut 6, for example, produced 4 kilowatts of power with its panels. Orbital's spacecraft, Cygnus, which is much smaller and solar powered, produces a similar amount of power.

Edited by Bill Phil
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1 minute ago, Bill Phil said:

Probably cheaper than plutonium, yeah.

But I think they're using it because it's only recently become an option. Power requirements for those probes aren't huge, and solar panels have been getting more efficient. Salyut 6, for example, produced 2 kilowatts of power with its panels. Antares' spacecraft, Cygnus, which is much smaller and solar powered, produces a similar amount of power.

Yeah, but still, RTGs are better.

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Edited by Spaceception
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1 minute ago, Spaceception said:

Yeah, but still, RTGs are better.

You are only allowed to give 25 likes per day. You cannot give any more likes today.

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That depends. RTGs have a limited lifetime, too. But they have expensive components. 

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Just now, Bill Phil said:

That depends. RTGs have a limited lifetime, too. But they have expensive components. 

And Solar panels have a limited range, but anything to keep costs down I guess, we don't want anymore budget cuts to NASA.

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3 minutes ago, Spaceception said:

And Solar panels have a limited range, but anything to keep costs down I guess, we don't want anymore budget cuts to NASA.

Galileo generated about 500 to 600 watts with its RTG. Juno will generate about 490 at Jupiter with its panels. In Earth orbit it would generate more than 10 kilowatts of power.

There's limited range, yes. But there's also a global shortage of RTG fuel ( is that what it's called?). Or at least there was, back when it launched.

Edited by Bill Phil
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1 minute ago, Bill Phil said:

Galileo generated about 500 to 600 watts with its RTG. Juno will generate about 490 at Jupiter with its panels. In Earth orbit it would generate more than 10 kilowatts of power.

There's limited range, yes. But there's also a global shortage of RTG fuel ( is that what it's called?). Or at least there was, back when it launched.

Oh, wow, that's pretty impressive.

I think it's called that.

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49 minutes ago, Spaceception said:

The solar panels are a result of Budget cuts (I'm pretty sure, I'm not sure why you'd want solar panels so far from the sun either)

46 minutes ago, Bill Phil said:

Probably cheaper than plutonium, yeah.

But I think they're using it because it's only recently become an option. Power requirements for those probes aren't huge, and solar panels have been getting more efficient. Salyut 6, for example, produced 4 kilowatts of power with its panels. Orbital's spacecraft, Cygnus, which is much smaller and solar powered, produces a similar amount of power.

Not budget cuts- Plutonium for RTGs is exceedingly rare, and NASA would not have been able to get any more had it not been for their restart of its production (a very slow production :P) plutonium that is needed for Probes beyond Jupiter (Saturn Solar is still pretty difficult, and impossible beyond Saturn) and heaters/emergency power for manned lunar flights (like on Apollo)

 

37 minutes ago, Bill Phil said:

Galileo generated about 500 to 600 watts with its RTG. Juno will generate about 490 at Jupiter with its panels. In Earth orbit it would generate more than 10 kilowatts of power.

There's limited range, yes. But there's also a global shortage of RTG fuel ( is that what it's called?). Or at least there was, back when it launched.

There still is. It's likely going to be cheaper to just launch on a SLS and solar panels than launch with RTGs, so there is even less of a reason to launch using RTGs now.

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The flight plan below has been updated, check new post on this thread (page 2).

The JOI (Jupiter Orbital Insertion) Phase begins four days ahead of the actual JOI burn. If things haven't change since I last checked, TIG (Time of Ignition) is scheduled for just before 2:30 am GMT on July 5th, so early July 4th in the US. The burn will be performed at perijove, some 4500 km above the 1-bar level (referred to as the "surface" of the planet, although obviously it's not solid). The JOI burn will last slightly over 30 minutes and result in a Delta-V of about 480 m/s. At JOI, there will be a 48.3-minute delay (one-way) in the communications due to Juno's distance from Earth.

The Capture Orbit has an inclination of 90 +/- 10 degrees and a period of 107 days. Approx. 50 hours after JOI, instruments are powered up and decommissioned.

Approx. 7.6 days after JOI, a small correction manoeuvre will take place to set up the Period Reduction Manoeuvre (PRM). The PRM burn will take place around October 19th, 2016, and lower the apojove. The burn will last 37 minutes and provide a Delta-V of about 540 m/s. The PRM will allow Juno to settle into its first Science Orbit, with an apojove of 39 Jupiter radii, a perijove of 1.06 Jupiter radii (4600 km above cloud tops), and a period of 10.9725 days.

Personally, what I'm most looking forward from this mission is finally understanding if Jupiter has a solid core or not - knowing the answer to this question would allow us to place significant constraints to our models of the formation of the entire solar system. Current models featuring only hydrogen (even in its liquid metallic state) and helium don't work, and the heavy elements seen by Galileo, despite being much more abundant than in our sun (hinting that Jupiter was formed from enriched materials) still aren't enough to explain its missing mass. The question is whether this missing mass is dispersed all around the planet or if it forms a solid, well-defined core. Can't wait to know!

Obviously, it will be interesting to know more about Jupiter's magnetic field, for e.g. by studying its auroras. (Plus, because the field is generated by the liquid metallic hydrogen layer, it will give us some insights on the internal structure too). And also we might finally understand whether the Galileo probe actually dived into a dry spot or if water vapour is actually globally scarse. Lots of things waiting to be discovered!

Edited by Frida Space
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  • 3 weeks later...
On 5/31/2016 at 6:37 AM, PB666 said:

JUNO space craft has apparently entered the Jovian hill sphere. 

Really? I didn't know Jupiter's SOI was that big. That's pretty cool.

Edited by Spaceception
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