130 votes
Accepted

Why destroy Juno at the end of the mission?

In order to assure that it cannot crash into Europa or other possible ocean moons and potentially contaminate them with Earth organisms. Juno is qualified to survive the radiation environment up to ...
Mark Adler's user avatar
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69 votes
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Why wasn't an RTG used on the Juno spacecraft?

That is precisely it. Plutonium-238, which is used in the creation of radioisotope thermoelectric generators (RTGs) is very difficult to come by. There are plenty of news articles on this, from ...
Phiteros's user avatar
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64 votes
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Is Jupiter bright enough to be seen in color by the naked eye from Jupiter orbit?

The distance from Jupiter to the Sun is about 4.95 to 5.46 AU (Astronomical Unit, the distance of Earth to Sun). So the intensity of sunlight at Jupiter is about 1/25 of the intensity at Earth. This ...
Uwe's user avatar
  • 49k
62 votes

Why destroy Juno at the end of the mission?

Why is it necessary to destroy the spacecraft? It's because life might well exist on some of Jupiter's moons. Despite the best efforts to assemble the spacecraft in extremely clean conditions, and ...
David Hammen's user avatar
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55 votes
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Why are photos from Juno such low resolution?

Short answer: JunoCam is not a scientific instrument; It was put onboard solely to get some neat pictures. It is not necessary for the scientific mission, and is mostly there just for public interest....
Phiteros's user avatar
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55 votes
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Why does this image of Jupiter look so strange?

As @Hobbes mentioned it is not an image of an entire hemisphere but it has been distorted to allow for wide angle vision. That's why it looks so strange. The image is a composite made by Kevin M. ...
Swike's user avatar
  • 2,501
42 votes
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How does a spacecraft know that it is in orbit?

The Juno spacecraft has no means to directly measure and compute that it is in orbit. It did not send any such confirmation message. All it sent was an FSK tone indicating that it had completed the ...
Mark Adler's user avatar
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37 votes

Why wasn't an RTG used on the Juno spacecraft?

Another interesting note is that this mission more than any other mission to the outer solar system can use solar power. Why? Juno is in a polar orbit, and will continually be in the sun. Solar panels ...
PearsonArtPhoto's user avatar
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27 votes

Is Jupiter bright enough to be seen in color by the naked eye from Jupiter orbit?

Jupiter is very bright and is one of the brightest things in the night sky when it is visible. Through even a small telescope (such as my own 100mm telescope) shades of dark brown, beige, cream and ...
Ags1's user avatar
  • 1,341
21 votes

How does a spacecraft know that it is in orbit?

Using attitude determination devices, (including doppler shift of radio signal from Earth), it can determine* its location and velocity relative to Jupiter, and from that data, and knowing Jupiter ...
SF.'s user avatar
  • 55k
20 votes

How long does it take for a signal to travel between Earth, and Juno at Jupiter?

Using NASA's Eyes measuring the distance from Jupiter to Earth at this moment (5th Jul 2016, 11:50 CEST) is 48 light minutes, 21.39 light seconds, and that would be the time Juno's communications ...
SF.'s user avatar
  • 55k
18 votes
Accepted

How is JunoCam different from a normal CCD camera?

JunoCam used different technologies than does the typical framing camera one buys at a store. A typical digital color camera uses a Bayer filter pattern, a row of alternating tiny blue and green ...
David Hammen's user avatar
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17 votes

How long does it take for a signal to travel between Earth, and Juno at Jupiter?

EDIT: based on @Beska's comment, I went back and calculated the difference including light time. In other words, you have to use Jupiter's position roughly 48 minutes ago to state the travel time. ...
uhoh's user avatar
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14 votes

Why wasn't an RTG used on the Juno spacecraft?

I had the opportunity to tour JPL a few months ago and asked this exact question to our tour guide. The solar panels on it are enormous and typically, spacecraft going beyond the asteroid belt are ...
C. Spencer's user avatar
13 votes

Why destroy Juno at the end of the mission?

You can't re-purpose Juno after its mission as: Its instruments are designed for a specific mission profile, if you sent it elsewhere it wouldn't be able to produce good science. Its solar panels won'...
GdD's user avatar
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12 votes
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Will Juno record its deorbit?

You won't see Jupiter's atmosphere from the "inside". The entry and destruction of the vehicle is very fast, and occurs relatively high in the atmosphere. Way, way above any clouds. There would not be ...
Mark Adler's user avatar
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11 votes
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When can we (public) expect to see the first optical images of Jupiter from the Juno spacecraft?

There's an interesting Planetary Society article about this: What to expect from Junocam We won't be able to see spectacular views of Jupiter's belts and zones from Jupiter orbit until the very end ...
Andy's user avatar
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9 votes

How was Juno's arrival set up to be on the evening of July 4th?

There have been four major US planetary probe events on (or scheduled for) 4th July. This compares to approximately a hundred "major events" for US planetary probes. At least one (Viking) was somewhat ...
Andrew is gone's user avatar
9 votes

Juno to Jupiter Budget

Was that option considered in detail? Almost certainly not. This question is based on the false assumption that staffing levels remain more or less constant across all phases of flight. This is not ...
David Hammen's user avatar
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9 votes
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Is there any publicly available logging, or "Wayback Machine" for DSN Now activity?

I have been looking into this as well. As I have been told by one NASA employee, there is no easy way to get old data, but there is a way if you're willing to go through lots of data. NASA saves old <...
Václav Pavlík's user avatar
9 votes

Why wasn't an RTG used on the Juno spacecraft?

Phiteros' answer states the fact that plutonium is in scarce supply and PearsonArtPhoto's answer points out that Juno's mission profile allows it to use solar panels. These issues are legitimate and (...
GreenMatt's user avatar
  • 1,431
9 votes

The plane of the orbit of Juno around Jupiter is not the ecliptic plane. How did it get into this plane?

The plane of the orbit around the Sun is not directly related to the planet-relative plane of the hyperbola on approach to Jupiter, or correspondingly the orbit around Jupiter after orbit insertion. ...
Mark Adler's user avatar
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9 votes
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Who built Juno's chipsets?

BAE Systems is one supplier for the command and data handling processor. https://en.wikipedia.org/wiki/RAD750 The RAD750 is a radiation-hardened single board computer manufactured by BAE Systems ...
swordfish45's user avatar
9 votes

Does NASA use Newtonian model of gravity for plotting the course of Juno or general relativity?

Not only does it use Einstein's Theory of Relativity, it's actually going to use Jupiter's huge mass to do a test that hasn't been done yet, on how it affects rotating objects. As it's expected to ...
PearsonArtPhoto's user avatar
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9 votes
Accepted

Why does Juno use "mixed oxides of nitrogen" oxidizer for propulsion? Which ones?

MON according to Wikipedia: Mixed oxides of nitrogen (MON) are solutions of nitric oxide (NO) in dinitrogen tetroxide/nitrogen dioxide (N2O4 and NO2). The addition of a small amount of nitric ...
Russell Borogove's user avatar
8 votes
Accepted

Juno Mission. How better resolution will the optical images be to previous missions?

Juno-cam is designed to achieve about 15km/pixel resolution, at 4300 km, and proportionately less at greater distance. At closest approach it may achieve 3km/pixel This compares with Galileo that ...
James K's user avatar
  • 1,456
8 votes

How does a spacecraft know that it is in orbit?

First a clarification. If one insists that "knowing" requires self awareness and intelligence, then the Juno spacecraft of course doesn't "know" anything. Rather than getting hung up on the silliness ...
8 votes
Accepted

When will Juno send us some pictures from it's tight orbit?

http://www.planetary.org/blogs/emily-lakdawalla/2016/06090600-what-to-expect-from-junocam.html The first major day for pictures should be August 27th, but image release shouldn't start occurring ...
M.A.H.'s user avatar
  • 1,266
8 votes
Accepted

If Juno's long orbit means a lower rate of radiation damage, why the planned short orbit?

Money. The mission was proposed to a cost cap, which includes operations costs. The science objectives could be achieved with a shorter primary mission and therefore lower cost using tighter orbits.
Mark Adler's user avatar
  • 58.2k
7 votes

How was Juno's arrival set up to be on the evening of July 4th?

I had thought that July the 4th was deliberately chosen, as it had been for a few previous missions where the celestial mechanics ended up with a range of dates that included July the 4th. However it ...
Mark Adler's user avatar
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