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124

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 the end of its mission. After that it could succumb to the radiation at any time and become uncontrollable. Planetary protection then requires the disposal of the ...


68

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 Popular Science to Space News. Basically, it comes down to the fact that plutonium-238 is in short supply now, and it is difficult to make more because of nuclear ...


64

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 light intensity is much more than neccessary to be seen in color by the naked eye enclosed in a space suit. About 1/1000 would be still bright enough. Neptune ...


59

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 despite exposing the spacecraft to vacuum and to the Sun's ultraviolet and X-ray radiation, there's a chance that Earth-borne life remains intact on the ...


55

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. You can interact with JunoCam by voting on what it takes pictures of. Long answer: There are several reasons which combine to result in Juno only being ...


53

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. Gill (a software engineer from NASA's JPL) using the JNCE_2019255_22C00023_V01, JNCE_2019255_22C00024_V01, JNCE_2019255_22C00025_V01, JNCE_2019255_22C00026_V01, ...


42

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 activities it was commanded to do. After the spacecraft turned back to Earth, it transmitted all of the recorded engineering data from the event, providing much ...


35

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 are also becoming more powerful than they have previously. Between the two of these, solar was a more attractive option than it has been in the past. If it was ...


27

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 salmon pink are visible, even though 100x or 200x magnification dims the image. From Jupiter orbit, it would be a dazzling sight.


22

While many missions have been able to continue beyond their design lifetimes (Cassini and the Mars Exploration Rovers being prominent examples), the type of mission and orbit Juno must undertake to accomplish its goals will subject the spacecraft to a truly massive radiation dose. In order to meet the mission’s science goals within the budget set by NASA, ...


21

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 mass, trajectory can be calculated. If the trajectory forms a loop around Jupiter - it's an orbit! * the actual determination is performed on Earth, Juno just ...


20

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 take to reach Earth.


18

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 filters, followed by a row of alternating tiny green and red filters, each filter covering a pixel, followed by a row of alternating tiny blue and green filters, and ...


16

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. Using the observe() method, which does this, there is a difference of 0.02 seconds. This doesn't really matter, considering that Juno is in a large orbit around ...


15

This paper describes the Juno telecomm system in detail. It is a standard deep-space X-band system with a 2.5 m high-gain antenna, a 25 W traveling-wave tube amplifier, and concatenated convolutional and Reed-Solomon or Turbo 1/6 rate error-correcting codes. It will get 18,000 bits per second down to a 34-m antenna on Earth at maximum range (6.459 AU) at a ...


13

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't produce enough power if you get much further away from the sun Juno is going to be exposed to a huge amount of radiation which will degrade its instruments, ...


13

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 equipped with RTGs, so why doesn't Juno have one? He told us that the US was on very short supply of Plutonium-238 at the time and that they would have had to ...


12

No, the Atlas 551 is not powerful enough to send Juno to Jupiter. From this article on NASA's website: The Juno spacecraft was launched from Kennedy Space Center in Florida on August 5, 2011. Juno’s launch vehicle was capable of giving the spacecraft only enough energy to reach the asteroid belt, at which point the sun’s gravity pulled it back ...


11

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 time to take an image, process it, and get it out the antenna, even if you happened to have Earth in view for the entry. Even if you did have a picture looking ...


11

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 of August, and it'll be November before we'll see automated release of high-resolution raw images. August 27 is expected to be a day when photography takes ...


10

During the maneuver? Certainly not. You don't mess with the spacecraft configuration around or anywhere near critical events unless it is absolutely necessary. Modern spacecraft are all designed to permit their flight software to be updated. A complete image of the new flight software is uploaded the spacecraft. The image's integrity is verified, and ...


9

Safe mode is a software state that is initiated by a detection of some inability of the system to do what it has been asked to do. There are many, many ways that can happen, such as insufficient power, inability to determine attitude, detection of a failed component, such as a reaction wheel, or a software fault or crash. In safe mode, only the minimum ...


9

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 the case. Staffing is very light during passive phases such as coast. Requirements for communications mandate a large antenna. No matter how good we become at ...


9

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 Electronics, Intelligence & Support.[1] The successor of the RAD6000, the RAD750 is for use in high radiation environments experienced on board satellites ...


9

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 affect the gyroscopes, that is most certainly something that will have to be taken into account.


9

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 oxide (1%-10%) makes the oxidizer less corrosive, but slightly less powerful as well, and changes the freezing point of the liquid. MON3 means 3% nitric oxide by ...


8

Solar arrays are wired as many strings of cells, where each string is a series of solar cells with the proper number to provide the required voltage. Those strings connected to each other in parallel to add their currents to provide the required total power. An individual cell failure will take out one entire string, so the resiliency against cell failures ...


8

Using gravity to remotely look at the hidden interior of a planet or moon has a remarkably long history. The idea goes back to Newton. He suggested measuring the divergence of a plumb bob near a mountain from the surveyed normal as a means of assessing the mass of the Earth. He dismissed this idea as impractical given the low quality of surveying ...


8

Most satellites have some sort of a safe mode, a mode the satellite enters when it is having difficulties with certain things. The exact nature of the safe mode varies from satellite to satellite, but in general, it is a lower power state, thermally stable and power positive, turns off science instruments, and relies less on absolute pointing. I can say ...


8

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 of what "knowing" means, it's better to look for an alternative way of answering the question. That alternative: How sophisticated is Juno's onboard computer ...


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