NASA's Juno Spacecraft Sends First Images From Jupiter (sciencedaily.com) 77
An anonymous reader writes: After its patriotic arrival at Jupiter on July 4th, the Juno spacecraft has sent its first images of the planet back to earth via the JunoCam. The visible-light camera aboard Juno was first turned on roughly six days ago after Juno placed itself into orbit. "This scene from JunoCam indicates it survived its first pass through Jupiter's extreme radiation environment without any degradation and is ready to take on Jupiter," said Scott Bolton, principal investigator from the Southwest Research Institute in San Antonio. "We can't wait to see the first view of Jupiter's poles." The color image, which was obtained on July 10th when the spacecraft was 2.7 million miles from Jupiter, shows atmospheric features on Jupiter, including the famous Great Red Spot, and three of the massive planet's four largest moons -- Io, Europa and Ganymede. "JunoCam will continue to take images as we go around in this first orbit," said Candy Hansen, Juno co-investigator from the Planetary Science Institute, Tucson, Arizona. "The first high-resolution images of the planet will be taken on August 27 when Juno makes its next close pass to Jupiter."
That far? (Score:2, Interesting)
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Juno is still quite a ways away. It's highly elliptical orbit will eventually take it within 2600 miles of Jupiter. The Voyager probes never got closer than about 100,000 miles. So maybe wait until the real images are available before you criticize.
Re:That far? (Score:5, Informative)
The orbit will eventually, after a couple of planned manoeuvres in the coming months, bring Juno as close at ~4500km from the surface of Jupitor. Currently the orbit brings Juno quite far from the planet, out beyond Callisto. Stage 1 was just to get Juno captured by Jupiter's gravity. We can expect better photos in the coming months when Juno gets closer.
Re:That far? (Score:4, Interesting)
Actually, download the demo of Kerbal Space Programme and play through the tutorial. It gives a really good example of how orbits work. You can learn a lot in just those few minutes.
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One of the things I learned is that the deeper in a planet's gravity well (ie. closer to the surface) I perform the braking maneouver, the less fuel I need to use, and obviously, the lower the periapsis of the resultant orbit. Why would they perform a braking maneouver resulting in orbit outside Callisto?
Braking maneuver at periapsis (Score:4, Informative)
One of the things I learned is that the deeper in a planet's gravity well (ie. closer to the surface) I perform the braking maneouver, the less fuel I need to use, and obviously, the lower the periapsis of the resultant orbit.
Right. This is the Oberth effect.
Why would they perform a braking maneouver resulting in orbit outside Callisto?
They performed the braking burn as close to Jupiter as possible, so the peri jove is right over Jupiter's clouds. But it's a highly elliptical orbit, so the apo jove is very high-- thus, the orbit moves from way in to way way out, beyond the moons.
They want to spend as little time close to Jupiter as possible, because being close to Jupiter is very unhealthy.
Partlyy, but actually, the perijove is in below the radiation belts. The highly elliptical orbit is because they want to traverse the whole of Jupiter's magnetic fields-- but also because the highly elliptical orbit is the one that takes the minimum amount of fuel to get into.
They're basically zipping in for a quick pass then retreating to transmit data and prepare for the next pass.
Yep.
Re:That far? (Score:5, Informative)
Why would they perform a braking maneouver resulting in orbit outside Callisto?
Juno is planned to have a very elliptic orbit. It will go close to collect data, then move far away to have time to send the data back to earth. They want to spend as little time close to Jupiter as possible to minimize radiation damage.
Also, the larger apoapsis means they can expend less fuel when breaking. If you just want to be captured, you get as close as possible to the planet and break until you're just gravitationally bound, which will result in an orbit with a very large apoapsis and very small periapsis.
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Brake the orbit, break the orbit, brick the orbit. (Score:2)
It is so hard to get a technician out to perform a hardware reboot if they accidentally brick the thing.
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It could also be spelled Brak [youtube.com]
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If one can spell apoapsis and periapsis correctly, surely one can spell "brake" and "braking" correctly.
Can, yes. Will always... apparently not.
For some reason I don't quite understand I've been rather sloppy on break/brake lately. Then again, I write way less English than I used to (it's my second language).
Oh well, thanks for the heads up, clearly I need to pay more attention to what I write.
Re:That far? (Score:4, Informative)
The reason the low periapsis is cheapest is because the closer to the planet you burn the more the planet is helping you slow down. There are two prices you pay for that though. The closer you put your periapsis the higher your orbital speed has to be - so lower periapsis decreases the available burn time to do the capture burn in. Depending on your engines, there is a lower limit below which you are going so fast you'll escape before you can slow down enough to be captured (and of course, go too low and you instead of orbiting you'll crash.
Even then your cheapest burn is not a very low orbit, it's a very eliptical orbit with a very low periapsis and an extremely high apoapsis, go as close as you can and burn as little as possible to be captured. My own jool captures look much the same, periapsis close to the atmosphere with the apoapsis barely inside the SOI.
Then you can do tricks like - when you hit ap lower your pe even further, and now use cheaper (but much slower engines) to lower the ap doing multiple burns on multiple orbits - which lets you lower it with engines that could never have managed the initial capture.
I'm not familiar enough with what equipment juno has to speak about the techniques they have in mind but this initial orbit looks exactly like what a typical first capture in KSP looks like. Where we are now is the post-capture cycle as it goes around that initial high-AP orbit the first time. That orbit has a very long period. Around Jool it's quite possible to get an orbit with a period of 20 or 30 years but this one isn't quite that long - it's around 2 months, and as the AP gets lowered to the final orbit in the upcoming maneuvers will ultimately be around 53 days (according to my memory of a report I read)
Re: That far? (Score:2)
That first comic was the reason I started playing KSP!
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It gives a really good example of how orbits work.
Or even better, download Orbiter which, unlike KSP, is physically correct.
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Surface ? Jupiter does not have a well-defined surface.
Re:That far? (Score:4, Informative)
There is a liquid core that has a very well defined surface.
Unless it's supercritical [wikipedia.org], right?
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Meh, it might. :) That's one of the things that Juno is present to try to accomplish, to study Jupiter's interior. Maybe there is some abrupt transition layer (say, to metallic hydrogen). And we know it's eaten plenty of rocky material over its lifetime.
But yeah, there should be no sudden, distinct transition between gas/liquid/supercritical/liquid crystal states.
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Surface ? Jupiter does not have a well-defined surface.
Yes, it does, but it's defined differently from what we define a surface as here on Earth. The 1 bar pressure point is defined as the zero point for altitudes[*], and thus the surface of Jupiter.
[*]: When we say 2000 km above the surface of Jupiter, we mean 2000 km away from the closest point that has a 1 bar pressure.
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Re:That far? (Score:4, Informative)
This is Juno's first pass around Jupiter, during which it just barely pushed itself into a highly elliptical orbit. It will continue travelling further from the planet until the end of the month, leaving plenty of time for equipment tests like this. The next engine burn to bring Juno into a closer orbit is scheduled for the 19th of October, two orbits from now.
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from the article,
The new view was obtained on July 10, 2016, at 10:30 a.m. PDT (1:30 p.m. EDT, 5:30 UTC), when the spacecraft was 2.7 million miles (4.3 million kilometers) from Jupiter on the outbound leg of its initial 53.5-day capture orbit. The color image shows atmospheric features on Jupiter, including the famous Great Red Spot, and three of the massive planet's four largest moons -- Io, Europa and Ganymede, from left to right in the image.
"JunoCam will continue to take images as we go around in this
Wow (Score:1)
Wow, it's almost as good as with my amateur telescope from a light polluted city!
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That's because it was taken from afar. Juno's orbit is highly elliptical and the photo was taken as proof-of-concept on the outbound leg. Wait till it starts taking pics around the next nearest approach...
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I was thinking to myself "Focus! FOCUS!!!"...
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I kid, I kid. I'm very excited about this mission, and can't wait for the first science pass. Those pictures are going to be stunning!
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Maybe you should keep up with the times, fellow anonymous coward.
Here are some recent samples of amateur astronomer observations of Jupiter https://astronomynow.com/2016/05/12/amateur-high-resolution-observations-of-jupiter-to-support-nasas-juno-mission/
Come back when you have some manners :-)
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Thanks. Also, you usually don't take pictures, but videos, and use the best details out of the frames :
http://www.autostakkert.com/wp... [autostakkert.com]
https://www.flickr.com/photos/... [flickr.com]
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Nevermind that JUNO was co-funded by multiple countries at that.
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Nevermind that JUNO was co-funded by multiple countries at that.
Sort of. The US funded the mission itself-- the launch, the spacecraft, the operations. Several European countries contributed science instruments (to be fair, since it's a science mission, the science instruments are the whole point of the mission.)
Details here:
http://www.europlanet-eu.org/juno-europe/ [europlanet-eu.org]
http://www.spaceref.com/news/viewpr.html?pid=49003 [spaceref.com]
labels (Score:4, Funny)
I never knew the moons had their names hovering below them like that... wow! The names look huge - should I be able to see them with the naked eye?
Re:labels (Score:5, Funny)
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Navigation in space - how do they do it? (Score:2)
A very impressive feat it is, putting that spacecraft into a very well defined orbit around this planet. But what I am wondering is how do they know where the thing really is? Just like catching up with that comet, the Rosetta mission. Sending a tiny craft out in space so far out you can't see it, to catch up with an equally invisible comet (invisible from earth for the first part of the mission at least).
It's too small to see from earth. There is no GPS system or so at Jupiter. No trees, no landmarks - the
Re: Navigation in space - how do they do it? (Score:1)
There are billions of landmarks. They're called stars.
There is also the deep space network, which send signals to probes that send them back. Let's the scientists know where it is to about 3 metres and the speed to 0.05mm per second
Re:Navigation in space - how do they do it? (Score:5, Informative)
If you want to learn about spacecraft design, I strongly recommend "Space Mission and Analysis Design" by Larson and Wertz. It's sort of the "fundamentals" of all aspects of mission design, and they spend all of section 5 ("Space Mission Geometry") on the topic of the different coordinate systems used in celestial navigation, how to gather the data needed to position in them, how to convert from one to another, and what sort of hardware is needed, how to estimate pointing/positioning errors, etc.
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Just the basic principles will do, not planning to launch my own space craft or so.
Re:Navigation in space - how do they do it? (Score:4, Informative)
The short of it is, for any coordinate system you want to define yourself in, you have to gather a few points of reference - the exact sort of points depending on the coordinate system. There's no single fixed system that all spacecraft have to use, but star trackers (usually combined with a gyroscope) are generally a good one for orientation. The "fixed" stars can give you an absolute frame of reference, while the relative position of the sun and the planets relative to them and the passage of time can give you a very good sense of where you are. Transmissions from Earth are often good for precise determination of distance and velocity, which can be done on either end; however, it's always important that the spacecraft be able to find Earth on its own.
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From there, it becomes simple multi-variable algebra. You take 3 photos of the target object at known time intervals. You measure the x and y position of the object (relative to the background) in each of those photos. If your photo platform is moving (i.e. taking photos from the spacecraft, or if the time interval is large
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If you're genuinely curious, you really do need to download the free demo of the game "Kerbal Space Program". You really can't grock space travel & orbital mechanics unless you play around with them.
Ideas like "faster is higher, slower is lower", and "burn at the low point to change the high point" don't make sense until you play with them. That and, there is no such thing as a straight line in space. Everything's an orbit.
Seriously, give it a try. You might just learn more than a year of college by j
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The probe has a very stable radio transmitter on board. The dishes on Earth can get direction, distance and radial velocity easily and directly from that.
The probe has cameras that can track stars accurately to establish its orientation (it's also spinning which keeps it stable). They also use the probes cameras to photgraph Jupiter its moons and selected stars to get additional information.
The position of Jupiter is known very accurately from previous missions, but New Horizons had to use its camera to ref
Awesome (Score:1)
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Europa (Score:2)
I just hope they plan on leaving Europa alone...we've been warned.
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