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Juno perijove 5, March 27, 2017
Bjorn Jonsson
post Mar 16 2017, 10:24 PM
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Juno's perijove 5 is coming up less than two weeks from now - it's on March 27, 2017.

The target selection voting has started and is open until almost four days from now: https://www.missionjuno.swri.edu/junocam/voting?current

A large part of the data volume will be reserved for polar time lapse sequences though.

John Rogers has written a helpful summary of the upcoming perijove 5: https://www.britastro.org/node/9377
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PhilipTerryGraha...
post Mar 21 2017, 06:07 AM
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An insignia for perijove 5 that I made for the subreddit. smile.gif

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JRehling
post Mar 22 2017, 12:50 AM
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Nice, Philip! (The board should have "Like" button…)
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belleraphon1
post Mar 22 2017, 11:39 AM
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Very cool Philip!

My desktop for March 27th

You plan to make one for each perijove?

Craig
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PhilipTerryGraha...
post Mar 24 2017, 12:29 AM
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Ehyup! I've got a few ideas for graphics each time the spacecraft comes 'round. cool.gif
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PhilipTerryGraha...
post Mar 25 2017, 11:29 PM
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The word from NASA: all instruments will be on, and the spacecraft will be making a closest approach of around 4,400 kilometers, with a top speed of 57.8 kilometers per second, relative to Jupiter.
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PhilipTerryGraha...
post Mar 27 2017, 09:37 AM
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Here's what Juno's signal looked like at closest approach on Perijove 5, capped from DSN Now at 09:30 UTC (08:57 UTC + 37 minutes, the current light travel distance from Earth to Jupiter). This has occurred only 7 minutes ago, as of me posting this.

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PhilipTerryGraha...
post Mar 27 2017, 11:45 PM
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Madrid downlinking data from the spacecraft at the moment, at a rate of 40 kilobits per second according to DSN Now. Fun fact - this is 325 times slower than the average download speed of my ADSL2 modem. I feel like I've been taking my Australian copper wire internet for granted. tongue.gif
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Bjorn Jonsson
post Mar 28 2017, 12:10 PM
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On the other hand this is almost 1000 times faster than the typical Galileo downlink speed from Jupiter was.
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PhilipTerryGraha...
post Mar 28 2017, 01:05 PM
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Imagine how different the Galileo mission would've been if that High-gain antenna had worked. unsure.gif
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Explorer1
post Mar 28 2017, 04:03 PM
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Things would be quite different, though I always prefer to look at the bright side of the Jupiter data loss. I bet there would be more missions afterward with antennas that deployed mechanically long after launch, and some other mission would have had the issue. We know better now.
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Bjorn Jonsson
post Mar 28 2017, 08:50 PM
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That was fast - the PJ5 images are now available at the Juno website.
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PhilipTerryGraha...
post Mar 28 2017, 11:43 PM
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The image of Trevmation's Dark Spot was reportedly taken at a distance of only 3,421.8 km, according to its metadata. Can this be true? Because if so, that's a thousand kilometers less than expected, and most certainly the closest approach of the mission so far. ohmy.gif
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Gerald
post Mar 29 2017, 01:46 AM
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Usually the metadata are pretty accurate. However, I'm in an early phase of processing, so can't yet verify by the images.

... Here an enhanced draft of PJ05, #109, rendered from the raw, yet without proper calibration nor trajectory or shape model, therefore the color channel poorly aligned. However, it's very facinating already, including dark boundaries along clouds, which look like shadows.
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mcaplinger
post Mar 29 2017, 02:51 AM
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QUOTE (PhilipTerryGraham @ Mar 28 2017, 03:43 PM) *
The image of Trevmation's Dark Spot was reportedly taken at a distance of only 3,421.8 km, according to its metadata. Can this be true? Because if so, that's a thousand kilometers less than expected...

Expected by who?

Obviously the metadata was computed with a predicted spacecraft position and that may change a little once we have the reconstruction, but I'm fairy confident that the calculation is right. Keep in mind that because of Jupiter's oblateness, the geometry to figure out the altitude is a little more complex than simply taking the distance to the center of Jupiter and subtracting the radius of Jupiter, which is what a simple calculation might do.

Here's the code that computes the metadata if you're interested (in Python, using NAIF/pyspice):
CODE

te = spkezr("juno", t, "iau_"+target, "LT+S", target)[0][0:3]
radii = bodvrd(target, "RADII", 3)[1]
lon, lat, alt = recpgr(target, te, radii[0], (radii[0]-radii[2])/radii[0])


--------------------
Disclaimer: This post is based on public information only. Any opinions are my own.
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