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Mercury Flyby 3
elakdawalla
post Sep 30 2009, 03:56 PM
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QUOTE (ugordan @ Sep 30 2009, 07:08 AM) *
Classic.
huh.gif

I'm very happy that their latest release is of this cool-looking double-ring basin, which was only half-seen on the previous flyby.


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Stu
post Sep 30 2009, 04:34 PM
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That just clinches it: there's an alien ship out there, tailing our spaceprobes, with a load of mischevious, drunk, giggling ET teenagers inside it, just waiting to fire their "Put little toy alien spacecraft into safe mode at just the worst possible moment!" ray at them...

Pesky alien kids!!! mad.gif


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Phil Stooke
post Sep 30 2009, 04:46 PM
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A couple more reprojections:

Attached Image


Attached Image


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mps
post Sep 30 2009, 06:57 PM
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Yes, back in the old days, we didn't know to fear safe modes during flybys. But this time I did... sad.gif
Was it actually first safe mode event for MESSENGER?
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antipode
post Oct 1 2009, 12:31 AM
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Some nice crater chains approx radial to that double ringed basin.

Does it have a name?

P
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nprev
post Oct 1 2009, 12:41 AM
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Great reprojs, Phil!

Noticed a crater that's apparently been buried by a lava flow (arrowed).


Attached thumbnail(s)
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Phil Stooke
post Oct 1 2009, 12:44 AM
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Yes, and a similarly buried big double-ring basin near the top of the same image.

Phil


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nprev
post Oct 1 2009, 12:53 AM
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I was struck by this one's symmetry...didn't have much time to melt down the rim walls, did it? Interesting.


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JohnVV
post Oct 1 2009, 07:17 AM
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it will be nice when the images get here
http://pds-imaging.jpl.nasa.gov/Admin/reso..._messenger.html
and i can remove the stripe from my map
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tanjent
post Oct 1 2009, 01:46 PM
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OK, no serious harm done this time but I sure hope there won't be a flyby #4 in March 2011.
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Guest_Sunspot_*
post Oct 1 2009, 01:49 PM
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Maybe this story can shed some light on it? http://science.nasa.gov/headlines/y2009/29sep_cosmicrays.htm More cosmic rays.
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ugordan
post Oct 1 2009, 02:59 PM
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QUOTE (tanjent @ Oct 1 2009, 03:46 PM) *
OK, no serious harm done this time but I sure hope there won't be a flyby #4 in March 2011.

I suspect they'll disable a bunch of fault handling before executing the MOI burn, the same way New Horizons plans to disable most of onboard fault protection during the Pluto flyby.


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elakdawalla
post Oct 1 2009, 03:05 PM
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Yeah -- fault handling on gravity assist flybys or opportunistic encounters is way, way different than for planned science flybys. Remember how OSIRIS on Rosetta safed before the Steins flyby, and how Dawn safed during its Mars flyby. On such encounters science is way, way down the list compared to spacecraft health. If the flyby is just for science, as with NH at Pluto and Mariner 10's Mercury flybys, then they disable a lot of the fault protection.

--Emily


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tanjent
post Oct 1 2009, 03:07 PM
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Galactic cosmic rays could have impacted the spacecraft at any time, regardless of its position relative to the planet.
The fact that this event came just as Messenger entered Mercury's shadow offers a strong hint that it was somehow
related to that transition. That said, I guess some of those 7000+ stored flyby commands could have been corrupted
by a CR incident, and we would not have discovered it until it came time to execute them.

Note - This was WRT Sunspot's earlier post. The subsequent posts are acknowledged with some relief.
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ugordan
post Oct 1 2009, 03:15 PM
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QUOTE (tanjent @ Oct 1 2009, 05:07 PM) *
That said, I guess some of those 7000+ stored flyby commands could have been corrupted
by a CR incident, and we would not have discovered it until it came time to execute them.

Commands are not typically as data intensive as science data so it's cheap to have several backup copies of them onboard. That goes for the flight software itself. There are ways very high priority maneuvers can be protected against memory and even processor trips via cosmic rays and several computers with redundant processing is one for example.


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