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Mercury Flyby 2
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post Sep 8 2008, 01:00 AM
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Apparently this is the first time the technique has been used to steer a spacecraft's trajectory. Mariner 4 had solar pressure vanes as an experiment to help control attitude, with mixed results. Mariner 10 successfully adjusted its attitude with solar pressure, which extended its life. But we are talking here about adjusting course.
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dmuller
post Sep 8 2008, 12:44 PM
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With the second flyby now just a month away, I have started to dig for events etc for my realtime simulation, and as always I am getting different times for the same events. I guess the closest approach time has not been inked in, but I thought I'd share my initial results anyway.

All times are Spacecraft Event Times in UTC:

Mercury closest approach (altitude 200km) on 6 Oct 2008 between 08:40 and 08:42

Horizons currently has closest approach at 06 Oct 2008 08:41:25, resulting in:
Entry into Mercury Hillsphere: 05 Oct 2008 20:33:55
Exit from Mercury Hillsphere: 06 Oct 2008 20:48:40

Again according to the Horizons information, the flyby changes the orbital elements as follows:
Periapsis: from 47.5 million km to 45.8 million km
Apoapsis: from 102.3 million km to 93.8 million km
Eccentricity: from 0.36 to 0.34
Inclination: from 6.94 deg to 7.03 deg

If anybody has more precise - or updated - information, please share, I will gladly put it on the realtime simulation


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elakdawalla
post Sep 8 2008, 11:45 PM
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I have from a very reliable source smile.gif the current best estimate (as of Friday, September 5) of flyby time being 08:40:21.4 UTC. At that time it'll be 200.2 km from Mercury.

My source has different orbital information -- is yours measured with respect to the ecliptic? I could also select "with respect to Earth mean equator" or "with respect to Mercury equator".

These are with respect to the ecliptic:

Semimajor axis: 7,596,000 before / 6,975,000 after
Periapsis radius: 4,720,000 before / 4,523,000 after
Eccentricity: 0.38 before / 0.35 after
Inclination: 6.9 before / 7.0 after


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dmuller
post Sep 9 2008, 12:14 AM
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QUOTE (elakdawalla @ Sep 9 2008, 09:45 AM) *
My source has different orbital information -- is yours measured with respect to the ecliptic?

Mine are the orbital information for Messenger's orbit around the Sun ... the Solar System Barycenter to be precise ... so maybe that is where the difference comes from.

Thanks for the current best estimate. Will work it into the model shortly. Mmmm if your reliable source changes its figures, please post it here :-)


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peter59
post Sep 12 2008, 08:56 PM
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Press Kit: MESSENGER Mercury Flyby 2 (PDF)


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Free software for planetary science (including Cassini Image Viewer).
http://members.tripod.com/petermasek/marinerall.html
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Decepticon
post Sep 13 2008, 10:54 PM
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Is there a flyby preview video available?
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dmuller
post Sep 15 2008, 03:34 AM
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The Messenger website says that there will be (if I read it correctly).

Since I downloaded the images for my realtime simulation anyway (in case that the Solar System Simulator goes down during C/A), here are the images stringed together into a movie for CA +/- 1 hour:
http://www.spaceoutreach.com/display.php?i...8nimdaq15025458

But I know there are people on here who can do much more impressive movies rolleyes.gif


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peter59
post Sep 25 2008, 09:40 PM
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Mercury Flyby 2 Visualization Tool
http://messenger.jhuapl.edu/encountersm2/
Hurrah! biggrin.gif


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Free software for planetary science (including Cassini Image Viewer).
http://members.tripod.com/petermasek/marinerall.html
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peter59
post Sep 25 2008, 10:01 PM
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Attached Image
Attached Image
Attached Image
Attached Image

NAC Departure Mosaic #2
NAC Departure Mosaic #3
NAC Departure Mosaic #4
WAC Departure Color Mosaic #2


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Free software for planetary science (including Cassini Image Viewer).
http://members.tripod.com/petermasek/marinerall.html
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leper
post Sep 29 2008, 12:35 AM
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QUOTE (peter59 @ Sep 26 2008, 07:40 AM) *
Mercury Flyby 2 Visualization Tool
http://messenger.jhuapl.edu/encountersm2/
Hurrah! biggrin.gif

Great tool, thanks!
Not quite as good as the Cassini one but gives a great sense of what will take place smile.gif
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charborob
post Sep 29 2008, 02:49 PM
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This page shows the part of Mercury that will be imaged during Flyby2.
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peter59
post Sep 30 2008, 03:40 PM
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New: Mercury Flyby 2 Instrument Operations.
http://messenger.jhuapl.edu/the_mission/mo...yby_web_sml.mov (17.8 MB)


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Free software for planetary science (including Cassini Image Viewer).
http://members.tripod.com/petermasek/marinerall.html
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Guest_PhilCo126_*
post Oct 2 2008, 09:25 AM
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That's great Peter!

The second Mercury flyby is slated for 2:40 a.m. MDT on Oct. 6 and the MESSENGER spacecraft will view areas not seen before by the 1974 & 1975 Mariner X flybys....
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Greg Hullender
post Oct 2 2008, 03:10 PM
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QUOTE (charborob @ Sep 29 2008, 07:49 AM) *
This page shows the part of Mercury that will be imaged during Flyby2.

Nice! What's great about that link is that it clearly shows what was imaged by Mariner 10 and Flyby 1 and what will be imaged in this flyby. It makes it fairly clear that there will be relatively little unimaged surface after this flyby.

I sent the Messenger team an e-mail about a month ago telling them I wished they'd show us something like this. They never replied, so maybe I'm vain to imagine this is a response to my request, but I was delighted to see it nonetheless!

--Greg
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vjkane
post Oct 2 2008, 05:59 PM
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I hope that someone eventually publishes a map showing coverage by resolution from the flybys. It would visually show how well flybys can cover a world (useful for considering flybys of Galilean satellites, Triton, etc.).


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