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Posted by: djellison Jan 18 2006, 10:27 PM

Frames at 10s intervals instead of the 20s intervals (iirc) they used to have.

Doug

Posted by: tacitus Jan 18 2006, 11:14 PM

Aside from the coolness factor, is there any remaining science to be gained from photographing these eclipses? I would have thought they had nailed down all the specifics about Phobos and Deimos by now.

Posted by: djellison Jan 19 2006, 12:22 AM

The more data sets they have on these events, the more they can bring in the limits of +/- on variables. Imaging at 10s gives another step in the level of accuracy available. It helps constrain the orbits of the moons, and mean better targeting for observations from orbit.

For total 'wow' factor, I'd very much like to see 10s sampled Navcam imagery of the terrain during a Phobos eclipse, as it gets quite dark during those. Pity there was no chance to do this from Husband hill, as the shadow might have even been visible racing across Gusev crater.

It would mean forgoing the Pancam imagery of the sun during that time, but ... it'd be cool

Doug

Posted by: djellison Jan 19 2006, 01:56 AM

One thing I've often thought of is that we have these great anims from time to time, but they're not 'real time'

What would that eclipse have looked like in REAL time?

It lasted about 80 seconds end to end, so I mocked up something in 3ds Max, and uses Quicktime to add a few effects to it, and this is what it might have looked like, if seen in real time.

Doug

Posted by: jamescanvin Jan 19 2006, 02:34 AM

Very cool Doug, I felt like I was there!

I was just thinking something like that would be nice, then lo and behold along you come.

James

Posted by: Pertinax Jan 19 2006, 02:31 PM

Thank you Doug. That is something that I have wished to see as well, but lacked the tools to acomplish it myself -- kind of like going to mars, only not quiet so hard .

-- Pertinax

Posted by: mars loon Jan 21 2006, 01:46 AM

That is indeed cool Doug. Thank you.

How about Phobos, that would be even cooler, if that is included in the rover plan

ken

Posted by: djellison Jan 21 2006, 11:02 AM

A phobos one was scheduled for a sol or two ago, but I've not seen the images come down. I intend to pull the same trick with that however.

Doug

Posted by: mars loon Jan 21 2006, 05:50 PM

I looked too but dont see them yet. Thanks in advance. ken

Posted by: fredk Jan 21 2006, 07:52 PM

That would be cool, but unfortunately Phobos only covers around 1/3 of the surface area of the sun, so that means you'd only be in the very diffuse penumbra. It's very hard to notice it when the sun is 1/3 covered by our moon during a solar eclipse. But in our case the sunlight dims very slowly, on a timescale of hours. For Mars, a Phobos eclipse lasts 30 seconds or so. So if you were standing there, I think you would notice a very subtle dimming if you payed close attention.

The width on the surface of Mars of the gradient part of Phobos' shadow (ie the distance from the outer edge of the penumbra to the outer edge of the region where Phobos is entirely in front of the sun) is equal to the diameter of Phobos, for an overhead eclipse. That's roughly 20km, depending on Phobos' orientation. So even from the summit of Husband, with a horizon distance on the order of 20km, you'd need a very wide view to see the extent of that gradient on the horizon (seeing it closer would be even harder). So a hazcam shot might have shown something very subtle (if there were any eclipses to see at that time!).

Actually though, I think with a pair of hazcams, one when the shadow was on the horizon and one a minute or so later or before, you could quite easily reveal the shadow using the dust devil diferencing technique. This could be doable from somewhat high ground.

That animation was nice, Doug. I've made gifs in the past with 10 second pauses each frame to achieve "real time", but the interpolation you've done between frames makes a big difference - did you do that interpolation by hand or was it some morphing app?

Posted by: ljk4-1 Jan 21 2006, 09:46 PM

Imagine future Mars colonists with various ways of racing the eclipses to keep the moons in front of Sol as long as possible, just as we do with jets on Earth.

Viking 1 had the shadow of Phobos pass right over it:

http://en.wikipedia.org/wiki/Shadow_of_Phobos_on_Mars

http://history.nasa.gov/SP-441/ch9.htm

http://history.nasa.gov/SP-425/ch38.htm

Posted by: ljk4-1 Jan 21 2006, 09:47 PM

Imagine future Mars colonists with various ways of racing the eclipses to keep the moons in front of Sol as long as possible, just as we do with jets on Earth.

Viking 1 had the shadow of Phobos pass right over it:

http://en.wikipedia.org/wiki/Shadow_of_Phobos_on_Mars

http://history.nasa.gov/SP-441/ch9.htm

http://history.nasa.gov/SP-425/ch38.htm

Posted by: djellison Jan 21 2006, 10:04 PM

I know - that's why I want to see them try a Navcam movie looking at the ground during one - because we know it makes a lot of difference to the terrain.

Doug

Posted by: djellison Jan 22 2006, 07:49 PM

Heck - the images are down but they're totally wierd I think I can extract what it SHOULD look like, but it'll be a bit of a challenge.

Doug

(PS - something done with what I THINK is actually an internal reflected images of the sun within the images - real-time-sim to follow)

Posted by: djellison Jan 22 2006, 09:47 PM

Obviously a little hard to see much in that anim gif, but I've done my best to try and replicate as close as I can what that might have looked like in real time - unlikely to be as accurate as the previous one, but I made the duration of the eclipse from 1st to last contact as about 37 seconds.

Doug

Posted by: fredk Jan 23 2006, 04:11 PM

Doug, really nice animation. How did you obtain the interpolated frames here?

Posted by: djellison Jan 23 2006, 04:28 PM

I didnt - I just made a total simualtion of the event. In my little realtime .movs - it's all simulated imagery, rendered in 3ds max, trying to replicate, as best possible, what it might look like

Doug

Posted by: fredk Jan 23 2006, 06:48 PM

Sure, I understand, but I'm curious if that involved piecing together a profile of Phobos by hand from the frames we have, or if it was automatically done by a morphing routine or whatever.

Fred.

Posted by: djellison Jan 23 2006, 08:20 PM

It's just an animation - I made a phobos-ish-shape ( not a very good one, just a slightly squished circle ) - and moved it across a circular white object, against a black background - and then added some blur to soften it appropriately, keyframed the motion of the 'moon' to my best guess of the real time, rendered out the sequence at the right resolution and badda bing.

Doug

Posted by: djellison Jan 26 2006, 10:39 AM

The raw JPG's are too bad to even worry about - but one image catches an utter bulls eye of the transit.
http://marsrovers.jpl.nasa.gov/gallery/all/1/p/709/1P191143171ESF64KSP2669R8M1.JPG

Posted by: CosmicRocker Jan 28 2006, 12:56 AM

It seems that more images of the Phobos eclipse came down today. Actually, I should say "eclipses." They apparently caught it three times between sol 707 and 709. I put together a quick animated gif.

Posted by: djellison Jan 28 2006, 01:15 AM

I told Jim about the JPG's being totally borked, and so the JPG's have been re-processed in a way that meant they were not stretched to hell and back - so we've had a 're-release' of the recent Phobos tranists - one of them is just an utter bullseye shot - the best to date I think - I call it the 'polo mint' transit These are using the new 'sport mode' for Pancam, down to 3 sec between shots in places - very clever indeed - as mentioned in the Pancam Update MP3

Doug

Posted by: CosmicRocker Jan 28 2006, 03:17 AM

Wow, talk about a man with "connections." Great work, Doug. I just may show these eclipses to the kiddies.

Posted by: dilo Jan 28 2006, 09:23 AM

I was thinking to do by myself, then I discovered your post... superb work, CosmicRocker!

Posted by: jvandriel Jan 28 2006, 12:44 PM

Opportunity as astronomer.

Here is the animation from the eclipse on Sol 707.

jvandriel

Posted by: jvandriel Jan 28 2006, 12:45 PM

Here from Sol 708.

jvandriel

Posted by: jvandriel Jan 28 2006, 12:46 PM

and the last one from Sol 709.

jvandriel

Posted by: ljk4-1 Jan 28 2006, 04:50 PM

Right after Phobos passes over Sol, a faint speck appears briefly to the lower right. Is it a star, a meteor, a cosmic ray, a camera artifact?

Posted by: Oersted Feb 1 2006, 11:18 AM

Polo mint for sure!

Posted by: djellison Feb 1 2006, 12:01 PM

Well - it's with the L8 filter - so it's not going to be a star or a meteor - particularly given that it's the middle of the day Cosmic Ray most likely

Doug

Posted by: Ant103 Feb 12 2006, 11:55 PM

Hello,

I've just made animated Gif of transits of Deimos and Phobos on the Sun.
I wanted to show this phenomena in real time (that the reason why that's a little slow -about 1 min-)

Deimos Sol 706



Phobos Sol 709


So, it's faster than solar eclipses on Earth

Posted by: ljk4-1 Feb 17 2006, 04:32 PM

Light and shadow on the surface of Mars

These images, taken by the High Resolution Stereo Camera (HRSC) on board ESA’s
Mars Express spacecraft, show the fast-moving shadow of the moon Phobos as it
moved across the Martian surface.

More at:

http://mars.esa.int

Posted by: djellison Feb 17 2006, 04:42 PM

Incase anyone missed it - Jim's added a transit page to the Pancam projects page
http://marswatch.astro.cornell.edu/pancam_instrument/projects_4.html

Doug

Posted by: mars loon Feb 18 2006, 02:33 PM

Thats a great page with lots of new stuff. ken