http://www.esa.int/SPECIALS/Mars_Express/

These images, taken by the High Resolution Stereo Camera (HRSC) on board ESA’s Mars Express spacecraft, are Europe’s highest-resolution pictures so far of the Martian moon Phobos.

http://www.esa.int/SPECIALS/Mars_Express/SEM21TVJD1E_0.html

Here's a Mars Express Phobos image from orbit 1607- a distant view. There is a close view on this orbit, but I haven't got the patience to download 600 Mb of mostly dark sky.

Phil

Click to view attachment

What is it with the PDS/PSA and their total hatred of Zip/Rar/GZ'ing files that actuall comrpess REALLY well...

At least the small bodies node have the right attitude for this stuff.

Doug

Waaw thanks for sharing those!

Mea culpa - I see now that the second image from that orbit, the 600 MB file, is of Mars, not Phobos.

Phil

600 MB? The biggest Phobos images from that orbit are about 2 MB. Where were you looking? I was on the PDS Geosciences node.

Here are the two highest resolution images from this orbi (1607).

I checked this after reading your question, Ted. The Data directory has the full res images, and for the largest image from that orbit it says:

Wednesday, April 26, 2006 6:49 AM 697587740 h1607_0009_nd2.img

697 Mb. But I was mistaken in thinking it was Phobos, I assumed that without checking - the second set of images from 1607 are of Mars. Even so, the largest Phobos image on that orbit, the nd2 image, is 9548940 bytes. Your images are the "super-resolution" images which are a lot smaller.

There are some very similar images of Phobos in orbit 1574 as well.

Phil

- and another in orbit 1558, but this one is from orbit 1212, the nadir (nd2) image:

Click to view attachment

Phil

I'm still exploring the Mars Express Phobos images. This, I think, is the highest resolution image yet, from orbit 756. The original file was 169 MB, but largely dark sky. I have played with the contrast a bit to brighten the terminator. Several blocks casting shadows can be found along the terminator.

Phil

Click to view attachment

Nice image, Phil. Where do the JPEG-ish artifacts come from, was this one lossy compressed before transmission?

No, I compressed it severely to reduce the file size for posting on UMSF.

Phil

Very impressive shot, Phil... resolution should be around 3m/pixel!
The file you posted is only 460k, I think is worth to re-post a less compressed version... please!

sorry, wrong re-post.

I will put the uncompressed image on an external website tomorrow.

Phil

The best I could do with 16 bit lossless compression was over 9 MB!

Good point, Ted - actually I'll be reducing it to 8 bit after a judicious contrast stretch (actually 2 different contrast stretches merged), and then saving it as a high quality jpg, so it will be compressed, but a lot less than my post.

Phil

Here's another one... orbit 748.

Phil

Click to view attachment

Oh, that's a nice one, Phil!

Are you methodically posting every halfway decent Phobos image here or are you just making selections of your favorites?

--Emily

I'm not being methodical, I'm just playing. I needed a break from more serious stuff. But I'll probably end up posting any decent Mars Express pics as I find them.

Phil

Good grief! Is it my imagination, or are there really two sets of grooves in the image that Phil just posted, intersecting at right angles?

How does this tally with the theory that the grooves were produced by interactions between Phobos and debris in orbit around Mars?

Ian.

Despite impeccible logic and analysis "proving" how the grooves were formed by impacting debris, I just don't believe it. Yah... one group from 10:00 clock to 4:00 clock and a second finer set from 1:00 clock to 7:00 clock angle. _AND_, roughly bisecting them at an angle of 5:30 to 11:30 clock angle is a non-groove linear splatter pattern that looks like it *IS* splatter-cratering from a jet of debris.

Good catch on the splatter pattern Ed. That certainly does look more like a crater chain from a debris or cometary impact.

Here's a link to the higher quality Phobos image posted above. It's reduced from 16 to 8 bit, cropped and saved as a high quality JPG, so it is compressed but not too badly. The 16 to 8 conversion was done twice, once to favour dark areas, and the results merged using my secret sauce recipe. I'll keep this up here for a few weeks and then remove it so get it while it's hot.

Phil

http://instruct.uwo.ca/geog/136a/hrsc756_phobos.jpg

I've mirrored it here...
http://s3.amazonaws.com/planetary/10212/hrsc756_phobos.jpg

--Emily

Phil, do you know the pixel scale on that particular image from orbit 756?

The PDS label says 5.9 m/pixel. and roughly 5000 pixels across 30 km seems to support that value.

Phil

Thanks for the great image Phil, I hope one day you will reveal your secret sauce recipe...
(I was wrong about image scale because I estimated it using Phobos mean radius instead of diameter)

Here's a nice new Phobos image from Mars Express, orbit 3909:

Click to view attachment

Phil

Out of curiosity, how are things going with mapping of Phobos? The best global map I've seen is the USGS airbrushed version. FWIW, my mapping software is approaching the point where I can consider utilizing more general shape models, vs a simpler triaxial ellipsoid.

I should have added to my previous post - it came from one of the abstracts at the ESA Mars Conference - see thread under Conferences. Willner et al., in the Friday Workshops.

Mapping - there has been no serious work since Viking. I've been saying for years that I'll make a new global mosaic with the best images, but other things have prevented me. But I will certainly do so when Phobos-Grunt flies, or if CSA's PRIME gets funded. The abstract above refers to a new global shape model, which will help improve the next round of mapping.

Phil

Now that is interesting. How do you get a splatter pattern/crater chain on a body with essentially zero gravity? It certainly can't be by stuff just falling back to the surface. Anything moving slowly enough to fall back on Phobos probably wouldn't be able to crater a marshmallow.
I suppose a string of debris might stay together well enough to hit Phobos on a subsequent orbit but it seems rather unlikely. It seems at least as likely to be debris coming from an impact on Mars itself.

Wow, Phil, that's a really cool image, thanks for pointing it out!

--Emily

... and add a bit of colour, just 'cos it's Sunday night and there's nothing on telly until Medium comes on...

Click to view attachment

Great stuff, Phil & Stu!!! Now I know exactly how Phobos must have appeared to the crew of the spacecraft Rolling Stone as it approached Phobos in Heinlein's immortal novel...absent the industrial complexes and filled landing berths, of course...

Quick inspiration:

we sense therefore we are

unmanned and alone
solitary robots peer deeply into the Unknown
seeing, tasting, hearing that which no human has yet known,
like a splash of water or blast of radiation
on tender skins

We, safe in the cradle, see vistas dreamed of
yearned for, in our infant dreams
by generations denied their future by tumult,
by the restless and capricious nature of our species
by priorities, set too often by
those who cannot see far horizons,
even through eyes of silicon, gallium arsinide, feed horns and reflectors...

blindness is inexcusable
as the spectrum of the Universe unveils itself, reluctantly,
as bigger than our minds
what challenge, what wonder, can possibly compare?

we must see, at least

in order that someday we may touch

Hey Phil, could you tell me where you got the pictures from orbit 3909, because I do find only the raw images until the orbit 3160 on the ESA server...
Thanks a lot

I found it in the place mentioned in post 30, above.

Phil

Here's the direct link to the Willner et al. abstract (PDF).

--Emily

Shall be interesting to see what shape model results Willner et al. are going to present at the November conference.

Seeing that image I wonder who launched that potato into low Mars orbit anyway ?

Dr. Willner said I'd need to ask Neukum directly for permission to post that other image, but he pointed out one that had been released on the Web in February (apologies if someone else already posted this elsewhere):

Phobos über der Marsatmosphäre

--Emily

Wow, that's a gorgeous picture of Phobos, thanks for the link Emily... that one passed me by, somehow...

Click to view attachment

That picture was around for quite a while now: http://www.unmannedspaceflight.com/index.p...ost&p=84812

Here are a couple of Mars Express HRSC images of Phobos, from the PDS courtesy of G. Neukum. They have had a bit of extra processing in my usual manner to brighten the terminator area.

Phil

Click to view attachment

Click to view attachment

That's something with three different orientations of grooves I can see in the top image...

It is already gridded, it will be easy for Phil to make us a new model and map.

At first glance, I thought we were looking at it through a screen door.

The High Resolution Stereo Camera (HRSC) on Mars Express is not the best instrument.

Orbit 3802, Phobos, image h3802_0003_sr2
Click to view attachment

Orbit 3802, Phobos, image h3802_0004_sr2
Click to view attachment

HRSC itself is great, but the super resolution bolt-on camera from which those two frames came from has never achieved good focus.

Doug

Mars Express (MEX) release #2.
February 14, 2008

Online Data Volumes - Mars Express

Orbit 3310, Phobos, image h3310_0000_s22
Click to view attachment

Orbit 3310, Phobos, image h3310_0000_s12
Click to view attachment

Another high (??) resolution image.

Orbit 3769, Phobos, image h3769_0004_sr2
Click to view attachment