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APOD: Phobos: Doomed Moon of Mars (2012 Oct 28)
Posted: Sat Oct 27, 2012 3:06 pm
by APOD Robot
Phobos: Doomed Moon of Mars
Explanation: This moon is doomed.
Mars, the red planet named for the
Roman god of war, has two tiny moons,
Phobos and
Deimos, whose names are derived from the Greek for
Fear and
Panic. These
martian moons may well be captured
asteroids originating in the main asteroid belt between Mars and
Jupiter or perhaps from even more distant reaches of the Solar System. The larger moon,
Phobos, is indeed seen to be a cratered, asteroid-like object in this
stunning color image from the
Mars Reconnaissance Orbiter, recorded at a resolution of about seven meters per pixel. But
Phobos orbits so close to Mars - about 5,800 kilometers above the surface compared to 400,000 kilometers for
our Moon - that gravitational
tidal forces are dragging it down. In 100 million years or so
Phobos will likely be shattered by stress caused by the
relentless tidal forces, the debris forming a decaying ring around Mars.
[/b]
Re: APOD: Phobos: Doomed Moon of Mars (2012 Oct 28)
Posted: Sun Oct 28, 2012 4:37 am
by owlice
Mirrored
here.
Please note some of the links on that mirrored page won't work until the NASA APOD site comes back up Sunday afternoon (at which time the mirrored page will no longer be useful, assuming it is useful now
).
Re: APOD: Phobos: Doomed Moon of Mars (2012 Oct 28)
Posted: Sun Oct 28, 2012 5:55 am
by starstruck
owlice wrote:Mirrored
here.
Yep, works for me, thanks!
Re: APOD: Phobos: Doomed Moon of Mars (2012 Oct 28)
Posted: Sun Oct 28, 2012 1:59 pm
by nstahl
I was thinking of buying real estate on Mars (not me buying it, but whomever might buy it). Clearly the prospect of moon parts falling on one's estate would eventually depress the market (hurtling moons are one thing, descending moons another). I see Phobos's orbit is within about 1 degree of Mars's equator so I guess one might hope the damage would be restricted to equatorial regions. Or maybe by then Martians will have learned how to boost Phobos's orbit safely up. There's surely time. And much sooner it should make a great base for exploring Mars.
I hope they show good sense in placing the giant air factories.
Re: APOD: Phobos: Doomed Moon of Mars (2012 Oct 28)
Posted: Sun Oct 28, 2012 2:50 pm
by rstevenson
nstahl wrote:... I see Phobos's orbit is within about 1 degree of Mars's equator so I guess one might hope the damage would be restricted to equatorial regions. ... I hope they show good sense in placing the giant air factories.
If you haven't already, I recommend reading the
Red Mars, Blue Mars, Green Mars trilogy by Kim Stanley Robinson. Such things as you mention are woven into the story line, as well as the most dramatic fall-from-the-heavens event I've ever read in science fiction. You'll be amazed!
Rob
Re: APOD: Phobos: Doomed Moon of Mars (2012 Oct 28)
Posted: Sun Oct 28, 2012 3:48 pm
by Tara_Li
Looking at the full image - in the area around pixel location 1997,1652 - there's something curious, at least to my eye. Zoomed in, it's about 5 pixels (35 ish meters) across, and very sharply demarked. The obvious answer is that it's a small upthrust of some kind, or a large loose boulder - but to my eye, it *LOOKS* almost as though it's above the surface. It would be awesome to have caught a meteor coming in before it struck, or a bouncing rock from ejecta.
Re: APOD: Phobos: Doomed Moon of Mars (2012 Oct 28)
Posted: Sun Oct 28, 2012 4:14 pm
by nstahl
Thanks rstevenson. I think I read the first of those long ago. I'll look into them.
Re: APOD: Phobos: Doomed Moon of Mars (2012 Oct 28)
Posted: Sun Oct 28, 2012 4:46 pm
by owlice
APOD is back online. (Yay!)
Re: APOD: Phobos: Doomed Moon of Mars (2012 Oct 28)
Posted: Sun Oct 28, 2012 5:25 pm
by orin stepanek
owlice wrote:APOD is back online. (Yay!)
+1
Re: APOD: Phobos: Doomed Moon of Mars (2012 Oct 28)
Posted: Sun Oct 28, 2012 6:51 pm
by Wadsworth
Tara_Li wrote:Looking at the full image - in the area around pixel location 1997,1652 - there's something curious, at least to my eye. Zoomed in, it's about 5 pixels (35 ish meters) across, and very sharply demarked. The obvious answer is that it's a small upthrust of some kind, or a large loose boulder - but to my eye, it *LOOKS* almost as though it's above the surface. It would be awesome to have caught a meteor coming in before it struck, or a bouncing rock from ejecta.
As you stated, it is most likely just a loose bolder or somthing similar. There are several more closer to the edge at 968,581 and 905,605 and 749,647 etc.. Because of their relative location to the light source, you can see the nice spikey shadows they create.
Re: APOD: Phobos: Doomed Moon of Mars (2012 Oct 28)
Posted: Sun Oct 28, 2012 8:04 pm
by nicodemus
Does anyone have an idea about how the linear chains of craters were formed?
Re: APOD: Phobos: Doomed Moon of Mars (2012 Oct 28)
Posted: Sun Oct 28, 2012 8:08 pm
by Tara_Li
Wadsworth wrote:Tara_Li wrote:Looking at the full image - in the area around pixel location 1997,1652 - there's something curious, at least to my eye. Zoomed in, it's about 5 pixels (35 ish meters) across, and very sharply demarked. The obvious answer is that it's a small upthrust of some kind, or a large loose boulder - but to my eye, it *LOOKS* almost as though it's above the surface. It would be awesome to have caught a meteor coming in before it struck, or a bouncing rock from ejecta.
As you stated, it is most likely just a loose bolder or somthing similar. There are several more closer to the edge at 968,581 and 905,605 and 749,647 etc.. Because of their relative location to the light source, you can see the nice spikey shadows they create.
Indeed - I see the spires you mention. I find it somewhat odd, though, that there are so few of them - especially in this part of the image. There's something similar, but much smaller, around 2527,1776 - but it just doesn't give the same feel of being away from the surface.
Re: APOD: Phobos: Doomed Moon of Mars (2012 Oct 28)
Posted: Sun Oct 28, 2012 9:21 pm
by keir
The striations running across the moon appear in many instances to be joining lines of impact crators.
This especially noticable top right. Also perhaps emanating from the mjar right crator.
Could this be like an "atmospheric" erosion where the atmosphere is something really erosive like vapourized rock. The whole moon seems to have been smoothed over as though sandblasted. The craters may be acting as an aerodynamic channeller of the "wind". Could the whole moon have passed through something gassesous?
Re: APOD: Phobos: Doomed Moon of Mars (2012 Oct 28)
Posted: Sun Oct 28, 2012 10:46 pm
by BDanielMayfield
keir wrote:The striations running across the moon appear in many instances to be joining lines of impact crators.
This especially noticable top right. Also perhaps emanating from the mjar right crator.
Could this be like an "atmospheric" erosion where the atmosphere is something really erosive like vapourized rock. The whole moon seems to have been smoothed over as though sandblasted. The craters may be acting as an aerodynamic channeller of the "wind". Could the whole moon have passed through something gassesous?
I wondered about these crater chains too. The link in the Explanation “stunning color image” links to a description of another Phobos photo on a JPL website. From it I quote:
“A series of troughs and crater chains is obvious on other parts of the moon. Although many appear radial to Stickney in this image, recent studies from the European Space Agency's Mars Express orbiter indicate that they are not related to Stickney. Instead, they may have formed when material ejected from impacts on Mars later collided with Phobos.”
Therefore it seems that these crater chains were caused by straffing from shrapnel blasted off Mars during a period of heavy bombardment from space. Truly a fearful time.
Bruce
Re: APOD: Phobos: Doomed Moon of Mars (2012 Oct 28)
Posted: Sun Oct 28, 2012 10:56 pm
by BDanielMayfield
Tara_Li wrote:Wadsworth wrote:Tara_Li wrote:Looking at the full image - in the area around pixel location 1997,1652 - there's something curious, at least to my eye. Zoomed in, it's about 5 pixels (35 ish meters) across, and very sharply demarked. The obvious answer is that it's a small upthrust of some kind, or a large loose boulder - but to my eye, it *LOOKS* almost as though it's above the surface. It would be awesome to have caught a meteor coming in before it struck, or a bouncing rock from ejecta.
As you stated, it is most likely just a loose bolder or somthing similar. There are several more closer to the edge at 968,581 and 905,605 and 749,647 etc.. Because of their relative location to the light source, you can see the nice spikey shadows they create.
Indeed - I see the spires you mention. I find it somewhat odd, though, that there are so few of them - especially in this part of the image. There's something similar, but much smaller, around 2527,1776 - but it just doesn't give the same feel of being away from the surface.
I'm trying to find what ya'll are discussing, but were are the numbers (pixel coordinates?) you're using?
Bruce
Re: APOD: Phobos: Doomed Moon of Mars (2012 Oct 28)
Posted: Sun Oct 28, 2012 11:24 pm
by Canadian Grandma
It looks like hieriglyphics in the highlighted area. Maybe a long ago martian caeved his name on his hackysack & gave it a really good toss.
Re: APOD: Phobos: Doomed Moon of Mars (2012 Oct 28)
Posted: Mon Oct 29, 2012 12:21 am
by rstevenson
It's possible to see a lot given just a few pixels. Or rather, it's possible to
imagine a lot given just a few pixels.
- Arty_Fact.jpg (11.25 KiB) Viewed 9649 times
Rob
Re: APOD: Phobos: Doomed Moon of Mars (2012 Oct 28)
Posted: Mon Oct 29, 2012 12:22 am
by Tara_Li
BDanielMayfield wrote:I'm trying to find what ya'll are discussing, but were are the numbers (pixel coordinates?) you're using?
Bruce
They're pixels, yes - and my image editor (Gimp in this case) has a scale along the sides, and a "cursor position information window" that gives me the location.
Re: APOD: Phobos: Doomed Moon of Mars (2012 Oct 28)
Posted: Mon Oct 29, 2012 12:23 am
by Tara_Li
rstevenson wrote:It's possible to see a lot given just a few pixels. Or rather, it's possible to
imagine a lot given just a few pixels.
Arty_Fact.jpg
Rob
So very very true.
Re: APOD: Phobos: Doomed Moon of Mars (2012 Oct 28)
Posted: Mon Oct 29, 2012 3:21 am
by Wadsworth
Tara_Li wrote:
Indeed - I see the spires you mention. I find it somewhat odd, though, that there are so few of them - especially in this part of the image. There's something similar, but much smaller, around 2527,1776 - but it just doesn't give the same feel of being away from the surface.
There are several more high resolution images on the
NASA site.
These images are most excelent.
Re: APOD: Phobos: Doomed Moon of Mars (2012 Oct 28)
Posted: Mon Oct 29, 2012 3:36 am
by Ann
Well, it's a good thing that our dear old Luna isn't going to fall down on our heads. Like
Vitalstatistix of the small Gaulish village of Asterix and Obelix used to say: We have nothing to fear but the sky falling on our heads!
As for Phobos itself and interesting-looking features on it, has anyone noticed the perfect "eye" at about two o'clock? To see it, note the long orange ridge running along the moon's upper right edge. Follow the ridge down until it ends in a crater with a white rim. From the crater, move straight to the left until you come to a rather narrow and small white ridge. This ridge, however, begins at the "eye"! Note the sharply delineated eyelid, which could have been drawn with a fine black pen. Note the round black iris with a white pupil inside. Hmmm. Phobos was the offspring of Ares (Mars) in Greek mythology. Maybe that eye is Phobos himself looking back at us? Look into my eye, ye mighty, and despair?
Ann
Re: APOD: Phobos: Doomed Moon of Mars (2012 Oct 28)
Posted: Mon Oct 29, 2012 3:57 am
by nicodemus
BDanielMayfield wrote:keir wrote:The striations running across the moon appear in many instances to be joining lines of impact crators.
This especially noticable top right. Also perhaps emanating from the mjar right crator.
Could this be like an "atmospheric" erosion where the atmosphere is something really erosive like vapourized rock. The whole moon seems to have been smoothed over as though sandblasted. The craters may be acting as an aerodynamic channeller of the "wind". Could the whole moon have passed through something gassesous?
I wondered about these crater chains too. The link in the Explanation “stunning color image” links to a description of another Phobos photo on a JPL website. From it I quote:
“A series of troughs and crater chains is obvious on other parts of the moon. Although many appear radial to Stickney in this image, recent studies from the European Space Agency's Mars Express orbiter indicate that they are not related to Stickney. Instead, they may have formed when material ejected from impacts on Mars later collided with Phobos.”
Therefore it seems that these crater chains were caused by straffing from shrapnel blasted off Mars during a period of heavy bombardment from space. Truly a fearful time.
Bruce
I posted the question about the craters.
I doubt that ejecta from a Mars impact would leave such precise chains of craters. I could see that a line of impactors striking as the moon rotated could leave a string of craters and maybe that would explain why the chains are parallel. But my conceptual model for that were the asteroid impacts on Jupiter, a much larger scale event.
Thanks for the tip on the link.
Nic
Re: APOD: Phobos: Doomed Moon of Mars (2012 Oct 28)
Posted: Mon Oct 29, 2012 1:44 pm
by BDanielMayfield
Say, wheren't there similar looking troughs on Vesta?
Bruce
ἈNΆГKH: DOOM, FATE
Posted: Mon Oct 29, 2012 1:46 pm
by neufer
A few years ago, while visiting or, rather, rummaging about Notre-Dame, the author of this book found, in an obscure nook of one of the towers, the following word, engraved by hand upon the wall:—
~ἈNΆГKH~
These Greek capitals, black with age, and quite deeply graven in the stone, with I know not what signs peculiar to Gothic caligraphy imprinted upon their forms and upon their attitudes, as though with the purpose of revealing that it had been a hand of the Middle Ages which had inscribed them there, and especially the fatal and melancholy meaning contained in them, struck the author deeply.
Re: APOD: Phobos: Doomed Moon of Mars (2012 Oct 28)
Posted: Wed Oct 31, 2012 9:18 am
by Bruce Mardle
I'm just reading the Wikipedia page on Phobos. It says, "Phobos orbits about 9,400 km (5,800 mi) from the center of Mars, or about 6,000 km (3,700 mi) from the Martian surface", whereas this APoD page says, "... Phobos orbits so close to Mars - about 5,800 kilometers above the surface...".
Which one is right?