Mars Express Captures Phobos and Deimos 84
westtxfun writes "The Mars Express Orbiter captured a very cool movie of Phobos and Deimos on Nov 5. Besides the 'wow factor,' the images will be used to refine models of the moons' orbits. The orbiter has also captured high resolution images of Phobos back in July. 'The images were acquired with the Super Resolution Channel (SRC) of the High Resolution Stereo Camera (HRSC). The camera took 130 images of the moons on 5 November at 9:14 CET in a span of 1.5 minutes at intervals of 1s, speeding up to 0.5-s intervals toward the end. The image resolution is 110 m/pixel for Phobos and 240 m/pixel for Deimos — Deimos was more than twice as far from the camera. '"
Wow. (Score:5, Funny)
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Hm, at NASA...I don't know, perhaps.
But Mars Express is ESA mission.
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Don’t shock them. They have yet to learn, that the world is not a state of the USA, and that hot dogs are actually no food at all. ^^
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I'm an american citizen and I do know this.
The problem is that my political masters up in DC don't care.
And yes, I already tried to vote them out, but with corporate whoring political parties drawing up who gets on the ballot, I really don't have much choice.
don't kiss up to foreigners. (Score:2)
I'm an american citizen and I do know this.
I'm an American too. My advise to my fellow citizens is not to kiss up to foreigners when they knock the country. They would knock the country no matter what we do. Of course they want to chat up their nation and knock ours down a peg to do it. Just don't get caught up into trying to believe that their bitching is true. 95% is a bunch of well, bitching, and there's not a single thing that they bitch about America doing that they have not or would not equally ra
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Or maybe... (Score:2)
Don’t shock them. They have yet to learn, that the world is not a state of the USA, and that hot dogs are actually no food at all. ^^
Maybe the world has yet to learn that, in fact, it really is a state of the USA, and that Hot Dogs are actually the -ultimate- food.
When will you poor barbarians learn SOMETHING.
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It looks kind of fake because it was taken through a telescopic lens, and thus you don't see the perspective of movement. When photographers and artists want to exaggerate perspective, they do the opposite: use a wide-angle lens.
Re:Wow. (Score:5, Informative)
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It's so weird when reality looks like bad Photoshop.
They can't afford tabletop models anymore, so in this project they used paper cutouts on a black canvas.
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Anyone noticed ... (Score:3, Interesting)
That the jpg weight in at 666kb ?!!!?
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and the devil wrote a little white "N" near the top.
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Ask slashdot (Score:3, Interesting)
Re:Ask slashdot (Score:5, Informative)
Solar radiation and the solar "wind" has an effect on smaller bodies, such as those moons. The effects vary depending on the color, composition, and texture of the moons' surfaces. We need better models to know their impact on orbits. Relativity may also have a very minor impact on orbital changes.
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That's "large scale" texture ;-)
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How does one calculate 'north' on the moon of another planet?
Everything rotates. The North Pole for a body is the pole that lies in the Northern hemisphere.
If you mean, how would you navigate if you were walking around on Phobos, well, first you wouldn't be walking - with an escape velocity of 11 meters / second and a surface gravity in the mm / second^2 range, a small hop might take hours to complete. You would presumably instead fly your spacesuit with a small thruster.
Second, if you were on the Mars side
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The North Pole for a body is the pole that lies in the Northern hemisphere.
That's tautologous. There are two common definitions of a body's North Pole. The first (and the International Astronomical Union's) is the pole of rotation that lies on the same side of the ecliptic plane as the Earth's north pole. This implies that Venus rotates "backwards".
The second definition is more local - it defines the North Pole as the pole around which the body rotates counterclockwise.
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Please, forgive my ignorance (physics is not my field): What orbit model is going to be refined? I've always thought that planetary movements were resolved centuries ago
Sure, the physics behind planetary movements is well-known, but the zillion parameters that are at play (including the mass distribution of the objects involved) are only measured to finite precision. They are talking about refining the model by refining its parameters.
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Planetary models from centuries were basically an example of:
a) idealized scenario (frictionless vacuum kind of stuff)
b) based on Newtonian physics; which is not quite accurate...
With the number of bodies and their interactions, Solar System is pretty much chaotic:
http://en.wikipedia.org/wiki/N-body_problem [wikipedia.org]
http://en.wikipedia.org/wiki/Stability_of_the_Solar_System [wikipedia.org]
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The theory behind orbits in general is a solved problem, for some limited specific condtions (i.e. gravity as a point source, two bodies, and stuff like that). But that doesn't mean you know the actual parameters of the orbit (inclination, semi-major axis (period), etc) of any particular body. Any orbit "fit" is alwasy being refined.
The other issue is that gravity actually isn't a point source with a simple inverse-square law nor are there only two bodies involved. The gravity o
Re:Ask slashdot (Score:4, Informative)
The orbit of Phobos, particularly, has an oddity that has attracted a lot of interest, and more data is always welcomed.
The orbit of Phobos is decaying, presumably due to tidal friction [cornell.edu] - the work required for Phobos to raise a small tidal bugle in the part of Mars below it. There is nothing surprising in that, per se (Moons inside a geostationary orbit will decay inwards due to tidal friction, Moons outside a geostationary orbit will "decay" outwards), but what is surprising is the "Q" required to match the observations. (The Q is total energy in the bulge divided by the rate of energy lost per orbit.) The Q inferred from observations of Phobos's orbital decay, and the rigidity of the Martian surface found from observations of the Martian Solar tide [berkeley.edu], is about 90. The corresponding Q for the Earth is about 12, but that is mostly due to ocean tides, and the Q inferred for the Earth's mantle is about 280.
So, the Mars-Phobos system has a higher solid-body dissipation [usra.edu] than the Earth-Moon system, which is surprising. In nailing this down, all sorts of data have been acquired for Phobos (including eclipse data from the Mars Rovers), but there is always room for more. What the current data should do is provide a tie for the relative longitudes of Phobos and Deimos which (especially if this can be repeated) will help make sure that there are no drifts between the orbits of the two Moons.
By the way, with the current orbital decay, the expected lifetime of the orbits is somewhere in the 20 to 40 million year range [arxiv.org] - it seems unlikely that we just happen to catch Phobos at its end-of-life, which has raised speculation about its decay being time variable.
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By the way, with the current orbital decay, the expected lifetime of the orbits is somewhere in the 20 to 40 million year range [arxiv.org] - it seems unlikely that we just happen to catch Phobos at its end-of-life, which has raised speculation about its decay being time variable
Why is it unlikely? That longer time period represents almost 1% of the lifetime of the entire solar system, (so far). Sure, 40 million years is considered short on a cosmic scale, but don't forget the fact that it is still a LO
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Well, if you pick times at random, we would say that a 1% chance of encountering something is fairly low. But, of course, 1% events happen all of the time, even in Astronomy.
Here is a better way to look at probability in astrophysics and planetary physics - if you conclude that you just happened to observe something or catch some event at an unlikely point of its life-cycle, that may be a clue that you are calculating your probabilities wrong, i.e., that your theory is wrong or incomplete. So, improbable ev
action films (Score:5, Insightful)
Maelstrom (Score:2)
My fingers instinctively groped for the keyboard when I saw the asteroids entering the picture. I find it alarming that the large asteroid is faster than the small one.
http://en.wikipedia.org/wiki/File:Maelstrom.png [wikipedia.org]
That's odd... (Score:4, Funny)
I don't see any Leather Goddesses. Maybe I need to set the naughtiness level to "lewd".
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Xaero has "humiliated" them on "Hardcore" i'm afraid...
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That will happen automatically, due to time dilation, once we accelerate to lewdicrous speed.
Nice mission overall (Score:2, Interesting)
Movie is only one of mission returns, and it surely looks like a video game to many who don't think further than WoW when thinking about exploring unknown :).
Mission itself is what is important here - being technologically advanced far more than Voyagers and giving us previews of what will come in future.... Better cameras and other instruments, better communications, faster spacecraft.... We are only beggining to see around solar system (Voyager is only 32 yrs old) and Mars Express is BIG THING.
What is als
Re:Nice mission overall (Score:5, Interesting)
What I can't understand is why they're still inventing whole lander thing when technology for safe landing (and going back up) of people is tried FORTY years ago?!!
We know how to land in dense atmosphere (Earth, Venus) and in vacuum (the Moon). But there are no good solutions for landing in thin atmosphere (Mars). You can't use a parachute because there isn't enough atmosphere for it, and you can't use a rocket engine because incoming flow of atmospheric gases interferes with the engine (extinguishes flame and creates oscillations like in a whistle.) That's why robots are just dropped on Mars in a big airbag. But the deceleration is too high for a human.
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You can't use a parachute because there isn't enough atmosphere for it,
And yet it has been done.
and you can't use a rocket engine because incoming flow of atmospheric gases interferes with the engine
And yet it has been done.
Any other wisdom you want to share?
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Yes, it has been done, but only for objects with small mass; decelerating them fairly easy in comparison to what would be required from several-tonne lander capable of carrying humans.
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And yet it has been done.
Given that of the 16 landers that have been dispatched to Mars, only 6 of them actually ended up on the surface in working order, I think it's more accurate to say that it hasn't been done.
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Given that of the 16 landers that have been dispatched to Mars, only 6 of them actually ended up on the surface in working order, I think it's more accurate to say that it hasn't been done.
If it's been done once, it's been done. It hasn't been done reliably but that's something different.
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Landing large payloads on Mars is tough [universetoday.com], if by landing you mean, at a reasonable G force.
"An airbag landing subjects the payload to forces between 10-20 G's." For a human, that's not a landing, that's a crash.
Parachutes are inefficient, especially for the last few hundred meters / second. The best solution for human sized crafts is probably parachutes plus rockets a la Viking.
I don't have a good solution, except that we should always land in Hellas (the deepest basin on Mars, with about 50% higher surface a
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"So much fuel" being one of crown problems with whole landing thing. Until we don't have very energy/fuel_mass efficient fuels and very sophisticated drives landing (and esp. returning it back to orbit) will present problems ranging from very hard to impossible.
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We know how to land in vacuum with little gravity. Mars has too strong gravity to use rockets all the way. Both parachutes and breaking rockets are still useful for landing on Mars, but it is very different from both Earth and the Moon.
Two Words (Score:1)
most awesome ...'awesome' is so over-used, but it's truly appropriate here
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most awesome ...'awesome' is so over-used, but it's truly appropriate here
Your comment is awesome dude....
Wow.... (Score:2)
It must stretch itself out really thin for only weighing 1123 kg.
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TIFF URLs missing extra "f" (Score:2)
If you want the "HI-RES TIFF" versions of the images, you'll need to add another "f" onto the ends of the URLs.
Pitch black. (Score:2)
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Just shows that also this move was done in Arizona desert.
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Sure, if you believe in (Score:1, Flamebait)
that whole "we've sent things to Mars" myth that the Conspiracy is trying to force on you. I think the whole thing was shot on a soundstage in Southern California ... I'm pretty sure I can see the support wires.
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No! Get away! (Score:2, Funny)
Or you might end knee-deep in the dead.
4X MORE magnification (Score:2)
Anybody know the absolute magnification? These objects are really close, but small. Whatever, I suppose. It would surely still be weird to see them track across the sky live.
Well that's disappointing... (Score:2)
Then I read the story and see we have a stop frame animation that looks like a cut from Robot Chicken.
It just doesn't pay to get excited about science.
Fake? (Score:2)
Did anyone else expect tumbling or rotation, however slowly?
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Odd Phobos striations (Score:3, Interesting)
What's the deal with the curious striations running longitudinally across the whole surface? Notice, in particular, that they even continue down into and through craters! What could cause that?
My first thought was that Phobos must have a fast spin in addition to its fast orbit, and that it was acquiring those gouges as it spins through clouds of debris. Then I read the notes and learned that the "N" marked the north pole of its axis, meaning that the striations are running perpendicular to its rotation!?
Back to the drawing board....
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After I commented, I found and read quite a few commentaries about them, none of which had an adequate explanation. The most curious aspect is how they continue THROUGH craters, even deep ones. It's almost as if something drove, or was dragged, across those areas. I'm having a hard time visualizing how any impactor could "slide" across the surface like that, even down into and then back out of craters and continuing. At first, second, and third glance they certainly appear to be unnatural.
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I believe they were caused by Barons of Hell.
Let's go (Score:1)
Phobos and Deimos have a significant amount of water.
How about a manned deep space mission to sample them...probably cheaper
than a return to the moon, and demonstrably more interesting.
Someone spot E1M1 (Score:1)
I'm looking at those craters and am trying to figure out where the Phobos bases are. Perhaps it's at the wrong angle. Did the UAC cover it up?