Slashdot Mirror

← Back to Stories (view on slashdot.org)

Mars Express Captures Phobos and Deimos

Posted by Soulskill on from the holding-for-ransom dept.

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. '"

62 of 84 comments (clear)

  1. Wow. by FlyingSquidStudios · · Score: 4, Funny

    It's so weird when reality looks like bad Photoshop.

    --
    http://twitter.com/OLDTELEGRAM
    1. Re:Wow. by Tablizer · · Score: 3, Informative

      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.

      --
      Table-ized A.I.
    2. Re:Wow. by DNS-and-BIND · · Score: 4, Informative

      Most "space images" are very heavily processed. If they took a normal picture it wouldn't look nearly as good. NASA learned a long time ago that its only reason for getting funded (besides being a jobs program) was making pretty pictures.

      --
      Shutting down free speech with violence isn't fighting fascism. It IS fascism!
    3. Re:Wow. by sznupi · · Score: 2, Informative

      Hm, at NASA...I don't know, perhaps.

      But Mars Express is ESA mission.

      --
      One that hath name thou can not otter
    4. Re:Wow. by Hurricane78 · · Score: 1

      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. ^^

      --
      Any sufficiently advanced intelligence is indistinguishable from stupidity.
    5. Re:Wow. by shentino · · Score: 1

      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.

    6. Re:Wow. by snaz555 · · Score: 1

      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.

    7. Re:Wow. by SlappyBastard · · Score: 1

      Not really. They look more like poorly tweened objects in Flash. Which is actually worse.

      --
      I scream. You scream. I assume that means we're both acquainted with the problem. We proceed.
    8. Re:Wow. by RavenLrD20k · · Score: 1

      So, is the circled location labeled "N" supposed to denote the location of the Leather Goddesses' base? Or is this where they've found the first signs of Denizens from Hell?

  2. Anyone noticed ... by PIBM · · Score: 2, Interesting

    That the jpg weight in at 666kb ?!!!?

    1. Re:Anyone noticed ... by Tablizer · · Score: 1

      and the devil wrote a little white "N" near the top.

      --
      Table-ized A.I.
    2. Re:Anyone noticed ... by HNS-I · · Score: 1

      I guess it won't fit in Bill's harddrive then. Can't they crop it just a little?

  3. Ask slashdot by papabob · · Score: 2, Interesting

    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, and that modern cosmology studies the 'very big' things, portions of universe so massive that introduce glitches in relativistic theories, instead of moons' orbits.

    1. Re:Ask slashdot by Tablizer · · Score: 5, Informative

      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

      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.
           

      --
      Table-ized A.I.
    2. Re:Ask slashdot by Linzer · · Score: 1

      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.

      --
      Gravitation is a theory, not a fact.
    3. Re:Ask slashdot by sznupi · · Score: 2, Interesting

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

      --
      One that hath name thou can not otter
    4. Re:Ask slashdot by Brett+Buck · · Score: 2, Informative

      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 of any real physical body is lumpy, other bodies pull on it, too, so the orbits are far from completely predictable and will never be perfectly well known.

              Brett

    5. Re:Ask slashdot by mbone · · Score: 3, 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 - 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, 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 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 - 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.

    6. Re:Ask slashdot by Bender0x7D1 · · Score: 1

      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 LONG period of time, and a lot of stuff can happen. In fact, with all of the moons observable from Earth, it would be surprising if nothing exciting was happening during that kind of time period.

      --
      Reading code is like reading the dictionary - you have to read half of it before you can go back and understand it.
    7. Re:Ask slashdot by mbone · · Score: 2, Interesting

      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 events tend to get the theorists interested. One obvious way to make Phobos less improbable is to see if the high dissipation could be intermittent.

      By the way, when the short lifetime for Phobos was first realized back in the 1950's, it was thought that the orbital decay was due to atmospheric drag, which required a lot of drag at a high altitude. One way to accomplish this would be to have a very low Phobos mass to area ratio, which lead to I.S. Shklovsky hypothesizing that Phobos was a hollow spacecraft. In that case, a short lifetime would not be surprising, as a spacecraft would presumably be a fairly recent addition to Mars's satellites. Alas, with a proper tidal model and data such as the OP, there is no more need for that hypothesis.

    8. Re:Ask slashdot by mbone · · Score: 1

      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, orienting yourself would be easy - Mars is about 40 degrees in diameter from Phobos. On the other side, well hopefully you thought to keep your spacecraft within range.

      By the way, Phobos is very non spherical, and the combination of that, its small gravity and the nearness of Mars means that the local gravitational field is very lumpy - the surface gravity varies by almost an order of magnitude around the body, and there are all sorts of odd local orbits. If you threw a rock, you would never know where it was going to go.

    9. Re:Ask slashdot by CecilPL · · Score: 2, Informative

      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.

    10. Re:Ask slashdot by Tablizer · · Score: 1

      That's "large scale" texture ;-)
         

      --
      Table-ized A.I.
  4. action films by f3r · · Score: 5, Insightful

    It's sad that we are so used to action and sci-fi films with amazing simulations of astonishing things, that when it comes to the real one (a piece of rock which really exists up there, and IS cool) we think we are seeing the intro for a 1985 asteroid game, and think for ourselves 'where are the explosions? I myself had to do an effort to rationally avoid that thinking and covince myself of the real coolness of the thing.

  5. That's odd... by jtownatpunk.net · · Score: 3, Funny

    I don't see any Leather Goddesses. Maybe I need to set the naughtiness level to "lewd".

    1. Re:That's odd... by MRe_nl · · Score: 1

      Xaero has "humiliated" them on "Hardcore" i'm afraid...

      --
      "Kill 'em all and let Root sort 'em out"
    2. Re:That's odd... by CarpetShark · · Score: 1

      That will happen automatically, due to time dilation, once we accelerate to lewdicrous speed.

  6. Nice mission overall by dragisha · · 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 also expected is downplay of whole thing, not-invented-here syndrome... But it's ok and it's temporary - results will surely be used without discrimination in world's scientific communities.

    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?!! One would expect it wil be everyday thing after so much time. Just think about how other technologies developed in 40 years span. Just compare already mentioned cameras and communications.... Weird.

    --
    http://opencm3.net, http://www.nongnu.org/gm2/
    1. Re:Nice mission overall by tftp · · Score: 4, 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.

    2. Re:Nice mission overall by Teun · · Score: 1

      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?

      --
      "The likes of Facebook and WhatsApp are free to those whose privacy is of zero value."
    3. Re:Nice mission overall by sznupi · · Score: 2, Informative

      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.

      --
      One that hath name thou can not otter
    4. Re:Nice mission overall by david.given · · Score: 1

      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.

    5. Re:Nice mission overall by Brett+Buck · · Score: 2, Interesting

      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.

                What in the world are you talking about? Both parachutes and rocket-braked landings have successfully been used, in combination on the same mission. Parachutes are marginal due to the thin air, so you use rocket engines to slow it down. There is no significant issue with firing engines in thin air, it's a non-issue - the bit about "atmospheric gasses interfering with the engine" is 99% nonsense. The only issue with doing it entirely with rocket engines is that it takes so much fuel that you would have trouble getting it there without a huge rocket. So you aerodynamically brake it to some reasonable velocity, then finish it off with rocket engines. It's a relatively simple problem that was solved and proven i 1976 and repeated many times since.

            Airbags are useful for smaller missions because it allows you to do less rocket-propelled braking and save fuel. But even the airbab missions used both parachutes and rocket braking. If you just let it fall at terminal velocity with no chute and no braking, no airbag is going to save it, you are going to dig a pretty deep hole.

                Brett

    6. Re:Nice mission overall by mbone · · Score: 1

      Landing large payloads on Mars is tough, 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 air density
      than the mean surface), and plan on building a space elevator as soon as is possible.

    7. Re:Nice mission overall by TorKlingberg · · Score: 1

      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.

    8. Re:Nice mission overall by bill_mcgonigle · · Score: 1

      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.

      --
      My God, it's Full of Source!
      OUTSIDE_IP=$(dig +short my.ip @outsideip.net)
    9. Re:Nice mission overall by rantingkitten · · Score: 1

      I think one problem with using rockets to slow your descent, at least near the ground, is that you risk serious damage to the very ground you want the robot to study.

      --
      mirrorshades radio -- darkwave, industrial, futurepop, ebm.
    10. Re:Nice mission overall by dragisha · · Score: 1

      "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.

      --
      http://opencm3.net, http://www.nongnu.org/gm2/
  7. Two Words by __aamisb9940 · · Score: 1

    most awesome ...'awesome' is so over-used, but it's truly appropriate here

    1. Re:Two Words by Brad1138 · · Score: 1

      most awesome ...'awesome' is so over-used, but it's truly appropriate here

      Your comment is awesome dude....

      --
      If you could reason with religious people, there would be no religious people
  8. Wow.... by WGFCrafty · · Score: 1

    Encapsulating planets takes a BIG satellite.

    It must stretch itself out really thin for only weighing 1123 kg.

    1. Re:Wow.... by WGFCrafty · · Score: 1

      errr, moons...

  9. TIFF URLs missing extra "f" by Wodin · · Score: 1

    If you want the "HI-RES TIFF" versions of the images, you'll need to add another "f" onto the ends of the URLs.

    --
    -- Wodin
  10. Pitch black. by yogibaer · · Score: 1

    What is really creepy about these movies and pictures is, that somehow you always expect stars in the background (like on a ship at night). Instead you get two rocks hanging in a black void. Just one vast emptiness. Scary.

    1. Re:Pitch black. by sznupi · · Score: 1

      Just shows that also this move was done in Arizona desert.

      --
      One that hath name thou can not otter
    2. Re:Pitch black. by Gerafix · · Score: 1

      Anybody with experience using a camera will not expect such a thing at all, in fact the opposite. Well, with current technology anyway. Plus big dynamic range isn't really that useful in space...

  11. No! Get away! by Windwraith · · Score: 2, Funny

    Or you might end knee-deep in the dead.

  12. 4X MORE magnification by smchris · · Score: 1

    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.

  13. Well that's disappointing... by FatdogHaiku · · Score: 1

    The RSS feed headline said "Mars Express Captures Phobos and Deimos" and I thought to myself, if we can do that then any future comet or asteroid impact should be easy to avoid, we just capture it and park it at Lagrange Point 4. Then we can maybe use the materials as resources for other missions....

    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.

    --
    You have the right to remain sentient. If you give up the right to remain sentient, you will be elected to public office
  14. Maelstrom by janwedekind · · Score: 1

    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

  15. Fake? by seven+of+five · · Score: 1

    Notice that both moons move in a perfect horizontal line? So the camera was perfectly aligned at the time? Or ???
    Did anyone else expect tumbling or rotation, however slowly?

    1. Re:Fake? by Gerafix · · Score: 1

      Post-processing is your best friend when dealing with the trials and tribulations of astrophotography. Or maybe it's because Mars Express has a pointing accuracy of 0.04 degrees with regard to its inertial reference frame and 0.08 for Mars orbital reference frame. Either way I guess.

  16. Re:Sure, if you believe in by Gerafix · · Score: 1

    Pff, seems like they got to you too. You see, Mars is just a conspiracy made by the Illuminati to take over the world with their panspermia.

  17. Odd Phobos striations by macraig · · Score: 2, 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....

    1. Re:Odd Phobos striations by reverseengineer · · Score: 1

      Well, I thought that they were a system of cracks spreading out from the largest crater on Phobos, Stickney (not visible on the still image in the story, but visible edge-on in the lower right in the movie, or here. It was thought that the impact that created Stickney nearly tore Phobos apart, leaving prominent scars all over the surface, but apparently the system of grooves is far more complex, as was actually determined by the Mars Express mission. One of the sources for the wikipedia page on Stickney is for this paper which maps the striations, and suggests they were formed by ejected material from a series of impacts on Mars.

      --
      "FDA staff reviewers expressed concern about the number of patients who were left out of the study because they died."
    2. Re:Odd Phobos striations by macraig · · Score: 2, Informative

      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.

    3. Re:Odd Phobos striations by dvs01 · · Score: 1

      I believe they were caused by Barons of Hell.

  18. Let's go by Yergle143 · · 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.

  19. Or maybe... by tjstork · · Score: 1

    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.

    --
    This is my sig.
  20. don't kiss up to foreigners. by tjstork · · Score: 1

    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 rationalize themselves into their country doing.

    --
    This is my sig.
  21. Re:Drunk Pirate with two peglegs. by reverseengineer · · Score: 1

    Those are Cyberdemon tracks!

    --
    "FDA staff reviewers expressed concern about the number of patients who were left out of the study because they died."
  22. Someone spot E1M1 by dvs01 · · 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?