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Mars

Mars Express Orbiter Buzzes Martian Moon Phobos 39

Posted by Unknown Lamer
from the watch-out-for-imps dept.
astroengine writes "On Sunday, at 5:17 p.m. GMT (12:17 p.m. EST), Europe's Mars Express orbiter successfully completed a daring low-pass of Mars' largest moon Phobos. In an effort to precisely measure the gravitational field of the moon, the 10 year-old mission was sent on a trajectory that took it only 45 kilometers (28 miles) from the dusty surface, the closest any spacecraft has ever come to the natural satellite."
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Mars Express Orbiter Buzzes Martian Moon Phobos

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  • On the surface (Score:5, Interesting)

    by mbone (558574) on Monday December 30, 2013 @07:52PM (#45824135)

    Here is a simulated view of the Mars Express pass from the surface of Phobos. https://www.youtube.com/watch?v=Z-YlKEKt-_k [youtube.com]

    However, the simulation missed something - Mars Express has a 40 meter dipole antenna - at 45 km, that's 3 arc min, so you could see Sun glint on the dipoles with your naked eye (i.e., you could resolve it as a structure, not just a dot of light). With a pair of binoculars, you could even see the spacecraft's solar panels.

    • by mcgrew (92797) *

      How about some closeup pictures of the satellite? The photo in the link in TFS was from 2010.

      I'm disappointed. Oh, well.

      • by mbone (558574)

        How about some closeup pictures of the satellite? The photo in the link in TFS was from 2010.

        I'm disappointed. Oh, well.

        Here you go [albertoconti.com] (from 2010, but pretty up close and personal).

        • by mcgrew (92797) *

          The thing is, this pass was supposed to be the closest, I've already seen the 2010 photos.

      • They had to keep the antenna pointed at Earth to get Doppler data from the signal. This meant that the cameras had to point somewhere else :)

        From the comment section on the update:

        Hi Gorp: No pics on this one! Radio science only. MEX was moving too fast for decent photos, and its communication antenna had to be pointed toward Earth throughout, meaning its cameras were NOT pointed at Phobos... so no pics. We have some nice ones coming up taken around 20 December...

  • by mbone (558574) on Monday December 30, 2013 @08:00PM (#45824205)

    This was a radiometric (Doppler tracking) pass, with the main antenna pointed at the Earth. Pictures would have required re-orienting the spacecraft, and ideally rotating it to remove any motion blur on the close approach. You cannot do that and keep lock on the Earth, and they wanted to nail down the mass of Phobos. Initial reports from the DSN are the the Phobos gravity Doppler shift was visible in the "raw" residuals, so it's likely they will meet this goal.

  • "[S]ent on a trajectory that took it only 45 kilometers (28 miles) from the dusty surface"

    What is the range of a BFG?
    • by mbone (558574)

      "[S]ent on a trajectory that took it only 45 kilometers (28 miles) from the dusty surface"

      What is the range of a BFG?

      In the context, effectively infinite, as the escape velocity is ~ 10 m / sec. In fact, that would be true for almost any projectile - a fastball in baseball is 90 mph or 40 m / sec.

      Now, hitting a target 45 km away moving at a few km / sec relative velocity is another matter...

    • by savuporo (658486)

      You couldnt hit it as techbase was on the other side of terminator.

  • Wow. What a moon. (Score:2, Interesting)

    by dubdays (410710)
    Not to take anything away from the orbiter team, but damn...that moon looks almost as exciting as a lump of coal. What a crappy black rock.
    • by dubdays (410710)

      What a crappy black rock.

      Okay, I was wrong...the photo was black and white. It would have been nice if they shot it with a color camera (unless, of course, that's coming later).

      • What a crappy black rock.

        Okay, I was wrong...the photo was black and white. It would have been nice if they shot it with a color camera (unless, of course, that's coming later).

        Color photography from spacecraft is a sub-disipline of spectroscopy. They take monochrome images with different filters, then produce color pictures from the composites.

    • by mbone (558574)

      There are plenty of color photographs [wikipedia.org] of Phobos.

      Phobos is one of the darkest (lowest albedo) bodies in the Solar System. Since it is probably a Carbonaceous chondrite [wikipedia.org], it really is not too far from just big lump of tar.

    • Yeah, the universe- what a gyp!

  • by dubdays (410710) on Monday December 30, 2013 @08:53PM (#45824787)
    The dimensions of this moon is only 13.4 × 11.2 × 9.2 km [wikipedia.org]. Pretty tiny, it seems to me, for a planet the size of Mars.
    • by cusco (717999)

      Phobos and Deimos are both almost certainly captured asteroids, rather than having formed in the planet's orbit like the moons of the gas giants and Earth.

  • Did they manage to capture any images of the elusive Leather Goddesses...?
  • What they aren't showing us are the huge half mechanical demons with rocket launchers grafted onto their arms........

  • It's about time we got some reconnaisance on this place, I remember many years ago stories of people fighting the most hellish of beasts here!

  • Sorry, Goose, but it's time to buzz a tower.

You see but you do not observe. Sir Arthur Conan Doyle, in "The Memoirs of Sherlock Holmes"

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