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Mars Express Captures Phobos and Deimos
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. '"
It's so weird when reality looks like bad Photoshop.
http://twitter.com/OLDTELEGRAM
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.
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.
I don't see any Leather Goddesses. Maybe I need to set the naughtiness level to "lewd".
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.
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.