Wild Little Mercury to Cause Interplanetary Smashup? Maybe.

by Anne Minard on June 10, 2009

Artistic design : J Vidal-Madjar; planet textures from NASA; copyright: IMCCE-CNRS

Artistic design : J Vidal-Madjar; planet textures from NASA; copyright: IMCCE-CNRS

The chaotic evolution of the planetary orbits in the Solar System could cause a close approach or even a collision within the next 5 billion years, according to a paper in this week’s issue of Nature.

The odds are small, but that didn’t stop NASA from releasing a series of really fun “what-if” images (below) …

Mercury is the wild card, according to co-authors Jacques Laskar and Mickael Gastineau of the Paris Observatory. If its orbit elongates, our puniest neighbor could throw the whole block in peril.

Because its orbit resonates with that of Jupiter, Mercury could become the planet gone wild (eccentric in astronomy speak), colliding with Venus.

The chance is slim, the authors point out — around 1 percent. But the finding — revealed through thousands of computer simulations — was a surpise.

“More surprisingly, in one of these high-eccentricity solutions, a subsequent decrease in Mercury’s eccentricity induces a transfer of angular momentum from the giant planets that destabilizes all the terrestrial planets,” the authors write, “with possible collisions of Mercury, Mars or Venus with the Earth.”

Gregory Laughlin, an astronomer at the University of California Santa Cruz who wrote an accompanying editorial about the new paper, couched it as “a note of definite cheer” in the midst of “a seemingly endless torrent of baleful economic and environmental news.” Indeed, there’s a 99 percent chance that the planets will not engage in a destructive round of planetary billiards, and that’s a good thing.

“With 99 percent certainty, we can rely on the clockwork of the celestial rhythm — but with the remaining 1 percent we are afforded a vicarious thrill of danger,” he writes.

Presumably inspired by that vicarious thrill, NASA teamed up with space artist J. Vidal-Madjar to craft the following smash-up images, which were provided by Nature. Enjoy!

Artistic design : J Vidal-Madjar; planet textures from NASA; copyright: IMCCE-CNRS

Artistic design : J Vidal-Madjar; planet textures from NASA; copyright: IMCCE-CNRS

Artistic design : J Vidal-Madjar; planet textures from NASA; copyright: IMCCE-CNRS

Artistic design : J Vidal-Madjar; planet textures from NASA; copyright: IMCCE-CNRS

Artistic design : J Vidal-Madjar; planet textures from NASA; copyright: IMCCE-CNRS

Artistic design : J Vidal-Madjar; planet textures from NASA; copyright: IMCCE-CNRS

Artistic design : J Vidal-Madjar; planet textures from NASA; copyright: IMCCE-CNRS

Artistic design : J Vidal-Madjar; planet textures from NASA; copyright: IMCCE-CNRS

  • Torbjorn Larsson OM

    On the previous mentioned paper: it dealt with Earth.

    It has interesting consequences for biosphere lifetimes though, when comparing tectonic biospheres vs others, or considering the future development of galactic habitable zones.

    extremophile species of prokaryotes.

    Those are the same as archaebacteria AFAIU. Bacteria can take 70-80 Celsius, at least it’s a constraint for their oxygenic photosynthesis, and according to protein and DNA fold data had such a bottleneck in precambrian times. This correlates with the temperature data on cherts harking back 3.5 Ga.

    [I'm not the only one noticing this. James Kasting spoke of this at the STScI -09 May symposium:

    Climate on the early Earth remains an enigma, as well. Despite the faintness of the young Sun, the early Earth appears to have been warm, or perhaps even hot. Taken at face value, oxygen and silicon isotopes in ancient cherts imply a mean surface temperature of 70(+/-15)oC at 3.3 Ga. A recently published analysis of the thermal stability of ancient proteins supports this conclusion. This evidence for hot early surface temperatures must be weighed against theoretical considerations, as well as geomorphic evidence for glaciation at 2.9 Ga, 2.4 Ga, and 0.6-0.7 Ga. Such models must also account for the well documented correlation between the rise of O2 at 2.4 Ga and the Paleoproterozoic glaciations which occurred at that same time.

    (I'm not as convinced of global or even local glaciations as Kasting.)

    According to the two isotope thermometers of cherts (and correlating with the two of proteins and DNA), sea temperatures linearly decreased from ~ 80 to ~ 20 Celsius at the start of the Cambrian.

    Also, while abiogenesis probably occurred in alkaline heat vents driven by redox potentials of circulating acidic sea water, it seems from the same data that the first proteins developed at moderate temperatures ~ 20 Celsius. Probably life developed before the late heavy bombardment originated the later green house carbon dioxide atmosphere. And now there is a paper showing that life probably can survive LHB.]

    According to a massive genome analysis last year, supporting Cavalier-Smith’s neomura theory, archaebacteria are sisters with eukaryotes. In the neomura theory they developed from actinobacteria as recent as ~ 850 Ma, which corresponds with fossil data. (Steroles which still in some cases are taken as evidence of ~ 2 Ga eukaryotes are also produced by actinobacteria.)

    Extremophiles (and so the methanogens) of Earth are then late developments of evolution. While abiogenesis seems simple and robust enough, biospheres are likely a lot less easy to mature and get robust than extremophiles would indicate.

    [Btw, and also less robust are then traces of methane as indicators of life, say on Mars. Albeit it could possibly been contingency that made it late here, it should be more researched.]

  • Lawrence B. Crowell

    So according to this things were quite warm in the late preCambrian. It is my understanding that about 700Mya the Earth did experience a considerable glacial period. This might have been a part of the 80-20C cooling.

    The data as I understand it does suggest that the Earth ~ 3.5Bya was comparatively warm. This is somewhat puzzling since the sun was likely about 25-20% cooler then. I suspect the solar system was in a different configuration then, though not drastically so. The Earth may well have been in a closer orbit to the sun. The solar system is not completely stable, and it might be wrong to suppose it had the same configuratio then that it does now.

    Lawrence B. Crowell

  • ND

    This topic is being discussed on NPR’s Science Friday right now.

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