Tag Archives: cryovolcano

Dwarf Planet Ceres reveals its colors, but keeps its secrets

NASA’s Dawn spacecraft already has an impressive resume – it’s traveled to the asteroid belt and managed to start orbiting the dwarf planet Ceres, even though Ceres measures only 950 kilometers (590 miles) in diameter and has a very small gravitational field. But it’s not stopping just yet – after previously revealing a number of black and white pictures, Dawn has now provided a color photograph, but here’s the thing – it poses more questions than it answers.

Infrared images suggest that Spot 1 (top row), an area on Ceres, is made of ice. But the pair of bright gleams known as Spot 5 were invisible to an infrared camera (bottom right). Image credits: NASA/JPL-Caltech/UCLA/ASI/INAF

Ceres is the largest object in the asteroid belt between Mars and Jupiter. It comprises of rock and ice, and despite its small size (it’s about as big as Argentina), it is considered to be a dwarf planet (though some astronomers consider it an asteroid). Subsequently, it’s drawn quite a lot of scientific interest, and Hubble first looked at it a few years ago; but it wasn’t until the Dawn spacecraft actually started orbiting it that we got a really good look at it.

“This is the first idea of what the surface looks like,” said Martin Hoffmann, a Dawn scientist from the Max Planck Institute for Solar System Research in Göttingen, Germany.

Dawn took several tantalizing pictures of bright spots on Ceres, which might be the result of some active geology – something extremely exciting. In total, astronomers noticed 5 particular spots which they are trying to figure out.

The surface of the dwarf planet Ceres (shown here) has fewer large craters than researchers expected. Image credits: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA.

But could a celestial body so small actually have proper geology? Some scientists have speculated that one of the spots could be linked to an icy plume – a feature of so-called ‘cryovolcanoes’, volcanoes that spew ice and water instead of magma and ash. Finding such a small and yet active body is intriguing to say the least, but for now, Ceres is still keeping its secrets. We don’t know for sure what those spots are, how they were created, whether or not there is active geology or even whether frozen volcanoes actually exist.

“Dawn took its most recent set of images on 10 April, but only a small fraction of Ceres’s surface was illuminated at the time and mission scientists have not yet released them. The spacecraft will begin detailed science investigations on 23 April, after it settles into permanent orbit around Ceres,” Nature writes.

Dawn will near Ceres even more and take even more revealing, hopefully helping unravel the secrets that Ceres is hiding. The fact that we can get up-close and personal with something that’s so small and 400 million km away is absolutely mind blowing to me

Tectonics on Enceladus

As you may or may not know, we’ve launched a new section of our website: Science Questions and Answers – a section aimed at you guys, where you can ask all questions science-related, and share your knowledge with others. We’re still in the beta version, but please, feel free to ask away – we’ll do our best to answer, answer, and vote.

So recently, somebody asked about tectonics on Enceladus. How does tectonics even work on a satellite like Enceladus? Well…

Plate tectonics

plate tectonics

Plate tectonics is a theory that emerged in the 1970s, as an attempt to describe the large-scale motions of Earth’s lithosphere. Basically, the litosphere of the Earth is composed of distinct rigid plates, comprising of continental crust or oceanic crust. These plates are in a continuous relative movement.

enceladus tectonics 1

Plate tectonics is, at its very basic level, a kinematic phenomenon. Generally, it is accepted that tectonic plates are able to move because of the relative density of oceanic lithosphere and the relative weakness of the asthenosphere, but there is still a lot of debate here. The energy is provided by dissipation of heat from the mantle through convection currents; how mantle convection relates directly and indirectly to the motion of the plates is a matter of ongoing study and discussion in geodynamics.

Enceladus tectonics

enceladus tectonics 2

Enceladus is a moon of Saturn, with a mean diameter of 505 kilometers, seven times smaller than the Earth’s Moon; it is covered in ice, but seems to have considerable amounts of water beneath its frozen surface. The surface is so cold that instead of traditional volcanoes, the surface of Enceladus is riddled with cryovolcanoes – volcanoes that erupt volatiles such as water, ammonia or methane, instead of molten rock.

Voyager 2 provided the first signs of tectonics on Enceladus; troughs, scarps, and belts of grooves and ridges were all observed. Perhaps the most shocking evidence was rifts; a rift is a linear zone where the litosphere is being bulled apart by tectonic forces. Observed canyons are up to 200 km long, 5–10 km wide, and one km deep. These features are relatively young and seem active.

Another evidence of tectonics is the grooved terrain; the surface of Enceladus is scarred with curvilinear grooves and ridges which often separate smooth areas from impact craters. Other tectonic features include numerous fractures on the surface of the moon. All in all, the geodynamic evidence is pretty convincing, but there’s even more.

enceladus stripes

Recent data from the Cassini spacecraft highlighted, aside from the prominent tectonic features, intense heat flow and geyser like plumes. Therefore, in the deeps of Enceladus, there lies a significant source of heat. Even a tiny, icy moon like Enceladus can develop complex surficial geomorphologies, high heat fluxes, and geyser-like activity, even without convection currents – which raises an interesting discussion about Earth’s tectonics, but that’s a different story.

Exobiology implications

Not entirely related to the question… but. If the satellite has a hot core and an icy surface, it’s only logical that it has a liquid water habitat inside, which is actually quite likely to host life! Researchers and exobiologists in particular are speculating a lot on this matter, and Enceladus is one of the top candidates for extraterrestrial life in our solar system.