Revealing the origin of Ceres’s water could determine whether there is the potential for life beneath its surface, as is thought to be the case on icy moons around Jupiter and Saturn.
Measurements from Rosetta’s Rosina instrument found that water on comet 67P /Churyumov-Gerasimenko contains about three times more deuterium – a heavy form of hydrogen – than water on Earth.
The discovery seems to overturn the theory that Earth got its water, and so its ability to harbour life, from water-bearing comets that slammed into the planet during its early history.
Comet 67P is thought to have come from what is called the Kuiper belt, a broad band of frozen bodies that begins beyond the orbit of Neptune. The main asteroid belt contains more rocky objects that circle the sun between the orbits of Mars and Jupiter.
Kathrin Altwegg at the University of Bern said that rather than comets ferrying water to Earth, it may have arrived onboard asteroids instead. Details of the discovery are reported in the journal, Science.
“Today asteroids have very limited water, that’s clear. But that was probably not always the case, said Altwegg. In the earliest period of the solar system, 3.8bn years ago, asteroids are thought to have crashed into Earth regularly in what is called the late heavy bombardment. “At that time, asteroids could well have had much more water than they have today,” Altwegg said.
The Rosina instrument measured water coming off the comet as it flew around the body. Scientists plan to take more measurements as the comet nears the sun and its begins to spew more water vapour and dust out into space.
Measurements from other comets have found water with similar deuterium contents to that on Earth. But the strange composition of comet 67P’s water suggests that the picture of comets bringing water to Earth is too simplistic.
TIRED: comets are the source of water for Earth.
WIRED: asteroids are the life giving, death dealing forces of nature.
Aside from a small amount of water acquired by the youthful Earth in the form of hydrated silicate rocks, the great bulk of Earth’s water must have been delivered from beyond. The pummelling Earth received in its youth from asteroids and comets will have delivered the water that is so vital to life as we know it.
The problem is actually exacerbated by the collision that formed the moon. That giant impact occurred after the proto-Earth had differentiated – with the heaviest elements (such as iron and nickel) settling to our planet’s core. This means that the mantle and crust of the Earth, stripped off by the collision, would also have contained most of Earth’s water at the time.
Without the asteroid and comet collisions that have occurred since the moon’s formation, the Earth would most likely be dry and lifeless. But impacts are a stochastic, chance thing – some planetary systems will have architectures that are poorly set up from the point of view of the delivery of volatiles to any terrestrial worlds therein.
On the other hand, studies of the formation and evolution of the “hot Jupiters” – planets like Jupiter orbiting far closer to their hosts than Mercury orbits the sun – suggest that the inward migration of such planets could drag with them vast amounts of volatiles.
In those models, so much water is delivered to the inner reaches of those systems that any Earth-like planets that form are water worlds – drenched in oceans hundreds of kilometres deep.
While such worlds might well be teeming with life, it is unlikely that it would be easy to detect. Indeed, without continents, the oceans could be almost completely lifeless, with the only source of nutrients being volcanoes on the ocean floor.
If life on such water worlds did exist, it might be so deeply buried in the ocean that any sign of it would be extremely challenging to detect, particularly from a distance measured in tens or hundreds of light-years. As such, ocean worlds would most likely be poor targets for the initial stages of the search for life elsewhere.Read more
fuckyeahdarkextropian: “Preparations for Asteroid Awareness Day will be unveiled alongside a declaration signed by leading figures that calls on governments, private companies and philanthropists to back technologies that spot and track space rocks that might one day slam into Earth. Signed by Lord Rees, the astronomer royal, Ed Lu, a former shuttle astronaut, and Brian […]Read more "COMING SOON: Asteroid Awareness Day"
Read more "The Dark Extropian Report: PANSPERMIA SPECIAL EDITION"
Welcome to a Special Edition of The Dark Extropian Report. It’s been a bumper few weeks, months and years even in the world of astrobiology, and in particular in the area related to the theory of Panspermia – the idea that life came riding in on an asteroid or comet to our planet. This is one of the very core ideas of Dark Extropianism; that we are inextricably bound to the cosmos, on a grand scale that at the very least is inter-planetary. That our fate lies there as much as our origins do. That we are more than just star dust, but part of a living system that spans billions of years, who’s distance is measured by the speed of light. That ecology is something that spans the galaxy. That we are not meant to stay here, that our destiny lies amongst the stars.
A few notes for asteroid death cultists:
That is all.
For those wondering, a new episode of multiverse tv is coming. It features Dolph Lundgren. He has a question, it’s on the tip of his brain. There will be GIFS.
Prompted by ello’s quick (d)evolution into becoming yet another soon to be forgotten FaceTwitter clone, rather than a unique, albeit anti-social social network and wanting to back-up the posts there that had developed into their own thing, and also with a need to create a new space to drop some excerpts from works-in-progress as they […]Read more "The first rule of (De)Extinction Club is…"
Perhaps a safer way for seed to spread would be for whole rocks to travel other worlds. Previous research has showed that, theoretically, a massive meteorite impact could blast up and scatter tonnes of rock across the solar system.
In their recent paper, Hara and colleagues considered one of the biggest meteorite hits known in Earth’s history: the Chicxulub impact 65 million years ago, usually blamed for killing off the dinosaurs. The 10-kilometre-wide asteroid weighed well over a trillion tonnes, and could have excavated as much mass from the surface of the Earth.
The team calculated how much of that stuff could have ended up on the bodies in the solar system thought most likely to be hospitable to life: Saturn’s moon Enceladus and Jupiter’s moon Europa, both of which are thought to have subsurface oceans of liquid water.
Under certain conditions, as many as 300 million individual rocks could have ended up on Europa, and 500 on Enceladus, they calculated. Even more could have ended up on the moon and Mars. The team write:
“Although it is uncertain how rocks enter the presumed sea under the surface, for example, of Enceladus and Europa, the probability may be high that microorganisms transferred from Earth would be adapted and grow there.”
A handful of rocks could even have made it to planets around other stars. Once such could be Gliese 581, a red dwarf 20 light years away with a super-Earth orbiting at the outer edge of its habitable zone, where water could be liquid. Hana and colleagues calculated that about 1000 rocks from the Chicxulub impact could have reached that far in about a million years, meaning any life that made it would have had 64 million years to develop – or die off.