Life on Earth might have come from Ceres

Friday, March 06, 2009

Well, this certainly is an interesting theory:

Early in the history of the solar system was a period known as Late Heavy Bombardment, a turbulent time when cataclysmic asteroid impacts were common. If there was life on Earth before this dangerous era, it was most likely eradicated and had to begin again after much of this cosmic debris had cleared out of the inner solar system. Interestingly, evidence indicates that Ceres avoided being pummelled by devastating impacts during this time. If it had been bombarded, it would have completely and forever lost its water mantle, as its gravitational force is too weak to recapture it. This is probably what happened to the asteroid Vesta, which has a very large impact crater and no water.
This is what Vesta looks like in comparison:

The crater is quite large (from Wikipedia)::
The most prominent surface feature is an enormous crater 460 kilometres in diameter centered near the south pole. Its width is 80% of the entire diameter of Vesta. The floor of this crater is about 13 kilometres below, and its rim rises 4–12 km above the surrounding terrain, with total surface relief of about 25 km. A central peak rises 18 kilometres above the crater floor. It is estimated that the impact responsible excavated about 1% of the entire volume of Vesta, and it is likely that the Vesta family and V-type asteroids are the products of this collision.
Okay, so Ceres escaped a collision of this type which was lucky, because otherwise it wouldn't have been able to retain its water ice. Then what?
"The evidence points to Ceres having remained relatively unscathed during the Late Heavy Bombardment," states Houtkooper. He says this means Ceres still could have "a water ocean where life could have originated early in the history of the solar system."

This leads to an interesting hypothesis. If the Earth was sterilized by colossal impacts, but Ceres hosted life which survived, could the dwarf planet have reseeded our world with life, via rock fragments that chipped off Ceres and then crashed into Earth? Are all organisms on Earth, including humans, descendants of Ceres? This is an idea that Houtkooper had to pursue.

"I looked at the different solar system bodies which either had or currently have oceans," he explains. "The planet Venus probably had an ocean early in its history, but the planet's greater mass means that more force is needed to chip off a piece of the planetary crust and propel it in the direction of the Earth. Smaller objects like Ceres have lower escape velocities, making it easier for parts of it to be separated."

Houtkooper then calculated the orbital paths of candidate planets, moons and asteroids to see which were in the best positions to have pieces successfully reach the Earth, without being intercepted by other objects. Ceres fared favourably in these calculations.
The escape velocities for Earth, Venus, Mars and Ceres are as follows:
  • Earth: 11.186 km/s
  • Venus: 10.46 km/s
  • Mars: 5.027 km/s
  • Ceres: 0.51 km/s
That escape velocity is a mere 1836 kph, or a bit over twice the velocity of your standard commercial jet. To escape Mars you need a velocity ten times that, and twenty time that for Venus and Earth.

Conclusion thus far: who knows? Put it on the list as an interesting hypothesis to think about when Dawn arrives (2015) and we know more. This low escape velocity is why I believe Ceres would be a better destination for a manned mission than Mars, and I'm in favour of any theory that puts Ceres on the map as an interesting destination worth exploring, correct or not. In any case, having such a small body nearby (relatively) with this much water ice is something definitely deserving of a lot of attention. Once Dawn arrives at Vesta we'll start to see more attention being paid attention to this part of the Solar System.


  © Blogger templates Newspaper by 2008

Back to TOP