It’s widely believed that a deadliest asteroid had doomed the dinosaurs to extinct on Earth 66 million years ago. Amid growing theories of how and what could have ensued current life form on Earth, here’s a new study Dinosaur-dooming asteroid struck earth at ‘deadliest possible’ angle.
The study, published in Nature Communications, is based on simulations showing that the asteroid hit Earth at an angle of about 60 degrees, thus maximizing the amount of climate-changing gases thrust into the upper atmosphere. It could have unleashed billions of tonnes of sulphur, blocking the sun and triggering the nuclear winter which could have killed the dinosaurs and wiped off 75% of life on Earth.
Using a combination of 3D numerical impact simulations and geophysical data from the site of the impact, the new models are used to reproduce the whole event – from the initial impact to the final crater, now known as Chicxulub. All the simulations used a 17-km diameter asteroid with a density of 2630 kgm3 and a speed of 12 km/s, and were performed on the Science and Technology Facilities Council (STFC) DiRAC High Performance Computing Facility.
Besides the lead researcher Prof. Gareth Collins of Imperial’s Department of Earth Science and Engineering, the team involved the University of Freiburg, and The University of Texas at Austin. “Our simulations provide compelling evidence that the asteroid struck at a steep angle, perhaps 60 degrees above the horizon, and approached its target from the north-east. We know that this was among the worst-case scenarios for the lethality on impact, because it put more hazardous debris into the upper atmosphere and scattered it everywhere – the very thing that led to a nuclear winter.”
The researchers say that while the study has also given them important insights into the dinosaur-dooming impact and project how large craters on other planets such as Mars are formed. The study co-author Thomas Davison, also of Imperial’s Department of Earth Science and Engineering, said: “Large craters like Chicxulub are formed in a matter of minutes, and involve a spectacular rebound of rock beneath the crater.”
The study of upper layers of earth at the Chicxulub 200-km wide crater in present-day Mexico showed high amounts of water as well as porous carbonate and evaporite rocks,indicating that when heated and disturbed by the impact, these rocks would have decomposed, flinging vast amounts of carbon dioxide, sulphur and water vapour into the atmosphere.
The sulphur, which rapidly forms aerosols that would have blocked the sun’s rays, halting photosynthesis in plants and rapidly cooling the climate would have eventually contributed to the mass extinction event that killed 75 per cent of life on Earth 66 million years ago.
The team of researchers also examined the shape and subsurface structure of the crater using geophysical data to feed into the simulations that helped diagnose the impact angle and direction, while they also drilled into the 200 km-wide crater for more evidence to corroborate with rocks experiencing enormous due to the asteroid’s impact.
At Chicxulub, these centres are aligned in a southwest-northeast direction, with the crater centre in between the peak-ring and mantle-uplift centres at the angle of 60 degrees.