An international team of researchers led by scientists from the University of Kent and Imperial College London have discovered extraterrestrial particles in Antarctica pointing to a medium-sized asteroid impact on the continent. Researchers believe the impact occurred about 430,000 years ago, and the particles were discovered on the summit of Walnumfjellet Mountain in Queen Maud Land, East Antarctica.
The particles discovered are called condensation spherules and suggest that an asteroid at least 100 meters in diameter impacted the ice at high-speed 430,000 years ago. The impact caused an explosion creating a jet of melted and vaporized meteor material that scattered and settled over the Antarctic ice sheet. Authors on the research paper say this is an important discovery for the geological record because evidence of this type of event is scarce.
The scarcity of evidence is mainly due to how difficult it is to identify and characterize impact particles. Researchers say they are pretty sure human ancestors didn’t witness the explosion. Study co-author Doctor Matthew Genge says that the explosion of an asteroid or comet only a few tens of meters in size at low altitude can be similar to a nuclear blast with energy measured in megatons. Asteroids exploding in the atmosphere at low altitudes are more common than those that create craters but are the most difficult to detect in advance.
Debris, in this instance, was examined from the mountain by analyzing extremely small amounts of different chemical elements. Researchers discovered high nickel content and unique oxygen signatures in the debris, allowing them to pin down a rough date of impact and highlight the extraterrestrial nature of the recovered particles. Team scientists also believe the study highlights the importance of reassessing the threat posed by medium-sized asteroids. An impact of this size would be highly destructive over a large area.