An international team of researchers led by scientists from the University of Kent and Imperial College London discovered extraterrestrial particles in Antarctica pointing to a medium-sized asteroid impact on the continent. The researchers believe the impact occurred about 430,000 years ago, and the particles were discovered at the top of the Walnumfjellet mountain in Queen Maud Land, in eastern Antarctica.
The discovered particles are called condensation beads 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 meteorological material that spread and settled on the Antarctic ice sheet. The authors of the research article say that this is an important discovery for the geological record because the evidence for this type of event is scarce.
The scarcity of evidence is mainly due to the difficulty of identifying and characterizing the impact particles. The researchers say they are sure that human ancestors did not witness the explosion. The study’s co-author, Dr. Matthew Genge, says the explosion of an asteroid or comet just a few tens of meters at low altitude can be similar to a nuclear explosion with energy measured in megatons. Asteroids exploding in the atmosphere at low altitudes are more common than those that create craters, but they are the most difficult to detect in advance.
Debris, in this case, was examined from the mountain by analyzing extremely small amounts of different chemical elements. The researchers found a high nickel content and unique oxygen signatures on the debris, allowing them to identify an approximate date of impact and highlight the extraterrestrial nature of the recovered particles. The team’s scientists also believe the study highlights the importance of reevaluating the threat posed by medium-sized asteroids. Such an impact would be highly destructive over a large area.