New Delhi: Scientists have carefully examined data captured by an old NASA spacecraft and a meteorite found in Northwest Africa to pinpoint the age of one of the largest and most ancient impact basins in the entire solar system, the South Pole-Aitken (SPA) basin on the Moon, that spans over 2,000 kilometres. The meteorite is designated as Northwest Africa (NWA) 2995, and was discovered in Algeria in 2005. The rock contains rocks that were once lunar soil that have fused together because of the heat and pressure of an impact event, forming what is called regolith breccia. This material was dated between 4.32 and 4.33 billion years ago.
NWA 2995. (Image Credit: University of Manchester).
The results were then compared to observations conducted by NASA’s Lunar Prospector mission between 1998 and 1999. The researchers found many chemical similarities between NWA 2995 and the rocks within the SPA basin, confirming the new estimated age of the formation of the SPA basin. According to the new research, the impact event that created the SPA basin occurred 4.32 billion years ago, which pushes back the data by 120 million years in comparison to conventional estimates. The research also indicates a longer period of gradual bombardment, as against a shorter period of intense bombardment on the lunar surface.
Implications beyond the Moon
A paper describing the findings have been published in Nature Astronomy. Corresponding author of the study, Katherine Joy says, “The proposed ancient 4.32 billion year old age of the South Pole-Aiken basin now needs to be tested by sample return missions collecting rocks from known localities within the crater itself.” The research challenges the conventional timeline of events built up over a series of lunar missions. The Earth and the inner planets too experienced a similar bombardment at the same time. The new research challenges the conventional history of impact events in the infancy of the solar system. India’s Chandrayaan 3 mission landed on an ancient and buried impact crater, which had material ejected from the SPA Basin.
