From William Robinson
Under the title “Space bling” you mention that asteroid 2011 UW-158 “is thought to have a core made of platinum” (25 July, p 5).
This seems unlikely to me. I have no reason to doubt that some asteroids are rich in precious metals, including platinum, but the term is relative. Here on Earth, in the platinum mines of South Africa, processing around 10 tonnes of rock yields less than 30 grams of pure platinum.
Looking on the bright side, mining these asteroids could give a kick-start to our moribund space programme. Scientific knowledge and national prestige have failed to get us out of Earth orbit for the last 43 years.
Slough, Berkshire, UK
