4 Vesta

• On close inspection, the rocks turned out to be from outer space: lumps of rubble billions of years old, left over from the dawn of the Solar System.
• This is one of the most precise ages ever calculated for an object from space – and our results also cast doubt on some common assumptions about the early Solar System.

The secret life of aluminium

• Among the many elements in this cloud was aluminium, which came in two forms.
• Aluminium-26 is very useful stuff for scientists who want to understand how the Solar System formed and developed.
• Because it decays over time, we can use it to date events – particularly within the first four or five million years of the Solar System’s life.

Uranium, lead and age

• To figure that out, we will need to calculate the absolute ages of some ancient space rocks more precisely.
• It’s useful for determining the relative ages of different objects, but not their absolute age in years.
• There are two important isotopes of uranium (uranium-235 and uranium-238), which decay into different isotopes of lead (lead-207 and lead-206, respectively).

Meteorite groups

• Achondrites are rocks formed from melted planetesimals, which is what we call solid lumps in the cloud of gas and debris that formed the Solar System.
• Still other achondrites, including Erg Chech 002, are “ungrouped”: their parent bodies and family relationships are unknown.

A clumpy spread of aluminium

• Measuring the ratios of all the lead and uranium isotopes was what helped us to estimate the age of the rock with such unprecedented accuracy.
• We also compared our calculated age with previously published aluminium-26 data for Erg Chech 002, as well as data for various other achondrites.
• This shows aluminium-26 was indeed distributed quite unevenly throughout the cloud of dust and gas which formed the solar system.