An unstable nucleus can emit a ‘package’ of two protons and two neutrons, called an alpha particle, to become more stable. Alpha radiation is made up of a stream of alpha particles emitted ...

As part of soil testing, the rover used its alpha-particle X-ray spectrometer 23 ... It also explains why so many moon rocks have a similar composition to those found on Earth.

The Alpha Particle X-ray Spectrometer (APXS ... revealing the elemental composition of the lunar terrain. Speaking to ...