单项选择题

The polar lights known as auroras are produced when charged subatomic
Line particles, such as protons and electrons flowing from the sun through Earth’s
magnetosphere, collide with atoms and molecules in Earth’s upper atmosphere.
For reasons not entirely understood, magnetic storms, called substorms,
(5) occasionally occur where the flow of particles greatly increases and the
interplanetary magnetic field becomes much stronger. These substorms are frequently
visible on the Earth because they increase the intensity of the polar lights.
Recently, five identical probes were blasted into orbit in a $200 million US
project known as the THEMIS mission. Scientists hope the probes will be able to
(10) investigate a number of mysteries about the nature of the substorm instabilities,
including when and where substorms begin, how the individual components
of the substorm interact, and how substorms power the auroras. The mission’s
secondary objectives involve understanding and predicting variations in the flux
of electrons in Earth’s outer radiation belt. These electrons pose a hazard to the
(15) safety of both astronauts and spacecraft. Understanding substorm instabilities
would thus improve success rates of future space missions. According to the passage, all of the following are objectives of the THEMIS mission EXCEPT: