 Another new technology used by the probe was its engine, called a Hall effect thruster , a new form of Ion thruster (first considered by scientists in the 1950's).
<fluency>  Another new technology used by the probe was its engine, called a Hall effect thruster , a new form of Ion thruster (first considered by scientists in the 1950's).
 Another new technology used by the probe was its engine, called a Hall effect thruster , a new form of w|Ion thruster (first considered by scientists in the 1950's).