  The electric solar wind sail is a novel propellantless space propulsion
concept. According to numerical estimates, the electric solar wind sail can
produce a large total impulse per propulsion system mass. Here we consider
using a 0.5 N electric solar wind sail for boosting a 550 kg spacecraft to
Uranus in less than 6 years. The spacecraft is a stack consisting of the
electric solar wind sail module which is jettisoned roughly at Saturn distance,
a carrier module and a probe for Uranus atmospheric entry. The carrier module
has a chemical propulsion ability for orbital corrections and it uses its
antenna for picking up the probe's data transmission and later relaying it to
Earth. The scientific output of the mission is similar to what the Galileo
Probe did at Jupiter. Measurements of the chemical and isotope composition of
the Uranian atmosphere can give key constraints to different formation theories
of the Solar System. A similar method could also be applied to other giant
planets and Titan by using a fleet of more or less identical probes.
