Jupiter to several seconds, and short bursts (or S-bursts) that had a duration of less than a hundredth of a second. Scientists discovered that there were three forms of radio signals transmitted from Jupiter. Since 1973 a number of automated spacecraft have visited Jupiter, most notably the "Pioneer 10" space probe, the first spacecraft to get close enough to Jupiter to send back revelations about the properties and phenomena of the Solar System's largest planet. Flights to other planets within the Solar System are accomplished at a cost in energy, which is described by the net change in velocity of the
Jupiter flyby missions and later by the "Galileo" orbiter. In late February 2007, Jupiter was visited by the "New Horizons" probe, which used Jupiter's gravity to increase its speed and bend its trajectory en route to Pluto. The latest probe to visit the planet is "Juno", which entered into orbit around Jupiter on July 4, 2016. Future targets for exploration in the Jupiter system include the probable ice-covered liquid ocean of its moon Europa. Astronomers have discovered nearly 500 planetary systems with multiple planets. Regularly these systems include a few planets with masses several times greater than Earth's (super-Earths), orbiting closer