Formation and evolution of the Solar System gravitational push against the outer planets, possibly causing Neptune to surge past Uranus and plough into the ancient Kuiper belt. The planets scattered the majority of the small icy bodies inwards, while themselves moving outwards. These planetesimals then scattered off the next planet they encountered in a similar manner, moving the planets' orbits outwards while they moved inwards. This process continued until the planetesimals interacted with Jupiter, whose immense gravity sent them into highly elliptical orbits or even ejected them outright from the Solar System. This caused Jupiter to move slightly inward. Those objects scattered by Jupiter into highly elliptical
Parker Solar Probe the early 2010s, plans for the "Solar Probe" mission were incorporated into a lower-cost "Solar Probe Plus". The redesigned mission uses multiple Venus gravity assists for a more direct flight path, which can be powered by solar panels. It also has a higher perihelion, reducing the demands on the thermal protection system. In May 2017, the spacecraft was renamed "Parker Solar Probe" in honor of astrophysicist Eugene Parker, coiner of the term "solar wind". The solar probe cost NASA US$1.5 billion. The launch rocket bore a dedication in memory of APL engineer Andrew A. Dantzler who had worked on the