Colonization of the outer Solar System is subject to only 0.01 rem a day. When NASA carried out a study called "HOPE" (Revolutionary Concepts for Human Outer Planet Exploration) regarding the future exploration of the Solar System, the target chosen was Callisto. It might be possible to build a surface base that would produce fuel for further exploration of the Solar System. The Keck Observatory announced in 2006 that the binary Jupiter trojan 617 Patroclus, and possibly many other Jupiter trojans, are likely composed of water ice, with a layer of dust. This suggests that mining water and other volatiles in this region and transporting them
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