# Sources of Extraterrestrial Rare Earth Elements: To the Moon and Beyond
## 5 Lunar Resources
### Missions beyond the Moon  
Current plans to explore Mars include NASA's upcoming InSight (Interior Exploration using Seismic Investigations, Geodesy and Heat Transport) mission and the Mars 2020 rover. The InSight mission will place a lander on the Martian surface with a launch date of 5 May 2018, and a landing date of 26 November 2018 [193]. The objective of this mission is to explore the Martian interior. The Mars 2020 rover is scheduled to launch in July/August 2020 with a proposed landing in February 2021 [194]. One of the aims of this mission to prepare for human exploration of Mars which will in-part be achieved through extraction of oxygen from Mars' CO\({}_{2}\) rich (\(\sim\)96%) atmosphere. Current plans for human exploration of Mars through NASA missions are associated with sending humans to the red planet in the 2030s [195]. Associated with this goal is transport of equipment to cislunar space and the establishment of a \"deep-space gateway\". Phase 1 of this is scheduled between 2018 and 2026 and would include four crewed flights that would deliver key components of the Deep Space Transport vehicle to cislunar space ([195], see also [196]). At the time of writing, no known mission plans exist to mine Mars with the existence of ones on Mars (REE-dominated or not) \"hypothetical\" [197]. Alongside NASA's interest in the red planet, the European Space Agency (ESA), in collaboration with the Roscosmos State Corporation, is planning to send its ExoMars lander in 2020. In addition, several nongovernment organizations also have plans to explore Mars with SpaceX planning to launch robotic capsules in 2018 and Mars One planning robotic missions in 2020, 2022, and 2024 [198].  
In addition to current, upcoming, and proposed missions to the Moon and Mars (see earlier), in situ chemical characterization of other rocky objects in our Solar System through missions to Near Earth Asteroids (NEAs) aim to advance our understanding of the elemental composition of planetary materials. This approach to quantifying the geological and geochemical features of nearby objects was pioneered in 2001 through NASA's Near-Earth Asteroid (NEA) Rendezvous-Shoemaker mission to Eros, the second largest NEA [199]. More recently, the Hayabusa mission administered by the Japanese Space Program, JAXA (Japan Aerospace Exploration Agency), landed on NEA 25143 Itokawa in 2005. This led to the return of regolith samples to Earth in 2010 [200]. A follow-up mission, Hayabusa 2, launched in 2014 to asteroid 162173 Ryugu. This mission is scheduled to land on the asteroids surface in 2018 prior to returning samples to Earth in 2020 [201]. More recently, 2016 saw the successful launch of OSIRIS-Rex (Origins-Spectral Interpretation-Resource Identification-Security Regolith Explorer) to the asteroid 101955 Bennu. This mission represents NASA's first attempt to return samples to Earth from a NEA [202].  
Whether an extraterrestrial resource is identified as an (REE) ore deposit or water, or even something else, the resources first need to be evaluated, the technology associated with their mining and extraction demonstrated and validated, and successful extraction and application shown [28]. As presented here, there are extraterrestrial sources of REEs in the form of volumetrically minor phosphate phases in lunar, martian, and other meteoritic material. Despite there being little geological and geochemical evidence to support the notion that these REEs exist in concentrations where mining them would be justifiable [186; 188] future explorations may change this [24]. It is likely that the future exploration of space will also be pursued for commercial reasons (Virgin Galactic as a current example) yet science stands to be a significant beneficiary of this endeavor [203].