  The lunar geological record has much to tell us about the earliest history of
the Solar System, the origin and evolution of the Earth-Moon system, the
geological evolution of rocky planets, and the near-Earth cosmic environment
throughout Solar System history. In addition, the lunar surface offers
outstanding opportunities for research in astronomy, astrobiology, fundamental
physics, life sciences and human physiology and medicine. This paper provides
an interdisciplinary review of outstanding lunar science objectives in all of
these different areas. It is concluded that addressing them satisfactorily will
require an end to the 40-year hiatus of lunar surface exploration, and the
placing of new scientific instruments on, and the return of additional samples
from, the surface of the Moon. Some of these objectives can be achieved
robotically (e.g. through targeted sample return, the deployment of geophysical
networks, and the placing of antennas on the lunar surface to form radio
telescopes). However, in the longer term, most of these scientific objectives
would benefit significantly from renewed human operations on the lunar surface.
For these reasons it is highly desirable that current plans for renewed robotic
surface exploration of the Moon are developed in the context of a future human
lunar exploration programme, such as that proposed by the recently formulated
Global Exploration Roadmap.
