Paul Spudis

The Clementine Mission to the Moon: Scientific Overview

In the course of 71 days in lunar orbit, from 19 February to 3 May 1994, the Clementine spacecraft acquired just under two million digital images of the moon at visible and infrared wavelengths. These data are enabling the global mapping of the rock types of the lunar crust and the first detailed investigation of the geology of the lunar polar regions and the lunar far side. In addition, laser-ranging measurements provided the first view of the global topographic figure of the moon. The topography of many ancient impact basins has been measured, and a global map of the thickness of the lunar crust has been derived from the topography and gravity.

Clementine Observations of the Aristarchus Region of the Moon

Multispectral and topographic data acquired by the Clementine spacecraft provide information on the composition and geologic history of the Aristarchus region of the moon. Altimetry profiles show the Aristarchus plateau dipping about 1� to the north-northwest and rising about 2 kilometers above the surrounding lavas of Oceanus Procellarum to the south. Dark, reddish pyroclastic glass covers the plateau to average depths of 10 to 30 meters, as determined from the estimated excavation depths of 100- to 1000-meter-diameter craters that have exposed materials below the pyroclastics. These craters and the walls of sinuous rilles also show that mare basalts underlie the pyroclastics across much of the plateau. Near-infrared images of Aristarchus crater reveal olivine-rich materials and two kilometer-sized outcrops of anorthosite in the central peaks. The anorthosite could be either a derivative of local magnesium-suite magmatism or a remnant of the ferroan anorthosite crust that formed over the primordial magma ocean.

Lunar polar topography derived from Clementine stereoimages

Clementine stereoimagery has been used to produce digital elevation models of the Moon, at a scale of ∼1 km/pixel. These models cover regions poleward of 60° in both hemispheres and reveal topography beyond that covered by the Clementine laser altimeter or Earth-based radar. By combining these polar terrain models with the current Clementine laser altimeter data we have produced a global topographic map of the lunar surface. Several topographic features in the new polar topographic data set are described, including three previously unrecognized pre-Nectarian impact basins. Several known basins have also been mapped, including the southern extent of the South Pole-Aitken basin, and other previously suspected basins have been verified.

Using the resources of the Moon to create a permanent, cislunar space fairing system

We have previously described an architecture that extends human reach beyond low Earth orbit by creating a permanent space transportation system with reusable and refuelable vehicles. Such a system is made possible by establishing an outpost on the Moon that harvests water and produces rocket propellant from the ice deposits of the permanently dark areas near the poles. Our plan is affordable, flexible and not tied to any specific launch vehicle or family of vehicles. Robotic assets are teleoperated from Earth to prospect, demonstrate and produce water from local resources. These robots are launched separately over several years, allowing the program to be implemented under constrained and uncertain funding conditions. In addition, the stepwise, incremental approach encourages and facilitates international and commercial participation. Humans arrive only after we have begun water production. Once there, the human mission begins to explore the potential for possible, practical, and affordable use of regolith for material production for outpost sustainment and growth. Consistent with the overarching goal to see if we can learn how to live off-planet, another objective of human activity on the Moon will be the experimentation of biological systems and their interaction and performance in the lunar environment. Our arbitrarily defined end stage is a fully functional, human-tended lunar outpost producing 150 metric tonnes of water per year ‐ enough to export water from the Moon to orbiting propellant depots and create a permanent, extensible reusable transportation system that allows routine access for people and machines to all points of cislunar space. This costeffective architecture advances technology and builds a sustainable space transportation infrastructure. By eliminating the need to launch everything from the surface of the Earth, we fundamentally change the paradigm of spaceflight. This lunar outpost serves as the vanguard for studying the practical employment of techniques, processes, and systems that allow humanity to effectively extend its reach off-planet.

New views of the Moon: Improved understanding through data integration

Understanding the Moon is crucial to future exploration of the solar system. The Moon preserves a record of the first billion years of the Earth-Moon systems history, including evidence of the Moons origin as accumulated debris from a giant impact into early Earth. Lunar rocks provide evidence of early differentiation and extraction of a crust. n nLacking an atmospheric shield, the Moons regolith retains a record of the activity of solar wind over the past 4 billion years. It also holds a complete record of impact cratering, and analysis of samples has allowed calibration of ages, and thus dating of other planetary surfaces. And because of its proximity to Earth, its low gravity well, and stable surface, the Moons resources will be useful both in establishing lunar habitations and as fuel for exploration beyond the Moon.