Acta Astronautica Vol, 28, pp. 387-389, 1992 0(04-$7~.q/92 $$.0040.00 Primed in Orest Britain Pergamon Press Ltd

THE RETURN OF HUMANS TO THE MOON: SCIENTIFIC CHALLENGES AND OPPORTUNITIES

David C. Black * Lunar and Planetary Institute

Houston, Texas

Abstract

In July.of 1989, on the occasion of the twentieth anmversary of the landing of Apollo 11, an American president challenged NASA. President Bush's challenge had three components; to complete the development and begin operation of Space Station Freedom by the end of the century, to return humans to the Moon - this time to stay, and lastly to expand human presence in the solar system to Mars and beyond. The focus of this paper is on the second component of President Bush's proposed challenge. Specifically, it deals with the opportunities and challenges which are inherent in the return of humans to the Moon. These

POrtunities involve scientific study of the on from the perspective of its ability to shed

light on the origin of the Earth-Moon system, as well as from the perspective of using the Moon as a platform from whence to conduct a wide variety of scientific activities. The challenges are equally varied, but foremost is the interaction of humans and machines to conduct these activities in the most effective manner.

I. Introduction

Arguably, the Moon is one of the better studied members of the solar system. It has been examined by a host of unmanned spacecraft beginning with the Ranger series (1961-1963), and progressing through the Surveyor (1966- 1968) and Lunar Orbiter (1966-1967) spacecraft. Samples have been returned by the automated Soviet Luna program which included among other features the Lunokhod rover. The pinnacle of lunar exploration is the Apollo

*Director, Lunar and Planetary Institute.

program with its blend of humans in the scientific examination of our nearest celestial neighbor.

However, in spite of this impressive array of efforts to study the Moon, and the substantial gains in understanding that followed from them, our knowledge of theMoon today and of its formation and evolution remain relatively incomplete. For example, less than 50 percent of the lunar surface has been imaged with sufficient resolution for scientific study. Indeed there are substantive regions of the surface for which there is very little information at all.

Scientifically speaking, the Moon remains a body of considerable interest and importance. Its obvious association with the Earth Implies that knowledge of its chemical composition will afford insight into the way in which the Earth itself was formed. The absence of significant eological activity on the Moon since its earliest istory, while viewed by some as making the

Moon a dull place, in fact makes the Moon an ideal laboratory to study traces of events in the inner solar system that have long since been obliterated on the geologically active planets such as the Earth, Venus, andMars. This pristine character of the lunar surface also makes it an ideal recording medium for events related to the evolution and behavior of the Sun, the absence of any atmosphere and magnetic fields of global consequence lays bare the surface to irradiation by charged particles flowing out from the Sun.

In addition to its intrinsic scientific value, the Moon is also extremely valuable as a platform from whence to conduct a variety of observational activities. Its inertia and terrain make itthe ideal "spacecraft" for many powerful types ot astronomical tools. Indeed, many of the fundamental and more challenging issues in

388 42nd IAF Congress

astronomy call for the use of large-scale interferometric systems, operated in environments free from the detriments of working below the Earth's atmosphere. Such systems are most readily realized on the lunar surface.

The scientific activities discussed above are certainly opportunities that will eventuate if President Bush's challenge to NASA is met, and humans return to the Moon to stay. However, these scientific opportunities bring with them associated techmcal challenges.

II, Scientific O000rtunities: An Examole

Rather than review all of the scientific opportunities that could result from a permanent human presence on the Moon, I want to focus here on one such opportunity and in so doing explore what I believe will be one of the more significant challenges that will face those who are involved with human exploration of the solar system.

The example I wish to consider is that of the geology of the Moon. Geological exploration of the Moon will certainly be a major element of the activities conducted by humans permanently located on the Moon. Further, it is the one way to gain insight into the true history of the Moon. Remote sensing studies of one sort or another can say a great deal about surficial, and to some extent structural, aspects of the Moon. Sample analyses can tell us a great deal about the physics and chemistry of the Moon. Detailed geological studies are necessary, however, to provide a context for both remote sensing and sample analyses, and through that context gain an understanding of the history and current state of the Moon.

It is important to recognize what is meant here by geologic study. Specifically, geologic study is taken to mean the understanding of P~hOCeSS and structural units at all levels of detail.

e importance of this rather all-encompassing definition is that a consequence is that one must have the involvement of humans in the activity. It is this need which makes the concept of permanent human presence such an attractive one to those who w~sh to understand the Moon from a geological perspective. It is also this need which leads to the challenge; what is the best mix

of humans and machines to undertake a scientifically comprehensive examination of the Moon, or any other planetary object for that matter?

III, The Challen~,e

The issue of humans and machines in the conduct of the space program has been much discussed recently. More often than not it is cast in an "either/or" context, as contrasted to a question of what is the proper mix of humans and machines. Clearly, humans are not needed to carry energeticparticle detectors into the radiation belts of Jupiter, nor are they necessary to gather spectral data from the surface of a satellite of Mars or of Saturn. It is a much different situation when one considers geologic field work; I will assert that humans are required for such tasks. The question then becomes what is the proper, perhaps the necessary, role for humans to play in geological field work on the Moon and what is the role for machines?

Associated with the question of the relative roles of humans and machines in geologic field work on the Moon, is the question of whether humans must actually be present, or whether their telepresence is sufficient. As far as I have been able to determine, this issue is unresolved. There are those who feel that the likely advances in the area of virtual reality will make it possible for scientists sitting comfortably in their offices to work remotely with robotic systems to conduct field work on the Moon. Others argue that there is a cognitive process that occurs when an experienced field geologist is at work that will be significantly, perhaps fundamentally, reduced if the scientist is not physically in the field. This issue is not resolved, and it stands as one of the major challenges to be addressed in anticipation of the return o f humans to the Moon.

The challenge identified here is more than a matter of advanced studies and system development in either artificial intelligence or robotics. It requires that an examination of the full nature of field geology be better understood than is the case presently, with emphasis on what attributes (if any) of the scientific presence in the field are truly necessary to the exploration process.

42rid IAF Congress 389

An understanding of the issues inherent in this challenge and opportunity will permit us to make more effective use of all of the resources that we will have at our disposal as we continue exploration of the solar system.