Field work

Field work is the in-situ investigation of surface and subsurface geologic structures. It entails imagery, collecting samples, on-site analysis, and documentation. The goal of field work is to gain an understanding of geological processes in detail, which expedites the search for valuable resources such as water-ice, other volatile materials, and areas where other resources are concentrated.

The return of humans to a permanent base on the Moon will inaugurate an extensive program of geologic investigation. Some field work will be done on-site by humans, but the majority of work will be done by geologists using robots that are tele-operated from the Earth or from a lunar base.1 Surface-roving, tele-operated robots are remarkable tools that will greatly multiply the efficiency and cost-effectiveness of field operations. Technology now makes possible unprecedented realism in the recreation of distant scenes for field geologists through the technique of virtual presence. High-resolution 3-D images can be presented to a pair of eyes (actually, multiple pairs of eyes) at the same time that tactile feedback is imparting touch sensations to the operator's hands. This technology has been spearheaded by medical/surgical procedures and by underwater robotics research. The advantages of robots for work on the Moon include the following:

• Virtually all robots will be sent to the Moon on one-way missions, so there will be no transportation costs for their return to Earth.

• They require no life-support systems.

• They can operate continuously, via direct tele-communication links from Earth.

• They can carry more sensors and larger sample-collection payloads than humans.

• They have greater range and duration than humans.

• They can be made stronger than humans.

• They can work in areas that are too hazardous for humans.

• They are expendable.

• Their parts can be recycled.

The robots that assist with field work will be equipped with cameras, hammers, drills, anthropomorphic arms with tactile feedback, compartments for sample storage, and a means of locomotion (wheeled, walking, or tracked vehicles). They will also carry spectrometers that can perform on-site mineral analyses of samples.

Robots can be designed to make long-distance traverses across the lunar surface. However, these "solo" excursions (such as the Russian Lunokhod rover) are basically one-way missions that end when the power supply or other critical system of the robot fails. More typically, future geologic expeditions will be round-trip missions that investigate a designated region in the vicinity of a lunar base. Each tele-operated robot will travel under its own (battery and solar) power from the lunar base to the area being investigated, conduct its studies over a period of days or weeks, and then return to the base. Excursions employing pairs of robots may be a desirable scenario. Each device can provide images of the other, for augmentation of their control. Like the "buddy system'' humans use in hazardous environments, each might be able to

1 Popular illustrations of geologists performing field work on the lunar surface are misleading. The hazard of cosmic radiation will limit human surface activity on the Moon to short-duration, high-priority tasks.

assist the other with various difficult or hazardous chores. The collected samples and data from the mission will be analyzed, and the robots will be serviced and repaired, if necessary, in preparation for the next expedition. In this manner, robots can be reused for multiple missions.

In addition to their use in field work, robots will be used for the transportation and placement of sensors on the lunar surface. For example, geophones can be placed at designated areas to gather seismic information which, when coupled with other geophysical techniques, can provide information about the depth of distinct layers in the lunar subsurface.2 Robots can also be used to conduct extensive ground-penetrating radar surveys, as discussed previously.

Mass spectrometers can be placed in regions of the Moon where outgassing is suspected to have occurred in the recent past. These areas include the Aristarchus Plateau, the crater Linne, and other sites where so-called "lunar transient events" have been reported (see Appendix M). While most scientific investigators doubt such occurrences, it would nevertheless be useful to document the existence (or lack thereof) of such sporadic events, which, if true, may indicate subsurface deposits of useful volatile materials.

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