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© 2006 by Donald F. Robertson.
This article may be distributed at will, but only if it is not changed in any way, and only if the author's name, the copyright notice, the name of the journal it first appeared in, and this notice remain attached. In addition, this article may not be sold for money, or published for sale in any way, without the author's prior written permission.
This article originally appeared in Space News.
Donald F. Robertson
The dispute between NASA’s Ames and Marshall centers over who gets to manage the automated exploration of Earth's moon begs a question. With NASA’s budget stretched beyond the breaking point, and we plan to send human scientists soon, why are we sending any large automated missions to Earth’s moon?
There is clearly a role for automated spacecraft in, say, mapping the lunar radiation environment. However, every one of the major outstanding questions involving exploitable resources and lunar geology involves activities in which human miners, geologists, and engineers are far more efficient, and usually better, than any foreseeable robot.
Consider the question of the moment. While any water at the lunar south pole just might exist as a block of ice on the surface, it is far more likely to be scattered through the regolith and buried deep underground. Finding it is not likely to be easy.
An automated lander would obtain one drill sample, or at best a small number of cores, at one site. In contrast, the Apollo-17 crew more than thirty years ago conducted an in-depth geologic survey of an entire large valley in only three days. A modern crew would have more time and far better tools. If we plan to send astronauts anyway, why are we contemplating spending the better part of a billion dollars per mission attempting to automate a set of tasks that astronauts are far more suited to accomplish?
The same question applies to geology. Detailed stratigraphic exploration of crater ejecta, with absolute dates, obtained over wide areas will provide a history of impact events in the inner Solar System. The moon’s early impact history should mirror the bombardments experienced by Earth when life was first appearing. In theory, an ejecta survey could be automated, but obtaining a large set of data with rovers would be far less efficient than doing the job with on-site geologists. Obtaining absolute dates requires complex laboratories on site, or returning samples to Earth. Studying the history and extent of lunar volcanism also involves the kind of field geology that is extremely difficult to effectively automate.
In fact, why are we spending more than half-a-billion dollars sending an ultraviolet mapper to orbit the moon when trans-Earth propulsion modules will soon be waiting in parking orbits? If the lunar base is at the south pole, these modules will wait in polar orbit. They spacecraft could easily piggyback mapping instruments in a manner similar to the Apollo Service Module Scientific Instrument bays flown on the advanced Apollo missions.
Each Apollo mission attempted to map the areas planned for the next landing -- a process that worked very well. Why are we not repeating that successful experience?
Perhaps the most important scientific reason to return to the moon is to attempt to find samples of Earth’s earliest continents splashed up in giant impacts. Such samples could contain unique evidence -- long since destroyed on Earth by geological activity -- of the formation of life on Earth, possibly including fossils.
For much of the lifetime of the Solar System, Earth’s moon has been a nearby static “trap” capturing a sample of the same debris that has struck Earth. Samples of all the other planets, obtained throughout the Solar System’s history, and even from interstellar space, are likely to be preserved in the lunar regolith. Collectively, these samples could prove revolutionary to the terrestrial sciences of geology, biology, and paleontology, and possibly to several branches of astronomy.
Such samples almost certainly exist but they will be rare, widely scattered, and probably deeply buried. No series of robotic missions, however elaborate, is likely to find them. Only detailed “Lewis and Clark” class expeditions would have the scientific efficiency to have any chance of finding these samples.
While we are spending vast sums of money trying to automate geologic field work and prospecting for resources at a location we know we can send real live geologists, we are cutting back on automated science at locations where we will not be sending astronauts for the foreseeable future. The highest priority for space science is Jupiter’s ocean world Europa, yet we are not sending a mission there.
Since NASA does not have the resources to do everything we want to do, it is an unconscionable waste to send expensive robots where astronauts will soon be exploring, especially to execute tasks that geologists can do far more efficiently.
Many argue that sending robots to the moon is essential to make human flights safer, but astronauts have already landed safely on the moon. We know how to stay alive there. The first human return mission should answer every question that a series of billion dollar automated landers is likely to answer -- and them some.
I would like to propose a rule of thumb. In a well-planned space program, automated landers should only be sent to locations where you cannot send scientist-astronauts within the next few decades. Automated missions -- and the severely limited ground-truth science they can accomplish -- should be reserved for where there is no better choice.
Anywhere you can, you should send geologists on site, with their inherent abilities to quickly and efficiently do detailed and in-depth field work -- skills that no foreseeable robot can duplicate. Locations that probably should wait for geologists include Earth’s moon, the nearest of near-Earth asteroids, and possibly the Martian moons -- all sites likely to be within relatively early reach of the transportation architecture being developed by Dr. Griffin’s NASA.
The only exceptions should be for very low cost mapping missions or to test fly a lunar lander. Since we have already landed on the moon many times with both human and automated spacecraft, and we did not feel the need to test the Lunar Excursion Module without a crew, it is not clear why we need to spend lots of money testing these skills now. But if we are going to send a lander, it should carry experiments designed to lower the cost of human missions, or increase their efficiency, not for science. The most useful experiment for such a test mission would be a prototype chemical plant to extract oxygen and other useful elements from the lunar regolith.
If humanity is to explore any part of the Solar System at reasonable cost, we must be prepared to take measured risks. The time to start taking those risks is today. NASA should immediately cancel all of the large automated lunar missions. The agency could split the savings between restoring automated missions deeper into the Solar System and the aeronautics funding NASA has been forced to cut -- and to speed astronaut-scientists on their way to the mountains of eternal sunlight at the lunar South pole.
Donald F. Robertson is a freelance space industry journalist based in San Francisco.
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