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Monday, February 13, 2012

Reading List: Lunar Impact

Hall, R. Cargill. Lunar Impact. Washington: National Aeronautics and Space Administration, 1977. ISBN 978-0-486-47757-2. NASA SP-4210.
One of the wonderful things about the emergence of electronic books is that long out-of-print works from publishers' back-lists are becoming available once again since the cost of keeping them in print, after the initial conversion to an electronic format, is essentially zero. The U.S. civilian space agency NASA is to be commended for their efforts to make publications in their NASA history series available electronically at a bargain price. Many of these documents, chronicling the early days of space exploration from a perspective only a few years after the events, have been out of print for decades and some command forbidding prices on used book markets. Those interested in reading them, as opposed to collectors, now have an option as inexpensive as it is convenient to put these works in their hands.

The present volume, originally published in 1977, chronicles Project Ranger, NASA's first attempt to obtain “ground truth” about the surface of the Moon by sending probes to crash on its surface, radioing back high-resolution pictures, measuring its composition, and hard-landing scientific instruments on the surface to study the Moon's geology. When the project was begun in 1959, it was breathtakingly ambitious—so much so that one gets the sense those who set its goals did not fully appreciate the difficulty of accomplishing them. Ranger was to be not just a purpose-built lunar probe, but rather a general-purpose “bus” for lunar and planetary missions which could be equipped with different scientific instruments depending upon the destination and goals of the flight. It would incorporate, for the first time in a deep space mission, three-axis stabilisation, a steerable high-gain antenna, midcourse and terminal trajectory correction, an onboard (albeit extremely primitive) computer, real-time transmission of television imagery, support by a global Deep Space Network of tracking stations which did not exist before Ranger, sterilisation of the spacecraft to protect against contamination of celestial bodies by terrestrial organisms, and a retro-rocket and landing capsule which would allow rudimentary scientific instruments to survive thumping down on the Moon and transmit their results back to Earth.

This was a great deal to bite off, and as those charged with delivering upon these lofty goals discovered, extremely difficult to chew, especially in a period where NASA was still in the process of organising itself and lines of authority among NASA Headquarters, the Jet Propulsion Laboratory (charged with developing the spacecraft and conducting the missions) and the Air Force (which provided the Atlas-Agena launch vehicle that propelled Ranger to the Moon) were ill-defined and shifting frequently. This, along with the inherent difficulty of what was being attempted, contributed to results which can scarcely be imagined in an era of super-conservative mission design: six consecutive failures between 1961 and 1964, with a wide variety of causes. Even in the early days of spaceflight, this was enough to get the attention of the press, politicians, and public, and it was highly probable that had Ranger 7 also failed, it would be the end of the program. But it didn't—de-scoped to just a camera platform, it performed flawlessly and provided the first close-up glimpse of the Moon's surface. Rangers 8 and 9 followed, both complete successes, with the latter relaying pictures “live from the Moon” to televisions of viewers around the world. To this day I recall seeing them and experiencing a sense of wonder which is difficult to appreciate in our jaded age.

Project Ranger provided both the technology and experience base used in the Mariner missions to Venus, Mars, and Mercury. While the scientific results of Ranger were soon eclipsed by those of the Surveyor soft landers, it is unlikely that program would have succeeded without learning the painful lessons from Ranger.

The electronic edition of this book appears to have been created by scanning a print copy and running it through an optical character recognition program, then performing a spelling check and fixing errors it noted. However, no close proofreading appears to have been done, so that scanning errors which resulted in words in the spelling dictionary were not corrected. This results in a number of goofs in the text, some of which are humorous. My favourite is the phrase “midcourse correction bum [burn]” which occurs on several occasions. I imagine a dissipated wino with his trembling finger quivering above a big red “FIRE” button at a console at JPL. British readers may…no, I'm not going there. Illustrations from the original book are scanned and included as tiny thumbnails which cannot be enlarged. This is adequate for head shots of people, but for diagrams, charts, and photographs of hardware and the lunar surface, next to useless. References to endnotes in the text look like links but (at least reading the Kindle edition on an iPad) do nothing. These minor flaws do not seriously detract from the glimpse this work provides of unmanned planetary exploration at its moment of creation or the joy that this account is once again readily available.

Unlike many of the NASA history series, a paperback reprint edition is available, published by Dover. It is, however, much more expensive than the electronic edition.

Update: Reader J. Peterson writes that a free on-line edition of this book is available on NASA's Web site, in which the illustrations may be clicked to view full-resolution images.

Posted at February 13, 2012 22:06