Publication: Air & Space Power Journal
Date published:
Language: English
PMID: 14520
ISSN: 1555385X
Journal code: FAPW

Planetary Landers and Entry Probes by Andrew J. Ball, James R. C. Garry, Ralph D. Lorenz, and Viktor V. Kerzhanovich. Cambridge University Press (, 32 Avenue of the Americas, New York, New York 10013-2473, 2007, 362 pages, $138.00 (hardcover), ISBN 0521820022; $111.00 (e-book).

A quartet of exceptionally qualified engineers and scientists, two in the United Kingdom and two in the United States, has collaborated to produce an important reference for industry professionals, academic researchers, and graduate students working in the fields of planetary science, aerospace engineering, and space-mission development. Their textbook, Planetary Landers and Entry Probes, draws from more than 45 years of operational history- over 100 missions- to deliver between its covers a fairly concise overview of the wide range of design and flight issues specifically associated with these types of vehicles, as opposed to Earth-orbiting satellites, planetary orbiters, or flyby spacecraft. Drawing examples from over 30 different designs for landers and entry probes used in lunar and planetary missions since the early 1960s, the authors discuss engineering aspects usually ignored by traditional texts on spacecraft engineering: landing systems, parachutes, planetary protection, and entry shields. Regardless of any particular mission's success or failure, Dr. Ball and his colleagues pull examples from space programs worldwide to explain the broad range of challenges and the surprising variety of solutions chosen to meet stated requirements.

Planetary Landers and Entry Probes includes three parts, the second and third parts shorter and more narrowly focused than their predecessors but all complementing each other. While serving as a guide to basic technological principles specific to landers, penetrators, and atmosphericentry probes, the first part also points readers toward more technical, supplementary sources of information. Avoiding minutiae, the authors provide an overview of problems and solutions for each subsystem or mission phase. The 14 chapters in this part cover mission goals and system engineering; launch, cruise, and arrival; entry and descent through an atmosphere; descent to an airless body and arrival at a surface; thermal control; power systems; communication and tracking; radiation protection; surface activities; structures; and contamination of spacecraft and planets. An especially interesting chapter deals with planetary balloons, aircraft, submarines, and cryobots. After studying part 1, readers should have a basic comprehension of the complexities surrounding the design of interplanetary probes and landers.

Part 2 offers a collection of significant information about more than 30 previously launched or planned near-term "atmosphere/surface" vehicles-from the first Soviet Venera and Mars entry probes to the upcoming Phoenix and the Mars Science Laboratory- and their missions. The authors divide these vehicles into six categories, based on the way each encounters an atmosphere or surface: destructive-impact probes; atmospheric-entry probes; pod landers, which land initially in any orientation; legged landers, which have a landing gear; paylo ad-delivery penetrators, which decelerate in the subsurface for payload emplacement; and small-body surface missions, in which the vehicle operates in a low-gravity surface environment. Their discussion of destructive -imp act probes, such as Luna 2 in 1959 or Deep Impact in 2004, occupies less than two pages but enables the reader to understand how crashing a vehicle onto another world can yield an abundance of useful scientific data. A plethora of tables, drawings, charts, and key references to sources for additional information makes this section of the book more interesting to a larger audience possessing limited technical knowledge or comprehension.

In part 3, the authors drill to another level of detail by presenting seven case studies of particular spacecraft, each selected because its program team faced and overcame an unusual challenge in the vehicle's design or mission. From the Surveyor lunar soft-landing vehicles (1966-68) to Spirit ana Opportunity (the Mars exploration rovers [2004-present]), spacecraft designers needed a "judicious mixture" of caution and innovation to deliver even the possibility of a successful mission (p. 312). Successful performance of the Huygens probe through Titan's atmosphere in 2005 depended on balancing conservatism and novelty in structural design, descent control, and scientific instrumentation. Other studies examine the Galileo probe, Mars Pathfinder and its Sojourner rover, the Deep Space 2 Mars microprobes, and the Rosetta lander known as Philae. Investigation of why the Deep Space 2 microprobe mission failed, aside from technical reasons, exposed programmatic deficiencies- "a rushed schedule, changing goals and inadequate testing" (p. 298). Rosetta, which aims to accomplish the first-ever controlled landing on a comet nucleus in 2014, underwent a significant reorientation of its mission in 1992 due to financial and programmatic difficulties. Collectively, these last seven chapters cover an amazing variety of static and mobile elements for missions to worlds with and without atmospheres, and worlds with low-and high-gravity environments.

At first glance, members of the Air Force community might think that Planetary Landers and Entry Probes deals with a realm so far beyond their Earth-orbiting focus that it could not contain useful information or insight. It would bea mistake, however, to make such a hasty judgment. This volume can expand one's conceptual understanding of spaceflight, thereby enabling Air Force space planners, engineers, and scientists to better grasp potential deficiencies in their own programs. The more extensive one's knowledge of the cultural and technical history of spaceflight, especially of the approaches and lessons learned from varied missions over five decades, the better one's comprehension of present and future challenges. Even when advances in science and engineering might seem to render decades-old accomplishments irrelevant or outdated, it remains important for spacefarers to understand in the broadest sense the foundations on which they build.

Author affiliation:

Dr. Rick W. Sturdevant

Peterson AFB, Colorado

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