Book Review: Sojourner, An Insider's View of the Mars Pathfinder Mission
Written by Mark Mortimer
Sojourner was one of the first of NASA's and JPL's mandated faster, better, and cheaper projects. Before this mandate, a mission's reliability was paramount and costs were correspondingly high. Sojourner's predecessor, the Cassini mission, costed close to $1 billion. On the other hand, the Mars Pathfinder (Sojourner and the lander) mission had a total budget of $171 million. The Sojourner rover itself was capped at $25 million for design, parts, development, assembly, tests, and all operations during the mission. In spite of this, or perhaps because of this, there is a lot of evidence of solid managerial support, coupled with the workers' nearly desperate attempts to scrounge resources and time. The book is a compendium of the problem definitions, the trial solutions, and the convergence to a workable solution that Mr. Mishkin and his colleagues faced for more than 10 years. Nevertheless, the skill, belief, and perseverance of many people made Sojourner faster, better, cheaper, and most importantly successful.
Sojourner's design roots extended to the Lunar Surveyor Vehicle prototype that was planned for the moon but never used. This robot, nearly trashed, was resurrected by a JPL tinkerer with an interest in locomotion, vehicle suspension, and autonomous direction finding. From this beginning, serendipity plays its part as fortuitous events led to this rover, or one of its offspring, being demonstrated at the right time and before the right people to ensure that funding continued. Earth itself is a daunting realm for autonomous rovers, but Mars was a totally new territory. The temperature range was large, 110F over the duration of a day. The terrain was rough and unpredictable, sand could capture a wheel, or a ledge may roll the rover. Most of all, the 20 minute communications made direct control impossible. The first part of the book largely deals with tackling and overcoming this. It describes getting a solution to accommodate an acceptable body size, an optimal number of wheels, a forgiving suspension, and a safe guidance system. The later part of the book largely deals with the challenges of integrating the many prototypes, their unit testing, and the ensuing system testing.
In addition to designing a robotic rover, the book provides a glimpse of the challenges that face anyone taking on the role of a systems engineer. This role is to balance the needs, requirements, and expectations of all the players of a project so that there is a working solution. The solution is not necessarily optimal for anyone as everyone's needs often directly conflict with others. The result is that no one is totally satisfied or completely happy. Mr. Mishkin displays a lot of the personality of his colleagues and himself as trade-offs are made, deals are done, and the rover comes together. This lends a wonderful human touch to what otherwise might be a somewhat dry and technical book. In accomplishing his goal Mr. Mishkin received some of the best words of praise for a systems engineer which are, "When you work on a job, things happen. Things get done".
Though this book is enjoyable to read, it is difficult to classify. There is a lot of discussion on the technical aspects of resolving issues that arose in designing Sojourner, but there is too little to recommend it as a design reference. The challenges of being a systems engineer in a large project comes out loud and clear, but there is little to offer a new systems engineer on lessons learned. There is a lot of detail on the bugs, errors, and complications that needed correcting, but it is not really a comprehensive story of Sojourner. Further, there is no presentation of the scientific results. In the end, this book is exactly what it was meant to be, the personal memoirs of a technical expert from an exciting and challenging project.
I enjoyed seeing the historical thread that the Sojourner project wove amongst people and events. I particularly liked how it connected the lunar rover project of the 1950's up to the start of the Spirit and Opportunity projects. As well, I could easily grasp the intangible value of team spirit, mutual support, and a work ethic that goes beyond a pay cheque. This is a book for engineers, especially those with an interest in robotics or space exploration. A person contemplating being a systems engineer would also enjoy reading this book to see the amazingly good things to which serendipity can lead.
Review by Mark Mortimer
Read more about the book at Amazon.com
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