Review: Exploration and Engineeringby Jeff Foust
|
| The book thus offers the reader a detailed look at the technical, programmatic, and other challenges faced by several missions, including how one mission’s problems could affect others. |
InSight will be the latest in a series of NASA Mars missions that stretches back decades. After an initial wave of flybys, orbiters, and landers that crested with the Viking program in the mid-1970s, NASA retrenched, not sending another Mars mission until the ill-fated Mars Observer in the early 1990s. NASA has maintained a regular pace of Mars missions since then, sending orbiters, landers, or rovers during nearly every once-per-26-months launch window since. That effort, filled with enormous successes and ignominious failures, is thoroughly examined in Erik Conway’s Exploration and Engineering.
Conway, a historian at JPL, devotes his book to that second wave of NASA Mars missions, starting with the efforts after Viking to restart Mars exploration that led to Mars Observer, through the Phoenix mission that landed in Mars’s north polar regions in 2008. The early development of the Mars Smart Lander, which became the Mars Science Laboratory and the rover Curiosity, is mentioned in the book, but he does not go into as much detail into its development, including the problems that delayed its launch from 2009 to 2011.
The ups and downs of that history are, in general terms, quite well known: the successes of missions like Pathfinder and the twin Mars Exploration Rovers, and the failures of Mars Climate Orbiter and Mars Polar Lander. Parts of this history have been told, such as Rob Manning’s 2014 book about his work as Curiosity’s chief engineer (see “Review: Mars Rover Curiosity”, The Space Review, October 20, 2014) and Scott Hubbard’s 2012 book about his time as the “Mars czar” after the late 1990s failures (see “Review: Exploring Mars”, The Space Review, February 13, 2012).
Conway, through interviews with the key people involved and access to project documents, offers both a comprehensive and in-depth review of many Mars missions during this period, and the overall robotic Mars exploration program (human Mars exploration concepts are mentioned only in passing, and primarily on how they affected the robotic program.) The book thus offers the reader a detailed look at the technical, programmatic, and other challenges faced by several missions, including how one mission’s problems could affect others. And, even the most successful missions had their share of issues that could, at times, look overwhelming.
One theme of the book is the rise and fall of the “faster, better, cheaper” mission philosophy as applied to Mars exploration. That approach encompasses most of the book: Pathfinder’s success demonstrated it was possible to do Mars missions far less expensively than conventional approaches; the failures of Mars Climate Orbiter and Mars Polar Lander showed what happened when it was taken too far.
| Conway also argues that Mars missions have been driven by a need for technological “novelty,” based not just on science and engineering requirements but also a need to engage the public, “which seems conditioned to expect technological novelty in Mars missions.” |
Conway, though, doesn’t close the book on “faster, better, cheaper” until the Phoenix mission launched in 2007. That spacecraft made use of the lander originally constructed for a 2001 lander mission cancelled in the aftermath of the 1999 failures. Getting that spacecraft, based on Mars Polar Lander, ready for flight showed that the lander had any number of flaws that would have caused the mission to fail. While an investigation into the failure pinned the blame on a software problem that caused the descent engine to shut off prematurely when the landing legs locked into place, the book makes the argument that the mission might have instead failed when the cruise stage failed to separate from the lander’s aeroshell in the early phases of the spacecraft’s entry into the Martian atmosphere. That failure would also explain the loss of the Deep Space 2 microprobes carried along with Mars Polar Lander.
Those failures caused a retrenchment back to better resourced, but also more expensive, missions, exemplified by Curiosity. Conway also argues that Mars missions have been driven by a need for technological “novelty” in the form of more complex missions. This is something he argues is based not just on science and engineering requirements but also a need to engage the public, “which seems conditioned to expect technological novelty in Mars missions.”
Sending dozens of copies of the Mars Exploration Rovers over the next several decades to different locations on Mars, he argues, would provide plenty of science, likening it to the geological surveys of the United States in the 19th century. “Yet I cannot imagine such a Mars program being funded,” he concludes. Or, for that matter, even offered: the complex missions like Curiosity and the planned 2020 rover are driven to meet requirements developed by scientists through mechanisms like the planetary science decadal surveys. If scientists are proposing fleets of Opportunity-like rovers there, they are not winning over their colleagues on scientific merits.
That scientific interest in Mars exploration is driven by a desire to return samples: the 2020 rover is intended to cache samples as a first step in sample return, a mission the most recent decadal survey concluded was the highest-ranking flagship-class mission. Interest in sample return is not new: scientists were studying sample return concepts back in the 1970s. It remained a long-term goal through the 1990s and 2000s, although in retrospect the proposed schedules and costs for some of those concepts were highly unrealistic. Even now, it’s unclear when any samples collected by the 2020 rover will be returned to Earth, as NASA has not laid out any plans for follow-up missions. In fact, recent discussion about the 2020 rover has suggested it would not collect samples on the rover itself, but instead leave them in place for a future rover to pick and up and return to an ascent vehicle of some kind.
NASA’s future Mars missions also bring up another topic addressed in the book: the concept of “heritage” in spacecraft designs. Heritage was often a goal in mission designs: if something had flown previously and successfully, it was presumed to be lower risk, and could, in turn, offer cost and schedule savings. But heritage was no guarantee of either technical success or cost savings: Mars Observer was based on a spacecraft design used for missions in Earth orbit, yet failed for reasons not anticipated when that design was used for a Mars mission. The Mars Exploration Rovers were initially sold on the heritage from the Pathfinder mission, but spacecraft growth linked to a desire to extend the rovers’ lifetimes caused them to rework much of the spacecraft design, losing that heritage. That’s something to keep in mind for both InSight (based on Phoenix) and, the 2020 rover (based on Curiosity.) One also wonders if the lesser “technological novelty” of these missions, reusing designs from previous spacecraft, might make them less interesting to the public.
The struggles in mounting robotic Mars missions leaves Conway skeptical about the propsects for sending humans to Mars in the foreseeable future. “I consider it unlikely that humans will reach Mars in my lifetime,” the 48-year-old Conway writes at the end of the book. “But I hope to see Mars science continue in the interim.” After reading the book, you can understand his pessimism about human Mars missions, but also his hopes that robotic exploration—as challenging as it can be at times—will continue.