The Design and Engineering of Curiosity
Page 1
Springer Praxis Books
Space Exploration
Emily Lakdawalla
The Design and Engineering of Curiosity
How the Mars Rover Performs Its Job
Emily LakdawallaThe Planetary Society, Pasadena, CA, USA
Springer Praxis Books
ISBN 978-3-319-68144-3e-ISBN 978-3-319-68146-7
https://doi.org/10.1007/978-3-319-68146-7
Library of Congress Control Number: 2017963344
© Springer International Publishing AG, part of Springer Nature 2018
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Dedication
For Anahita, who challenged me to be “a writer who writes a book ”
Foreword
On the night of August 5th, 2012, I was sitting in my room watching a video stream from JPL’s Mission Control as the Curiosity rover descended toward Mars. As I watched, I sketched a comic about the Curiosity landing on my drawing tablet.
I’ve often anthropomorphized our space robots in my comics. In one sense, this is silly. A rover like Curiosity is a piece of hardware. It’s a collection of motors, computers, and sensors. It can’t think or feel. Maybe, someday, a robot will blur the line between “machine” and a “thing with feelings,” but Curiosity isn’t that. It’s just a big, complicated car.
But in another sense, anthropomorphizing these robots feels natural. It’s not that there’s some magic in the circuits. It’s that every single piece of hardware on Curiosity is the physical manifestation of years of planning by real people, sending it out to act on their behalf in the universe. The hardware carries with it our hopes and fears.
When Curiosity touched down on Mars, I felt so proud of our robot. I wasn’t really proud of the mechanical actuators for actuating right. I was proud because I knew that each actuator, each spring, each wire, each sensor, and each line of code was lovingly crafted by someone. I knew all those people were watching along with me, all thinking, “I hope I did a good job.” And they did!
While I was sitting in front of my computer that night, Emily was in the JPL press room. She had a front row seat to the action, and, through her Twitter feed, helped interpret what was going on for those of us at home.
Emily is a space enthusiast’s space enthusiast and an incredible font of knowledge. A few years ago, I started wondering whether the photos taken by the new Juno spacecraft would be better than any of the ones from previous missions. After spending a few hours struggling to figure out how to compare the cameras on various spacecraft, I asked Emily for help. A moment later, she replied with an incredible spreadsheet she’d created listing every camera that had been sent into the outer solar system along with technical specifications for each. It was exactly what I was looking for. Later, when I decided to include a diagram of the Curiosity rover in one of my books, I made sure to run it by her first, to find out which parts I got wrong and which cool details I missed.
In this book, she describes how Curiosity works. She gives a window into the hopes, fears, and improbable what-if scenarios embedded in each technical decision. To tell the story, she draws on published papers, internal documents, photograph archives, and her own conversations with members of the Curiosity team over the course of the mission. For anyone curious about Curiosity – if you wonder “why was it lowered from a sky crane?” or “what's that weird thing sticking off the side?” – then this is the book for you.
Randall Munroe
Author of What If?, Thing Explainer , and xkcd
Preface
The book you are holding is not quite the one I intended to write. I embarked on this project in 2013, with the working title Curiosity on Mars - Design, Planning, and the First Mars Year of Operations . I thought two years was a reasonable timeline, as I’d already done a lot of writing about the mission. I had been covering the Mars Science Laboratory mission as senior editor for The Planetary Society’s blog since the mission’s announcement, and attended most of the landing site selection meetings. Five times I had visited the gallery above the clean room where all the mission hardware came together at the Jet Propulsion Laboratory, and I returned to “the Lab” (as those in the know call it) for the landing and every press briefing. I’ve written three feature stories about it for Sky and Telescope . I’m an administrator of an online discussion forum full of armchair geologists and engineers who follow the daily motions of the rover, so I was cognizant of every twist and turn of the mission. It seemed possible that with steady work I should be able to write this book relatively rapidly.
It didn’t turn out that way. I decided that understanding how the hardware worked was crucial to narrating the mission, because holey wheels, “Florida air,” contaminated drill bits, and balky sampling mechanisms loomed large in the story of the rover’s daily operations. I set to work researching rover engineering. The more I learned about Curiosity, the more rabbit holes I fell down. It had so many subsystems, and most had complicated histories, fascinating stories worth telling. Many of those stories hadn’t been told in print, at least not in any document that the public can access. The publications that did describe Curiosity’s engineering had mostly been written before launch, and contained inaccuracies that were corrected for me by helpful engineers. I came to understand that this machine was the most complicated thing ever sent beyond our planet and that no one person on Earth understands all of its parts and functions. I wrote and wrote about its design, its engineering, and its journey. Many mission engineers and scientists have contributed to making this text describe the actual spacecraft as accurately as possible.
Years passed. By 2015 Curiosity had traveled more than 10 kilometers across Mars and still the full depth of its scientific promise hadn’t been realized. I changed my working title, dropping the “First Mars Year” bit, as the rover drove into its second Mars year and had only just reached the base of the mountain its science team hoped to study.
I asked my boss at The Planetary Society for permission to take a three-month sabbatical at the beginning of 2017 to finish up the project. It wasn’t until the end of that sabbatical that I realized why I’d had so much trouble finishing the work. I hadn’t written my book yet because I had, by now, nearly written
two. I had to write a book about how the rover worked in order to be able to write the book I had intended to write about what it did on Mars. Fortunately, my editors at Springer-Praxis were amenable to splitting the project into two books. The one you’re holding is the first of these: how and why the spacecraft was designed, the function of every system, and the engineering of every instrument. It’s a reference work designed to answer your – and my! – questions about how the rover works and why it was built that way. It answers the same questions for all the other Mars Science Laboratory hardware, from cruise stage to Earth testbeds.
Of course, the mission has continued operating all this time, so parts of this book will be out of date immediately. It is certain to be complete as of sol 1514, and as complete as possible through sol 1800.
Now that I’ve written the reference book I needed, I can proceed with the second book, which will cover the mission’s science, from landing site selection, through pre-landing mapping, the operational adventure, and the science results. Look for Curiosity and Its Science Mission: A Mars Rover Goes to Work in 2019.
Acknowledgments
This book would not exist without the generous assistance of numerous members of the Mars Science Laboratory team and the wider space science community. In particular, Ashwin Vasavada kept me updated in frequent telephone conversations, replied quickly to countless emails, and read every word of the first draft. Guy Webster and Veronica McGregor helped me access JPL and its scientists and engineers and steered the book through sometimes painful export-control review. John Grotzinger welcomed me into the mission’s science team, and Jim Erickson trusted me to talk with engineers.
A huge number of people contributed to this book through interviews, email correspondence, and/or technical reviews of book sections, including Ryan Anderson, Ray Arvidson, Magdy Bareh, Paolo Bellutta, Mike Caplinger, Fred Calef, Allen Chen, Steven Collins, Nagin Cox, Joy Crisp, Mark Dahl, Lauren Edgar, Ken Edgett, Chad Edwards, Doug Ellison, Abigail Fraeman, Travis Gabriel, Matt Golombek, Javier Gomez-Elvira, Peter Grindrod, Cambria Hanson, Craig Hardgrove, Matt Heverly, Sarah Hörst, Louise Jandura, Jason Kastner, Stephen Kuhn, Danny Lam, Steve Lee, Mark Lemmon, Dan Limonadi, Maxim Litvak, Paul Mahaffy, Charles Malespin, Mike Malin, Rob Manning, Scott Maxwell, Sarah Milkovich, Andy Mishkin, Jeff Moersch, Glen Nagle, Keith Novak, Betina Pavri, the RAD team, Scot Rafkin, Rich Rainen, Elizabeth Rampe, Mike Ravine, Melissa Rice, Matt Robinson, Mariek Schmidt, Katie Stack, Dawn Sumner, Lucy Thompson, Vandi Verma, Noah Warner, David Woerner, Aileen Yingst, and Allison Zastrow. With such a long list I am sure I am missing some names. To those I have missed, please accept my apologies and gratitude for your help.
Thanks to Phil Stooke for generously sharing content of his own book in progress, particularly his frequently updated maps of the rover traverse. (The book, International Atlas of Mars Exploration Volume 2 , complements this one.) Thanks to Mike Brown for helping me gain access to the Caltech library, which made remote research possible. Thanks to Tom Stein for supporting my use of the Analyst’s Notebook and taking some of my suggestions on improving its user interface. Thanks to Ralph Lorenz for his valuable advice on book writing: “Write chaptesimals, and eventually they will accrete into chapters.”
The international community of space image processing enthusiasts at the online forum unmannedspaceflight.com contributed many of the beautiful mosaics you’ll see in this book and helped me monitor ongoing rover activity. I want to single out Mike Howard and Joe Knapp for developing valuable software tools for browsing raw images (midnightplanets.com and curiosityrover.com); Thomas Appéré, Damia Bouic, Seán Doran, and James Sorenson for their exceptional image processing work; and Nick Previsich for singlehandedly administering the forum after I and the rest of the admins got too busy.
I’m deeply grateful to the members, staff, and board of The Planetary Society, represented by chief operating officer Jennifer Vaughn and chief executive officer Bill Nye, for their generous support of my time to perform the research and writing necessary to produce this book.
Thanks to the teachers and mentors who raised me, especially Ms. Foster, Mr. Killion, Ms. Hamilton, Dr. Aldridge, Mr. Atkison, Ms. Koeppe, Tekla Harms, Jack Cheney, Jim Head, Geoff Collins, Louise Prockter, Sasha Basilevsky, and Charlene Anderson. Finally, thanks to my husband Darius, my daughters Anahita and Sanaya, and my parents Karen Stewart, Rick and Murfy Stewart, and Rhoda and Noshir Lakdawalla for supporting my writerly ambitions – and to Concepción Peña for supporting me in supporting them, enabling this wife, mom, and daughter to be a writer, too.
Contents
1 Mars Science Laboratory
1.1 Introduction
1.2 Designing a Bigger Lander (2000–2003)
1.3 Becoming Mars Science Laboratory (2003–2004)
1.4 Preliminary Design (2005–2006)
1.5 The Cost of Complexity (2007–2008)
1.6 A Two-Year Respite (2009–2010)
1.7 Final Preparations (2010–2011)
1.8 References
2 Getting to Mars
2.1 Launch
2.2 Cruise
2.3 EDL: Entry, Descent, and Landing
2.4 Curiosity on Mars
2.5 Epilogue: Views of the Cruise Hardware
2.6 References
3 Mars Operations
3.1 Introduction
3.2 Mars’ Calendar
3.3 Strategic, Supratactical, and Tactical Planning
3.4 Tactical Planning Process
3.5 Mission Summary
3.6 References
4 How the Rover Works
4.1 Introduction
4.2 Power System and MMRTG
4.3 Avionics
4.4 Thermal Control
4.5 Telecommunication
4.6 Mobility System
4.7 Testbeds
4.8 References
5 SA/SPaH: Sample Acquisition, Processing, and Handling
5.1 Introduction
5.2 Robotic Arm and Turret
5.3 The Drill
5.4 CHIMRA: Collection and Handling for In Situ Martian Rock Analysis
5.5 DRT: Dust Removal Tool
5.6 Organic Check Material
5.7 Sample Playground
5.8 Sam and CheMin Inlets and Wind Guards
5.9 References
6 The Mast, Engineering Cameras, Navigation, and Hazard Avoidance
6.1 Introduction
6.2 Remote Sensing Mast
6.3 Engineering Cameras: Navcams and Hazcams
6.4 Using the Engineering Cameras
6.5 Rover Driving
6.6 References
7 Curiosity’s Science Cameras
7.1 Introduction
7.2 Mastcam
7.3 MARDI: Mars Descent Imager
7.4 MAHLI: Mars Hand Lens Imager
7.5 References
8 Curiosity’s Environmental Sensing Instruments
8.1 Introduction
8.2 RAD: Radiation Assessment Detector
8.3 DAN: Dynamic Albedo of Neutrons
8.4 REMS: Rover Environmental Monitoring Station
8.5 References
9 Curiosity’s Chemistry Instruments
9.1 Introduction
9.2 ChemCam
9.3 APXS: Alpha Particle X-Ray Spectrometer
9.4 CheMin: Chemistry and Mineralogy
9.5 SAM: Sample Analysis at Mars
9.6 References
Epilogue: Back on Earth
Appendix: Curiosity Activity Summary
About the Author
Index
© Springer International Publishing AG, part of Springer Nature 2018
Emily LakdawallaThe Design and Engineering of CuriositySpringer Praxis Bookshttps://doi.org/10.1007/978-3-319-68146-7_1
1. Mars Science Laboratory<
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Emily Lakdawalla1
(1)The Planetary Society, Pasadena, CA, USA
1.1 INTRODUCTION
Curiosity began in the wreckage of NASA’s Mars hopes. Two spacecraft launched to Mars in 1998. Neither survived arrival. The twin disasters could have doomed NASA’s Mars program – again. But the American public enthusiastically supported a NASA search for Martian life following the announcement of possible fossils in a Mars meteorite recovered from Antarctica.
NASA had enjoyed early success at Mars with the Mariners and Vikings, though the Viking landers’ powerful (and expensive) life-detection experiments had failed to reveal signs of biologic activity on Mars. A lengthy hiatus in Mars exploration followed Viking in the 1980s, and the 1990s were mostly cruel to Mars missions. NASA’s Mars Observer, launched in 1992, failed just days before arrival. Mars 96, a Russian mission, failed to leave Earth parking orbit. But things had been looking up at the end of the decade. Mars Global Surveyor successfully entered orbit in 1997 and began its mapping mission in 1999. And the world fell in love with a little six-wheeled robot named Sojourner that had trundled around NASA’s Pathfinder lander for three months in the summer of 1997, sharing daily reports and Mars photos on the new medium of the Internet. The American public was willing to support another try at Mars.