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On a hot August Earth night in 2012, NASA’s Curiosity rover began its celebrated “seven minutes of terror” --- slowing from 12,600 mph to a triumphant gentle landing at Mars’ Gale Crater.
The engineering feat of sending this pickup truck-sized rover rocketing through Mars’ thin atmosphere on a years-long mission to its surface instilled most Americans with newfound pride. And it made those of us who grew up with Apollo a little wistful.
Rob Manning --- the man arguably at the center of it all --- has documented both the acrobatics needed to enable the rover to slow itself to land and the decade of design and testing that led up to this moment in “Mars Rover Curiosity: An Inside Account from Curiosity’s Chief Engineer.”
Manning’s just published account of years at NASA’s venerable Jet Propulsion Laboratory (JPL), co-written with best-selling non-fiction author William L. Simon, will resonate most with those who want an excellent inside take on the rigorous and often arduous task of designing interplanetary landers and the eureka moments that affords.
Manning deserves credit for bringing his own sense of candor and humility to the prose, even if the book sometimes lacks the kind of narrative verve that might have given it broader appeal.
The promise of science with the rover’s ten instruments notwithstanding, a large part of the book addresses the mantra of EDL --- Entry, Descent and Landing.
After all, if Manning and his JPL colleagues can’t land safely on the Martian surface, the $2.5 billion Mars Science Laboratory mission and a decade of design work and years of potential science will disappear with it.
“[Mars] has too much atmosphere to land as we do on the moon and not enough to land as we do on Earth,” the authors write. “We have to combine all of the tricks we use to land on Earth (heat shields, parachutes) with the techniques we use to land on the Moon (retro rockets, air bags), among many others.”
But if anything, live coverage of the mission’s Entry, Descent and Landing with continual social media reporting from the JPL control room, made us all realize how much times had changed since NASA’s Viking 1 landed on Mars some forty years earlier. I personally streamed Curiosity’s landing at a local Starbucks.
“Within minutes after the landing at 10:30 pm PDT August 5,” the authors note, “images taken from the front and rear hazcams arrived at JPL, giving startling visceral proof to our anxious team that Curiosity had landed on Mars.” With Mt. Sharp a few kilometers to the south, Manning admits that reception of these first Curiosity images will forever be one of his life’s high points.
Two plus years into its mission, hundreds of scientific articles based on Curiosity data have already been published. Among the findings --- river rocks within two football fields of Curiosity’s landing site were found to be much like rocks at the bottom of Earth’s own riverbeds. As the book notes, analysis showed that the rover was sitting on clay of “a type that can only form in fresh water with neutral pH conditions --- the conditions like our own lakes and oceans that are breeding grounds for life.”
But something as seemingly elementary as choosing a landing site took five years, as some 400 scientists debated the pros and cons of 60 candidate sites.
The mission’s landing criteria, Manning notes, had to include a site within plus or minus 30 degrees of the Martian equator; elevations less than 0.6 miles above the mean elevation; no excessive winds; few escarpments or cliffs; and a radar-reflective surface.
Gale Crater with Mt. Sharp as the “target of greatest interest” won out.
To get there, Manning and colleagues had to come up with what he notes was the “most complex lander scheme in the history of spacecraft”; one that required expertise in fields as esoteric as cabling and cable ties, material properties, explosives, fabrics, magnetic fields, fluids, battery chemistry, antenna patterns, flash-memory file systems, hypersonics, and nuclear physics.
Not unlike a Russian matryoshka doll, for the months-long journey to Mars, the Curiosity spacecraft would need to be tucked up within an aeroshell. And once finally slowed to within a few hundred feet above the surface; then a revolutionary, hovering sky crane would lower the rover to a soft landing.
On the surface, the rover would rely on a radioisotope thermoelectric generator (RTG) fueled by 10.6 lbs of plutonium dioxide to produce 2,000 watts of heat; of which 95 to 110 watts would go into producing electricity.
As Manning explains, “to get the [rover] warm enough to operate by noon, we would need a lot of heater power. The Curiosity’s thermal team captured some of the 2000 watts of waste heat by putting catcher’s mitts on either side of the hot container of plutonium and running tubing that passes through the mitts.
The fact that Curiosity is still very much alive and kicking is testament to such ingenuity. But getting such innovation in the final product can often be an unruly process.
“On a spacecraft project almost every day one team will discover that something another team is planning raises some kind of conflict with their one piece,” the authors note.
Manning describes a management lesson he learned from a JPL colleague about how to make a project’s various teams actually listen to each other. The idea is, in part, to put all the team leaders in the same conference room, without laptops, tablets or cell phones in tow and let each tell the others their biggest problem with the project. That is, in multiple round-robin fashion.
Despite such efforts, however, the mission’s initial launch was pushed from 2009 to 2011 due in part to “lingering technical problems.” NASA increased the project’s budget by $400 million and put the rover into mothballs until headquarters gave the JPL teams the go-ahead to continue work.
“The trick for successfully building complex one-of-a-kind machines where hundreds of thousands of things need to be done exactly right is to expect mistakes,” notes Manning.
NASA’s doomed Mars Climate Orbiter became a poster child for more independent testing. The failed orbiter’s thruster firings in 1999 were mistakenly noted in English pounds instead of metric newtons which led to the spacecraft being put on a fatal trajectory. Without a heat shield, it’s thought that the mission likely burned up in Mars’ atmosphere.
“The real mistake made on Mars Climate Orbiter was not the English to metric error,” Manning notes, “but an error in not checking enough for errors.”
Perhaps partly as a result, Manning personally fielded 100 to 200 project emails a day --- knowing that some emails would fall through the cracks. So, he told his colleagues, “if it’s important and you don’t hear back from me, call me or come find me.”
In the end, the Curiosity project prevailed and was dubbed “the right kind of crazy” by then NASA Administrator Michael Griffin, who added it was “so crazy it might just work.”
By book’s end, I was left with renewed respect for the engineering that goes into any Mars mission. But the account also provides readers with a real sense of caution about just how far we have to go to send astronauts to the Martian surface, be it on a one-way ticket or for an eventual return.
At a 2004 preliminary meeting to discuss Curiosity, Manning considered just what future astronauts would need at the surface. The list would include food, fuel, oxygen, energy, breathable air, living quarters, roving equipment, and a return vehicle.
“Even if we counted on resupply missions, the initial landings would probably require a spacecraft weighing 30 to 70 metric tons (27,000 --- 63,000 kg),” Manning notes. “How could one possibly bring that much stuff to a stop at a precise location on Mars?”
And if such logistics issues aren’t trouble enough, a paper appearing in the journal Space Weather posits that the Sun’s current weak solar magnetic field is allowing more galactic cosmic rays to overrun the solar system, increasing the potential astronaut radiation risk.
Thus, despite the current spate of manned Mars efforts, the odds of putting astronauts on the Red planet’s surface within the next decade or so still seem long.
As for Manning?
He’s now the Mars Engineering Manager at JPL and has also moved onto his next project involving supersonic Mars lander deceleration. However, JPL’s Mars 2020 rover will be largely based on Curiosity technology and will also aim for “sample caching” --- that is, collecting and storing Mars rock core samples for eventual return to Earth.
For that, NASA will need much larger landers that can “retrieve the cached samples and rocket them into Mars orbit for capture and return to Earth.”
As for Curiosity's most important management lesson?
Success in fielding interplanetary spacecraft depends on more than just communication and teamwork. It also requires audacity, self-confidence and the courage to put one’s career on the line for a project about which you are passionate. Although that sort of mix could help almost any career take off, Manning does warn against over-confidence.
“Arrogance has no place in this work,” he writes. “No matter how smart you think you are, if your Mars lander didn’t work, you were probably not smart enough, and if it did, well maybe you just got lucky.”
