Mars Rover Curiosity by Rob Manning William L. Simon

Author:Rob Manning,William L. Simon [Manning, Rob]
Language: eng
Format: epub, azw3
ISBN: 978-1-58834-474-8
Publisher: Random House Publisher Services
Published: 2014-10-21T04:00:00+00:00

CHAPTER 11

It’s All About the People

This work is all about the energy, drive, and persistence of the people involved. If I thought what we had already overcome was like climbing Mount Kilimanjaro, I was about to discover that in fact we were a long way from reaching the peak of the mountain, and the rest of the climb was going to be far worse.

I was still Mars Program chief engineer, which meant that I was splitting my time between a lot of separate Mars efforts. I was still supporting Dara Sabahi’s EDL team for the Phoenix spacecraft due to launch the following year, giving detailed design advice at MSL’s subsystem reviews, and supporting long-term planning for the someday human Mars exploration.

Dara Sabahi shared with me his concerns about the MSL mechanical engineering work. He felt they were getting further and further behind. In his part-time role as JPL’s chief mechanical engineer, he had been walking around and interviewing mechanical engineers on MSL to see if there were places that needed closer scrutiny. He suggested that I should do the same for other areas on MSL, spending time simply chatting with people to get a sense of how various team members thought things were going and if they were facing challenges that they were concerned about finding solutions for. Since Phoenix was looking in pretty good shape, I agreed, acknowledging that I thought I should spend a lot more of my time on MSL.

It wasn’t long before Dara and I learned about one of the first big cracks in the machine. Adam Steltzner had called a meeting to inform us of some unsettling news about the viability of MSL’s heat shield. All of our Mars landers require a heat shield to protect the lander or rover from the intense heat of entry into the Mars atmosphere. Back in the 1970s, researchers at Lockheed Martin (then called Martin Marietta) had invented a “thermal protection system” material, a blend of corkwood, epoxy, and millions of tiny gas-filled silica glass spheres, technically described as a Super Lightweight Ablator, with this specific version designated as SLA-561V. This material had been used on our Mars missions since Viking.

SLA has a unique quality. As the friction of the Mars carbon dioxide atmosphere begins to heat it, gases trapped inside the glass spheres slowly escape. This gas leaks into the oncoming hot flow of carbon dioxide, reacting with it and in the process stealing heat from around the heat shield before being blown away by the incoming airflow. The process creates a long contrail of hot gas in the vehicle’s wake and leaves the heat shield much cooler than it would otherwise get. Without this process that we call “ablation,” our heat shield and everything inside would melt.

When it came time to run the routine tests of our MSL heat shield material, the team put a “coupon”—a specimen of the material—into an Arcjet test facility. This is a hypersonic-thermal, ultra-high-temperature wind tunnel, able to produce an approximation of

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