### Mighty daring on Mars

Engineer Steltzner took his rapt audience striding with him through the wrong solutions for landing a one-ton rover on Mars that his team worked through a decade ago. Previous rovers had weighed 50 pounds, 385 pounds. This traveling “Mars Science Laboratory” would weigh 1,984 pounds. The old airbag trick wouldn’t work this time, nor would a palette, or legs.

After exhausting everything that looked reasonable but could not work, the team settled on a mini-rocket “sky crane” approach that might be able to work, but there was nothing reasonable-looking about it. Selling the concept, Steltzner invoked arguments such as: “Great works and great follies may be indistinguishable at the outset,” while reminding himself that “Sometimes what looks crazy is crazy.” To make things worse, the idea could not be tested on Earth, because our atmosphere and gravity situation is so different from Mars, “and simulations only answer things you know to worry about.”

Furthermore, the landing had to occur within a tiny target ellipse only 4 by 12 miles in the Gale Crater at the base of Mount Sharp, which stands 15,000 feet about the crater floor. To “kiss the Martian surface” at that spot, the landing system had to go through multiple stages (the “seven minutes of terror”) totally on its own, decelerating violently from 10,000 miles per hour to a gentle 0 mph without a single flaw at any stage. On August 6, 2012, with the whole world watching, the system performed perfectly, and Steltzner’s team at JPL exploded with high-fives and tears on the world’s screens.

After showing the video, Steltzner asked, “Why do it, why spend the $2.5 billion the mission cost?” One eternal question about Mars is whether life is there, or was there. This rover has already determined that Mars once had sufficient amounts of the right kind of water that life could have managed there. “It would have been something bacterial, pond-scummy.” He is now at work on a conjectural series of three missions to bring samples of Martian material back to Earth. The first mission would collect and cache the samples; the second would launch the cache to Mars orbit; the third would return it to Earth. Later projects should explore the ice-covered ocean of Jupiter’s moon Europa and the methane lakes of Saturn’s moon Titan.

“With this kind of exploration,“ Steltzner said, “we’re really asking questions about ourselves. How great is our reach? How grand are we? Exploration of this kind is not practical, but it is essential.” He quoted Theodore Roosevelt: “Far better it is to dare mighty things, to win glorious triumphs even though checkered by failure, than to rank with those timid spirits who neither enjoy nor suffer much because they live in the gray twilight that knows neither victory nor defeat.”

Steltzner reminded the audience of the relative inhospitability of Mars and the intense inhospitability of space. “Outside of the magnetic field of this planet that shelters us from the streaming radiation of the Sun, it’s a really nasty place. It’s inconceivably cold or indescribably hot, bathed in radiation.” To contemplate terraforming Mars or building colonies in space, he said, makes solving the problems here on Earth of maintaining this planet’s exquisite balance for life seem so obvious and doable.

In the harsh lifelessness of space we discover how precious is life on Earth.