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1 chapter one Mars Is Hard On September 23, 1999, near 2 a.m. Pacific daylight time, the Mars Climate Orbiter, known as MCO, a National Aeronautics and Space Administration (NASA) spacecraft that had been launched nine months earlier from Cape Kennedy in Florida, was just arriving at the red planet. The control center at NASA’s Jet Propulsion Laboratory (JPL) in Pasadena, California, was abuzz with excitement and expectation. The gratifying culmination of several years’ work from one of the greatest space engineering centers ever established was nearly upon us. Concepts, designs, test programs, calculations , discussions, highly skilled teams carefully garbed in white suits, scientists, and engineers had all played their parts in ensuring mission success. Engineers sent the signal necessary to fire the spacecraft’s engines and put the probe into orbit. The only thing left to do was wait the required ten minutes for the spacecraft to reemerge from its loop around the back of Mars. A simple signal would then be transmitted from the 2-­ meter-­ high (about 6-­ feet-­ high) craft the approximately 200 million kilometers (about 120 million miles) back to Earth, indicating that all was well. The signal never arrived. Deafening silence hardly describes the dismay and disbelief that filled the room. Over the next several weeks, possibilities were calculated and recalculated, theories were examined, searches were conducted with radio antennas listening from all over the world—to no avail. MCO had vanished. As Mars and Earth each orbit the Sun on their set paths, they come in proper alignment for a launch every 26 months or so. A rocket must launch 2 · Exploring Mars out of the grip of Earth’s gravity and transfer to a path, or trajectory, ultimately allowing the spacecraft to catch up with Mars and fall into the pull of its gravity. The launch energy requirements outside of this 26-­ month opportunity are generally well beyond the ability of any rocket we have on Earth. There are some special cases where a mission might go at another time—for example, while the typical duration of a trip to Mars is 7 to 9 months, there are other trajectories that will transport the spacecraft from Earth to Mars in 2 to 3 years—but these launch opportunities have not been used because of the additional time required and the resulting cost to the program. If you want to send a spaceship from Earth to Mars, this means, in effect , that you have to take advantage of this repeating launch window to reach the red planet. This window is only about 20 days long. Because of the short window, missions have occasionally been sent in pairs, spaced days or a week apart rather than waiting the full 26 months that would be required for a whole new opportunity. This was one such occasion. A month after MCO disappeared, the far more challenging mission, the Mars Polar Lander (MPL), having been launched shortly after its companion craft, also completed the journey to Mars and was set to enter, descend, Figure 1. A top-­ down view of the path a spacecraft must travel from Earth to Mars. Launch opportunities occur every 26 months, and the launch window is open for only 20 days. Mars Is Hard · 3 and land on the surface of the inhospitable Martian south pole. Signals were received as the space probe approached. Then, stunningly, as with MCO, all transmissions suddenly stopped. Once again, scenarios were put forward and calculations were made, and again they were in vain. MPL had disappeared as well. Two such failures, one on top of the other, were unthinkable to NASA. We were good at space. We had been to Mars recently with the very successful Mars Pathfinder mission. We knew how to do this. The public was equally dismayed. The visibility of the Mars failures and the importance of the Mars program to NASA were such that a review board of high-­ profile experts was commissioned to find the causes of the failures of the two missions . The results of that board’s findings ultimately sent me, a senior civil servant from the NASA Ames Research Center in Mountain View, California , to Washington, D.C., to completely restructure NASA’s approach to Mars exploration and to create the first true Mars Exploration Program. Why do we go to Mars and why does it matter so much when missions fail? Mars has fascinated humanity for thousands of years. The Roman Mars and Greek Ares...

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