Since the 1960s humans have been engaged on a concerted effort to understand Mars. The landing of Mars Curiosity on the surface in the early hours of August 6, 2012, is the latest effort to learn about one of our closest neighbors in the solar system. And its success has been remarkable.
NASA has been pursuing a strategy for Mars exploration that may best be characterized with the motto, “Follow the Water.” In essence, this approach noted that life on Earth is built upon liquid water and that any life elsewhere would probably have chemistries built upon these same elements. Accordingly, to search for life on Mars, past or present, NASA’s strategy must be to follow the water. If scientists could find any liquid water on Mars, probably only deep beneath the surface, the potential for life to exist was also present.
The Mars of today, without any evidence of water whatsoever currently on the surface, probably had water flowing freely in its ancient history. Evidence of changes to the planet’s surface from fast flowing water has been collected by many space probes orbiting the planet since the latter 1990s. The spacecraft to open this possibility was Mars Global Surveyor, reaching the planet in 1998 and a new and exciting era of scientific missions to study the red planet. Its discoveries tantalized us about the possibility of life on Mars, at least in the distant past, for there was evidence present that there might actually be water in the substrata of Mars.
But reaching Mars has always been difficult, and globally more missions have failed than have succeeded in accomplishing what they set out to do. Early on, there were spectacular failures, but even in the last fifteen years there have been several failures. Until Curiosity’s successful landing, out of 40 missions, only 16 have been successful. This means that overall any individual Mars mission has a 1 in 3 chance of success. That is not a bad batting average in major league baseball, but for the limited number of chances we have for reaching Mars with individual missions we have to increase our success rate.
With Mars Curiosity’s successful landing on August 6, this new mission represents a major step forward in a long process of Mars exploration. It is important to recognize just how difficult exploration of the red planet has been and continues to be. For one thing, the success of the entry, descent, and landing technology pioneered on this mission will permanently affect how NASA undertakes future Mars efforts. Many were skeptical about the Sky Crane Landing System used here, questioning its complexity, but it proved to be spectacularly effective. This will become a standard approach to touching down on the Martian surface for successively heavier and more capable payloads in the future.
Since landing, Curiosity has made some stunning discoveries. For example, in measuring radiation levels on the surface of the red planets it has found that Martian radiation levels are comparable to those experienced by astronauts aboard the International Space Station. This enhances the possibility that human activities on the surface are possible. Additionally, Curiosity has found beyond any real doubt that there is an ancient streambed where water once flowed roughly knee-deep for thousands of years at a time. In drilling into the soil, Curiosity also spotted some of the key chemical ingredients for life, including sulfur, nitrogen, hydrogen, oxygen, phosphorus and carbon.