This weekend we will see Curiosity attempt a dramatic Mars landing inside of Gale Crater. Its mission will be to study the Martian rocks to determine how they were formed and try to answer whether conditions on Mars once could have supported life in its most simple form – tiny, microbial cells. The rover’s intended destination after landing is a series of layered rock outcrops on the slopes of Mount Sharp. These layers were spied from orbit only a few years ago and appear to provide a geological record of Mars spanning hundreds of millions of years that Curiosity can spend months touring and reading back to us on Earth. With Curiosity’s hypersonic entry guidance, this is the first Mars rover that could safely land inside Gale and reach these layers.
As interest and enthusiasm mounts for one of the greatest exploration missions of the last decade, it is worth remembering what it took to get here and consider what should be next. We’ve been fortunate to witness a golden age of Mars exploration over the last fifteen years of orbiters, landers, and rovers. The successful international missions of Mars Global Surveyor, Pathfinder, Mars Odyssey, Mars Express, Spirit, Opportunity, Mars Reconnaissance Orbiter, and Phoenix have helped us “follow the water”.
The assumption, given our experience here on Earth, is that where there was water on Mars there may also have been life. The probes orbiting Mars have been outfitted with a dazzling array of sensors and cameras to identify sites that may have been formed or affected by the presence of water. All this feeds into the landing site selection process using the best available data to find sites that are also safe to land at. The rovers have found proof of water in the past, confirming what we see from orbit, and Phoenix found ice just inches under the surface in the far north regions of Mars.
As we explore Mars, we are learning how Mars formed and changed throughout its history. This will help us understand the history of the Earth better as well. Mars is right next door and formed the same time as the Earth did, but how did Mars come to be so different? And despite its differences, did life exist on Mars too? Is life still there, hidden in the ground? In ways we can never predict, we are all enlightened and benefit from discoveries in the jungles or the deep oceans of Earth, the microscopic intricacies of the human genome, the elusive Higgs particle, and delving into the puzzles and opportunities that space exploration presents.
Besides the science, why do we do this? Why spend the years of dedicated effort, the long days away from our families, the meticulous designing, building, and testing? Why do we feel that emotional rush when we attempt a nearly impossible task, or when we watch someone make such an attempt? Theodore Roosevelt offered a fitting answer. “Far better is it to dare mighty things, to win glorious triumphs even through checkered by failure, than to rank with those poor spirits who neither enjoy nor suffer much because they live in the gray twilight that knows neither victory nor defeat.”
It is no coincidence that as Jet Propulsion Laboratory engineers monitor Curiosity on its Mars approach and landing this weekend, only a few miles away the Mars Society is convening its 15th international conference. Enthusiastic people from all over the world and of various professions are discussing how we should reach and perhaps settle Mars this century. If you want to dare mightily, I cannot think of anything more challenging or fitting for the 21st century.
But getting humans to Mars is technically very difficult, and while we don’t yet know how to do it we have a few promising ideas. Curiosity had to give up the proven airbag technique because of its weight, and human missions will be much more massive. Curiosity has a few things important to a future human mission: it will demonstrate a hypersonic guided entry to land close to a site, and radiation sensors to inform what environment a crew and vehicle would withstand throughout the whole mission.
There is so much more to figure out and test. The recent Mars program has been set up to test things incrementally, to build off of what has been done before. Before we bring people to and from Mars, we can bring something from Mars back home to study. Curiosity has an incredible miniature laboratory tucked inside of it, but it can only carry so much instrumentation with it. We can use the orbiters, what Curiosity and other landers find, to help us pick out the rocks that will tell us the most about Mars. We have never been more prepared than we are right now to mount a sample return mission or begin the preparations for a human expedition.
The question facing the American administration and Congress is whether to support one now, in a time where NASA is seeing flat-lined budgets with other high-profile, billion dollar programs such as Webb Space Telescope, the heavy-lift launch vehicle, and the Orion human exploration spacecraft wrestling for those funds.
As America is dealing with large budget deficits, it is unlikely that NASA will receive enough funding to successfully finish all of these this decade, let alone a Mars sample return mission. With Congress focusing on issues of the magnitude of trillions of dollars it will be difficult to get their attention for programs on the order of billions. Expect no decision on anything of significance until after the American presidential and congressional elections this fall. If Mars exploration is to continue, public support is very important so that the politicians can accurately gauge the interest and the benefits.
There have been two grand periods of exploration of Mars. The first was led by a vanguard of American and Soviet probes in the 1960s and 1970s, radioing back amazing pictures of the largest volcanoes and canyons found in our solar system. That first period, suffering many failures as we learned how to reach to Mars, culminated in the successful Viking orbiters and landers.
And then, Mars was left alone — it seemed lifeless to our 1970s technology. The American Mars exploration team that had pulled off so many successes over those dozen years, that had engineered how to land safely on Mars, was scattered. Much of the talent and engineering knowledge from those early days of Mars exploration was lost. Today’s period of exploration had to assemble a new team, tempered by the successes and failures of recent missions, to attempt something as audacious as Curiosity.
We find ourselves again at the crossroads for Mars exploration. Dare we follow where curiosity leads us? Do we decide instead to start over again later this century?