Over the past decade, NASA’s robotic explorers have opened our eyes to the scientific beauty and dynamic complexity of Mars. At this very hour, the Spirit and Opportunity rovers are continuing their exploration of the surface of Mars; the Phoenix spacecraft is cruising toward a May 2008 landing in the planet’s north polar region; and the MRO and Odyssey orbiters continue their global observation campaigns.

Paced by the robotic exploration successes of the past few years, our country has completed the critical first steps of a truly phenomenal exploration adventure. Through these missions we have gained an understanding of Mars’ past water environment and the implications for life on the Earth’s closest sibling.

NASA’s robotic explorers have shown Mars to be a complex and dynamic world, provided intriguing evidence for present-day water on Mars, and offered tantalizing clues regarding the potential that Mars could once have harbored life. Conclusive evidence, gained over the past decade, shows that Mars was once a warmer, wetter planet. However, our understanding of the natural forces that drove Mars’ climate change to its present cold, arid state is in its infancy, and the implications to the future of our own planet are unknown.

It is not any one mission or science measurement that has singularly changed our view of Mars. Rather, it is the conglomeration of evidence, gathered through an interconnected set of measurements, obtained by a carefully engineered sequence of science missions. This is the definition of a successful exploration program. Rather than flying a series of independent missions, the Mars program has constructed a system that is greater than the sum of its parts. For example, in addition to their primary science mission, the Mars orbiters serve as communication nodes for the landers and rovers, and provide imagery that allows the selection of safe and scientifically interesting landing sites.

Each mission in the Mars program builds upon the scientific discoveries and the technological breakthroughs that arise from the previous missions. There is continuity of people and processes that enable cost-effective exploration of Mars, with a success rate that belies the inherent risks of these endeavors. To achieve this exploration capability, the Mars program has been funded in the $600 million to $700 million range in recent years, a few percent of NASA’s total budget.

On Feb. 4, in stark contrast to the successful performance of the Mars exploration program, NASA announced a significant reduction in the 2009 budget request for Mars exploration. This budget request is not only in direct contradiction to the guidance NASA received in the 2008 Consolidated Appropriations Act, but also is clear evidence of the gutting of what the American people consider one of NASA’s most successful programs.

The 2008 Consolidated Appropriations Act, enacted into law in December 2007 states:

“The Appropriations Committees agree with the comments in the House report commending NASA for its robotic Mars program which is one of the agency’s most successful programs that has made major scientific discoveries and engaged the public. The Appropriations Committees continue to strongly support a robust Mars Exploration Program with a rate of at least one mission at every opportunity (every 26 months), which is consistent with the administration’s fiscal year 2008 request of $625.7 million. Full funding is provided to: continue operating all present missions (Odyssey, Mars Reconnaissance Orbiter, Spirit and Opportunity); prepare Phoenix for launch in 2007, Mars Science Lab for a launch in 2009, and Scout in 2011; and to start the definition and development of Mars Science orbiter for launch in 2013, and the Astrobiology Field Lab or mid size rovers for launch in 2016. NASA is expected to continue with the development and launch of the Mars Science Lab.”

Funded at $386.5 million, this budget request is well below the 2008 congressionally mandated floor of $626.4 million, and is characterized by a $200 million reduction — about 35 percent — relative to that planned for 2009 in the December 2007 enacted legislation.

Making this request even more alarming is the $350 million proposed five-year annual budget average for Mars exploration, with only $300 million in 2010 — less than one-half of the 2007 Mars program budget. This compares to an average annual budget of about $620 million planned from 2009 to 2012 in last year’s NASA budget request.

By removing any semblance of a continuous exploration program, NASA’s 2009 budget request puts the Mars program on a path toward irrelevance. The budget requested is simply inadequate to complete the next steps in this remarkable exploration program.

Take a closer look at one likely future. Following the Phoenix landing later this year, the Mars Science Laboratory will be launched in 2009. Beyond this date, the future Mars program consists of: nothing in 2011, a Mars Scout orbiter in 2013, the potential for a modest orbital mission in 2016, nothing in 2018, and the glimmer of hope for an international Mars Sample Return campaign that may begin in 2020.

Of course, since this is a five-year budget request that runs through 2013, there need be essentially no funds for Mars Sample Return development contained within it. This is not a program that will produce the type of compelling science that has been achieved over the past decade. Rather, it is the beginning of the end of what has been a dramatic advancement in our understanding of the Mars system.

This budget request also portends a potential decade gap between Mars Science Laboratory and our next Mars surface mission. NASA Administrator Mike Griffin has spoken eloquently about the ramifications that a gap in human spaceflight would have on the United States. Is this Mars surface exploration gap no less significant or concerning for the scientific and engineering literacy of our country?

And what of the scientific and engineering talent that has been developed over the last decade? These people are currently at the top of their game. However, NASA’s 2009 budget request sets into motion a means by which the engineering and science talent that delivered these recent exploration achievements will be lost. Already Mars program personnel at the Jet Propulsion Laboratory and some of the NASA centers are making plans to pursue other endeavors in 2009. As a country, we have invested a great deal of time and effort in these people and the technologies they have advanced.

As an aerospace engineering faculty member, I know firsthand the impact that the Mars program has had on drawing engineering and science students into U.S. universities. I hear the students’ stories and dreams of one day being part of the Mars program every day. We have a pipeline of new science and engineering talent just beginning to come into our program. What will continue to inspire them to work to improve the United States’ scientific drive, technological leadership and economic edge?

The Mars exploration program is a unique symbol of our country’s scientific drive, pioneering spirit and sustained technological interest. Over the past decade, this program has been the strongest and most successful element in NASA’s exploration portfolio. The Mars program has addressed scientific questions of fundamental importance, inspired our children, built the scientific and engineering literacy of our country, and increased our economic and technological competitiveness. Now is the time to accelerate, not curtail, the pace and scope of our robotic Mars exploration program.

Robert D. Braun currently serves as the David and Andrew Lewis Associate Professor of Space Technology in the Guggenheim School of Aerospace Engineering at Georgia Institute of Technology. From 1989 to 2003, he worked at the NASA Langley Research Center.