By any objective measure, planetary science is one of America’s crown jewels. A unique symbol of our country’s technological leadership and pioneering spirit, this endeavor has consistently demonstrated that the United States is a bold and curious nation interested in discovering and exploring the richness of worlds beyond our own. In addition to informing our worldview, these missions are inspirational beacons, pulling young people into educational and career paths aligned with science, technology, engineering and mathematics, the foundation of continued U.S. economic competitiveness.

Beginning with the flight of Mariner 2 more than 50 years ago, the United States has consistently led the robotic exploration of our solar system. Decade by decade, we have created, flown and operated a balanced portfolio of missions to explore destinations across the solar system. For example, in the 1970s, the U.S. conducted the Viking missions at Mars, the Pioneer missions at Venus, and the Voyager and Pioneer missions to the outer planets. In the 1990s, the U.S. carried out multiple missions at Mars, Cassini to Saturn, as well as missions to our Moon, the asteroids and a comet. Today, U.S. spacecraft are en route to Jupiter and Pluto, two rovers trundle across the martian surface, and orbiters at Mars and Saturn are returning tantalizing insights.

Despite the success that has built up over decades, today we are on a path that relinquishes U.S. planetary science leadership. Starting in 2017, with the end of the Juno mission at Jupiter and the Cassini mission at Saturn, NASA will only have spacecraft at or on their way to one planet: Mars. Most striking is that after four decades of U.S. spacecraft operating in the vast outer solar system, there are currently no outer planet missions of any kind planned until after 2030 — when the European Jupiter Icy Moons Explorer is scheduled to arrive at its destination. In 2017, our insight into much of the solar system will go dark. Because it takes at least five years to conceive, design and implement a planetary science mission, this cliff is not only upon us, it is getting larger with each passing day. The next suite of planetary science missions should already be in development.

The emergence of the Chinese and Indian space programs and the continued successes of the European and Japanese programs illustrate that robotic exploration of space is an international priority — a way to gain scientific knowledge, global prestige and advance technological capability. In the coming decade, China is preparing a series of robotic lunar missions, Russia is preparing lunar, Venus and Mars missions, India has plans to go to the Moon and Mars, Japan is planning a second asteroid sample-return mission, and the Europeans are headed to Mercury, Mars, the asteroids and Jupiter.

Unfortunately, President Barack Obama’s 2014 budget request for NASA continues the draconian path for planetary science laid out in the administration’s 2013 request. Most striking, this budget line is reduced approximately $200 million relative to the 2013 level appropriated by Congress and signed into law by the president just three weeks ago. While a series of Mars missions is scheduled through 2020, NASA remains without plans for the development of missions to any other planets. Does the U.S. really want to cede leadership of the scientific exploration of the rest of the solar system to other nations?

Mars exploration can tell us much about our past and our potential future, but we have learned that our solar system and other planetary systems are exceedingly diverse. From the subsurface ocean of Jupiter’s moon Europa to the vast hydrocarbon seas on Saturn’s moon Titan to the mysterious ice giants Uranus and Neptune that stand like sentinels at the solar system’s edge, there is much yet to discover in our cosmic backyard. A year ago, the National Academies put forward a roadmap for solar system science in the 2013-2022 decade. Balance was sought, both in the destination of the U.S. science missions and in their scope, to enable a steady stream of new discoveries and the capability to address grand challenges like sample return and outer planet exploration. However, driven by budget shortfalls and its own penchant for large, expensive missions, NASA has abandoned this balanced approach, resulting in a complete shutdown of missions to planets other than Mars after 2017.

For 50 years, NASA’s program of robotic planetary science has been unparalleled in its successes and scope. Continuing this success requires action now, as these missions take years to develop and then to reach their destinations. We can continue U.S. leadership in this field or we can abandon an endeavor that inspires our children, builds the scientific and engineering literacy of our country, and increases our economic and technological competitiveness. Now is not the time to curtail the pace and scope of our planetary science program. This is a pursuit worthy of a great nation.

Robert D. Braun is the David and Andrew Lewis Professor of Space Technology at the Georgia Institute of Technology and served as NASA chief technologist in 2010 and 2011. Noel W. Hinners retired as vice president of flight systems for Lockheed Martin Space Systems and formerly served as associate deputy administrator and chief scientist of NASA, director of the NASA Goddard Space Flight Center, and NASA associate administrator of space science.