Astronomers, engineers, scientists and those who dream of space eagerly watched as a NASA spacecraft flew 3 billion miles from Earth near the edges of our solar system. When New Horizons reached its closest approach to Pluto, one Texas Engineering alumnus had particular cause to celebrate the historic accomplishment: Alan Stern, the mission’s leader.

Stern, who holds two bachelor’s and two master’s degrees from UT Austin, is the principal investigator on the New Horizons mission. After nearly 10 years in flight, New Horizons is spending five months studying Pluto and its moons. On Tuesday, July 14, at 6:49 a.m. central time, the spacecraft got as close as it could get to Pluto, some 7,800 miles from the surface.

The New Horizons mission has already helped scientists determine that Pluto is larger than many prior estimates and will ultimately help us understand worlds at the edge of our solar system. Equipped with high-tech cameras, the spacecraft has helped astronomers see Pluto in never-before-seen detail. Images reveal icy mountain ranges as large as the Rockies, flowing ices — much like glaciers on Earth, textured plains and evidence of geological activity in the last 100 million years.

“It says something very deep about humans and our society, something very good about us, that we’ve invested our time and treasure in building a machine that can fly across 3 billion miles of space to explore the Pluto system,” Stern said in an interview with the Smithsonian.

As a young child, Stern dreamed of exploring space as an astronaut. After enrolling at UT Austin in 1975, he devoted himself to becoming the ideal candidate for NASA’s astronaut corps. After studying chemistry and physics as an undergraduate, he stayed at the university to pursue master’s degrees in aerospace engineering and planetary atmospheres at the Cockrell School of Engineering. In his limited free time as a student, he earned his pilot’s license, learned to sky dive and trained to be a flight instructor.

Stern first became interested in Pluto during his time as a graduate student at the Cockrell School. In 1978, astronomers discovered Charon, one of Pluto’s five known moons, and saw indications that Pluto might have an atmosphere that could foster seasons. For his master’s thesis, Stern modeled the range of Pluto’s atmospheric possibilities.

After completing his UT Austin degrees in 1981, he moved to the Laboratory for Atmospheric and Space Physics at the University of Colorado Boulder, where he earned his doctorate in astrophysics and planetary science.

Still determined to travel to space, Stern applied to become an astronaut three times and came very close to joining a shuttle launch to accompany an instrument he developed to study the composition of comets. Ultimately, he was never selected for a space mission, so he devoted his career to his other passion: exploring Pluto.

Stern began advocating for NASA to send a mission to this mysterious planet more than 25 years ago. He persevered through multiple set backs, including several canceled missions and the demotion of Pluto to “dwarf planet,” which occurred a few weeks after New Horizons was finally launched into space.

Finally, on July 14, together with his family, friends and colleagues, Stern celebrated the success of New Horizons’ Pluto flyby. For months to come, the images and data collected on the spacecraft’s incredible journey will continue to unravel more of Pluto’s mysteries, finally bringing this once obscure planet into the light.

Stern resides in Boulder, where he is an associate vice president for research and development at Southwest Research Institute. In addition to overseeing space missions, he has co-founded multiple companies related to space exploration and travel.