Mark Geyer, senior advisor to NASA’s associate administrator Bob Cabana and former NASA Johnson Space Center director, died Tuesday, Dec. 7, in Houston, after a battle with pancreatic cancer. The Indianapolis native was 63.

“Mark Geyer shaped history,” said NASA Administrator Bill Nelson. “He strengthened this agency and the bonds of our NASA family. We will miss this champion for exploration and forever be grateful for his service.”

Geyer served as the leader of NASA Johnson in Houston, the hub of human spaceflight activity, during a critical period of transition as more human space flight programs were led from Houston during his tenure than ever in history, helping NASA return launch capability to American soil.

Geyer joined NASA as part of the International Space Station Program in 1994, where he served a variety of roles, including NASA’s lead negotiator with Russia on space station requirements, plans, and strategies. He was the first program manager for Orion, a key component of NASA’s Artemis program, which will land the first woman and the first person of color on the lunar surface. Geyer served as deputy program manager of the Constellation Program, before transitioning to manager of the Orion Program, a position he held until 2015. Under Geyer’s direction, Orion was successfully tested in space in 2014 for the first time, bringing NASA another step closer to sending astronauts to deep space destinations.

In 2017 and 2018, Geyer served as the acting deputy associate administrator for technical for the Human Exploration and Operations Mission Directorate at NASA Headquarters in Washington. In this position, he was responsible for assisting the associate administrator in providing strategic direction for all aspects of NASA’s human spaceflight exploration mission. He also facilitated the initial development of Gateway, an outpost built by NASA’s commercial and international partners orbiting the Moon that will provide vital support for a long-term human return to the lunar surface, as well as a staging point for deep space exploration.

“Today NASA mourns the loss of former Johnson Space Center Director Mark Geyer, a leader of human spaceflight, champion of diversity and inclusion, and friend to all who knew him,” said NASA Johnson Space Center Director Vanessa Wyche, who succeeded Geyer. “Mark’s initiation of the center’s vision to dare to expand frontiers, unite with partners to complete bold missions, and explore space to benefit humanity is the hallmark of his legacy for Johnson Space Center.”

Geyer also led NASA Johnson through the longest government shutdown in American history, an unprecedented pandemic, as well as economic and equity challenges.

“As the NASA family mourns his passing, we are forever grateful for Mark’s leadership, and will continue to honor his legacy as a champion of human spaceflight for all,” Wyche said.

Geyer is survived by his wife, Jackie, and three children. A tree dedication will be held at NASA Johnson’s memorial grove in the coming months.