Gaylord National Convention Center, National Harbor, MD - MARCH 7: Mark Sirangelo Corporate Vice President, Space Systems, Sierra Nevada Corporation. Credit: SpaceNews/Kate Patterson.

WASHINGTON — Mark Sirangelo, the longtime leader and public face of Sierra Nevada Corporation’s space business, has resigned from the company for personal reasons but as part of a “friendly transition,” the company confirmed July 2.

In a statement to SpaceNews, Fatih Ozmen, owner and chief executive of SNC, said that Sirangelo stepped down from his position as executive vice president for Sierra Nevada Space Systems at the end of June. Ozmen cited only “personal reasons” for Sirangelo’s departure.

“We are proud and grateful for all we have achieved in partnership with Mark over the last ten years,” Ozmen said. “Mark has an inspiring enthusiasm for space and a strong entrepreneurial spirit, both of which he has cultivated among our exceptionally talented Space Systems team.”

In an internal memo, Sirangelo said his departure was a “friendly transition” from the company and “is being made from a positive personal place.” The memo, obtained by SpaceNews, was first published by SpaceRef.

“I understand this change may be perceived as challenging but I wanted you to know that the state of our business is very good with strong leadership behind it,” Sirangelo said in the memo to employees. “We were a founding entity of the new commercial space industry and are now seen as one of its most successful leaders.”

Sirangelo said that Fatih Ozmen and Eren Ozmen, the president and co-owner of SNC, were “completely and positively committed” to its space systems business, and that he had been working with them on a transition plan for his departure for weeks. Sirangelo said he would work with company leadership on transition activities through July and serve in a “strategic advisory capacity for some time” after leaving the company.

Fatih Ozmen will take over as head of Sierra Nevada Space Systems on an interim basis. A company source, speaking on background, said SNC was in talks with potential candidates for Sirangelo’s former position.

Sirangelo had been at SNC since the company’s acquisition of San Diego-based SpaceDev in 2008. SpaceDev was best known for producing the hybrid rocket motor used by Scaled Composites’ SpaceShipOne suborbital vehicle that won the $10 million Ansari X Prize in 2004. SpaceDev had also acquired Starsys, a producer of spacecraft structures and mechanisms. SNC combined SpaceDev with MicroSat Systems, a smallsat manufacturer, to form its Space Systems unit.

SNC’s marquee space project has been Dream Chaser, a lifting body vehicle based on NASA’s HL-20. Dream Chaser work started at SpaceDev and SNC later won NASA funding through the agency’s commercial crew program to support its development. NASA ultimately did not select Dream Chaser for crewed missions but did award SNC a contract in 2016 to use Dream Chaser for International Space Station cargo resupply services. The first mission under that contract is scheduled for late 2020.

SNC is engaged in other space projects, including an award through NASA’s Next Space Technologies for Exploration Partnerships (NextSTEP) program, where the company is developing a ground prototype of a habitation module that could be used on the agency’s proposed Lunar Orbital Platform-Gateway.

For most of that last decade, Sirangelo has represented SNC in space issues and also served the broader industry as former chairman of the Commercial Spaceflight Federation, an industry group. More recently, though, the Ozmens have been playing a more public role regarding the company’s space activities. Fatih Ozmen testified at the first public meeting of the reconstituted National Space Council in October 2017 and serves on the council’s Users’ Advisory Group.

Jeff Foust writes about space policy, commercial space, and related topics for SpaceNews. He earned a Ph.D. in planetary sciences from the Massachusetts Institute of Technology and a bachelor’s degree with honors in geophysics and planetary science...