Boeing Co. has agreed to acquire Millennium Space Systems Inc., an El Segundo-based small flight system developer and satellite manufacturer.

Terms of the August 16 agreement were not disclosed.

Millennium Space was founded in 2001 and develops satellites for extracting missions. It employs an estimated 260 employees.

“Millennium Space Systems’ expertise in vertically-integrated small-satellite solutions perfectly complements Boeing’s existing satellite portfolio, and will allow us to meet the needs of a diverse customer set,” said Leanne Caret, chief executive of Boeing’s defense, space & security program.

Millennium Space Systems will become a Boeing subsidiary and report to Mark Cherry, executive in Boeing’s Phantom Works Technology Group, a part of the company’s space unit.

The acquisition is expected to close by the end of the third quarter, according to Boeing.

Tech reporter Samson Amore can be reached at [email protected] or (323) 556-8335. Follow him on Twitter @samsonamore.