SpaceX disclosed in a filing on Friday that longtime board member Donald Harrison has stepped down, a move that comes as CEO Elon Musk pushes for a merger between SpaceX and Tesla. Harrison serves as Google's president of corporate development and joined the board in 2015, when Google invested nearly $1 billion in SpaceX; Google still holds a substantial stake in the company. According to the filing, Harrison submitted his resignation on November 4 and explicitly stated that his decision was not due to any disagreement with the company over its operations, policies, or business practices. Harrison was part of SpaceX's independent director group, which is assessing the possibility of a merger with Tesla. SpaceX now has five independent directors remaining.