Trump's Golden Dome defense system could spark a space arms race and has drawn concerns from experts and other countries.

The summary highlights three major developments in space science: two galaxies set for a mega-merger, Trump's Golden Dome defense project, and SpaceX Starship's authorized return after a failed test.

President Trump on Tuesday announced that his ambitious, multibillion-dollar Golden Dome missile defense shield would only cost $175 billion to build and be “fully operational” in less than three years,

Several major defense contractors will likely be called on to construct the Golden Dome, though President Trump did not name specific companies in his initial announcement.