Congressional leadership first floated the creation of sixth branch of the armed forces focused on space combat (sadly, not against invading alien insects though) past year... and Mattis promptly blasted the idea.
If the phrase "separate but equal" sounds familiar, it's a racial segregation doctrine adopted in by the Supreme Court's 1896 Plessy v. Ferguson decision and overturned by the court's 1955 Brown v. Board of Education decision. "We must have American dominance in space".
Trump envisioned a bright future for the USA space program, pledging to revive the country's flagging efforts, return to the moon and eventually send a manned mission that would reach Mars.
Trump is due to meet with his National Space Council on Monday. Air Force chief of staff Gen. David Goldfein said talk about a separate military branch for space is "moving in the wrong direction".
Since then, US efforts to explore beyond the Earth's orbit have largely focused on remote spacecraft that do not have human crew members, though American presidents have repeatedly raised the idea of sending human explorers back to the moon or further.
Retired Air Force Lieutenant General Dave Deptula, dean of the Air Force Association-founded Mitchell Institute for Aerospace Studies, described the decision to create a Space Force as "another example of ready, fire, aim", in a Monday news briefing.
"I oppose the creation of a new military service and additional organisational layers at a time when we are focused on reducing overhead and integrating joint warfighting functions", Mattis said in October in a memo to Senator John McCain, chairman of the Senate Armed Services Committee. It is created to avoid collisions and spacecraft breakups.
Trump also declared that "there's no place like space". NASA astronauts Eileen Collins, Terry Virts and Scott Parazynski also spoke, calling for a clear action-plan toward the country's space exploration goals.
The National Aeronautics and Space Administration is planning a series of lunar missions beginning next year aimed at developing the capacity for a return to the moon.