The US Air Force succeeded in launching the Atlas 5 rocket carrying the X-37B spacecraft on a secret mission.
The missile was launched on Sunday from Cape Canaveral, after its launch was delayed on Saturday due to bad weather.
The plane, also known as OTV, will deploy a satellite into orbit and test new energy technologies.
This is the sixth mission of the X37B in space.
The US forces gave the missile a launch to salute front-line workers whom counter the Coronavirus, and those directly affected by it.
The US Army is sending them a letter written on the launch pad, containing the words “America is strong”.
The Pentagon has not previously disclosed much of the information about the X37B, the type of mission and capabilities.
The US Air Force Secretary, Barbara Barrett, said earlier this month that the plane would conduct more experiments, including testing the effect of radiation on seeds and other materials.
The space plane project began in 1999, and it resembles a smaller version of the spacecraft that was pulled from the US space program in 2011.
It can slide through the atmosphere and land on the runway.
The plane, built by Boeing, uses solar panels for power in orbit, is 29 feet (9 meters) long, has a wingspan of about 15 feet and weighs 4,988 kg.
The first plane left into space in April 2010 and returned after an eight-month mission.
Its last mission ended in October, after spending 780 days in orbit, and the time the plane had spent in space more than seven years.