A SpaceX Falcon Heavy rocket, carrying the U.S. Air Force's Space Test Program 2 MissionTwitter

SpaceX launched its third Falcon Heavy rocket from Kennedy Space Center in Florido on Tuesday, June 25. The CEO of the private US aerospace manufacturer, Elon Musk, called the launch one of the most challenging launches that they have attempted. 

The rocket carrying 24 experimental satellites was launched at 2.30 am after a three-hour delay, reported Reuters.

The mission, Space Test Program 2 (STP-2), was described as the most powerful space launch in the world. SpaceX said it was the first time the company experimented with reuse of side boosters. The side boosters in the STP-2 were used in the Arabsat-6A mission in April.

While the mission was commissioned by the US Department of Defense under the US Air Force Space and Missile Systems Center (SMC), satellite for agencies including NASA, the National Oceanic and Atmospheric Administration (NOAA), defence department laboratories, university research projects and a non-profit were also carried, reported Reuters.

The STP-2 carries satellites for 'deep space atomic clock' for space navigation and 'space environment testbeds' for weather research developed by NASA technology. The mission is also the first time NASA-designed green propellant fuel will be tested in space.

The STP-2 is described as a "unique space access opportunity for DoD and inter-agency science and technology missions that directly enhance the space capabilities of the US and its allies and partners" in the official SpaceX website.

Earlier this month, Space X's Falcon 9 had returned to Earth after launching the RADARSAT Constellation Mission to orbit.

Watch the video of the six-hour mission to deploy the satellites below: