The spacecraft has entered the lunar sphere of influence making the Moon, instead of Earth, the main gravitational force acting on the spacecraft.

By India Today Web Desk: Days after it was launched from the shores of Florida in Cape Canaveral, the Orion spacecraft is set to reach its target destination - the Moon. The spacecraft, which will soon return humans to the lunar world, will buzz the Moon on the sixth day of its 25.5-day-long mission.

The Orion spacecraft completed its third trajectory correction burn, firing the auxiliary thruster engines for a duration of 6 seconds at a rate of 3.39 feet per second to accelerate Orion and adjust the spacecraft’s path while en route to the Moon. The burn led to a speed change and determined which of Orion’s service module engines – reaction control, auxiliary, or orbital maneuvering system – to use for a particular maneuver.

Nasa said that with the Orion feeling the lunar gravity flight controllers will conduct the outbound powered flyby burn by firing the orbital maneuvering system engine for 2 minutes and 30 seconds to accelerate the spacecraft, harness the force from the Moon’s gravity, and direct it toward a distant retrograde orbit beyond the Moon.

“The outbound powered flyby burn is the first of a pair of maneuvers required to enter a distant retrograde orbit around the Moon,” Nasa said.

The burn will begin later in the day, with Orion’s closest approach to the Moon targeted following that, when it will pass about 80 miles above the lunar surface. A communication loss with the spacecraft is expected as is passes behind the Moon for approximately 34 minutes.

Nasa said that the spacecraft has captured additional imagery of the Moon using the optical navigation camera. Gathering imagery of the Earth and the Moon at different phases and distances will provide an enhanced body of data to certify its effectiveness as a location determination aid for future missions under changing lighting conditions.

The $4.1 billion test flight is set to last 25 days, roughly the same as when crews will be aboard. The space agency intends to push the spacecraft to its limits and uncover any problems before astronauts strap in. The test dummies — Nasa calls them moonikins — are fitted with sensors to measure such things as vibration, acceleration and cosmic radiation.