BEIJING -- China's spacecraft testing technology for the Chang'e-5 return lunar mission, trimmed its orbit on Friday afternoon.

This was the first modification during a journey scheduled to take about eight days, according to a statement from the State Administration of Science, Technology and Industry for National Defense.

The modification was necessary because the unmanned spacecraft is affected by external factors during the transfer from a terrestrial orbit to a lunar orbit, according to the statement. Updated software allows monitors in Beijing to spot glitches during the journey immediately and respond to them.

The orbiter was launched by a Long March-3C rocket from the Xichang Satellite Launch Center in southwest China's Sichuan Province on early Friday.

Developed by China Aerospace Science and Technology Corporation, the spacecraft will fly around the moon half a circle and return to Earth.

The mission is to collect data and validate re-entry technology such as guidance, navigation and control systems, and the heat shield in anticipation of a moon landing by Chang'e-5, which will collect samples and return to Earth, probably in 2017.

It is the first time China has conducted a test involving a half-orbit around the moon at a height of 380,000 kilometers before having the spacecraft return to Earth.

The test orbiter is a precursor to the last phase of a three-step moon probe project, a lunar sample return mission.

China carried out Chang'e-1 and Chang'e-2 missions in 2007 and 2010, respectively, capping the orbital phase.

The ongoing second phase saw Chang'e-3 with the country's first moon rover, Yutu, on board succeed in soft landing on the moon in December 2013. Chang'e-4 is the backup probe of Chang'e-3 and will help pave the way for future probes.