PASADENA, Calif. -- NASA says a rocket engine burn designed to put a spacecraft close to Jupiter has been delayed until December.

The space agency said Friday the manoeuvre scheduled for Oct. 19 has been postponed as engineers investigate a valve issue.

Juno entered orbit around Jupiter in July after a nearly five-year journey to map the giant planet's poles, atmosphere and interior.

The solar-powered spacecraft made its first close pass over Jupiter in late August, coming within 2,500 miles of the planet's dense clouds and beaming back stunning pictures of turbulent storms in the north pole.

Juno chief scientist Scott Bolton says the delay will not affect the quality of the science collected.

Some three dozen close flybys of Jupiter are planned during the 20-month mission.