Nasa says it has postponed a manoeuvre planned for the Jupiter-bound spacecraft Juno.
The decision comes a week after Juno successfully fired its main engine. The second engine firing was slated for Tuesday but was delayed until September 14.
After the last manoeuvre, engineers noticed higher-than-expected pressure in the propulsion system and wanted time to check it out.
The back-to-back burns are needed to put the spacecraft on course to fly by Earth next year and use the planet's gravity to accelerate to the outer solar system.
The space agency says the delay will not affect Juno's arrival at Jupiter, scheduled for 2016.
Juno was launched last year. It is on a mission to peer through Jupiter's cloud cover and map its magnetic and gravity fields.