The Emirates Mars Mission has been delayed because of bad weather.
The historic launch was due to happen from Japan on Tuesday, but "weather conditions at the launch site" led the UAE space agency to postpone it.
The Hope Probe, as the Arab world's first interplanetary mission is known, will instead be launched on Friday, 17 July local time, or 8.43pm on Thursday evening in the UK.
It is one of three missions to Mars hoping to launch in quick succession, and will be followed by China and the US's own launches.
The three almost simultaneous launches are a result of the fact that Mars missions must be timed for the period when Mars, the Earth and the Sun align to allow a probe to efficiently sent to the red planet.
That also means that any more significant delay will force the missions to be pushed back by more than two years. The launch window only opens once every 26 months.