The launch of the James Webb telescope has been delayed again due to poor weather conditions, the US space agency NASA says.
The latest in a series of delays means the Ariane 5 rocket that will carry the telescope is not expected to lift off from the Kourou spaceport in French Guyana until Saturday, a day later than planned.
The telescope is a joint project of the space agencies of Europe, the US and Canada.
The launch was originally scheduled for October 2018.
Scientists plan to use the telescope to learn more about the early universe.
The telescope is scheduled to fly 1.5 million kilometres into space. It will take about four weeks to get there.
They hope to look back into the universe shortly after the Big Bang 13.8 billion years ago.
The James Webb is a successor to the Hubble telescope, which has been in use for more than 30 years.