NASA's James Webb Space Telescope (JWST) has had its launched delayed until spring 2019. The telescope was previously scheduled to launch in October 2018.
The wait is not due to technical or performance concerns, says NASA, but rather because of the complexity of the task.
"Webb's spacecraft and sunshield are larger and more complex than most spacecraft," said Thomas Zurbuchen, associate administrator for NASA's Science Mission Directorate at Headquarters in Washington.
"The combination of some integration activities taking longer than initially planned, such as the installation of more than 100 sunshield membrane release devices, factoring in lessons learned from earlier testing, like longer time spans for vibration testing, has meant the integration and testing process is just taking longer."
The 21-foot (6.5-meter) telescope was designed to examine a broad range of astrophysical phenomena, including the first stars and galaxies to have formed in the universe.
The JWST will be the world's most powerful space telescope ever built, according to NASA, and it will serve thousands of astronomers worldwide.