After more than two decades of delays and ballooning development costs, NASA’s next-generation space observatory, the James Webb Space Telescope, has arrived in French Guiana, South America — the site of the spacecraft’s planned launch later this year. Its arrival sparks the beginning of weeks of final preparations before the telescope is loaded on the top of its rocket for flight.

The James Webb Space Telescope, or JWST, spent 16 days at sea, packed inside an environmentally controlled, custom-built shipping container aboard a French cargo ship. The vessel transported the spacecraft from Redondo Beach, California, the site of the telescope’s primary contractor, Northrup Grumman. JWST had been at Northrop since early 2018, where it was undergoing final assembly and testing.

Now that JWST is in French Guiana, the spacecraft is closer than ever to its launch, which has long been a moving target. Originally proposed in 1996, JWST was supposed to launch as early as 2007 for a cost of $1 billion. But the project’s timeline has been delayed numerous times, as the budget of the mission has increased to $9.7 billion. On September 8th, NASA set a target launch date for December 18th, 2021, 14 years later than originally planned.

Image: NASA/Chris Gunn

Many of the delays resulted from problems that arose during testing of the spacecraft. JWST has undergone a battery of tests, including vibrational and cryogenic testing, to ensure that spacecraft can withstand the intensity of launch and the harsh space environment. However, during testing and assembly at Northrop Grumman, some screws came loose, valves leaked, and engineers found tears in the spacecraft’s thin sunshield, which is crucial for protecting JWST from overheating while in direct view of the Sun.

Testing eventually wrapped up on JWST in August of this year, and Northrop Grumman spent the next month carefully folding the telescope into the right configuration it needed to be in for transport to French Guiana. NASA also purposefully did not reveal the exact date JWST left Redondo Beach at the time, over fears that the vessel carrying the spacecraft might be intercepted by pirates. Late in the night on September 24th, a police escort accompanied JWST in its shipping container on a 26-mile journey through Los Angeles to Naval Weapons Station Seal Beach, where it was loaded onto its ride to Kourou, French Guiana.

There’s still plenty left to do before flight, but when JWST does launch, it’s set to revolutionize astronomy, allowing researchers to peer deeper into the cosmos than ever before. Set to fly to space on top of a European Ariane 5 rocket, the telescope is supposed to journey to a spot one million miles from Earth. With a massive gold-plated mirror spanning 25 feet wide, JWST will be able to gather light from the oldest objects in the Universe — some that formed just after the Big Bang.