All four of the James Webb Space Telescope’s primary instruments have been mounted to the observatory’s integrated science instrument module by engineers at NASA’s Goddard Space Flight Center in Greenbelt, Md., the space agency said April 8.

NASA announced the milestone, in which the European Space Agency’s Near Infrared Spectrograph was fitted alongside the Canadian Space Agency’s Fine Guidance Sensor, ESA’s Mid-Infrared Instrument and the Lockheed Martin-built Near Infrared Camera, in an online post.

JWST’s four main instruments are set to undergo cryogenic testing at Goddard as a unit for the first time in June or July. The Fine Guidance Sensor — which hosts the Near Infrared Imager and Slitless Spectrograph — and the Mid-Infrared Instrument were integrated with the science module for a round of cryotesting at Goddard that started last August and concluded in November. 

Both the Near Infrared Spectrometer and the Near Infrared Camera were delivered to Goddard about a year later than anticipated when NASA completed an extensive rebaselining of the JWST program in 2012. The flagship astrophysics mission is now expected to cost $8.8 billion to build, launch and operate for five years. The mission required new technology development and is now years behind schedule and billions of dollars over initial budget estimates.

JWST is still on track to launch in late 2018, NASA Astrophysics Division Director Paul Hertz said in an April 9 conference call with members of the NASA Advisory Council’s science committee.