The launch of NASA's James Webb Space Telescope (JWST) has been delayed once again, with a revised lift-off window set for no earlier than May 2020. The next-generation space telescope had previously been slated to launch into orbit atop an Ariane 5 rocket from the European Space Agency's spaceport in Kourou, French Guiana, in the Spring of 2019.

Recent hardware testing of the JWST's telescope and spacecraft elements revealed that the individual components of the JWST each met their specified requirements. However, findings from the Standing Review Board set up to watch over the project concluded that more time was needed in order to properly test the components, both separately, and integrated as part of a unified spacecraft.

This will include environmental testing of the JWST by NASA's partner Northrop Grumman Aerospace Systems, who will subject it to extreme vibrational, acoustic, and thermal conditions that it will need to withstand during launch and subsequently, in the hostile environment of space.

News of this latest delay came via a teleconference attended by acting NASA administrator Robert Lightfoot.

"Webb is the highest priority project for the agency's Science Mission Directorate, and the largest international space science project in US history," comments Lightfoot. "All the observatory's flight hardware is now complete, however, the issues brought to light with the spacecraft element are prompting us to take the necessary steps to refocus our efforts on the completion of this ambitious and complex observatory."

During the teleconference, problems that had arisen with the propulsion system, and tears in the spacecraft's sunshield were cited as examples of issues that had caused delays. Seven tears were sustained during deployment testing, puncturing the five membranes that make up the shield, with the largest being roughly 10 cm (4 inches) in length. NASA revealed that it had a confidence level of 70 percent that the JWST would be prepared to launch in the new May 2020 window.

NASA has stated that it is working with its partner, the European Space Agency (ESA), to prepare a new launch readiness date for the JWST's Ariane 5.

The delay will add to the ever-mounting cost of the telescope. As it stands, NASA is rapidly approaching the US$8 billion pre-launch budget allocated to the project by Congress. If the JWST were to exceed this cap by even a single dollar, NASA would be required to go back and attain congressional approval for further spending.

Whilst the news will undoubtedly come as a blow to the countless astronomy enthusiasts who are eagerly awaiting the launch of the JWST, it is important to remember that NASA and its partners have only one chance to get this right. The JWST is a phenomenally complex and ambitious undertaking, and once operational, will be the largest and most powerful orbital telescope ever created.

Simply to fit inside the fairing of its Ariane 5 launch vehicle, it is required to fold in upon itself like a delicate piece of origami. This complexity adds an increased risk of failure, and NASA is keen to take every measure to ensure that a functional observatory is sent in to orbit.

What's more, unlike the Hubble Space Telescope, which was close enough to Earth to benefit from multiple rescue and servicing missions, the JWST will be unreachable after launch. This is because, even if NASA and its partners had the capabilities of the Space Shuttle program, it would be far too distant to reach and service once in its operational orbit, just under one million miles from Earth.

Source: NASA