The international James Webb Space Telescope has passed the final mission analysis review for its launch on an Ariane 5 rocket from Europe’s Spaceport in French Guiana.

This major milestone, carried out with Arianespace, the Webb launch service provider, confirms that Ariane 5, the Webb spacecraft and the flight plan are set for launch. It also specifically provides the final confirmation that all aspects of the launch vehicle and spacecraft are fully compatible.

During launch, the spacecraft experiences a range of mechanical forces, vibrations, temperature changes, and electromagnetic radiation. All technical evaluations performed by Arianespace on the mission’s key aspects, including the launch trajectory and payload separation, have shown positive results.

“We are thrilled to have passed this important step towards the launch of Webb and to have received the green light from Arianespace and NASA,” says Peter Rumler, ESA Webb project manager.

Webb will be the largest, most powerful telescope ever launched into space. As part of an international collaboration agreement, ESA is providing the observatory’s launch service using the Ariane 5 launch vehicle. Working with partners, ESA was responsible for the development and qualification of Ariane 5 adaptations for the Webb mission and for the procurement of the launch service.

Ariane 5 will deliver the telescope directly into a precision transfer orbit towards its destination, the second Lagrange point (L2). After separation from the launcher, Webb will continue its four-week long journey to L2 alone. L2 is four times farther away than the Moon, 1.5 million km from Earth in the direction away from the Sun.

Mission analysis experts at ESA helped to compute the launch window, a complex issue because it involves ensuring that Webb can be inserted into its target orbit and at the same time the Ariane 5 upper stage will safely escape from Earth.

The telescope will observe the Universe in the near-infrared and mid-infrared – at wavelengths longer than visible light. To do so, it carries a suite of state-of-the-art cameras, spectrographs and coronagraphs.

ESA plays a crucial role in the Webb mission. Aside from procuring the Ariane 5 launcher and launch services, ESA is contributing the NIRSpec instrument and a 50% share of the MIRI instrument, as well as personnel to support mission operations.

Webb is an international partnership between NASA, ESA and the Canadian Space Agency (CSA). Webb’s partners are working towards the launch readiness date of 31 October 2021. The precise launch date following 31 October depends on the spaceport’s launch schedule and will be finalised closer to the launch readiness date.

—ESA