The James Webb telescope has a bona fide launch date

NASA announced in August that the James Webb Space Telescope had passed its final ground-based tests and was being prepared for shipment to its launch site in Kourou, French Guiana. Now, the oft-delayed $10 billion telescope has an official launch date: December 18, 2021.

The date was announced on Wednesday by NASA, the European Space Agency, and the launch provider, Arianespace. The space telescope will launch on an Ariane 5 rocket.

Why is NASA's most expensive scientific instrument ever launching on a European rocket? Because the European Space Agency is conducting the launch for NASA in return for a share of observation time using the infrared telescope. Webb will observe wavelengths of light longer than those of the Hubble Space telescope, and this should allow the new instrument to see the earliest galaxies of the Universe.

To the frustration of scientists and policymakers, myriad technical problems have delayed Webb's development over the last decade, leading to enormous cost overruns. Some of this is understandable, as unfurling the 20-meter-long telescope in deep space requires 50 major deployments and 178 major release mechanisms. All of these systems must work or the instrument will fail. There is no easy means of servicing the telescope at its location near a Sun-Earth LaGrange point 1.5 million km from Earth, or four times the distance to the Moon.

This summer, as NASA has worked to address the final issues with Webb, the European Space Agency and Arianespace have had problems of their own with the Ariane 5 rocket. A venerable rocket in service for more than 25 years, the Ariane 5 was grounded from August 2020 to July 2021 due to a payload fairing issue. However, officials with Arianespace say the fairing issue has been diagnosed and addressed with a redesign, and the rocket launched successfully on July 30, 2021.

The Ariane 5 rocket has one more mission to launch two commercial satellites, scheduled for October 15, before the Webb launch. If the Ariane rocket's next flight proceeds nominally, Arianespace will be ready for the Webb telescope.

“ESA is proud that Webb will launch from Europe’s Spaceport on an Ariane 5 rocket specially adapted for this mission," said ESA Director of Space Transportation Daniel Neuenschwander in a news release. "We are on track, the spaceport is busy preparing for the arrival of this extraordinary payload, and the Ariane 5 elements for this launch are coming together. We are fully committed, with all Webb partners, to the success of this once-in-a-generation mission.”