Shown during an inspection in the clean room in Greenbelt, Maryland, NASA’s James Webb Space Telescope is complete. It has been transported, tested, fueled, and readied for launch inside an Ariane 5 rocket. On December 22, 2021, and for about a month afterwards, it will be put to the ultimate test: launch and deployment. (Credit: NASA/Desiree Stover)

5 critical moments will determine the success or failure of NASA’s James Webb Space Telescope

After decades of development, whether NASA’s Webb succeeds or fails all comes down to 5 critical milestones that are only days away.

On December 22, 2021, NASA’s James Webb Space Telescope will finally launch.

James Webb will have seven times the light-gathering power of Hubble, but will be able to see much farther into the infrared portion of the spectrum, revealing those galaxies existing even earlier than what Hubble could ever see. Galaxy populations seen prior to the epoch of reionization should abundantly be discovered, including at low masses and low luminosities, by James Webb beginning in 2022. (Credit: NASA/JWST Science Team; composite by E. Siegel)

Success means humanity’s most powerful space observatory ever.

The same object, the Pillars of Creation in the Eagle Nebula, can have vastly different details revealed dependent on the wavelength of light used. Here, the visible light (L) and near-infrared (R) views are shown, both taken with the Hubble Space Telescope. Capable of extending much farther in the infrared than Hubble, James Webb will view details in this (and other) objects that have never been glimpsed before. (Credit: NASA, ESA/Hubble and the Hubble Heritage Team)

Failure means the most expensive “space junk” in history.

NASA’s James Webb Space Telescope, as shown during a “lights out” inspection after its final vibration and acoustic test, performed in October of 2020. Having passed that final test without any red or yellow flags, Webb is ready for launch, but must endure and survive a number of critical milestones before it can even begin taking science data. (Credit: NASA/Chris Gunn)

These five critical events will determine its fate.

A rough launch-and-deployment diagram of the order-of-operations of the James Webb Space Telescope. Depending on what happens during the mission, these timetables may vary significantly, but this is the expected order of the most critical stages of initial deployment. (Credit: NASA/Clampin/GSFC)