NASA's newest space telescope will face 29 "harrowing" days after launch as it makes its way to a deep-space destination nearly 1 million miles (1.6 million km) from Earth, the agency says in a new YouTube video.

It focuses on the journey and 50 expected deployments the James Webb Space Telescope will undergo after its expected launch on Dec.

When you're a million miles from the Earth, you can't send someone to fix it," Webb program director Greg Robinson says in the video. .

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And Webb's own thrusters must work properly as well — particularly about 12 hours after liftoff, when they're expected to fire up and send Webb toward its deep-space destination.

As Webb makes that journey, it will be pushed around by the solar wind, or the constant stream of particles coming from the sun, so the telescope will unfold a "trim tab" for stability. .

One of the biggest things Webb will have to unfold is a complex, tennis court-sized sunshield array, which has 140 release mechanisms, 70 hinge assemblies, 400 pulleys, 90 cables and 8 deployment motors, bearing springs and gears, NASA says in the video.

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