>Watching that launch will be the most heartstopping moment of my life.
You got that right. When Elon launched the car I was like "eh this will be just like any other launch" then as the launch started I was perched on the edge of my chair shouting "CLIMB CLIMB CLIMB BABY CLIMB" at my phone. JWST will be one of the most nerve-racking moments of my life if I watch the launch due to it's many delays.
I wish they've invented notebooks or something. So we could build a second JWST at a smaller cost.
Very similar with how building a Saturn V today is logistically impossible, even if we can build more modern, efficient and cheaper rockets.
At best we could send a robot, which would probably be more easily operated from the ground.
Even coming up with something from scratch is unlikely to cost the $10B we'd lose from a failed JWST.
Near Infrared Spectroscopy [0]. JWST will be the first instrument in space capable of performing NIR spectroscopy, which will be used to analyze the starlight shining through exoplanets' atmospheres for evidence of biological molecules.
[0] https://dms.cosmos.esa.int/COSMOS/doc_fetch.php?id=3372219