As from my latter question it seems Betelgeuse might be much closer than the usually presumed 640 light years. It might be as close as ~440 ly. Suppose it is, would this have any dangerous effects on the Earth's ozone layer (damaging it dangerously) and on orbital spaceflight? How close would a star like Betelgeuse have to be to have dangerous effects on the ozone layer and above (and thus on humans and other life on Earth)?
I came across your question and figured I would reply to it because doing a project on the subject. Explanations here are draw from the website astronimate.com
Would a supernova of Betelgeuse only 440 light years from Earth have any dangerous effects on the Earth's ozone layer (damaging it dangerously) and on orbital spaceflight?
No. A star would need to explode within 30 to 50 light-years to jeopardize Earth. Fortunately, no stars even remotely close to such distances are prime to explode any time soon. In fact, the most likely bomb candidate, IK Pegasi, is a safe 150 light-years away. And, at such distances, we would see the spectacular celestial object, but avoid virtually all danger!
However, were a star 30 light-years away to explode, Earth would be in major danger. Some, or all, of our ozone layer, would disintegrate, leaving us vulnerable to lethal radiation from our Sun.
Not to mention, phytoplankton and other aquatic food chain staples would completely parish. Ultimately, our ocean life and primary food chain would die off, creating massive evolutionary problems.
Plus, essential gases in our atmosphere, like nitrogen and oxygen would likely be ionized by bombarding radiation. Eventually, this would cause obvious dangers to most living organisms. Alas, Earth seems to be quite safe from supernovae for several million, or billions of years. Yet, hopefully, we will experience a supernova from a safe distance. After all, this would be one of the most notable sights in recent human history!