> but shouldn't it be simple to make a high altitude balloon out of a material that doesn't explode so easily when it gets to the lower pressures in low earth orbit?
No, because balloons don't orbit, they follow the wind patterns at a lower altitude than the lowest satellite orbits. And they're relatively short-lived at altitude -- from seconds to days.
> Or even some kind of contraption that slowly releases gas from the balloon as it detects lower pressure in the atmosphere to help it maintain altitude and prevent the balloon from rupturing?
No, not "releases gas" -- that would lose the gas irreversibly. Instead, consider a scheme that used solar power to drive a pump to put some of the gas under pressure as needed, and releases it later as needed to maintain altitude. Sort of how a submarine maintains its buoyancy by filling tanks with either water or gas, depending on the need, and that does this by putting the gas under pressure to change buoyancy (and avoid losing the gas).
But balloons don't have very long lifetimes at the moment. This might change in the future.
No, because balloons don't orbit, they follow the wind patterns at a lower altitude than the lowest satellite orbits. And they're relatively short-lived at altitude -- from seconds to days.
> Or even some kind of contraption that slowly releases gas from the balloon as it detects lower pressure in the atmosphere to help it maintain altitude and prevent the balloon from rupturing?
No, not "releases gas" -- that would lose the gas irreversibly. Instead, consider a scheme that used solar power to drive a pump to put some of the gas under pressure as needed, and releases it later as needed to maintain altitude. Sort of how a submarine maintains its buoyancy by filling tanks with either water or gas, depending on the need, and that does this by putting the gas under pressure to change buoyancy (and avoid losing the gas).
But balloons don't have very long lifetimes at the moment. This might change in the future.