Re: 1957: Russia is planning to launch an artificial satellite
"I'm stupid, but why can't we mix helium and hydrogen?"
You can, but why would you bother? If you're going to use hydrogen then you'd use 100% as the embrittlement and flammability issues are already there and hydrogen is cheap.
FWIW modern airship technology includes pressurisation tech to inflate/deflate the gasbags rather than simply dumping the gas overboard and/or using water ballast. Venting and ballast still exist for emergency use but for more gentle ascent/descent you can keep all your gas. Walrus technology proves you can "stick" your airship to the ground if needed too.
It's also worth noting that unlike the 1940s (The US military used airships up to the loss of the Akron) we have lidar and radar tech which enables spotting clear air turbulence and weather cells at long enough range to go around them. Todays rigid airships are a far cry from the Hindenberg and blimps are used routinely for stuff like skycrane work in a fixed environment (such as forestry where tractors dragging logs would do a lot of ground damage or aren't practical on steep slopes)
The best way to position Airships is "slow, cheap, high capacity haulage". The hard part is their poor weather performance but that's not much different to helicoptors and things like a Mil 11 are much more expensive to run. If you can live with them being a fair-weather only device then they're useful.