Comment by DoctorOetker
10 months ago
Sure there will be leakage.
Let's look at the composition vs height:
https://en.wikipedia.org/wiki/Atmosphere_of_Earth#/media/Fil...
I understand helium will be sparse at low heights, but at each height there is a diversity of species, among which will be a lighter one. Could a balloon be oversized so that instead of using helium, at each height an 80% fill of the locally (that height) lightest gas could keep the balloon afloat. Oversized for this but also for the added weight for separating equipment for the wanted gas and associated panels to power it.
I.e. what prevents a balloon from flying indefinitely? At least up until radiation damage of the balloon membrane...
Have such attempts been made and what were the lessons?
These guys [https://www.scientificballoonsolutions.com/news/], as of October 2018, claim the world record. [edit: the site linked says Alan Adamson but an upstream post mentions Lee Meadows. That thread also credits Bill Brown as a pioneer - https://www.stratoballooning.org/membership#!biz/id/5f4d7b97...]
The world record balloon was launched on September 21, 2016, stayed up over 767 days, circled the world 35 times and traveled over 1.5 million kilometers.
Their website, still from 2018, indicates they are working on even better designs.