I'm an unabashed space cadet from waaaaay back. Nothing interests me more than ideas to get humans out of earth's cradle to become a space faring culture. The problem has always been the high cost of getting to orbit. Once you are there, as Heinlein said, you are halfway to anywhere. Therefore any out of the box thinking on cheap to orbit capability is of interest.
Which makes John Powell's "Floating to Space: The Airship to Orbit Program" a fascinating read. Powell asks the question, can we float to space using lighter than air vehicles? Initially this seems like a stupid question, eliciting an "of course not!" answer. But hold your horses. Powell makes a convincing case that the idea is feasible. His proposal is quite simple. First build a station that floats in the stratosphere, about 25 miles up, where the pressure is less than 1% of sea level. This station is manned, serviced and maintained using a large, V-shaped airship. To get to orbit, an even larger V-shaped airship, with "wings" about 1 mile long is used. This airship uses both buoyancy and dynamic lift to slowly rise to orbit, using low thrust engines achieve the necessary velocity. The idea is compelling and makes you want to write a check to help fund the concept.
At this point, Powell's aerospace company has built and flown test vehicles for both the floating station and the lower atmosphere airship. These seem to prove that this part of the program is feasible and could be scaled up. What has not been done is to test whether airship designs could fly from the station to orbit. This needs a lot of work to determine if ships this large can be stable and whether a propulsion device can be made to propel the vehicle to orbital velocity in the near vacuum of the upper atmosphere, around mach 25.
The sheer beauty of this idea is that even if Powell is wrong about getting all the way to space using the proposed approach, just the floating station component is a great idea - a platform that can be used for a host of commercial applications and tourism. While I think a true space station makes for a better space experience, I can't help but think a floating station that has a black sky above and gravity is going to make for a more popular destination than one with zero gravity: if you can live without the zero-G sex experience, which I assume our first commercial tourists to the ISS have.
Powell stresses that the airship approach is inherently much safer than the current rocket approach, which seems intuitively true, although actual operations would determine that. certainly the idea of traveling slowly but surely, with minimal discomfort is very appealing, even if several hours without a restroom on ascent to the station might be problematic, but not unfixable.
I thoroughly recommend this book and wish Powell all the luck in getting his vision realized.