By one of those weird coincidences, I had been on [JP Aerospace][1]'s site mere hours before reading [this question about space dirigibles][2] here. Their [mission plan][3] seems too good to be true.  

They are proposing a three part infrastructure
>**Earth to the top of the atmosphere.**  
High Altitude airships fly from the ground to the station at
140,000 feet.

>**Transfer point at the edge of space.**  
A two mile wide station parked at 140,000 feet is the new way station to space. The station acts not only as a port for the orbital airship but also as a research center, construction site and tourist destination. 

>**From the edge of space to orbit.**  
This 6,000 foot long vehicle never touches the ground. This
airship flies from the upper atmospheric station to orbit. It
uses hybrid chemical/electric propulsion to slowly
accelerate and reach orbit. 

![airship, station, orbitor][4]  
*L to R: Airship, Station and Orbitor (not to scale).*  

Set aside, for the moment, the engineering & technical challenges of establishing a permanent, crewed "suborbital space station" two miles wide at 140,000 feet. The company does, after all, hold the world's record for the [highest flying airship][5]. What really lifted my eyebrow was their Orbital Ascender:  

![enter image description here][6]  
This is a huge (a mile or more long) lighter-than-air craft to be assembled at 140,000 feet.  
> The airship uses buoyancy to climb to 200,000 feet. From there it uses hybrid electric/chemical propulsion to slowly accelerate. As it accelerate it dynamically climbs. In nearly nine hours it achieves orbital velocity.  

They're a bit cagey about their "hybrid electric/chemical propulsion," but the ion engine (or whatever) is to be powered by solar cells overlaying most of the top surface.  

**Is there anything about high-altitude dynamics or orbital mechanics that renders this unlikely? Or are there any other show-stoppers to this concept?** 

If you're interested, there's a book by the concept's originator:  
*[Floating to Space: The Airship to Orbit Program][7]*, by John M. Powell (Apogee Books Space Series, 2008)


  [1]: http://www.jpaerospace.com/
  [2]: http://space.stackexchange.com/questions/6517/has-anyone-proposed-a-serious-space-dirigible-design
  [3]: http://www.jpaerospace.com/atohandout.pdf
  [4]: https://i.sstatic.net/MtYI3.jpg
  [5]: http://www.aero-news.net/index.cfm?do=main.textpost&id=0fcb3845-ad1f-4b08-b6f1-8a7e5d0c66e6
  [6]: https://i.sstatic.net/WNYXC.jpg
  [7]: http://www.amazon.com/Floating-Space-Airship-Program-Apogee/dp/1894959736