Via NY Times:
"Stratospheric airships could give us spacelike conditions from a spacelike platform, but without the spacelike costs," said Sarah Miller, an astrophysicist at the University of California, Irvine.
High-altitude airships are still in their relative infancy. None has ever flown at 65,000 feet for longer than eight hours. But a recent study from the Keck Institute for Space Studies at Caltech suggests that a more capable airship may not be far-off...