BradGuth wrote:

With new and improved technology, why doesn't ISS orbit above 500 km?

A maximum of about 425km is due to the rendezvous operational limits of
the Soyuz (Soyuz can hit 460km, but is lower due to fuel consumption
during rendezvous). Add the heavy-lifting limits of the shuttle and you
see the altitudes stay down in the mid 300km range.

Granted, the shuttle can reach a theoretical altitude of 960km, but
that's pretty much emptying the tanks to get there with practically zero
cargo. IIRC, the current record is around 600km (one of the Hubble
flights).

I'm sure the sights would be quite interesting from an altitude over
900km--I recall the one comment in a documentary about the flights to
Hubble where the crew were surprised with how different things (Earth)
looked compared to ISS flights.