Was the Shuttle Orbiter in contact with air traffic control during its descent & landing?
Well, sort of. The Kennedy Space Center, where the shuttle operations were conducted, has an ATC. but then, the show was run by NASA, not FAA.

The shuttle operations were coordinated through the Aerospace Control Officer (ACO) at the Air Force 45 th Space Wing’s Eastern Range (it used a military TACAN). FAA was informed of the shuttle landing and nothing else. NASA simply cleared the airspace for a 30 mile radius around the intended landing site to prevent collisions.

In the trajectory of the shuttle landing, FAA issued a NOTAM called 'Space Shuttle Landing Operations Advisory' to warn the users that 25 miles to either side of the nominal reentry trajectory is potentially vulnerable to debris, but the airspace is not closed, like this example:


  FDC 9/1945 (A0856/09) - ...SPACE SHUTTLE LANDING OPERATIONS ADVISORY...
  EFFECTIVE 0911271848 UTC UNTIL 0911271923 UTC SPACE SHUTTLE
  LANDING OPERATIONS 25 NM EITHER SIDE OF THE LINE BETWEEN
  2743S/17214W 0411N/16214W 2925N/13455W 3440N/11828W 3457N/11745W
  FROM SURFACE TO UNLIMITED. WIE UNTIL UFN. CREATED: 25 NOV 21:11 2009


For these actions, Special Use Airspace was activated. The ACO coordinates these actions with the FAA’s ARTCC (Air Route Traffic Control Center) in Miami, Florida