Highly classified advanced US signals intelligence satellite.

Typical orbit: 33856 km x 37192 km at 0 degrees inclination. Associated Launch Vehicle: Titan 4, Titan 4B.

• 1995 May 14 - USA 110 - Launch Site: Cape Canaveral. Launch Vehicle: Titan 4. Perigee: 35,787 km (22,236 mi). Apogee: 35,787 km (22,236 mi). Inclination: 0.00 deg.

  First launch of 'Advanced Orion' (real code name unknown) new model geostationary ELINT satellite.

• 1998 May 9 - USA 139 - Launch Site: Cape Canaveral. Launch Vehicle: Titan 4B. Perigee: 35,780 km (22,230 mi). Apogee: 35,800 km (22,200 mi). Inclination: 0.00 deg.

• 2003 September 9 - USA 171 - Launch Site: Cape Canaveral. Launch Vehicle: Titan 4B. Mass: 5,200 kg (11,400 lb).

  American signals intelligence satellite placed into geostationary orbit. It was believed the payload was a successor to the USA-110 and USA-139 satellites launched in May 1995 and May 1998, referred to as 'Advanced ORION' by those not in the know. They were thought to be successors to the RHYOLITE missions of the 1970s. The satellite was originally to have launched April 28, 2002. Launch delayed seven times.

• JPL Mission and Spacecraft Library, Jet Propulsion Laboratory, 1997. Accessed at: http://msl.jpl.nasa.gov/home.html.

• McDowell, Jonathon, Quest, "US Reconnaissance Satellite Programs Part 2", 1995, Volume 4, Issue 4, page 49.

• McDowell, Jonathan, Jonathan's Space Report (Internet Newsletter), Harvard University, Weekly, 1989 to Present. Essential internet newsletter recording worldwide weekly space events. Accessed at: http://www.planet4589.org/jsr.html.

• McDowell, Jonathan, Jonathan's Space Home Page, Harvard University, 1997-present. Jonathan McDowell's complete on-line listing of all objects orbited and over 20,000 rocket launches Accessed at: http://www.planet4589.org/jsr.html.

• Krebs, Gunter, Gunter's Space Page, University of Frankfurt, 1996. Accessed at: http://www.skyrocket.de/space.