A transatmospheric orbit (TAO) is an orbit around a celestial body in which the perigee of the orbit intersects with the defined atmosphere.[1][2][3] Transatmospheric Earth orbits generally use the FAI defined Kármán line of 100 km (62 miles) altitude to differentiate between transatmospheric Earth orbits or low Earth orbits but altitudes such as the U.S. defined 50 mi (80 km) line may be used. Such orbits are subject to significant atmospheric drag, causing rapid orbital decay if left unchecked.

A number of artificial satellites have been placed into transatmospheric Earth orbits,[4] usually due to a launch vehicle malfunction. Such satellites include EOS 02 and AzaadiSAT, which were deployed into a 76 km x 356 km (47 mi x 221 mi) transatmospheric orbit due to an upper stage malfunction on the SSLV rocket. Transatmospheric orbits have limited practical applications because objects placed into such orbits are subject to rapid orbital decay. One such application was used to test the reentry of the IXV spaceplane. It was launched into a 76 km x 416 km orbit (47 mi x 258 mi) transatmospheric orbit.[5]

The Boeing Starliner spacecraft is placed in a transatmospheric orbit by the Atlas V launcher. It uses its onboard propulsion to go to LEO to reach the International Space Station.

Astrobotic Technology's Peregrine lunar lander was moved to a transatmospheric orbit following a fuel leak to avoid becoming hazardous space derbis.[6]

See also


  1. ^ McDowell, Jonathan (24 May 1998). "Jonathan's Space Report". Transatmospheric orbit (TAO): orbital flight with perigee less than 80 km but more than zero. Potentially used by aerobraking missions and transatmospheric vehicles, also in some temporary phases of orbital flight (e.g. STS pre OMS-2, some failures when no apogee restart)
  2. ^ "ADB143755" (PDF). 5 August 1997.
  3. ^ Graham, William (10 February 2015). "Vega rocket launches IXV spaceplane – Mission Complete".
  4. ^ McDowell, Jonathan (26 December 2022). "Definitions Uncataloged ('U') Launches". Retrieved 4 January 2023.
  5. ^ "VV04-launchkit-GB" (PDF). February 2015. Retrieved 4 January 2023.
  6. ^ Astrobotic Technology (2024-01-14). "Update #17 for Peregrine Mission One". Astrobotic. Retrieved 2024-01-15.