"Extending the GPS Paradigm to Space Exploration“(*)
Flights with an atomic clock around the world show both the special relativity (time dilatation and Sagnac rotational) and the general relativity (gravitational redshift) effects.
Some bizarre theories say that the space can be wrapped by a huge mass, like black hole, to another dimension. For the moment, we have no experimental indications for such phenomena.
In 1918 J. Lense and H. Thirring, noted from the general relativity theory, that a rotating mass creates time-space deformation (besides "ordinary" deformation caused by mass in itself) - like pulling it in the direction of rotation. Unfortunately such an effect in the case of Earth is insignificantly small - it causes change of Moon's orbit just by a few millimetres per year.
Einstein, commenting Lens-Thirring's equation noted, that the effect would be greater if Moon was closer to Earth. He did not predict satellites!
The equation of motion for satellites contain several corrections, all due to the General Relativity
In 1996, small changes in the orbit of “Lageos” satellite, were measured with the 1 cm precision, using laser impulses from Earth. A shift of the orbit of about 1 degree per 120 years was noticed. This confirms the Lens-Thirring effect.
Taking into account that changes of the orbit caused by non spherical shape of the Earth are 10 million times bigger in the magnitude, Einstein would say for sure: "E pur si muove (the time-space)!"
Credits: Abel 1689 cluster is by Andrew Fruchter
(STScI) et al., WFPC2, HST, NASA
http://oposite.stsci.edu/pubinfo/PR/2001/32/content/0132w.jpg
Quasar Q2237+0305 is by J.Rhoads, S.Malhotra, I.Dell'Antonio
(NOAO)/WIYN/NOAO/NSF
HST 01247+0352 Kavan Ratnatunga (Carnegie Mellon Univ.) and NASA
http://hubblesite.org/newscenter/newsdesk/archive/releases/1999/18/image/c
(*) Dr. Robert A. Nelson
Satellite Engineering Research Corporation
Bethesda, Maryland USA
Civil GPS Service Interface Committee (CGSIC) Meeting
Long Beach, California USA, September 21, 2004