Clock-comparison experiments conducted in space can provide access to many unmeasured coefficients for Lorentz and CPT violation. The orbital configuration of a satellite platform and the relatively large velocities attainable in a deep-space mission would permit a broad range of tests with Planck-scale sensitivity.
" Probing Lorentz and CPT Violation with Space-based Experiments," Physical Review D 68 125008 (2003)
"Clock-Comparison Tests of Lorentz and CPT Symmetry in Space," Physical Review Letters 88, 090801 (2002).
Published work on Lorentz tests in space