CoAuthors

Alexandre Couhert (CNES, France); Sean Bruinsma (CNES, France); Frank Lemoine (NASA GSFC, USA)

Satellite Laser Ranging (SLR) data, made available by the International Laser Ranging Service (ILRS), is essential to validate and quantify the orbit precision of the altimeter satellites. It is the only independent and unambiguous validation method that can provide the absolute radial orbit accuracy by means of high elevation passes. However, now that we are looking for sub-centimeter accuracy, SLR performance is stretched close to the present limit even for the core stations. In particular, biases and drifts have been detected in the ranging data, the amplitudes of which appear to be altitude (i.e. range) dependent. That complicates the determination of accurate station bias corrections because highest precision and accuracy is achieved on the LAGEOS satellites, which are in orbits several thousand km above the altimeter satellites. A relatively recent geodetic satellite, LARES, is at an altitude of about 1500 km, i.e. only a few hundred km above Jason, and it currently is the optimal LEO target.
In this analysis, SLR station biases from 2001 to 2016 were estimated in precise orbit determinations on the geodetic satellites LAGEOS-1/2 (at 5900 km altitude), Starlette/Stella (at about 850 km) as well as LARES (at about 1500 km), using the ITRF2014 station coordinates in this. Jason-2 GPS+DORIS precision orbits are also used to compute SLR ranging biases.