Conveners
Geodesy and Ranging
- Antonio Font Roda (chair)
Geodesy and Ranging
- Antonio Font Roda (chair)
Gravity measurements are a crucial tool to peek through the surface of planetary bodies and reveal their interior structure. As a consequence of the equivalence principle, every gravity measurement in space must be a differential one, therefore requiring two test masses. Microwave links provide the observable quantities needed to follow the free fall of a probe mass (the spacecraft) in the...
Invited talk
Optical atomic clocks have demonstrated unprecedented stability and estimated systematic uncertainty, far surpassing the current generation of caesium primary frequency standards. Large-scale efforts are underway to verify their uncertainty budgets by means of international comparisons using optical fibre networks or satellite-based frequency comparison techniques. Such comparisons, together...
There are laser retroreflector arrays (LRAs) on the Moon since 50+ years ago (deployed by Apollo and Luna missions). There were no laser retroreflectors on Mars until microreflectors (of ~25 gr mass) were recently deployed on Mars (deployed by the InSight and Perseverance missions). These instruments are positioned using specialized ephemeris software (Planetary Ephemeris Program, from the...
The GRACE-FO twin satellites were launched in mid 2018 to continue the enormously useful Earth gravity field measurements from GRACE (2002-2017). The novel feature is the Laser Ranging Interferometer (LRI), which improves the noise of the inter-satellite separation measurement from 2 μm to 200 pm at high frequencies. The LRI was designed as an experimental demonstrator, but continues to work...
