WP2: Earth-bound SI-traceable validation of SLR and GNSS
The aim of this work package is to investigate and establish SI-traceable verification of space-geodetic measurement technologies like SLR or GNSS over distances over several hundred metres up to five kilometres. Reference baselines realized by geodetic pillars are used as transfer standards for the verification of these complex technologies. Their reference distance must be determined traceably to the SI definition of the metre with low uncertainty. This will be achieved using many of the instruments developed in WP1 i.e. the long-range distance meters Arpent and CombiYAG, as well as Absolute3D, the spectroscopic and acoustic 1D thermometers, in comparison to standard approaches.
In task 2.1 and task 2.2 existing reference baselines of distances up to 864 m (like the Nummela Standard Baseline or the PTB 600 m baseline PTB600) are used to verify the novel instruments developed in WP1 as a prerequisite for their role as standards in the subsequent tasks in WP2 and in WP3. For verification and mutual comparison, the various intrinsic thermometers are verified at WUT200. This 230 m baseline will be setup through the project in Poland and will there serve as a reference baseline for short range distance meters in the future.
In task 2.3 the novel instrument Arpent is used to perform a case study on the verification of an SLR telemeter at the Nice observatory in Grasse. In task 2.4 and 2.5 comparison measurements of directly SI-traceable optical measurements and GNSS-based distance measurements are performed. These studies will establish SI-traceable verification of these space-geodetic techniques over 5 km at 1 mm uncertainty level (k = 2). Results will be disseminated by an extended report (SLR) and a good practice guide (GNSS).
Finally, the existing Geodynamic Test Field at the Pieniny Klippen Belt in Poland will be refurbished and thoroughly investigated in task 2.5 by various standards and methods. This will establish this network as the first European reference standard for distances up to 5 km (labelled EURO5000 in the following).