Speakers
Description
BIOMASS was selected as the 7th Earth Explorer mission and will be the 4th Core Earth Explorer Mission. The overall objective of the mission is to reduce the uncertainty in the worldwide spatial distribution and dynamics of forest biomass to improve current assessments and future projections of the global carbon cycle. BIOMASS P-band SAR will enable the first global scale, systematic measurement of forest biomass, providing global maps of forest biomass stocks, forest disturbance and growth.
BIOMASS pointing budget is one of the mission’s demanding requirement: the precise knowledge of the Payload pointing direction is fundamental for the scientific observations’ success.
One of the contributors to the overall pointing budget are the Thermo-Elastically induced Deformations (TED) caused by the temperature gradient along the satellite structure when subject to the mission’s environmental loads, whose estimate in Space applications is typically predicted by means of Finite Element Modelling.
In the frame of BIOMASS design and verification process, an innovative thermoelastic test at ambient pressure has been designed and successfully executed with the goal of obtaining an experimental feedback of the as-builts structure response, which has been then compared to the FE model predictions.
Scope of the test has been the application of a set of known boundary conditions comparable with the predicted flight thermal gradients and to measure, by means of photogrammetry and laser trackers techniques, the BIOMASS structure’s overall deformations under such loads. The collected displacements and rotations measurements have been used to identify the correlation factor between experimental data and FE model predictions.
This presentation addresses the TED test setup description and the measurements results, both in terms of thermal mapping and deformations response.
BIOMASS test instrumentation is presented, and the measurement system choices justified; all the test phases are then detailed and finally the correlation criteria to reach the goals illustrated.
Test outcome and post-processing analyses are presented; final correlation of both Thermal and FE models is then described.
The objective and conclusions of the completed campaign are discussed with the scope of providing the engineering community audience the lessons learned, the advantages, the encountered criticalities and the challenged experienced in the frame of an innovative full scale Thermo Elastic test approach to experimentally determine the behaviour of medium sized satellite structure.
It had been demonstrated how the BIOMASS structure was successful to undergo a thermoelastic campaign at ambient pressure, which is an innovative approach able to reduce the complexities of a Thermal Vacuum setup, especially concerning the deformation measurements on a large mechanical structure.
