LISA telescope assembly optical stability characterization for ESA

Abstract

The LISA Optical Stability Characterization project is part of the LISA CTP activities to achieve the required Technonlogy Readiness Level (TRL) for all of the LISA technologies used. This activity aims demonstration of the Telescope Assembly (TA), with a structure based on CFRP technology, that a CTE of 10 -7 1/K can be achieved with measures to tune the CTE to this level. In addition the demonstration is required to prove that the structure exhibits highly predictable mechanical distortion characteristics when cooling down to -90°C, during outgassing in space and when going from 1g environment to 0g. This paper describes the test facilities as well as the first test results. A dedicated test setup is designed and realized to allow monitoring dimensional variations of the TA using three interferometers, while varying the temperature in a thermal vacuum chamber. Critical parameters of the verification setup are the length metrology accuracy in thermal vacuum and the thermal vacuum flexibility and stability. The test programme includes Telescope Assembly CTE measurements and thermal gradient characterization.

The Breadboard model of the LISA telescope assembly

“…Currently the Thermal Vacuum Chamber and the Length Metrology system, specifically developed by TNO for the LISA TA measurement, are being integrated and tested together using a dummy telescope [3]. This dummy telescope will undergo a similar thermal trajectory as the breadboard model demonstrating the performance and limitations of the setup.…”

Multifunctional Nanostructures with Controllable Band Gap Giving Highly Stable Infrared Emissivity for Smart Thermal Management

“…Thermal control is essential for spacecraft systems, in order to maintain the temperature of the spacecraft within a narrow range of operating temperatures during the operational lifetime. , The design of thermal control systems (TCSs) on satellites is dictated by the extreme conditions of the harsh environment in space. Large temperature differentials across mission payloads can exert dimensional changes that result in mechanical stresses, which must be mitigated, to avoid structural distortions and ensure mission success. − Without TCSs, these dimensional changes can result in misalignment of scientific instruments: i.e., optical components that are required to observe deep space and discover or monitor planets, as demonstrated recently. − The spacecraft temperature is maintained by means of a delicate balance among external fluxes, emitted radiation, and heat that is produced internally (Figure a). State-of-the-art TCSs include passive methods such as thin foils, multilayer insulation (MLI), sun shields, etc.…”

Lisa telescope assembly optical stability characterization for ESA

“…Inside this shroud an electrically heated shroud is adjusted to the desired temperature. Commissioning experiments [1] demonstrate over the operational temperature range of ˗90°C to ˗45°C that a shroud homogeneity of <1.2K and stability of 12mK/hr can be obtained.…”

“…Previously the test facilities as well as the first test results were presented [1]. In this paper the results of these thermal vacuum experiments are described.…”