Testing NISP instrument on ground

The Laboratoire d’Astrophysique de Marseille (LAM) is deeply involved in the development and the test of the NISP (Near Infrared Spectro-Photometer) instrument for the ESA EUCLID mission that will be launched in 2020. The goal of the mission is to understand the nature of the dark energy responsible for the accelerating expansion of the Universe. NISP is one of its two instruments operating in the near-IR spectral region (0.9-2μm) to map the geometry of the dark Universe. The integration of the NISP flight model (FM) has been started at LAM to allow its delivery in 2019 to the payload after vibration test and two thermal vacuum test campaigns to demonstrate the performance of the instrument. The thermal vacuum test will take place in ERIOS chamber, a 90m3 chamber developed by LAM to test optical instruments at cryogenics temperature and high vacuum. In addition to the chamber, a full and specialised set of ground support equipment called the Verification Ground System (VGS) is developed to fill the goal of the NISP test campaign. The test campaign combines functional tests of the detectors and wheels, performance tests of the instrument, calibration procedure validation and observations scenario test, all done at LAM. One of the main objectives of the test campaign is the measurement of NISP focus position with respect to the EUCLID object plane. The VGS is made of i) a telescope simulator to simulate the EUCLID telescope for optical performance tests, ii) a thermal environment to simulate the Euclid PLM thermal interfaces, iii) the NISP Electrical GSE (EGSE) to control the instrument during the test and iv) a Metrology Verification System (MVS) to measure the positions of NISP and the telescope simulator during the test. We present the set of GSE developed for NISP and their performance already validated during two blank tests: thermal blank test and metrology blank test. In addition, a blank test with all the VGS parts (thermal, optical, metrology) is scheduled in the coming months to validate the overall performance of this GSE including the telescope simulator. The goal is to measure with a high precision the focus distance of the telescope simulator at cold and the stability of the focus in time, and to demonstrate the functionality of the telescope simulator for NISP test campaign needs. Finally, we describe the thermal vacuum test configuration for the “end to end” test on the NISP flight model foreseen by beginning of 2019.