ESA Science & Technology - Publication Archive
SPICA is a JAXA led astronomical mission. The ESA contribution to the SPICA mission, mainly entailing the provision of the cryogenic telescope assembly, is a M-class candidate in the Cosmic Vision 2015-2025 Plan. This document provides a summary of the work performed between August 2008 and September 2009 as part of the SPICA assessment phase study.
The Mid Infrared Instrument (MIRI), one of the four instruments on the Integrated Science Instrument Module (ISIM) of the James Webb Space Telescope (JWST), supports all of the science objectives of the observatory. MIRI optical alignment is an important step in the verification process, directly affecting mission success. The MIRI optical alignment is verified on the ground at the integrated ISIM level using an element in the MIRI Filter Wheel, the pupil alignment reference (PAR), developed by NASA GSFC and provided to MIRI. It is a ~2.3g aluminum piece that has a flat, specularly reflective, 3mm diameter surface in its center, with laser-etched fiducials within its aperture. The PAR is illuminated via an optical stimulus (ground support equipment) and imaged using a pupil imaging camera, during the ISIM test program in order to determine absolute and relative changes in the alignment that impact pupil shear and roll. Here we describe the MIRI PAR; its physical properties and challenges during its design, manufacturing, and testing.
The James Webb Space Telescope, an infrared-optimized space telescope being developed by NASA for launch in 2014, will utilize cutting-edge detector technology in its investigation of fundamental questions in astrophysics. JWST's near infrared spectrograph, NIRSpec utilizes two 2048 × 2048 HdCdTe arrays with Sidecar ASIC readout electronics developed by Teledyne to provide spectral coverage from 0.6 microns to 5 microns. We present recent test and calibration results for the "pathfinder NIRSpec detector subsystem" as well as data processing routines for noise reduction and cosmic ray rejection.
The Mid-Infrared Instrument (MIRI) is one of four scientific instruments on the James Webb Space Telescope (JWST) observatory, scheduled for launch in 2014. It will provide unique capabilities to probe the deeply dust-enshrouded regions of the Universe, investigating the history of star formation both near and far. The MIRI is the coldest instrument on the observatory. Its thermal design is driven by requirements to cool an Optics Module (OM) to below 15.5 K and detectors within this to below 6.7 K with a stability of \ml10 mK over 1000 seconds. The OM is accommodated within the JWST Integrated Science Instrument Module (ISIM) which is cooled passively to between 32 and 40 K. The instrument temperatures are achieved by a combination of thermal isolation of the OM and the ISIM supplemented with active cooling of the OM by a dedicated cryo-cooler. A flight representative "verification model" underwent two cryogenic thermal test campaigns at the UK's STFC Rutherford Appleton Laboratory between December 2007 and September 2008. This paper begins by summarizing the thermal design of the MIRI OM and describing the design of the cryogenic test facility. It goes on to describe the two test campaigns and the correlation of the MIRI OM thermal model to the thermal balance test measurements, concluding with the predicted in-flight thermal performance of the instrument based on this testing.
In the frame of ESA Cosmic Vision assessment study, Thales propose a 3.5m diameter Ritchey-Chretien telescope in HB-Cesic ceramics. The evaluation of its performances demonstrate that the proposed design perfectly fulfils the mission requirements. The objective of this paper is to provide to the reader an overview of the telescope design and performances of the HB-Cesic SPICA Telescope. The development plan is also addressed. It has been established to minimize risks and schedule. The last point is a sensitivity analysis to pupil diameter reduction: an interesting way to further reduce development schedule.