The Ariel space mission will characterize spectroscopically the atmospheres of a large and diverse sample of hundreds of exoplanets. Through the study of targets with a wide range of planetary parameters (mass, density, equilibrium temperature) and host star types the origin for the diversity observed in known exoplanets will be better understood. Ariel is an ESA Medium class science mission (M4) with a spacecraft bus developed by industry under contract to ESA, and a Payload provided by a consortium of national funding agencies in ESA member states, plus contributions from NASA, the CSA and JAXA. The payload is based on a 1-meter class telescope operated at below 60K, built all in Aluminium, which feeds two science instruments. A multi-channel photometer and low-resolution spectrometer instrument (the FGS, Fine Guidance System instrument) operating from 0.5 – 1.95 microns in wavelength provides both guidance information for stabilizing the spacecraft pointing as well as vital scientific information from spectroscopy in the near-infrared and photometry in the visible channels. The Ariel InfraRed Spectrometer (AIRS) instrument provides medium resolution spectroscopy from 1.95 – 7.8 microns wavelength coverage over two instrument channels. Supporting subsystems provide the necessary mechanical, thermal and electronics support to the cryogenic payload. This paper presents the overall picture of the payload for the Ariel mission. The payload tightly integrates the design and analysis of the various payload elements (including for example the integrated STOP analysis of the Telescope and Common Optics) in order to allow the exacting photometric stability requirements for the mission to be met. The Ariel payload has passed through the Preliminary Design Review (completed in Q2 2023) and is now developing and building prototype models of the Telescope, Instruments and Subsystems (details of which will be provided in other contributions to this conference). This paper will present the current status of the development work and outline the future plans to complete the build and verification of the integrated payload.
In this proceeding, we present the development of the Optical Ground Support Equipment (OGSE) used for payload-level testing of the Ariel space mission. Ariel is an ESA mission that will use the transit spectroscopy method to observe the atmospheres of nominally ~1000 exoplanets. Ariel is a 1 m class cryogenic (∼ 40 K) space telescope that will be placed in a halo orbit around the Earth-Sun L2 point. To detect atmospheric molecular absorption features, Ariel will produce medium-resolution spectra (R ≥ 15) using three spectroscopic channels covering 1.1 – 7.9 μm as well as having photometric channels covering 0.5 – 1.1 μm. To achieve Ariel’s science goals, the payload requires detailed calibration and performance verification. The payload-level performance verification of the Ariel payload will take place in 2026 in a 5-meter vacuum chamber at the Rutherford Appleton Laboratory’s Space Instruments Test Facility. The payload will be enclosed in a Cryogenic Test Rig (CTR) to provide a space-like (~35 K) thermal environment and is illuminated by the OGSE. The OGSE provides point as well as extended source illumination across Ariel’s full wavelength range. The OGSE design also includes a series of mechanisms and features to enable the various illumination conditions required to test Ariel. Here we report design updates to the OGSE after a preliminary design review (PDR). Since PDR, there have been substantial revisions to the OGSE architecture. In this proceeding, we describe the evolution of the OGSE architecture. The updated OGSE design will then be presented.
SPICE is an imaging spectrometer operating at vacuum ultraviolet (VUV) wavelengths, 70.4 – 79.0 nm and 97.3 - 104.9 nm. It is a facility instrument on the Solar Orbiter mission, which carries 10 science instruments in all, to make observations of the Sun’s atmosphere and heliosphere, at close proximity to the Sun, i.e to 0.28 A.U. at perihelion. SPICE’s role is to make VUV measurements of plasma in the solar atmosphere. SPICE is designed to achieve spectral imaging at spectral resolution >1500, spatial resolution of several arcsec, and two-dimensional FOV of 11 x16arcmins. The many strong constraints on the instrument design imposed by the mission requirements prevent the imaging performance from exceeding those of previous instruments, but by being closer to the sun there is a gain in spatial resolution. The price which is paid is the harsher environment, particularly thermal. This leads to some novel features in the design, which needed to be proven by ground test programs. These include a dichroic solar-transmitting primary mirror to dump the solar heat, a high in-flight temperature (60deg.C) and gradients in the optics box, and a bespoke variable-line-spacing grating to minimise the number of reflective components used. The tests culminate in the systemlevel test of VUV imaging performance and pointing stability. We will describe how our dedicated facility with heritage from previous solar instruments, is used to make these tests, and show the results, firstly on the Engineering Model of the optics unit, and more recently on the Flight Model. For the keywords, select up to 8 key terms for a search on your manuscript's subject.
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