Euclid is a European Space Agency mission dedicated to the mapping of the dark Universe launched the 1st of July 2023. The mission will investigate the distance-redshift relationship and the evolution of cosmic structures. This is achieved by measuring shapes and redshifts of galaxies and clusters of galaxies up to 10 billion years away. Euclid makes use of two cosmological probes, in a wide survey over the full extragalactic sky: the Weak Gravitational Lensing (WL) and the Baryonic Acoustic Oscillations (BAOs). The WL is a method to map the dark matter and measure dark energy by measuring the apparent distortion of galaxy images by mass inhomogeneities along the line-of-sight. This probe requires extreme image quality thus constraining the optical system imaging quality and its characterization both on-ground and in-flight. The BAOs are wiggle patterns, imprinted in the clustering of galaxies, which provide a standard ruler to measure dark energy and the expansion in the Universe. The first images were released on the 7th of November 2023 showcasing the capabilities of the space segment. To achieve the stunning first images and the scientific objectives of the mission, the space segment (i.e. the spacecraft) underwent a thorough and extensive test campaign on-ground. These tests demonstrated the excellent image quality and the overall stability of both the payload and the spacecraft in a representative operational environment. In complement, further tests were performed during the commissioning phase, just after launch, to validate the spacecraft pointing stability.
Bena Mero, Kim Lake, Alexander Upcott-Gill, Allan Edwards, Mark Herrington, Pierre Coste, Francois Binter, Sebastien Lopez, Sylvain Fournier, Mathieu Ballester, Lucas Courcoult Mifsud, Harbinder Rana, Michael Kritzler, Alessandro Zuccaro Marchi
The TRUTHS (Traceable Radiometry Underpinning Terrestrial and Helio Studies) mission is a concept initially proposed by NPL which will enhance our understanding of the Earth’s changing radiation budget by an order of magnitude. This is a UK led mission within the ESA Earthwatch programme with prime, platform and instrument being led by Airbus UK. At the heart of the payload is the ability to calibrate the high resolution hyperspectral imager with a SI calibration traceable to national standards using the payload’s on-board calibration system (OBCS). This in turn provides accurate continuous measurements from the top of atmosphere of reflected, lunar and spectral solar radiance. This paper will concentrate on the hyperspectral instrument part of the payload. The optical design boasts low polarisation sensitivity, good MTF and Smile, and has a compact accommodation to optimise the instruments size and weight footprint within the Payload. The electro-optical back end consists of one Teledyne CHROMA-D MCT detector, with low noise and high SNR achieved through cold operation through a passive cooling system. Pixel correction, customised spectral and spatial binning and compression provided by the electronics front end produces an output dataset with a Spatial Sampling Distance (SSD) of 50m over a spectral range from 320 to 2400nm with a Spectral resolution between 0.3 and 7 nm. This paper will summarise the design status of the TRUTHS hyperspectral imager at the end of phase A/B1. The current spatial and spectral performance will be presented as well as the accommodation and thermal performance.
TRUTHS (Traceable Radiometry Underpinning Terrestrial – and Helio- Studies) is a hyperspectral climate mission which, with the support of an on board calibration system traceable to national standards, will enhance our understanding of the Earths changing radiation budget by an order of magnitude. The payload being developed by consortium led by Airbus UK includes three major subsystems: a hyperspectral imager capable of high resolution spatial and spectral lunar and earth measurements, a cryogenic radiometer with three high precision temperature controlled cavities traceable to national standards and a transfer systemto convert this calibration into one of diffused radiance for comparability with measurements made with the hyperspectral imager. The on board calibration system also includes a solar monochromator and a range of mechanisms and distribution optics to enable the calibration sequence and the required modes of the instrument. This paper will summarise the design concept for the on board calibration chain developed during the Phase A/B1 instrument studies carried out in 2020-2022. The presentation will discuss the main engineering challenges and tradeoffs and the outlook and development plan for the Phase B2CD programme will be presented.
The ESA/JAXA SPICA mission is a candidate for the ESA Cosmic Vision Medium Class M5 opportunity. Since 2019 an Airbus Defence and Space team has been performing a trade-off study (on behalf of ESA) to establish a baseline telescope optical configuration and design, which can meet the mission scientific performance requirements. This paper describes the telescope baseline design selected, with first estimates of the expected optical performance. The optical design wavelength is 20 microns for an operating temperature of 8 K covering a total bandwidth of 12 to 420 microns over a 30 arc minutes field of view, with a total required collecting area of at least 4.0 m². The fundamental mission science driver is to achieve a sky background (astrophysical sources) limited performance. The telescope is designed to illuminate three instruments namely; SMI (JAXA - Japan), SAFARI (SRON - Netherlands) and B-BOP (CEA - France).
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