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Register a new userFlight demonstration of formation flying capabilities for future missions (NEAT Pathfinder)
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M. Delpech
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PRISMA is a demonstration mission for formation-flying and on-orbit-servicing critical technologies that involves two spacecraft launched in low Earth orbit in June 2010 and still in operation. Funded by the Swedish National Space Board, PRISMA mission has been developed by OHB Sweden with important contributions from the German Aerospace Centre (DLR/GSOC), the French Space Agency (CNES), and the Technical University of Denmark (DTU). The paper focuses on the last CNES experiment achieved in September 2012 that was devoted to the preparation of future astrometry missions illustrated by the NEAT and microNEAT mission concepts. The experiment consisted in performing the type of formation maneuvers required to point the two-satellite axis to a celestial target and maintain it fixed during the observation period. Achieving inertial pointing for a LEO formation represented a new challenge given the numerous constraints from propellant usage to star tracker blinding. The paper presents the experiment objectives in relation with the NEAT/microNEAT mission concept, describes its main design features along with the guidance and control algorithms evolutions and discusses the results in terms of performances achieved during the two rehearsals
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This document summarizes how far the Nancy Grace Roman Space Telescope Coronagraph Instrument (Roman CGI) will go toward demonstrating high-contrast imaging and spectroscopic requirements for potential future exoplanet direct imaging missions, illustrated by the HabEx and LUVOIR concepts. The assessment is made for two levels of assumed CGI performance: (i) current best estimate (CBE) as of August 2020, based on laboratory results and realistic end-to-end simulations with JPL-standard Model Uncertainty Factors (MUFs); (ii) CGI design specifications inherited from Phase B requirements. We find that the predicted performance (CBE) of many CGI subsystems compares favorably with the needs of future missions, despite providing more modest point source detection limits than future missions. This is essentially due to the challenging pupil of the Roman Space Telescope; this pupil pushes the coronagraph masks sensitivities to misalignments to be commensurate with future missions. In particular, CGI will demonstrate active low-order wavefront control and photon counting capabilities at levels of performance either higher than, or comparable to, the needs of future missions.
Thanks to high-resolution and non-dispersive spectrometers onboard future X-ray missions such as XRISM and Athena, we are finally poised to answer important questions about the formation and evolution of galaxies and large-scale structure. However, we currently lack an adequate understanding of many atomic processes behind the spectral features we will soon observe. Large error bars on parameters as critical as transition energies and atomic cross sections can lead to unacceptable uncertainties in the calculations of e.g., elemental abundance, velocity, and temperature. Unless we address these issues, we risk limiting the full scientific potential of these missions. Laboratory astrophysics, which comprises theoretical and experimental studies of the underlying physics behind observable astrophysical processes, is therefore central to the success of these missions.
Instrumentation techniques in the field of direct imaging of exoplanets have greatly advanced over the last two decades. Two of the four NASA-commissioned large concept studies involve a high-contrast instrument for the imaging and spectral characterization of exo-Earths from space: LUVOIR and HabEx. This whitepaper describes the status of 8 optical testbeds in the US and France currently in operation to experimentally validate the necessary technologies to image exo-Earths from space. They explore two complementary axes of research: (i) coronagraph designs and manufacturing and (ii) active wavefront correction methods and technologies. Several instrument architectures are currently being analyzed in parallel to provide more degrees of freedom for designing the future coronagraphic instruments. The necessary level of performance has already been demonstrated in-laboratory for clear off-axis telescopes (HabEx-like) and important efforts are currently in development to reproduce this accomplishment on segmented and/or on-axis telescopes (LUVOIR-like) over the next two years.
Current and future Cosmic Microwave Background (CMB) Radiation experiments are targeting the polarized $B$-mode signal. The small amplitude of this signal makes a successful measurement challenging for current technologies. Therefore, very accurate studies to mitigate and control possible systematic effects are vital to achieve a successful observation. An additional challenge is coming from the presence of polarized Galactic foreground signals that contaminate the CMB signal. When they are combined, the foreground signals dominate the polarized CMB signal at almost every relevant frequency. Future experiments, like the LiteBIRD space-borne mission, aim at measuring the CMB $B$-mode signal with high accuracy to measure the tensor-to-scalar ratio $r$ at the $10^{-3}$ level. We present a method to study the photometric calibration requirement needed to minimize the leakage of polarized Galactic foreground signals into CMB polarization maps for a multi-frequency CMB experiment. We applied this method to the LiteBIRD case, and we found precision requirements for the photometric calibration in the range $sim10^{-4}-2.5times10^{-3}$ depending on the frequency band. Under the assumption that the detectors are uncorrelated, we found requirements per detector in the range $sim0.18times10^{-2}-2.0times10^{-2}$. Finally, we relate the calibration requirements to the band-pass resolution to define constraints for a few representative band-pass responses: $Delta usim0.2-2$ GHz.
We review the history of space mission in Korea focusing on the field of astronomy and astrophysics. For each mission, scientific motivation and achievement are reviewed together with some technical details of the program including mission schedule. This review includes the ongoing and currently approved missions as well as some planned ones. Within the admitted limitations of authors perspectives, some comments on the future direction of space program for astronomy and astrophysics in Korea are made at the end of this review.
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