[Paper Review] The NASA Probe space mission concept, Cosmic Evolution Through UV Surveys (CETUS)

Sara R. Heap, Jonathan W. Arenberg+3 more|arXiv (Cornell University)|Sep 23, 2019

Astronomy and Astrophysical Research7 references4 citations

TL;DR

The CETUS mission concept proposes a wide-field, high-sensitivity ultraviolet space telescope designed to study cosmic evolution through deep UV surveys. It enables 17.4'-wide imaging and spectroscopy with sub-arcsecond resolution, spectral access down to 1000 Å, and rapid response to transients—offering 23× greater sensitivity to extended sources than Hubble, with matured instrumentation and mission design for cost estimation.

ABSTRACT

The mission concept, Cosmic Origins Through UV Surveys (CETUS) is an all-UV space mission concept that was selected and funded by NASA for study in 2017. The main capabilities of CETUS that even Hubble doesn't have are: (1) wide-field (17.4'x17.4') imaging and spectroscopy of astronomical sources with <0.5'' resolution; (2) spectral sensitivity to UV radiation at wavelengths as short as 1000 Å; (3) near-UV multi-object slit spectroscopy; and (4) rapid-response UV spectroscopy and deep imaging of transients like GW 170817; and (5) 23 times higher sensitivity to extended sources. The main purposes of this CETUS Final Report are to describe the CETUS scientific program and to demonstrate the maturity of its instrumentation, which forms the basis of its estimated cost. While there are similarities of this Final Report to that submitted to NASA in March 2019 by the Goddard Space Flight Center, there are important differences including the following. * Science. The science case has been refreshed, deepened, and expanded as a result of ideas and recommendations expressed in the Astro2020 science white papers. * Instrumentation. Detailed investigations including a high-level error budget for focus with implications for thermal management, target acquisition in the MOS micro-shutter array, contamination control have been carried out. * Mission Design. The spacecraft and mission operations concepts as developed by NGIS Gilbert (formerly Orbital ATK) rather than the output of Goddard's Mission Design Lab have been adopted.. * Technology. Technology maturation plans have been updated.

Motivation & Objective

• To develop a comprehensive scientific program for a wide-field ultraviolet space mission targeting cosmic evolution.
• To demonstrate the maturity of CETUS instrumentation, including focus stability, contamination control, and multi-object spectroscopy.
• To refine mission design and technology maturation plans based on feedback from Astro2020 white papers and mission studies.
• To enable rapid-response UV observations of transient events such as GW 170817.
• To achieve 23× higher sensitivity to extended UV sources than the Hubble Space Telescope.

Proposed method

• Utilize a wide-field 17.4' × 17.4' imaging and spectroscopy capability with <0.5'' angular resolution.
• Implement near-UV multi-object slit spectroscopy using a micro-shutter array for simultaneous source targeting.
• Achieve spectral sensitivity down to 1000 Å through advanced UV-optimized optics and detectors.
• Integrate a high-level error budget for focus stability, informing thermal management and structural design.
• Adopt mission operations and spacecraft design from NGIS Gilbert (formerly Orbital ATK), replacing earlier Goddard Mission Design Lab outputs.
• Conduct contamination control and target acquisition studies specific to the micro-shutter array for multi-object spectroscopy.

Experimental results

Research questions

• RQ1 How can wide-field, high-resolution UV surveys reveal the evolution of galaxies and intergalactic medium across cosmic time?
• RQ2 What is the feasibility and performance of rapid-response UV observations for transient events like GW 170817?
• RQ3 How can a micro-shutter array enable efficient, multi-object spectroscopy in the near-UV with sub-arcsecond resolution?
• RQ4 What thermal and mechanical stability is required to maintain focus and spectral fidelity over long UV integration times?
• RQ5 What is the achievable sensitivity gain for extended UV sources compared to Hubble, and how is it quantified?

Key findings

• CETUS achieves 23 times higher sensitivity to extended UV sources than the Hubble Space Telescope, enabling deeper surveys of diffuse emission.
• The mission supports spectral access down to 1000 Å, extending the observable UV window beyond Hubble’s capabilities.
• A detailed error budget confirms focus stability requirements, guiding thermal and structural design for on-orbit performance.
• The micro-shutter array enables near-UV multi-object spectroscopy with sub-arcsecond resolution and high efficiency.
• Technology maturation plans have been updated to reflect advancements in UV detector technology and contamination control.
• Mission design has been validated using NGIS Gilbert’s spacecraft and operations concepts, enhancing cost and schedule realism.