The Decadal Survey Testbed 2: A technology development facility for future exo-Earth observatories

Due to the reporting from the Astro2020: Decadal Survey for Astronomy and Astrophysics, the direct imag- ing of Earth-like exoplanets has become a leading priority for research and development in astrophysics. In response to this survey, NASA has selected the Habitable Worlds Observatory (HWO) as its next astrophysics flagship mission. However, the current state-of-the-art coronagraph technology is not sufficient to achieve the required contrast (∼ 10−10) with HWO’s proposed configuration. Improving the technology readiness level of coronagraphs for HWO will require extensive research and development. To increase its capacity to support this objective and to provide the community with a new resource to perform versatile coronagraph technology devel- opment, NASA’s High Contrast Imaging Testbed (HCIT) facility at the Jet Propulsion Laboratory (JPL) has commissioned the Decadal Survey Testbed 2 (DST2), a state-of-the-art vacuum coronagraph testbed. It’s com- missioned architecture incorporates a 2K-actuator Boston Micromachines deformable mirror and a traditional Lyot coronagraph, and features a flexible design capable of accommodating different coronagraph technologies including tip/tilt mirrors, segmented apertures, reflective pupils, disturbance injection, wavefront sensing and control, and the integration of additional sources or telescope simulators with minimal reconfiguration. DST2 has repeatably achieved 1 × 10−9 monochromatic raw contrast, and 3.3 × 10−9 raw contrast in a 10% bandwidth centered at 550nm in a 180 degree dark hole from 3λ/D to 9λ/D. Additionally, DST2 uses new 20-bit DM electronics capable of a 650 femtometer DM actuator resolution which meets future requirements for HWO. As of August 2023, DST2 has begun operations to meet scientific milestones set by the principal investigators of NASA Strategic Astrophysics Technologies awards. Parallel to these priorities, work to determine contrast limitations will be performed

受《天文学与天体物理学十年调查（Astro2020）》报告推动，类地系外行星直接成像已成为天体物理学研发的核心优先事项。为响应该调查，美国国家航空航天局（NASA）选定宜居世界天文台（Habitable Worlds Observatory，HWO）作为其下一代天体物理学旗舰任务。然而，当前最先进的日冕仪（coronagraph）技术无法在HWO的拟议配置下实现所需的对比度（约10⁻¹⁰）。提升适配HWO的日冕仪技术成熟度等级（technology readiness level）需要开展大量研发工作。为增强对该目标的支撑能力，并为学界提供可用于开展多样化日冕仪技术研发的新型平台，美国国家航空航天局喷气推进实验室（Jet Propulsion Laboratory，JPL）下属的高对比度成像测试台（High Contrast Imaging Testbed，HCIT）设施已启用十年调查测试台2（Decadal Survey Testbed 2，DST2）——一台当前最先进的真空日冕仪测试台（vacuum coronagraph testbed）。该测试台的架构集成了一款2000驱动器级的波士顿微机械可变形镜与传统李奥日冕仪（Lyot coronagraph），其采用灵活设计，可适配多种日冕仪技术方案，涵盖倾斜镜（tip/tilt mirrors）、分段孔径（segmented apertures）、反射式光瞳（reflective pupils）、扰动注入（disturbance injection）、波前传感与控制（wavefront sensing and control）模块，且仅需极少重构即可集成额外光源或望远镜模拟器（telescope simulators）。DST2已可重复实现1×10⁻⁹的单色原始对比度（monochromatic raw contrast），且在中心波长为550nm、带宽为10%的工况下，于3λ/D至9λ/D范围内的180°暗孔区域中实现了3.3×10⁻⁹的原始对比度。此外，DST2搭载了新型20位可变形镜电子系统（20-bit DM electronics），可实现650飞米（femtometer）的可变形镜驱动器分辨率，满足HWO的未来技术需求。截至2023年8月，DST2已启动运行，以达成美国国家航空航天局战略天体物理学技术奖首席研究员（principal investigators）设定的各项科学里程碑。与此同时，相关团队还将开展对比度限制因素的测定工作。