The Earth 2.0 (ET) space mission has entered its phase B study in China. It seeks to understand how frequently habitable Earth-like planets orbit solar-type stars (Earth 2.0s), the formation and evolution of terrestrial-like planets, and the origin of free-floating planets. The final design of ET includes six 28 cm diameter transit telescope systems, each with a field of view of 550 square degrees, and one 35 cm diameter microlensing telescope with a field of view of 4 square degrees. In transit mode, ET will continuously monitor over 2 million FGKM dwarfs in the original Kepler field and its neighboring fields for four years. Simultaneously, in microlensing mode, it will observe over 30 million I < 20.5 stars in the Galactic bulge direction. Simulations indicate that ET mission could identify approximately 40,000 new planets, including about 4,000 terrestrial-like planets across a wide range of orbital periods and in the interstellar space, ~1000 microlensing planets, ~10 Earth 2.0s and around 25 free-floating Earth mass planets. Coordinated observations with ground-based KMTNet telescopes will enable the measurement of masses for ~300 microlensing planets, helping determine the mass distribution functions of free-floating planets and cold planets. ET will operate from the Earth-Sun L2 halo orbit with a designed lifetime exceeding 4 years. The phase B study involves detailed design and engineering development of the transit and microlensing telescopes. Updates on this mission study are reported.
Large field-of-view rapid sky surveys are pivotal methodologies for research in time-domain astronomy. The project entitled ”Antarctic Time Domain Astronomical Optical Observational Array Based on Drift Scanning CCD Technology”, also known as the Antarctic Tianmu Plan, is based in Antarctica and comprises an assemblage of numerous small wide-field optical telescope systems. This expansive array covers a sky area of 10,000 square degrees. Each wide-field optical telescope unit is fitted with a low noise drift scanning CCD camera, facilitating rapid observations without the necessity of moving parts within the telescope system. The advantageous clear polar night conditions of Antarctica are employed to enable repeated and continuous wide-area observations, providing an optimal environment for the monitoring of transient events. A prototype of the Antarctic Tianmu Program was constructed from 2020 to 2022 and subsequently dispatched to the Zhongshan Station in Antarctica for installation, debugging, and operational observation in concurrence with the 39th scientific research vessel at the culmination of 2022. This manuscript primarily presents the quality of raw images and limiting magnitudes acquired at varying exposure times, observational results encompassing photometry precision, and the long-term stability of the system operation during the initial year of observation.
Photo plates have been used to capture and store astronomical images for quite a long time. In recent years, several projects are carried out to digitize photo plates and these digitized photo plates are shared through the Internet. We could extract invaluable astronomical data from digitized photo plates to analyse astronomical targets with very long temporal variations (up to decades). Extracting positions of celestial objects from photo plates and calculating their positions in celestial coordinates would be the first step. However, since astronomers would use multiple exposures to obtain images in photo plates and there are some scratches and mildews during storage of these photo plates, it becomes hard for us to directly obtain necessary information from digitized photo plates. In this paper, we will discuss the data processing pipeline developed by us to process photo plates digital archives.
A space mission called “Earth 2.0 (ET)” is being developed in China to address a few of fundamental questions in the exoplanet field: How frequently habitable Earth-like planets orbit solar type stars (Earth 2.0s)? How do terrestrial planets form and evolve? Where did floating planets come from? ET consists of six 30 cm diameter transit telescope systems with each field of view of 500 square degrees and one 35 cm diameter microlensing telescope with a field of view of 4 square degrees. The ET transit mode will monitor ~1.2M FGKM dwarfs in the original Kepler field and its neighboring fields continuously for four years while the microlensing mode monitors over 30M I< 20.6 stars in the Galactic bulge direction. ET will merge its photometry data with that from Kepler to increase the time baseline to 8 years. This enhances the transit signal-to-noise ratio, reduce false positives, and greatly increases the chance to discover Earth 2.0s. Simulations show that ET transit telescopes will be able to identify ~17 Earth 2.0s, about 4,900 Earth-sized terrestrial planets and about 29,000 new planets. In addition, ET will detect about 2,000 transit-timingvariation (TTV) planets and 700 of them will have mass and eccentricity measurements. The ET microlensing telescope will be able to identify over 1,000 microlensing planets. With simultaneous observations with the ground-based KMTNet telescopes, ET will be able to measure masses of over 300 microlensing planets and determine the mass distribution functions of free-floating planets and cold planets. ET will be operated at the Earth-Sun L2 orbit with a designed lifetime longer than 4 years.
The Earth 2.0 (ET) mission is a Chinese next-generation space mission aiming at detecting thousands of terrestrial-like planets, including habitable Earth-like planets orbiting solar type stars (i.e., Earth’s 2.0s), cold low-mass planets, and free-floating planets. The ET mission will use six 300 mm diameter wide field telescope arrays to continuously monitor 1.2 million FGKM dwarf stars in the original Kepler field and its adjacent regions for four consecutive years to search for new planets including Earth 2.0s using the transit technique. The six telescopes have the same configuration, point to the same sky area, and constitute the main scientific payload. Each telescope has an effective aperture of 300 mm with a very wide field of view (FOV) of 500 square degrees and a wavelength coverage of 450-900 nm. Each telescope is equipped with a focal plane mosaic camera. The mosaic camera is composed of 2×2, 9k×9k CMOS detectors with pixel size of 10μm. The optical design results in the diameter of the 90% encircled energy (EE90%) less than 40μm (or 4 pixels) over the entire FOV. About 20% vignetting at the edge of the FOV is introduced to provide good throughput for the entire FOV while keeping optics size and weight down to reduce manufacturing risk and scientific payload within the mass and volume limit. In this paper, we will present the optical design details, including influence analysis of various factors on image quality, e.g., glass material, detector flatness, manufacturing and assembly tolerances. In addition, we will describe temperature stability analysis of the telescope on image quality and photometry measurements.
The Earth 2.0 (ET) mission is a Chinese next-generation space mission to detect thousands of Earth-sized terrestrial planets, including habitable Earth-like planets orbiting solar type stars (Earth 2.0s), cold low-mass planets, and freefloating planets. To meet the scientific goals, the ET spacecraft will carry six 30 cm diameter transit telescopes with each field of view of 500 square degrees, and one 35 cm diameter microlensing telescope with a field of view of 4 square degrees, monitor ~1.2M FGKM dwarfs in the original Kepler field and its neighboring fields continuously while monitoring over 30M stars in the Galactic bulge direction. The high precision transit observations require high photometry precision and pointing stability, which is the key drive for the ET spacecraft design. In this paper, details of the overall mission modeling and analysis will be presented. The spacecraft orbit, pointing strategy, stability requirements are presented, as well as the space-ground communication analysis. The ET spacecraft adopts an ultra-high photometry precision & high stable platform, largely inherited from other space science missions. The preliminary design of spacecraft which meets mission requirements is introduced, including the spacecraft overall configuration, observation modes, avionics architecture and development plan, which pays great attention to the pointing stability and huge volume science telemetry download.
To address the problem of online measurement of the base vector angle of beacon light in satellite-ground quantum optical communication, a measurement scheme is proposed to decouple the spatial base vector angle by using RGB tri-color combined beam as the beacon light with different light intensity values after beam splitting. The RGB combined beam with three different polarization angles carries the optical basis vector angle information of the carrier platform. After transmitted in free space, the RGB combined beam is decoupled from the basis vector angle by the ground receiving system. The receiving system reflects the RGB tri-color light in a split beam, uses photo detectors to obtain the intensity values of different wavelengths. According to the differential and ratio operation of the intensity values of the tri-color wavelengths, the receiving system obtains the characteristic parameter β and establishes the θ-β curve. With this curve, it is possible to inverse perform the spatial base vector angle θ information of the beacon light carrier platform in real time. The corresponding values of σ are inverted by analyzing the results of different operations on β. The verification of the experimental system shows that the accuracy of the beacon base vector angle θ obtained by the inversion of the real-time parameter β can reach ±0.05°, the standard deviation value of 3σ for random fluctuations is less than 0.1°, and the value of 3σ in the case of complex outdoor interference is less than 0.5°.
The Astrometric Gravitation Probe mission is a modern version of the 1919 Dyson-Eddington-Davidson experiment, based on a space-borne telescope with a permanent built-in eclipse, provided by a coronagraphic system. The expected improvement on experimental bounds to General Relativity and competing gravitation theories is by at least two orders of magnitude. The measurement principle is reviewed, in particular the principle of Fizeau-like combination of a set of individual inverted coronagraphs simultaneously feeding a common high resolution telescope. Also, the payload has a dual field of view property, in order to support simultaneous observations of stellar fields either very close, or far away, from the Sun, i.e. fields affected by either high or low light bending. We discuss a set of solutions introduced in the optical design to improve on technical feasibility and robustness of the optical performance against perturbations, in particular induced by manufacturing and alignment tolerances, and launch stresses.
Astrometric Science and Technology Roadmap for Astrophysics (ASTRA) is a bilateral cooperation between China and Italy with the goal of consolidating astrometric measurement concepts and technologies. In particular, the objectives include critical analysis of the Gaia methodology and performance, as well as principle demonstration experiments aimed at future innovative astrometric applications requiring high precision over large angular separations (one to 180 degrees). Such measurement technologies will be the building blocks for future instrumentation focused on the "great questions" of modern cosmology, like General Relativity validity (including Dark Matter and Dark Energy behavior), formation and evolution of structure like proto-galaxies, and planetary systems formation in bio compatibles environments. We describe three principle demonstration tests designed to address some of the potential showstoppers for high astrometric precision experiments. The three tests are focused on the key concepts of multiple fields telescopes, astrometric metrology and very fine sub-pixel precision (goal: < 1/2000 pixel) in white light.
Ground based optical observation is widely used in the field of astrometry of moving objects such as Near-Earth Objects and space debris due to its low cost and easy deployment. However, it’s difficult for traditional optical telescopes to have both large aperture and wide FOV, making it impossible to achieve both observation depth and observation efficiency. We propose the computational imaging astrometry method to solve this problem. Based on a scientific CMOS detector and a small-aperture telescope with wide FOV, through strict correction of various astronomical effects and instrumental errors, we establish a high-precision overlay enhancement method for wide-FOV astronomic images. Including displacement overlay of high frame rate images at sub-pixel scale. In the case of no mechanical tracking device, the computational imaging astrometry method enables the observation system to simultaneously track multiple types of moving objects, and exert the ability of image overlay to reduce background noise, thus improving the SNR of the target and enhancing the observation depth of the system.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.