Astronomical Research Articles

On-orbit beam pointing calibration for nanosatellite laser communications

We describe techniques developed to optimize beam pointing control for a CubeSat laser downlink demonstration mission being developed at the MIT Space Telecommunications, Astronomy, and Radiation Laboratory. To fine-point its downlink beam, the mission utilizes an uplink beacon signal at 976 nm captured by an on-board ±5-deg field-of-view detector and tracked by a 3.6-mm commercial, off-the-shelf MEMS fast steering mirror. As these miniature actuators lack feedback sensors, the system design is augmented with an optical calibration signal to provide the mirror’s pointing feedback. We describe the system and introduce calibration algorithms utilizing the feedback signal to achieve higher fidelity beam pointing control. A demonstration in the laboratory is conducted to obtain a quantitative performance analysis using quasi-flight hardware with simulated spacecraft body pointing disturbances. Experimental results show that beacon tracking errors of only 16 μrad root-mean-square are feasible for both axes, significantly exceeding the mission pointing requirement of 0.65 mrad and indicating the feasibility of narrower beams and higher data throughputs for next-generation downlink demonstration missions.

Fully scalable forward model grid of exoplanet transmission spectra (dataset)

Jayesh Goyal and Nathan Mayne are part funded by a Leverhulme Trust Research Project Grant, and in part by a University of Exeter College of Engineering, Mathematics and Physical Sciences PhD studentship. Hannah Wakeford acknowledges funding by Association of Universities for Research in Astronomy (AURA) through a Giacconi Fellowship appointed at Space Telescope Science Institute (STScI). David Sing and Benjamin Drummond acknowledge support from the European Research Council under the European Unions Seventh Framework Programme (FP7/2007-2013)/ ERC grant agreement number 336792. We acknowledge support from the Space Telescope Science Institute (STScI) Research Visitors Program. This work used the DiRAC Complexity system, operated by the University of Leicester IT Services, which forms part of the STFC DiRAC HPC Facility. This work also used the University of Exeter Supercomputer, a DiRAC Facility jointly funded by STFC, the Large Facilities Capital Fund of BIS and the University of Exeter.

A Citation Study of Citizen Science Projects in Space Science and Astronomy

This paper presents a citation study of 143 publications in refereed journals resulting from 23 citizen science (CS) projects in space science and astronomy. The projects generated a median of two papers during their average of six years of operation. The 143 papers produced 4,515 citations for a median of 10 citations/paper. These papers were compared to a uniform group of papers published in the year 2000 in refereed space science journals. The CS papers have an average annual peak citation rate that is about four times the average of the year-2000 sample. The CS citation history profiles peak within 3 years after paper publication but decline thereafter at a faster pace than the average paper published in 2000. This suggests that CS papers “burn brighter” but remain of interest for only half as long as other papers in space science and astronomy. Nevertheless, CS papers compare well with some of the most highly ranked “Top-1000” research papers of the modern era. The proportion of CS papers surpassing 200 citations is one-in-26, which is 40-fold higher than the proportion for the typical paper published in 2000. The study concludes that CS projects are not only as good as conventional non-CS research projects in generating publishable results, but can actually outperform the citation rates of the typical non-CS papers in space science and astronomy.

Philately for astronomers

Philately for astronomers

Science DMZ network architecture deployment and performance evaluation to large scaled data transfer efficiency

Background/Objectives: Recently, it has been great issue to transfer large-scale science dada such as scientific field of high energy physic, astronomical space, super-computing simulation. To solve the transfer issue and to increase transfer efficiency, it needs a multi-dimensional approaches.Methods/Statistical analysis: To improve the transfer performance, approaches from the perspective of components such as network equipment, transmission protocol, and transmission application have been suggested. Effort to TCP congestion control algorithm and parallelism of data transfer channel are representative example to improve performance. However, the solution through the each component has a limitation in maximizing the transmission efficiency.Findings: Science DMZ is a new network architecture that can maximize transfer performance. It maximizes transfer efficiency through approach to all components, such as network equipment, dedicated network path, transfer applications, and local institute firewall policies. With these complicated components, science DMZ network architecture can greatly improve the transfer efficiency. In this paper, we design and construct a science DMZ network architecture between two organizations that utilize supercomputing resources based on KREONET and evaluate the performance.Improvements/Applications: After configuring the experiment environment, we measured network performance through iperf and file transfer performance test through SCP. Experiment result showed around 388% Improvement than that of existing method.

Report on the Workshop "Dispersing Elements for Astronomy: New Trends and Possibilities"

Report on the Workshop "Dispersing Elements for Astronomy: New Trends and Possibilities"

Astronomers spot helium on exoplanet for first time

After more than a decade of searching, scientists finally detect the element billowing out of a gas giant. After more than a decade of searching, scientists finally detect the element billowing out of a gas giant.

The World Space Observatory Ultraviolet (WSO–UV), as a bridge to future UV astronomy

The ultraviolet (UV) astronomy is a very demanded branch of space astronomy. Many dozens of short-term UV-experiments in space, as well as long-term observatories, have brought a very important knowledge on the physics and chemistry of the Universe during the last decades. Unfortunately, no large UV-observatories are planned to be launched by most of space agencies in the coming 10 -- 15 years. Conversely, the large UVOIR observatories of the future will appear not earlier than in 2030s. This paper briefly describes the projects that have been proposed by various groups. We conclude that the World Space Observatory -- Ultraviolet (WSO-UV) will be the only 2-m class UV telescope with capabilities similar to those of the HST for the next decade. The WSO-UV has been described in detail in previous publications, and this paper updates the main characteristics of its instruments and the current state of the whole project. It also addresses the major science topics that have been included in the core program of the WSO-UV, making this core program very relevant to the current state of the UV-astronomy. Finally, we also present here the ground segment architecture that will implement this program.

The award rejection that shook astronomy

The award rejection that shook astronomy

‘Still working’: Astronomers explain why they don’t publish

‘Still working’: Astronomers explain why they don’t publish

Venus Seen on the Sun: <i>The First Observation of a Transit of Venus</i>

Preface Introduction Chapter 1 The Occasion, Utility, and Excellence of this Observation Chapter 2 The Manner and History of my Observation Chapter 3 What Others Observed or Could Have Observed of this Conjunction Chapter 4 It is Proved that the Spot Observed by Us Was Really Venus Herself Chapter 5 An Investigation of the Apparent Longitude and Latitude of Venus from the Center of the Sun Chapter 6 Change of the Apparent Place of Venus into the True Chapter 7 An Inquiry into the Time and Place of the True Conjunction of the Sun and Venus Chapter 8 Demonstration of the Node of Venus Chapter 9 The Beginning, Middle, End, and Magnitude of This Transit Chapter 10 A Consideration of the Calculations of Astronomers on the Foregoing Chapter 11 The Calculations of Copernicus Chapter 12 The Calculation of Lansberge Chapter 13 The Calculation of Longomont Chapter 14 The Calculation of Kepler Chapter 15 Corrections of the Rudolphine Numbers Chapter 16 On the diameter of Venus Chapter 17 On the Diameters of the Rest of the Planets, the Proportion of the Celestial Spheres, and the Parallax of the Sun Chapter 18 The Planets are Dark Bodies

Astronomers ready to unveil prototype radio dish for landmark observatory

Astronomers ready to unveil prototype radio dish for landmark observatory

Can we make a case for astronomy?

Can we make a case for astronomy?

Ottoman Mathematicians and Astronomers

Ottoman Mathematicians and Astronomers

A Review of Astronomy Education Researches Related The Moon : Focusing on Domestic Academic Journal Articles and National Science Curriculums

A Review of Astronomy Education Researches Related The Moon : Focusing on Domestic Academic Journal Articles and National Science Curriculums

Mitigation strategies against radiation-induced background for space astronomy missions

The Advanced Telescope for High ENergy Astrophysics (ATHENA) mission is a major upcoming space-based X-ray observatory due to be launched in 2028 by ESA, with the purpose of mapping the early universe and observing black holes. Background radiation is expected to constitute a large fraction of the total system noise in the Wide Field Imager (WFI) instrument on ATHENA, and designing an effective system to reduce the background radiation impacting the WFI will be crucial for maximising its sensitivity. Significant background sources are expected to include high energy protons, X-ray fluorescence lines, 'knock-on' electrons and Compton electrons. Due to the variety of the different background sources, multiple shielding methods may be required to achieve maximum sensitivity in the WFI. These techniques may also be of great interest for use in future space-based X-ray experiments. Simulations have been developed to model the effect of a graded-Z shield on the X-ray fluorescence background. In addition the effect of a 90nm optical blocking filter on the secondary electron background has been investigated and shown to modify the requirements of any secondary electron shielding that is to be used.

Book Review: EMMANUEL PASCHOS - CHRISTOS SIMELIDIS, Introduction to Astronomy by Theodore Metochites (Stoicheiosis Astronomike 1.5-30), Singapore - Hackensack, NJ: World Scientific 2017

Book Review:: EMMANUEL PASCHOS - CHRISTOS SIMELIDIS, Introduction to Astronomy by Theodore Metochites (Stoicheiosis Astronomike 1.5-30), Singapore - Hackensack, NJ: World Scientific 2017

Date of Mahabharata War based on Astronomical References-A Reassessment

Date of Mahabharata War based on Astronomical References-A Reassessment

Design and fabrication of cooled silicon bolometers for mm wave detection

CEA has a long history of customizing optoelectronic components for space and astronomy applications. With this expertise we are undertaking a development of cooled silicon bolometers for millimeter (mm) wave polarization detection, typically at λ=1.5 mm, in order to address the next generation of space astronomy missions. This work presents the early results on the design and fabrication of an innovative pixel operating at very low temperature between 50 and 100 mK. This pixel is using a Ti/TiN thin film absorber and an ion-implanted silicon thermometer which exhibits a very small heat capacity and a very low 1/f noise at low temperature. This sensor is implemented on a standard SOI substrate. We performed a 2D process simulation of the silicon thermometer and an electromagnetic simulation of the pixel absorption to obtain good performances at low temperature. We present R(T) electrical characterizations of simplified silicon thermometers at low temperature showing a variable range hopping (VRH) model dominating effect. The model prediction shows a good agreement with experimental results.

Enhanced dynamic data storage for enabling low cost space astronomy observations for capital constrained astronomy organizations

Mechanisms that reduce the capital and operational costs are important for increased participation in astronomy. It is important that capital constrained organizations can engage in astronomy in cost effective manner. Approaches such as telescope conversion and using small satellites reduce the cost of astronomy observations. However, astronomy data observed by converted and small satellite telescopes require storage and processing by high performance computing infrastructure. High performance computing infrastructure acquisition is expensive for capital constrained astronomy organizations. The reduction in costs obtained by using converted and small satellite telescopes is not matched by a corresponding reduction in high performance computing. This paper addresses this challenge and proposes using a software defined space data storage system. The software defined space data storage system considers space telescopes as primary satellites and telecommunication and earth observation satellites as secondary satellites. The primary and secondary satellites are grouped in logical clusters. Secondary satellites are temporal data centers that store the astronomy data that cannot be held on primary satellites. The discussion in this paper presents algorithms that enable the identification of suitable secondary satellites and also influence the entry and exit of secondary satellite into dynamic clusters.