Discovering the sky at the Longest Wavelengths (DSL)

Boonstra, Albert‐Jan; Garrett, M. A.; Kruithof, Gert; Wise, Michael; Ardenne, A. van; Yan, Jingye; Wu, Ji; Zheng, Jianhua; Gill, Eberhard; Guo, Jian; Bentum, Mark J.; Girard, Julien N.; Hong, Xiaoyu; An, Tao; Falcke, H.; Klein-Wolt, M.; Wu, Shufan; Chen, Wen; Koopmans, L. V. E.; Rothkaehl, Hanna; Chen, Xuelei; Huang, M.; Chen, Linjie; Gurvits, L. I.; Zarka, Philippe; Cecconi, Baptiste; Haan, Hans de

doi:10.1109/aero.2016.7500678

Cited by 26 publications

(25 citation statements)

References 32 publications

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“…Discovering the Sky at the Longest Wavelengths (DSL) is a small-scaled mission presented by a joint China-Europe scientific team [9]. It will consist of a mother ship and eight daughter-satellites in near-identical low altitude lunar orbits.…”

Section: Antenna System Requirementsmentioning

confidence: 99%

“…Their locations cover the lunar surface, lunar orbit, the Sun-Earth L2 point, etc. Within the boundary of a small affordable space mission, a new concept, Discovering the Sky at Longest wavelength(DSL) [9], has been proposed in 2014. It involves one mothership spacecraft and eight nano-satellites placed into a lunar orbit, which enable observations in the RFI-free environment above the far side of the Moon, with the data downlink arranged in the orbital phase above the near side of Moon.…”

Section: Introductionmentioning

confidence: 99%

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Antenna design and implementation for the future space Ultra-Long wavelength radio telescope

et al. 2018

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In radio astronomy, the Ultra-Long Wavelengths (ULW) regime of longer than 10 m (frequencies below 30 MHz), remains the last virtually unexplored window of the celestial electromagnetic spectrum.The strength of the science case for extending radio astronomy into the ULW window is growing.However, the opaqueness of the Earth's ionosphere makes ULW observations by ground-based facilities practically impossible. Furthermore, the ULW spectrum is full of anthropogenic radio frequency interference (RFI). The only radical solution for both problems is in placing an ULW astronomy facility in space. We present a concept of a key element of a space-borne ULW array facility, an antenna that addresses radio astronomical specifications. A tripole-type antenna and amplifier are analysed as a solution for ULW implementation. A receiver system with a low power dissipation is discussed as well. The active antenna is optimized to operate at the noise level defined by the celestial emission in the frequency band 1 − 30 MHz. Field experiments with a prototype tripole antenna enabled estimates of the system noise temperature. They indicated that the proposed concept meets the requirements of a space-borne ULW array facility.

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Section: Antenna System Requirementsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Antenna design and implementation for the future space Ultra-Long wavelength radio telescope

et al. 2018

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“…The latter category of experiments, including the Experiment to Detect the Global EoR Signature (EDGES; Rogers, Bowman & Hewitt 2008;Bowman & Rogers 2010;Monsalve et al 2017b;Bowman et al 2018), the Shaped Antenna measurement of the background RAdio Spectrum (SARAS; Patra et al 2013 and SARAS2;Singh et al 2017a,b), the Large Aperture Experiment to Detect the Dark Age (LEDA; Bernardi et al 2016), the Dark Ages Radio Explorer (DARE; Burns et al 2012), Discovering the Sky at the Longest wavelength (DSL; Boonstra et al 2016), the Broadband Instrument for Global HydrOgen ReioNisation Signal (BIGHORNS; Sokolowski et al 2015b) and SCI-HI (Voytek et al 2014) use (or will use) single-antennas to measure the all-sky or 'global' signal. This approach has the advantage of an increased signal-to-noise ratio (SNR), but is challenging due to systematic instrumental effects (Monsalve et al 2017a;Singh et al 2017a;Sokolowski et al 2015b).…”

Section: Introductionmentioning

confidence: 99%

Measuring the global 21-cm signal with the MWA-I: improved measurements of the Galactic synchrotron background using lunar occultation

McKinley

Bernardi

Trott

et al. 2018

Monthly Notices of the Royal Astronomical Society

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We present early results from a project to measure the sky-averaged (global), redshifted 21 cm signal from the Epoch of Reionisation (EoR), using the Murchison Widefield Array (MWA) telescope. Because interferometers are not sensitive to a spatially-invariant global average, they cannot be used to detect this signal using standard techniques. However, lunar occultation of the radio sky imprints a spatial structure on the global signal, allowing us to measure the average brightness temperature of the patch of sky immediately surrounding the Moon. In this paper we present one night of Moon observations with the MWA between 72 -230 MHz and verify our techniques to extract the background sky temperature from measurements of the Moon's flux density. We improve upon previous work using the lunar occultation technique by using a more sophisticated model for reflected 'earthshine' and by employing image differencing to remove imaging artefacts. We leave the Moon's (constant) radio brightness temperature as a free parameter in our fit to the data and as a result, measure T moon = 180±12 K and a Galactic synchrotron spectral index of −2.64 ± 0.14, at the position of the Moon. Finally, we evaluate the prospects of the lunar occultation technique for a global EoR detection and map out a way forward for future work with the MWA.

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“…Many conventional studies of space VLBI included satellites which are either in the Earth's orbit or a large elliptical orbit around the Earth. However, advances in lunar exploration during the past decade mean that a Moon-based radio astronomical observatory is also under consideration (e.g., [Boonstra et al(2016)]). In the latest Chang'E-4 mission, the lander is equipped with a low-frequency radio telescope and it landed on the far side of the Moon.…”

Section: Space Vlbi In the Futurementioning

confidence: 99%

Space very long baseline interferometry in China

Tao

Hong

Zheng

et al. 2020

Advances in Space Research

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Space very long baseline interferometry (VLBI) has unique applications in high-resolution imaging of fine structure of astronomical objects and high-precision astrometry due to the key long space-Earth or space-space baselines beyond the Earth's diameter. China has been actively involved in the development of space VLBI in recent years. This review briefly summarizes China's research progress in space VLBI and the future development plan. Keyword: Radio Astronomy; space science; Very long baseline interferometry BackgroundVery long baseline interferometry (VLBI) is a modern observational technique based on combining geographically distributed radio telescopes to form an observation network, thereby enabling the highest possible angular resolution. The imaging resolution provided by VLBI is inversely proportional to the maximum baseline (the separation between two telescopes in the network) length and proportional to the observation wavelength. VLBI allows astronomers to observe the fine structure of compact celestial objects and acquire high-precision astrometry with sub-mas resolutions. Routinely operational VLBI networks, such as the European VLBI Network (EVN), the Very Long Baseline Array (VLBA) in the USA and East Asia VLBI Network (EAVN), have maximum baselines of 5000-10,000 km, and they yield high resolutions of 0.08-0.5 mas ], which are 100-600 times higher than those of the Hubble space telescope. However this is still not sufficient for some extremely compact unresolved objects. For example, imaging the black hole shadow of Sgr A*, the supermassive black hole (SMBH) at the heart of the Milky Way, requires a resolution of about 0.02 mas, which is on a scale comparable to the event horizon of the SMBH [Goddi, et al.(2017)].Two conventional methods can be used to increase the imaging resolution: observing at highest possible frequency, and increasing the VLBI baseline length. The former method motivated the development of the Event Horizon Telescope [Doeleman(2017)] for directly observing the immediate environment of Sgr A* and M87 SMBHs at 230 GHz. The baseline lengths of ground-based VLBI networks are constrained by the size of the Earth. In order to acquire larger baseline length, astronomers have proposed sending radio telescopes into space to create a space-Earth VLBI network, i.e., space VLBI.Despite various technical difficulties and the huge associated costs, space VLBI can provide the highest resolution, as well as opening new observation windows in the electromagnetic spectrum by exploiting the lack of atmospheric disturbance in the space environment. Sub-millimeter (submm) wavelength and infrared observations from the Earth are highly constrained by the broad-band absorption of molecules in the atmosphere. Moreover, the turbulence in the atmosphere results in rapid fluctuations of the visibility phase to significantly reduce the coherence time for mm and submm wavelength interferometers, thereby decreasing the fringe detection sensitivity of VLBI. These factors motivated the development of spac...

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Discovering the sky at the Longest Wavelengths (DSL)

Cited by 26 publications

References 32 publications

Antenna design and implementation for the future space Ultra-Long wavelength radio telescope

Antenna design and implementation for the future space Ultra-Long wavelength radio telescope

Measuring the global 21-cm signal with the MWA-I: improved measurements of the Galactic synchrotron background using lunar occultation

Space very long baseline interferometry in China

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