Discovering Earth’s transient moons with the Large Synoptic Survey Telescope

Fedorets, Grigori; Granvik, Mikael; Jones, Lynne; Jurić, Mario; Jedicke, Robert

doi:10.1016/j.icarus.2019.113517

Cited by 14 publications

(12 citation statements)

References 44 publications

(84 reference statements)

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“…NEOs and mini-moons need to be robustly separated from these artificial objects for discovery operations to be successful. Space debris is mainly confined to two regions, namely close to Earth (< 3 × 10 3 km altitude) or close to geostationary orbit (∼ 3.6 × 10 4 km altitude; Krisko, 2010;Flegel et al, 2009). Our results show that the typical mini-moon or NEO detection will be made at altitudes larger than these regions and up to 3.8 × 10 5 km altitude.…”

Section: Discussionmentioning

confidence: 66%

“…For example, beam park observations, i.e. a single constant pointing direction with high-power, large-aperture radars, are an important source of information when modelling the space debris population (Krisko, 2014;Flegel et al, 2009;Banka et al, 2000). The current EISCAT system also has a history of providing significant contributions to space debris observations, such as the Chinese antisatellite event (Markkanen et al, 2009;Li et al, 2012), the Iridium-Cosmos collision , and the Indian antisatellite event (Vierinen, 2019).…”

Section: Introductionmentioning

confidence: 99%

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Radar observability of near-Earth objects using EISCAT 3D

et al. 2020

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Abstract. Radar observations can be used to obtain accurate orbital elements for near-Earth objects (NEOs) as a result of the very accurate range and range rate measureables. These observations allow the prediction of NEO orbits further into the future and also provide more information about the properties of the NEO population. This study evaluates the observability of NEOs with the EISCAT 3D 233 MHz 5 MW high-power, large-aperture radar, which is currently under construction. Three different populations are considered, namely NEOs passing by the Earth with a size distribution extrapolated from fireball statistics, catalogued NEOs detected with ground-based optical telescopes and temporarily captured NEOs, i.e. mini-moons. Two types of observation schemes are evaluated, namely the serendipitous discovery of unknown NEOs passing the radar beam and the post-discovery tracking of NEOs using a priori orbital elements. The results indicate that 60–1200 objects per year, with diameters D>0.01 m, can be discovered. Assuming the current NEO discovery rate, approximately 20 objects per year can be tracked post-discovery near the closest approach to Earth. Only a marginally smaller number of tracking opportunities are also possible for the existing EISCAT ultra-high frequency (UHF) system. The mini-moon study, which used a theoretical population model, orbital propagation, and a model for radar scanning, indicates that approximately seven objects per year can be discovered using 8 %–16 % of the total radar time. If all mini-moons had known orbits, approximately 80–160 objects per year could be tracked using a priori orbital elements. The results of this study indicate that it is feasible to perform routine NEO post-discovery tracking observations using both the existing EISCAT UHF radar and the upcoming EISCAT 3D radar. Most detectable objects are within 1 lunar distance (LD) of the radar. Such observations would complement the capabilities of the more powerful planetary radars that typically observe objects further away from Earth. It is also plausible that EISCAT 3D could be used as a novel type of an instrument for NEO discovery, assuming that a sufficiently large amount of radar time can be used. This could be achieved, for example by time-sharing with ionospheric and space-debris-observing modes.

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Section: Discussionmentioning

confidence: 66%

Section: Introductionmentioning

confidence: 99%

Radar observability of near-Earth objects using EISCAT 3D

et al. 2020

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“…There is currently only one minimoon in Earth orbit, but it is no longer observable using EISCAT UHF or E3D due to the long range when the object is in the radar field of view. However, there will be more opportunities in the future for such observations as new minimoons are discovered (Fedorets et al, 2020). Our study shows that an E3D based radar search for minimoons is one potential way for 520 discovering these objects.…”

Section: Discussionmentioning

confidence: 81%

Radar observability of near-Earth objects using EISCAT 3D

Kastinen¹,

Tveito²,

Vierinen³

et al. 2020

Preprint

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Radar observations can be used to obtain accurate orbital elements for near-Earth objects (NEOs) as a result of the very accurate range and range-rate measureables. These observations allow predicting NEO orbits further into the future, and also provide more information about the properties of the NEO population. This study evaluates the observability of NEOs with the EISCAT 3D high-power large-aperture radar, which is currently under construction. Three different populations are considered: NEOs passing by the Earth with a size distribution extrapolated from fireball statistics, catalogued NEOs 5 detected with ground-based optical telescopes, and temporarily-captured NEOs, i.e., minimoons. Two types of observation schemes are evaluated: serendipitous discovery of unknown NEOs passing the radar beam, and post-discovery tracking of NEOs using a priori orbital elements. The results indicate that 60-1200 objects per year with diameters D > 0.01 m can be discovered. Assuming the current NEO discovery rate, approximately 20 objects per year can be tracked post-discovery near closest approach. Only a marginally smaller number of tracking opportunities are also possible for the existing EISCAT UHF 10 system. The minimoon study, which used a theoretical population model, orbital propagation, and a model for radar scanning, indicates that approximately 7 objects per year can be discovered using 8-16% of the total radar time. If all minimoons had known orbits, approximately 80-160 objects per year could be tracked using a priori orbital elements. The results of this study indicate that it is feasible to perform routine NEO post-discovery tracking observations using both the existing EISCAT UHF radar and the upcoming EISCAT 3D radar. Most detectable objects are within 1 LD distance of the radar. Such observations 15 would complement the capabilities of the more powerful planetary radars that typically observe objects further away from Earth. It is also plausible that EISCAT 3D could be used as a novel type of an instrument for NEO discovery, assuming a sufficiently large amount of radar time can be used. This could be achieved, e.g., by time-sharing with ionospheric and space debris observing modes.

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“…5). However, simulations by Fedorets et al (2020), and the fact that 2006 RH 120 was discovered only three months into its captured time period of one year, suggest that the last-minute discovery of 2020 CD 3 is not a typical situation. During the undisputed capture period of 2.7 years there were six distinct intervals during which 2020 CD 3 was brighter than the discovery observatory's (CSS's Mt.…”

Section: Detectability Of 2020 CDmentioning

confidence: 99%

Establishing Earth’s Minimoon Population through Characterization of Asteroid 2020 CD₃

Fedorets

Micheli

Jedicke

et al. 2020

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We report on our detailed characterisation of Earth's second known temporary natural satellite, or minimoon, asteroid 2020 CD 3. An artificial origin can be ruled out based on its area-to-mass ratio and broad-band photometry, which suggest that it is a silicate asteroid belonging to the S or V complex in asteroid taxonomy. The discovery of 2020 CD 3 allows for the first time a comparison between known minimoons and theoretical models of their expected physical and dynamical properties. The estimated diameter of 1.2 +0.4 −0.2 meters and geocentric capture approximately a decade after the first known minimoon, 2006 RH 120 , are in agreement with theoretical predictions. The capture duration of 2020 CD 3 of at least 2.7 years is unexpectedly long compared to the simulation average, but it is in agreement with simulated minimoons that have close lunar encounters, providing additional support for the orbital models. 2020 CD 3 's atypical rotation period, significantly longer than theoretical predictions, suggests that our understanding of meter-scale asteroids needs revision. More discoveries and a detailed characterisation of the population can be expected with the forthcoming Vera C. Rubin Observatory Legacy Survey of Space and Time (LSST).

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Discovering Earth’s transient moons with the Large Synoptic Survey Telescope

Cited by 14 publications

References 44 publications

Radar observability of near-Earth objects using EISCAT 3D

Radar observability of near-Earth objects using EISCAT 3D

Radar observability of near-Earth objects using EISCAT 3D

Establishing Earth’s Minimoon Population through Characterization of Asteroid 2020 CD₃

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Discovering Earth’s transient moons with the Large Synoptic Survey Telescope

Cited by 14 publications

References 44 publications

Radar observability of near-Earth objects using EISCAT 3D

Radar observability of near-Earth objects using EISCAT 3D

Radar observability of near-Earth objects using EISCAT 3D

Establishing Earth’s Minimoon Population through Characterization of Asteroid 2020 CD3

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Establishing Earth’s Minimoon Population through Characterization of Asteroid 2020 CD₃