The Southern Argentina Agile Meteor Radar Orbital System (Saamer-Os): An Initial Sporadic Meteoroid Orbital Survey in the Southern Sky

Abstract

We present an initial survey in the southern sky of the sporadic meteoroid orbital environment obtained with the Southern Argentina Agile MEteor Radar (SAAMER) Orbital System (OS), in which over three-quarters of a million orbits of dust particles were determined from 2012 January through 2015 April. SAAMER-OS is located at the southernmost tip of Argentina and is currently the only operational radar with orbit determination capability providing continuous observations of the southern hemisphere. Distributions of the observed meteoroid speed, radiant, and heliocentric orbital parameters are presented, as well as those corrected by the observational biases associated with the SAAMER-OS operating parameters. The results are compared with those reported by three previous surveys performed with the Harvard Radio Meteor Project, the Advanced Meteor Orbit Radar, and the Canadian Meteor Orbit Radar, and they are in agreement with these previous studies. Weighted distributions for meteoroids above the thresholds for meteor trail electron line density, meteoroid mass, and meteoroid kinetic energyare also considered. Finally, the minimum line density and kinetic energy weighting factors are found to be very suitable for meteroid applications. The outcomes of this work show that, given SAAMER's location, the system is ideal for providing crucial data to continuously study the South Toroidal and South Apex sporadic meteoroid apparent sources.

Meteoroids at the Moon: Orbital Properties, Surface Vaporization, and Impact Ejecta Production

“…Figure shows the radiant distribution of meteoroids impacting the Moon for four different Moon phases during the first lunation in our model (July–August 2013). The predicted radiant distributions are similar to what different radar and optical facilities observe at Earth (e.g., Campbell‐Brown, ; Janches et al, ; Jenniskens et al, ). The x axis in Figure is the LT at the Moon.…”

“…It can be observed from this figure that for α = 3.4 our model can reproduce the LT distribution of M + observed by LDEX even for a scenario where there is no contribution from either JFC or OCC meteoroids, with HTC meteoroids being the sole source of lunar surface impacting meteoroids. However, decades of Earth‐based observations, ground‐based observations, and dynamical modeling have demonstrated that the fluxes of both JFC and OCC meteoroids should represent a significant portion of the incoming meteoroid flux at Earth (Campbell‐Brown, ; Fentzke & Janches, ; Janches et al, ; Nesvorný, Janches, et al, ; Nesvorný, Vokrouhlický, et al, ). Furthermore, Carrillo‐Sánchez et al () required a JFC‐to‐LPC ratio at Earth of in order to simultaneously reproduce lidar observations of the vertical Na and Fe fluxes above 87.5 km and the measured cosmic spherule accretion rate at the South Pole.…”

“…Szalay and Horányi () found that, while this asymmetric cloud can be well explained by combining three sources of meteors observed at Earth, the Helion, Antihelion, and Apex sources, the ejecta mass production rate from the Helion source was found to be approximately twice as strong as the Antihelion source (Szalay & Horányi, ). Such asymmetry has not been observed in the distribution of meteors measured by radars (Campbell‐Brown, ; Janches et al, ) and optical systems (Jenniskens et al, ), although Suggs et al () suggested an asymmetry in impactor directions for kilogram‐sized meteoroids.…”

Radar Detectability Studies of Slow and Small Zodiacal Dust Cloud Particles. III. The Role of Sodium and the Head Echo Size on the Probability of Detection

“…Similarly, for the case of meteor radars, this portion increases to where these populations do not represent more than ∼45% (see Table 2 in Janches et al 2015a). Thus, even though the results presented in Figure 8 show that the predicted detection rates at Arecibo are, in general, below the actual detected rates, for the case of smaller HE radius, they are nevertheless significantly higher than expected (∼71% of the observed counts).…”

Constraining the Ratio of Micrometeoroids From Short‐ and Long‐Period Comets at 1 AU From LADEE Observations of the Lunar Dust Cloud

“…To describe the contribution of long-period HTCs, we utilized the steady state model by Pokorný et al (2014), who used it to explain the origin of the toroidal meteoroid sources (Campbell-Brown & Wiegert, 2009;Janches et al, 2015;Jones & Brown, 1993). The toroidal meteoroids are characterized by high-ecliptic latitude radiants ( ∼ ±55 ∘ -60 ∘ ), both located north and south from the apex direction, impacting the Earth with a typical velocity of ∼35 km s −1 , and resulting in high-inclination preatmospheric orbits with respect to the ecliptic (∼70 ∘ ).…”