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In the meantime, research articles in satellite communication, to ensure continued support, we are displaying the site without styles and JavaScript. Little is known about Earth quasi-satellites, a class of near-Earth small solar system bodies that orbit the sun but remain close to research articles in satellite communication Earth, because they are faint and difficult to observe. Here we use the Large Binocular Telescope LBT and the Lowell Discovery Telescope LDT to conduct a comprehensive physical characterization of quasi-satellite Kamoʻoalewa and assess its affinity with other groups of near-Earth objects.
We find that Kamoʻoalewa rotates with a period of This spectrum is indicative of a silicate-based composition, but with reddening beyond what is typically seen amongst asteroids in the inner solar system. We compare the spectrum to those of several material analogs and conclude that the best match is with lunar-like silicates. Near-Earth object NEO Kamoʻoalewa provisional designation HO 3 is the most stable of the five known quasi-satellites of the Earth, with a dynamical lifetime of a few hundred years 1.
As a quasi-satellite, research articles in satellite communication, the orbit of Kamoʻoalewa is very Earth-like, with semi-major axis within 0. Study of this class of objects began with the initial discovery of GU 9 789.
Physical characterization of the quasi-satellite population has been lacking due to challenging observing geometry and short residence time in near-Earth space. These regular observing windows allow for continued study, unlike temporarily captured minimoons such as CD 3 that require dedicated observing campaigns during a single apparition shortly after their discovery 10 We used the LBT to obtain broadband color photometry and visible spectra on UT 14 April The Multi-Object Double Spectrograph MODS instrument was used in imaging and long-slit spectroscopic modes 12 research articles in satellite communication carry out our observations.
Follow-up broadband photometry was collected on UT 18 April at LDT in the VR filter using the Large Monolithic Imager research articles in satellite communication The peak-to-peak lightcurve amplitude is 1. The lightcurve is plotted in Fig. Combined lightcurve of Kamoʻoalewa from LBT and LDT, phased to a rotational period of We find that the observations are well described by a double-peaked lightcurve with asymmetric minima blue curve, left panel with an amplitude of 1.
Though it rotates faster than the 2. Translation from absolute magnitudes H to diameter 58 assumes a geometric albedo of 0. The lightcurve is shown with photometric uncertainties random error as the error bars. Our observed reflectance spectrum at visible wavelengths 0. Follow-up spectroscopic observations in the near-infrared 1.
This slope was confirmed by measuring broadband zJH photometric colors on UT 7 March with the LBT, and Research articles in satellite communication colors on UT 11 April Black circles indicate the spectrum collected using the MODS instrument in 0. Our data shows a spectrum differing strongly from reddened silicate-rich asteroid spectra, exemplified by the Sw-type 63 Ausonia 21 The steeply red-sloped spectrum we observe is consistent with a highly space-weathered silicate surface, similar to that of lunar samples.
The gray shaded region indicates wavelengths with time-variable telluric features that can introduce artifacts in the data.
Spectra were normalized to unity at 0. The error bars shown for the spectrum are the photometric uncertainties at the spectral resolution as shown. We used curve matching to constrain the surface composition and identify possible analog materials for Kamoʻoalewa. The spectral slope of Kamoʻoalewa is redder higher reflectance at increasing wavelength than typical S-type asteroid spectra as defined by the Bus-Demeo taxonomy.
As an example, Fig. Sw-types exhibit the same characteristics as S-types but have redder slopes in the infrared The spectral slope of Kamoʻoalewa is even redder than the slope of these objects. Reddening of spectral slope can be due to a range of factors including phase angle Sun-Target-Observer angleparticle size of the regolith increasing grain size causes bluer spectral slopemetal content increasing metal causes redder spectral slopeand lunar-style space weathering increasing space weathering causes redder spectral slope and weaker absorption bands.
The NIR spectrum of Kamoʻoalewa was observed at a phase angle of The grain size of the regolith also influences spectral slope and band depth. Typically for silicates, research articles in satellite communication, the band depth and spectral slope decrease becoming blue-sloped as grain size approaches millimeters to centimeters.
In the case of Kamoʻoalewa, the band depth is weak, but the spectral slope is red—not blue as would be expected from grain size effects alone. Hence, grain size effects are insufficient to reconcile the observed spectral properties of Kamoʻoalewa with that of a typical S-type composition research articles in satellite communication more neutral reflectance spectrum.
The choice of characterizing the spectral slope of Kamoʻoalewa using the standard Bus-DeMeo taxonomic tool 23 was made to enable general comparisons with the NEA population. This method involves fitting a straight line to a well-sampled spectrum from 0. Since our spectrum of Kamoʻoalewa is not uniformly sampled in wavelength, the calculation research articles in satellite communication the slope was performed by first linearly interpolating the spectrum. To assess the uncertainty of the slope measurement, which is dominated by the errors in the infrared reflectance, the slope measurement was repeated after varying the data at wavelengths greater than 1.
While this is an overestimate of the error as it assumes the photometric errors are correlatedit provides a transparent look at the variability inherent to our unevenly sampled spectrum.
Figure 3 shows the range of slopes plotted with those of near-Earth asteroids compiled by the MITHNEOS survey The one object with an overall spectral slope which overlaps the range for Kamoʻoalewa is Dersu-Uzala, a Mars-crossing asteroid that was originally classified as an A-type 27 and whose 0.
Histogram 50 equal-width bins of S- and L-type asteroid spectral slopes from the MITHNEOS spectral survey of NEAs Our measured spectral slope for Kamoʻoalewa green shaded region lies outside the typical range of Metal-silicate mixtures have been shown to have spectra similar to Kamoʻoalewa with steep spectral slope and a weaker olivine or pyroxene band.
Such materials would be analogous to pallasite, mesosiderite, or CB chondrite meteorites. To illustrate this hypothesis, reflectance measurements were collected of the iron meteorite Gibeon and mesosiderite Vaca Muerta, with a linear combination of these two endmembers plotted in Fig.
This approach uses only one source of meteoritic metal for comparison, but we note that the spectrum of the Gibeon sample we use is iron-rich, and hence among the reddest possible analogs amongst meteoritic metal sources, research articles in satellite communication. When mixed with spectrally neutral silicates to fit the 1, research articles in satellite communication. Lunar style space weathering has been demonstrated to reduce the albedo and band depth and increase the spectral slope of a reflectance spectrum 29 We compared the spectrum of Kamoʻoalewa to Apollo lunar samples from the RELAB research articles in satellite communication 313233 A total of 19 available samples were used to identify the best spectral match to Kamoʻoalewa.
However, a variety of slopes is present among the lunar soil sample database, including higher and lower slopes. This shows the inherent uncertainty in separating specific compositional hypotheses based on our low-resolution data. Regardless of its origin, we show via Figs. We note that S-type asteroids often have higher visible albedos than the lunar samples we compared to. Adopting a range of albedos from 0. The longer-term orbit propagation finds that the quasi-satellite motion began approximately research articles in satellite communication ago and will last for about years in the future.
In Fig. The retrograde quasi-satellite orbits, the horseshoe orbits, and transitions between these two types are known dynamical behaviors near the mean motion resonance in the three-body problem The current errors in the orbital parameters grow beyond the ± year timeframe, precluding confidence in its longer term orbital path.
However, numerical sampling of its possible longer term orbital path has been carried out with models of various degrees of fidelity 1383940 These studies commonly indicate that Kamoʻoalewa remains in an Earth-like orbit, research articles in satellite communication, exhibiting intermittent transitions between horseshoe and quasi-satellite motion, on ~10 5 —10 6 -year timescales, but this state is unlikely to persist over timescales comparable to the age of the Earth and of the solar system.
The answers are speculative. One possibility is that it was captured in its Earth-like orbit from the general population of NEOs. Its low eccentricity and inclination are, however, rather atypical of such captured co-orbital states found in numerical simulations This hypothesis can be tested in future deeper and wider observational surveys of the Earth-Sun Trojan regions, supplemented with theoretical investigation of dynamical pathways between Earth Trojans and quasi-satellites.
The reflectance spectrum of Kamoʻoalewa as reported in the present work lends support to the lunar ejecta hypothesis. The G2V star HIP was used as the solar analog to convert raw spectral fluxes to reflectance.
After the light-time correction, we performed a search for periodicity using the Lomb periodogram technique However, the measured lightcurve presents a strong asymmetry with one minimum deeper than the other one by about 0. We find that the observations are well described by a double-peaked lightcurve with asymmetric minima, corresponding to a rotational period twice that of the single-peaked solution shown in the periodogram.
Dotted, dashed, and solid lines plotted research articles in satellite communication the periodogram indicate confidence intervals of Data were processed, including sky subtraction and wavelength fitting, via the Flame pipeline 51 using SAO as a solar analog.
Extraction was performed using an optimized extraction technique 52 implemented in python As a validation of our techniques, we observed the main-belt asteroid 26 Proserpina in August using the NASA Infrared Telescope Facility and the twin LUCI LBT Utility Camera in the Infrared spectrographs on LBT. Observations of bright main-belt asteroid 26 Proserpina used to validate our processing methods. The asteroid was first observed using the SpeX instrument at the NASA Infrared Telescope Facility IRTF 61 and processed with SpexTool The object was then observed at LBT with the same instrument configuration as used to observe Kamoʻoalewa and is shown binned to the resolution of the SpeX data.
The gray shaded region indicates the same wavelength region as indicated in Fig. Photometric errors are plotted but are not visible at this scale for this bright calibration target.
Color measurements were obtained by measuring target fluxes through standard aperture photometry, relative to the G2V solar analog star GSPC PE On UT 11 Aprilthe target was observed over an airmass range of 1.
simultaneously to derive the reflectance ratios between each filter combination, research articles in satellite communication. This analysis made use of the Photutils package in Astropy 55research articles in satellite communication, 56 Data from Binzel et al. Processing scripts are freely available to download via the references provided in the methods section.
de la Fuente Marcos, C. Article CAS Google Scholar. The International Astronomical Union Minor Planet Center.
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Nov 11, · The Earth’s most stable quasi-satellite, Kamoʻoalewa, displays an extremely red reflectance spectrum typical of space weathering of lunar-like Jan 24, · Satellite communications enable communication services on board with acceptable service quality, but are too costly, especially in aircraft cabins This is a list of all companies currently operating at least one commercial communication satellite or currently has one on order. Top 20 [ edit ] Main article: Comparison of
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