Asteroid

The Cretaceous-Paleogene boundary~ 65.5 million years ago marks one of the three largest mass extinctions in the past 500 million years. The extinction event coincided with a large asteroid impact at Chicxulub, Mexico, and occurred within the time of Deccan flood basalt volcanism in India. Here, we synthesize records of the global stratigraphy across this boundary to assess the proposed causes of the mass extinction. Notably, a single ejecta-rich deposit compositionally linked to the Chicxulub impact is globally distributed at the ...

20. yüzyılın sonuna dek güneş sisteminin son sınırı Plüton ve milyonlarca kuyruklu yıldızın bulunduğu bölge olan oort bulutu olarak biliniyordu, Gerard Kuiper 1950 yılında yayımladığı makaleye göre güneş sisteminin ilk oluşum dönemlerinde Kuiper kuşağı adında bir yapı zamanla yok olmuş ve günümüze kadar tamamen temizlenmişti. Ancak 10. Gezegen arayışı ve güneş sisteminin nerede başlayıp nerede bittiği tartışması 1990’lı yıllarda Plüton ve ötesinin tekrar araştırılması ile oort bulutundan daha yakın bir bölgede Plüton benzeri onlarca gökcisminin keşfedilmesi, Kuiper kuşağı denen bölgenin halen var olduğunu kanıtladı. 
Bu bölge Adını Gerard Kuiper adlı bilim adamından aldı. 2000li yıllara geldiğimizde 40’dan fazla irili ufaklı minik gezegenler keşfedildi. Yeni keşfedilen bu gezegenlerin bir kısmı hemen hemen Plüton ile aynı boyutta ve özellikle Eris’in kütle olarak ondan daha büyük olduğu anlaşılınca Plüton ana gezegen olma vasfını kaybetti. Eğer Plüton halen 9. Gezegen olarak kabul ediliyor olsaydı şimdi güneş sisteminde 50’den fazla gezegen ismi  sayıyor olurduk. Cüce gezegen olarak vasıflandırılan bu gök cisimlerinin oluşumları döneminde çeşitli etkenlerle kimi iç güneş sistemindeki yörüngelerinden dış güneş sistemi yörüngelerine taşınmış, kimi ise dış güneş sisteminden iç güneş sistemine göç etmiştir. Gezegen bilimi ile ilgili çalışmalar son zamanlarda sürekli gelişim halinde olduğundan dolayı elde ettiğimiz tecrübeler ve bilgiler de sürekli değişmektedir. Dolayısıyla gezegen sınıflandırması ile ilgili bilgiler de bu doğrultuda tazelenmektedir.

Abstract We present the results of our ground-based astrometric observation campaign of BepiColombo during its Earth fly-by on 2020 April 10. The observational circumstances induced by the fly-by geometry made this event an excellent proxy for a close fly-by or an imminent impact of a natural body with a diameter of a few meters, with the added benefit of having a ground-truth orbit (from radio tracking) to compare with our purely optical orbit determination.

Organics found in comet 81P/Wild 2 samples show a heterogeneous and unequilibrated distribution in abundance and composition. Some organics are similar, but not identical, to those in interplanetary dust particles and carbonaceous meteorites. A class of aromatic-poor organic material is also present. The organics are rich in oxygen and nitrogen compared with meteoritic organics. Aromatic compounds are present, but the samples tend to be relatively poorer in aromatics than are meteorites and interplanetary dust particles. The presence of deuterium and nitrogen-15 excesses suggest that some organics have an interstellar/protostellar heritage. Although the variable extent of modification of these materials by impact capture is not yet fully constrained, a diverse suite of organic compounds is present and identifiable within the returned samples.

This paper discusses one of the sensor concepts that have been considered for the attitude determination system of the mobile asteroid surface scout (Mascot), flying aboard the Hayabusa2 spacecraft. Newly developed orientation temperature sensor (OTS) are used to acquire temperature readings from multiple sides of Mascot, and determine the orientation of the lander relative to the asteroid surface based on these readings. We describe the modelling and hardware testing of the OTS using different optical surfaces with high and low absorptance and emittance. OTS performance is then evaluated under actual mission conditions to determine which sensor type or combination of sensor types can be used for attitude determination. The results show that both single and multiple sensor type concepts can be used to determine the attitude relative to the asteroid surface. A single type low alpha, high epsilon sensor provides information on which side of the lander is facing the surface, while a co...

<p><strong>Hypervelocity impacts on carbonaceous asteroid simulants: comparison with observations</strong></p> <p><strong>C. Avdellidou</strong><strong><sup>(1,2)</sup></strong>, Marco Delbo<sup>(1)</sup>, Cody Schultz<sup>(3)</sup>, Mark Price<sup>(2)</sup>, Alice DiDonna<sup>(4)</sup>, Bart Harthong<sup>(4)</sup>, Mike Cole<sup>(2)</sup>,Daniel Britt<sup>(3)</sup>, Robert Peyroux<sup>(4)</sup></p> <ol> <li>Laboratoire Lagrange, Observatoire de la Côte d’Azur, UCA, France<span class="Apple-converted-space"> </span></li> <li>CAPS, University of Kent, UK</li> <li>Exolith Lab, University of Central Florida, US</li> <li>3SR Lab, Grenoble, France</li> </ol> <p>contact: <a href="mailto:chrysa.avdellidou@oca.eu">chrysa.avdellidou@oca.eu</a></p> <p><strong>Introduction</strong></p> <p>Two on-going sample return space missions, Hayabusa2 and OSIRIS-REx are orbiting and characterising two near-Earth asteroids, (162173) Ryugu and (101955) Bennu respectively. Initial ground-based observations and mission data indicate that the composition of these small objects is similar to the CM or CI meteorites (1-4). However, their thermo-mechanical properties appear to be different (5,6). This is expected since Earth's atmosphere filters out the weakest materials and thus we do not have them in our meteoritic collections. How does this weak materials respond to impacts? What type of regolith is produced during micrometeoroid bombardment? Will we expect to find exogenous materials embedded on the weak surfaces of Bennu and Ryugu?</p> <p><strong>Materials</strong></p> <p>In our work we used as targets to hypervelocity impact experiments, asteroid analogue materials with mineralogy similar to the CM meteorites. Specifically, the CM2 regolith simulant is a close mineralogical match to the Murchison CM2 carbonaceous chondrite meteorite Since one of the aims of the project was to examine qualitatively the produced regolith after impact events, we used as inclusions glass beads for an easier examination. The samples were produced and casted at the Exolith Lab of the University of central Florida. Samples were also mechanically tested at the 3SR Lab in Grenoble, where the compressive stress and tensile strength were measured. In addition we measured the thermal conductivity of the samples.</p> <p><strong>Experiments</strong></p> <p>In order to study the response of the CM-like asteroid analogue material to collisions with small projectiles, at typical impact speeds occurring in the asteroid Main Belt, we performed a series of laboratory hypervelocity impact experiments. We used the facilities of the Impact Lab of the University of Kent in the UK. main instrument used here is a 2-stage light-gas gun (LGG), which can achieve speeds up to 7.5 km/s. Targets were the squared blocks of CM analogues with dimensions 9.5 cm x 9.5 cm and 4.4 cm thickness, while as projectile we used stainless steel of different diameters. In these experiments we measured the depth and diameter of the craters, the quality of the ejecta and the state of the inclusions. In particular we wanted to test a part of the hypothesis that on materials with inclusions, impacts produce mainly ``multimineralic" fragments, whereas thermal cracking, as a slower process can produce fragments of single composition. After the impact experiments the roughness of the impacted samples was also calculated.</p> <p><strong>Comparison with spacecraft observations</strong></p> <p>First of all we compare the materials we produced with the inferred data from the space mission observations. Furthermore, we compare our laboratory impact results with impact observations of the same scale on the boulders of asteroid Bennu (mini-craters,7).<span class="Apple-converted-space"> </span></p> <p>Combining the mechanical properties of the asteroid simulants and the impact results, we predict that the impact shockwave dissipates very rapidly in such a soft material, therefore one would expect to see also fragments with one unique composition.<span class="Apple-converted-space"> </span></p> <p><span class="Apple-converted-space"><img…

1 page.Here we present observations of the asteroid 572 Rebekka that were obtained in August 2020 at Pine Mountain Observatory (PMO). The target was observed with the 0.35m Robbins telescope at PMO, using a Sloan g’ filter, for a total of 8.5 hours over three nights. The observations produced 605 images of the target which were then analyzed to produce a “lightcurve” of the asteroid. Through photometric analysis of the lightcurve, we have produced a 3-dimensional model of the asteroid which is presented here. Using the programs MPO Canopus (MPO) and Aperture Photometry Tool (APT), photometric estimates of the asteroid’s brightness over time are plotted in order to extract the rotation period as well as the shape of the target. To calibrate this data, we compare the asteroid to multiple stars of constant brightness within the same image. This process, known as “relative photometry”, allows us to remove atmospheric effects due to air quality, light pollution, and changing air mass. An...

This paper describes the results of a study into the feasibility of identifying, robotically capturing, and returning an entire Near-Earth Asteroid (NEA) to the vicinity of the Earth by the middle of the next decade. The feasibility of such an asteroid retrieval mission hinges on finding an overlap between the smallest NEAs that could be reasonably discovered and characterized and the largest NEAs that could be captured and transported in a reasonable flight time. This overlap appears to be centered on NEAs roughly 7 m in diameter corresponding to masses in the range of 250,000 kg to 1,000,000 kg. The study concluded that it would be possible to return a ~500,000-kg NEA to high lunar orbit by around 2025. The feasibility is enabled by three key developments: the ability to discover and characterize an adequate number of sufficiently small near-Earth asteroids for capture and return; the ability to implement sufficiently powerful solar electric propulsion systems to enable transporta...

This report presents the results from the nine-month, Phase 1 investigation for the Robotic Asteroid Prospector (RAP). This project investigated several aspects of developing an asteroid mining mission. It conceived a Space Infrastructure Framework that would create a demand for in space-produced resources. The resources identified as potentially feasible in the near-term were water and platinum group metals. The project’s mission design stages spacecraft from an Earth Moon Lagrange (EML) point and returns them to an EML. The spacecraft’s distinguishing design feature is its solar thermal propulsion system (STP) that can provide for three functions: propulsive thrust, process heat for mining and mineral processing, and electricity. The preferred
propellant is water since this would allow the spacecraft to refuel at an asteroid for its return voyage to Cis-Lunar space thus reducing the mass that must be staged out of the EML point. The spacecraft will rendezvous with an asteroid at its pole, match rotation rate, and attach to begin mining operations. The team conducted an experiment in extracting and distilling water from frozen regolith simulant.

Introduction: 63803 Didymos is a binary nearEarth asteroid which will make a close approach to Earth in early October, 2022. Observations show that the Didymos primary is roughly spherical with a diameter of ∼800 m [1, 2, 3], while the secondary, the “Didymoon”, is roughly 150 m in diameter with an orbital period of ∼11.9 hours and an orbital radius of 1.18 km. The ESA Asteroid Impact Monitoring (AIM) mission [4] was intended to rendezvous with the Didymos system as one component of the Asteroid Impact & Deflection Assessment (AIDA), mission, a planetary defense test [5]. The other AIDA component, the NASA Double Asteroid Redirection Test (DART) [6], is intended to impact the Didymoon in October, 2012, demonstrating the effectiveness of kinetic impactors for asteroid deflection. The DART impact is expected to change the Didymoon velocity by 0.3 β mm s, where β is a scale factor between the momentum of DART and the Didymoon post-impact momentum change. β is expected to be > 1 due ...

The Near-Earth Asteroids (NEAs) are relatively small celestial bodies with perihelion distances of less than 1.3 au. They can have impacts with the terrestrial planets and therefore they are a permanent danger for the Earth and some of them are also called Potential-Hazardous Asteroids, PHAs. In this work some of the possible sources of NEAs are analysed in detail. In particular we analyse two asteroid groups, the Hungarias and the Vestians from the Main Belt region (asteroids from between the orbits of Mars and Jupiter), and the inner region of the Centaurs, bodies between the orbits of Jupiter and Saturn. In addition a photometrical study of an important approaching comet, C/2012 S1 ISON, plus some hints on its orbits, close encounters and some physical constraints, i.e. the encounter velocity, are presented. Furthermore, another work on the origin of a paleo-impact event, namely the Bosumtwi crater one, is studied. One of the main parts of this thesis is devoted to the dynamical ...