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near-Earth Objects (near-earth + object)

Distribution by Scientific Domains
Physics and Astronomy100%

Selected Abstracts

The WASP project in the era of robotic telescope networks

ASTRONOMISCHE NACHRICHTEN, Issue 8 2006
D. J. Christian
Abstract We present the current status of the WASP project, a pair of wide angle photometric telescopes, individually called Super-WASP. SuperWASP-I is located in La Palma, and SuperWASP-II at Sutherland in South Africa. SW-I began operations in April 2004. SW-II is expected to be operational in early 2006. Each SuperWASP instrument consists of up to 8 individual cameras using ultra-wide field lenses backed by high-quality passively cooled CCDs. Each camera covers 7.8 × 7.8 sq degrees of sky, for nearly 500 sq degrees of total sky coverage. One of the current aims of the WASP project is the search for extra-solar planet transits with a focus on brighter stars in the magnitude range ,8 to 13. Additionally, WASP will search for optical transients, track Near-Earth Objects, and study many types of variable stars and extragalactic objects. The collaboration has developed a custom-built reduction pipeline that achieves better than 1 percent photometric precision. We discuss future goals, which include: nightly on-mountain reductions that could be used to automatically drive alerts via a small robotic telescope network, and possible roles of the WASP telescopes as providers in such a network. Additional technical details of the telescopes, data reduction, and consortium members and institutions can be found on the web site at: http://www.superwasp.org/. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

Review of the population of impactors and the impact cratering rate in the inner solar system

METEORITICS & PLANETARY SCIENCE, Issue 11 2007
Patrick Michel
The best witness of these events is the lunar surface, which kept the memory of the impacts that it underwent during the last 3.8 Gyr. In this paper, we review the recent studies at the origin of a reliable model of the impactor population in the inner solar system, namely the near-Earth object (NEO) population. Then we briefly expose the scaling laws used to relate a crater diameter to body size. The model of the NEO population and its impact frequency on terrestrial planets is consistent with the crater distribution on the lunar surface when appropriate scaling laws are used. Concerning the early phases of our solar system's history, a scenario has recently been proposed that explains the origin of the Late Heavy Bombardment (LHB) and some other properties of our solar system. In this scenario, the four giant planets had initially circular orbits, were much closer to each other, and were surrounded by a massive disk of planetesimals. Dynamical interactions with this disk destabilized the planetary system after 500,600 Myr. Consequently, a large portion of the planetesimal disk, as well as 95% of the Main Belt asteroids, were sent into the inner solar system, causing the LHB while the planets reached their current orbits. Our knowledge of solar system evolution has thus improved in the last decade despite our still-poor understanding of the complex cratering process. [source]

Scientific exploration of near-Earth objects via the Orion Crew Exploration Vehicle

METEORITICS & PLANETARY SCIENCE, Issue 12 2009
Paul A. Abell
The ideal mission profile would involve two or three astronauts on a 90 to 180 day flight, which would include a 7 to 14 day stay for proximity operations at the target NEO. This mission would be the first human expedition to an interplanetary body beyond the Earth-Moon system and would prove useful for testing technologies required for human missions to Mars and other solar system destinations. Piloted missions to NEOs using the CEV would undoubtedly provide a great deal of technical and engineering data on spacecraft operations for future human space exploration while conducting in-depth scientific investigations of these primitive objects. The main scientific advantage of sending piloted missions to NEOs would be the flexibility of the crew to perform tasks and to adapt to situations in real time. A crewed vehicle would be able to test several different sample collection techniques and target specific areas of interest via extra-vehicular activities (EVAs) more efficiently than robotic spacecraft. Such capabilities greatly enhance the scientific return from these missions to NEOs, destinations vital to understanding the evolution and thermal histories of primitive bodies during the formation of the early solar system. Data collected from these missions would help constrain the suite of materials possibly delivered to the early Earth, and would identify potential source regions from which NEOs originate. In addition, the resulting scientific investigations would refine designs for future extraterrestrial resource extraction and utilization, and assist in the development of hazard mitigation techniques for planetary defense. [source]

Heating of near-Earth objects and meteoroids due to close approaches to the Sun

MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, Issue 1 2009
S. Marchi
ABSTRACT It is known that near-Earth objects (NEOs) during their orbital evolution may often undergo close approaches to the Sun. Indeed it is estimated that up to ,70 per cent of them end their orbital evolution colliding with the Sun. Starting from the present orbital properties, it is possible to compute the most likely past evolution for every NEO, and to trace its distance from the Sun. We find that a large fraction of the population may have experienced in the past frequent close approaches, and thus, as a consequence, a considerable Sun-driven heating, not trivially correlated to the present orbits. The detailed dynamical behaviour, the rotational and the thermal properties of NEOs determine the exact amount of the resulting heating due to the Sun. In the present paper, we discuss the general features of the process, providing estimates of the surface temperature reached by NEOs during their evolution. Moreover, we investigate the effects of this process on meteor-size bodies, analysing possible differences with the NEO population. We also discuss some possible effects of the heating which can be observed through remote sensing by ground-based surveys or space missions. [source]

Life, the universe and everything, with GAIA

ASTRONOMY & GEOPHYSICS, Issue 5 2001
Gerry Gilmore
Great things are expected of the GAIA Observatory, currently expected to launch in 2011. Gerry Gilmore explains how it will provide accurate measurements that will help us understand the formation of the Milky Way and the distribution of dark matter. The GAIA Observatory, ESA's Cornerstone 6 mission, addresses the origin and evolution of our galaxy, and a host of other scientific challenges. GAIA will provide unprecedented positional and radial velocity measurements with the accuracies needed to produce a stereoscopic and kinematic census of about one billion stars in our galaxy and throughout the Local Group, about 1% of the galactic stellar population. Combined with astrophysical information for each star, provided by on-board multicolour photometry, these data will have the precision and depth necessary to address the three key questions which underlie the GAIA science case: l when did the stars in the Milky Way form? l when and how was the Milky Way assembled? l what is the distribution of dark matter in our galaxy? The accurate stellar data acquired for this purpose will also have an enormous impact on all areas of stellar astrophysics, including luminosity calibrations, structural studies, and the cosmic distance scale. Additional scientific products include detection and orbital classification of tens of thousands of extrasolar planetary systems, a comprehensive survey of objects ranging from huge numbers of minor bodies in our solar system, including near-Earth objects, through galaxies in the nearby universe, to some 500 000 distant quasars. GAIA will also provide several stringent new tests of general relativity and cosmology. [source]