Planetary science: Tunguska at 100

Steel, Duncan

doi:10.1038/4531157a

Cited by 16 publications

(6 citation statements)

References 11 publications

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“…Thus, for example, Eq. (5) can yield the total mass of "Tunguska" size objects (i.e., from 50 m to 70 m diameter) in near Earth space as being in the order of 10 14 kg [17]. More recent estimates of the population of small asteroids [11] seem to indicate a possible drop by a factor of 2/3 on the estimations given by Eq.…”

Section: 1mentioning

confidence: 97%

Assessment on the feasibility of future shepherding of asteroid resources

Sánchez

McInnes

2012

Acta Astronautica

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This version is available at https://strathprints.strath.ac.uk/37672/ Strathprints is designed to allow users to access the research output of the University of Strathclyde. Unless otherwise explicitly stated on the manuscript, Copyright © and Moral Rights for the papers on this site are retained by the individual authors and/or other copyright owners. Please check the manuscript for details of any other licences that may have been applied. You may not engage in further distribution of the material for any profitmaking activities or any commercial gain. You may freely distribute both the url (https://strathprints.strath.ac.uk/) and the content of this paper for research or private study, educational, or not-for-profit purposes without prior permission or charge.Any correspondence concerning this service should be sent to the Strathprints administrator: strathprints@strath.ac.ukThe Strathprints institutional repository (https://strathprints.strath.ac.uk) is a digital archive of University of Strathclyde research outputs. It has been developed to disseminate open access research outputs, expose data about those outputs, and enable the management and persistent access to Strathclyde's intellectual output. Most plausible futures for space exploration and exploitation require a large mass in Earth orbit. Delivering this mass requires overcoming the Earth's natural gravity well, which imposes a distinct obstacle to any future space venture. An alternative solution is to search for more accessible resources elsewhere. In particular, this paper examines the possibility of future utilisation of near Earth asteroid resources. The accessibility of asteroid material can be estimated by analysing the volume of Keplerian orbital element space from which Earth can be reached under a certain energy threshold and then by mapping this analysis onto an existing statistical near Earth objects (NEO) model. Earth is reached through orbital transfers defined by a series of impulsive manoeuvres and computed using the patched-conic approximation. The NEO model allows an estimation of the probability of finding an object that could be transferred with a given ∆v budget. For the first time, a resource map provides a realistic assessment of the mass of material resources in near Earth space as a function of energy investment. The results show that there is a considerable mass of resources that can be accessed and exploited at relatively low levels of energy. More importantly, asteroid resources can be accessed with an entire spectrum of levels of energy, unlike other more massive bodies such as the Earth or Moon, which require a minimum energy threshold implicit in their gravity well. With this resource map, the total change of velocity required to capture an asteroid, or transfer its resources to Earth, can be estimated as a function of object size. Thus, realistic examples of asteroid resource utilisation can be provided.

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Section: 1mentioning

confidence: 97%

Assessment on the feasibility of future shepherding of asteroid resources

Sánchez

McInnes

2012

Acta Astronautica

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“…Hills and Goda [16] estimated that asteroidal bolides larger than a few tens of meters in diameter are already able to cause damage to the Earth surface, although only due to the sudden blast produced in the final moments of the dissipation of the bolide when crossing the Earth atmosphere. This will not leave long lasting scars on the surface, but only cause an atmospheric explosion like the one occurred in Tunguska (Siberia) in 1908 [15] . Instead, bolides above 150-200m in diameter [16; 17] reach the Earth surface producing cratering events and, if falling into the sea, dangerous tsunamis [18] .…”

Section: B Expected Damage: 500 J/kg Casementioning

confidence: 99%

“…It is known that asteroidal bolides larger than a few tens of meters in diameter are already able to cause significant damage to the Earth surface due to the sudden blast produced by the dissipation of the bolide when crossing the Earth atmosphere, e.g. Tunguska impact [15] . Bolides above 150-200m in diameter [16; 17] , instead, reach the Earth surface producing cratering events and, if falling into the sea, dangerous tsunamis [18] .…”

mentioning

confidence: 99%

Consequences of Asteroid Fragmentation During Impact Hazard Mitigation

Sánchez

Vasile

Radice

2010

Journal of Guidance, Control, and Dynamics

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The consequences of the fragmentation of an Earth threatening asteroid due to an attempted deflection are examined in this paper. The minimum required energy for a successful impulsive deflection of a threatening object is computed and compared to the energy required to break-up a small size asteroid. The results show that the fragmentation of an asteroid that underwent an impulsive deflection, such as a kinetic impact or a nuclear explosion, is a very plausible event. A statistical model is used to approximate the number and size of the fragments as well as the distribution of velocities at the instant after the deflection attempt takes place. This distribution of velocities is a function of the energy provided by the deflection attempt, while the number and size of the asteroidal fragments is a function of the size of the largest fragment. The model takes also into account the gravity forces that could lead to a re-aggregation of the asteroid after fragmentation. The probability distribution of the pieces after the deflection is then propagated forward in time until the encounter with the Earth. A probability damage factor (i.e., expected damage caused by a given size fragment multiplied by its impact probability) is then computed and analyzed for different plausible scenarios, characterized by different levels of deflection energies and lead times.

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“…On the other hand, Earth is periodically hit by these objects, which permanently alters the characteristics of our planet to varying degrees [1]. Asteroid impacts range from events causing mass extinctions such as the Cretacious-Terciary impact that resulted on the extinction of the dinosaurs [2], to much more modest impacts such as the air blast occurred in 1908 near the Russian Tunguska river [3]. The awareness of the impact risk has led to an intense surveying effort, which now-a-days is responsible for tracking about 9000 Near-Earth Objects (NEOs) [4].…”

Section: Introductionmentioning

confidence: 99%

“…The general recognition that Earth is regularly struck by small objects, together with the increasing number of asteroid discoveries, has also stimulated an intense debate on deflection strategies (see, for example, in the Planetary Defence Conference series 3 ). An outcome of this is a growing catalogue of different concepts for asteroid deflection that range from very subtle changes on the optical properties of the asteroid [5] to the much more blunt use of nuclear warheads [6].…”

Section: Introductionmentioning

confidence: 99%