The Neoshield project for Near-Earth object impact threat mitigation

Every day Earth is hit by around 100 tonnes of cosmic material, most of it comes in the form of dust or small rocks, which burn up as meteors in the atmosphere. Sometimes, however, larger objects, asteroids or comets, enter the Earth’s atmosphere and then even relatively small objects can cause considerable damage. The object that exploded over the Russian city of Chelyabinsk in February 2013 had a diameter of only 17–20 m, yet it produced a blast wave that damaged buildings and injured some 1500 people. It entered the Earth’s atmosphere with a velocity of 65 000 km/h and, due to the frictional heating and stresses caused by compression of the air, it exploded at an altitude of some 25 km releasing an energy 30 times that of the Hiroshima bomb. The potentially devastating effects on Earth of a collision with a large asteroid or comet are now well recognized by scientists and policy makers. So the question is now, can we protect our civilization from the next major impact? NEOShield, a project funded by the European Commission’ Seventh Framework Programme, brought together an international team of 13 partner organizations from 6 countries to address the global issue of near-­‐Earth object (NEO) impact prevention. The project ran from 2012 to mid 2015, after which the NEOShield-­‐2 project funded by the European Commission’ H2020 Programme is continuing the research until fall 2017. The purpose of the projects is to carry out detailed analysis of realistic options for preventing a potentially catastrophic impact of a NEO on Earth. While a mitigation test mission is beyond the financial scope of the current project, the NEOShield technical partners, with the support of the science team, aim to provide detailed designs of appropriate test-­‐missions for the 3 most feasible mitigation concepts: kinetic impactor, gravity tractor, and blast deflection, so that it will be possible to quickly develop an actual test mission at a later stage. Project partners are also carrying out research into the mitigation-­‐relevant physical properties of NEOs, including observations of near-­‐Earth asteroids, analysis of available observational data, laboratory experiments on asteroid analogue materials, and modelling and computer simulations. The aim of the scientific work is to facilitate predictions of the outcome of deflection attempts using different techniques on a variety of NEO types

Metallic Asteroids in the IRAS Minor Planet Survey - a NEOShield Study

Studies of the compositions of asteroids, especially their metal content, are relevant not only to investigations of their nature, but also to estimations of their potential to wreak devastation on impacting the Earth. In this respect it is informative to compare the airburst of a stony object, such as the Tunguska event, which destroyed a forest but left no crater, with the impact of a similarly sized metallic object, which produced the 1.2 km diameter Barringer Crater in Arizona. In view of the evident link between metal content and the near-Earth asteroid thermal model (NEATM; Harris 1998) fitting parameter, eta, which carries information on thermal inertia (Harris and Drube, 2014; see abstract submitted to this conference), we are carrying out a re-analysis of Infrared Astronomical Satellite (IRAS) data (Tedesco et al., 2002) with NEATM to further explore the dependence of eta and thermal inertia on metal content. In addition to calculating best-fit values of eta, we are calculating the angle between the spin vector and the solar direction, theta, for all IRAS sightings of each asteroid for which a spin vector is available. The eta values of objects with high thermal inertia and moderate to high spin rates should depend strongly on theta, whereas those with low thermal inertia and/or low spin rates should not. By studying the relationships between theta and eta, we aim to further explore the potential of the results of Harris and Drube (2014) and provide insight into relationships between asteroid thermal properties, taxonomic type, albedo, spin rate, etc. We will present the first results of our work and provide a demonstration of its potential. The research leading to these results has received funding from the European Union's Seventh Framework Programme (FP7/2007-2013) under grant agreement no. 282703 (NEOShield Project). Harris, A. W., 1998, Icarus, 131, 291. Harris, A. W. and Drube, L, 2014, Ap. J. Letters, 785, L4 Tedesco, E. F. et al, 2002, Astron. J., 123, 1056

Asteroid Thermal Inertia Estimates from Remote Infrared Observations: The Effects of Surface Roughness and Rotation Rate

The thermal inertia of an asteroid's surface can provide insight into regolith properties, such as the presence of a layer of fine dust, the density and thermal conductivity of a rocky surface, and, together with other observational data, mineralogy. Knowledge of the surface characteristics of asteroids is important for planetary defense initiatives and the extraction of resources ("asteroid mining"). A simple means of estimating asteroid thermal inertia has been proposed by Harris & Drube, which is suitable for application to large sets of thermal-infrared observational data, such as those obtained by infrared space telescopes. We compare results from the Harris-Drube estimator with recently published values of asteroid thermal inertia from detailed thermophysical modeling, and provide an explanation in terms of reduced surface roughness for some discrepant results. Smooth surfaces covered in fine dust may provide an explanation for the unexpectedly low values of thermal inertia derived from thermophysical modeling for some slowly rotating main-belt asteroids (MBAs). In the case of near-Earth objects (NEOs) we show that results from the estimator are in good agreement with those from thermophysical modeling, with just a few exceptions. We discuss the special cases of the NEOs (101955) Bennu, (162173) Ryugu, and (29075) 1950 DA in the context of results from our estimator. Given the data requirements and complexity of thermophysical modeling, data-analysis tools based on relatively simple concepts can play an important role in allowing "quick-look" assessment of thermal-infrared data of asteroids, especially NEOs.Comment: 24 pages, 9 figures, Accepted Manuscript, Ap

Instrumentation for an asteroid kinetic-impactor demonstration mission

For selecting instruments to fulfill the objectives of a mission to impact an asteroid, it is important to get an idea of the effects of such an impact event. Therefore the expected crater and ejecta cloud have to be calculated. The calculations need to take into consideration the properties of the asteroid as well as the impactor. The main objective of the NEOTwIST mission is to transfer angular momentum by impacting the asteroid far from the rotation axis to change the rotation period as well as observe the resulting ejecta cloud and possibly the crater. There are three different mission concepts, the 1st includes only an impactor spacecraft, the 2nd adds a flyby subunit the 3rd one to two chasers. Due to the fact that the three concepts have different mission objectives the instrumentation of the concepts are different

NEOShield kinetic impactor demonstration mission

This paper outlines a near-term mission concept developed under the NEOShield Project, for the demonstration of deflection capability of Potentially Hazardous Objects (PHOs). Potentially Hazardous Objects are a subclass of NEOs consisting mostly of asteroids (Potentially Hazardous Asteroids) that have the potential to make close approaches to the Earth whilst featuring a size large enough to cause significant regional damage in the event of an impact. It is currently (as of 2012) expected that only 20 - 30 percent of all existing PHOs are already known. This gives an indication that NEOs, in particular PHOs, are likely to pose a real threat to earth on a long time scale. Among the possible mitigation and deflection options, the mission outlined here seeks to demonstrate NEO deflection by means of a kinetic impactor. The main objectives of the mission are technology demonstration, deflection validation and beta-factor determination. This requires a mission that impacts a NEO in a representative velocity regime, allows measurement of the deflection sufficiently accurately to clearly demonstrate the momentum transfer by the impactor. The beta-factor quantifies the additional momentum transfer achieved through ejecta from the asteroid, which can be achieved both through accurate deflection measurement or ejecta observation, ideally through both. For the development of a fitting mission concept the NEOShield project performed a wide range of trade-offs while taking into consideration a variety of previously developed mission concepts such as Don Quijote

NEOTωIST: A relatively Inexpensive Kinetic Impactor Demonstration Mission Concept

Mission concept: NEOTωIST stands for Near-Earth Object Transfer of angular momentum (ω∙I) Spin Test, and is a concept for a kinetic impactor demonstration mission, which aims to change the spin rate of an asteroid by impacting it off-center (Drube et al. 2016, Engel et al. 2016). The change would be measured by means of lightcurve measurements with Earth-based telescopes. In contrast to most other kinetic impactor demonstration mission concepts, NEOTωIST does not require a reconnaissance spacecraft to rendezvous with the target asteroid for orbit change and impact-effect measurements, and is therefore a relatively inexpensive alternative. The NEOTωIST mission would determine the efficiency of momentum transfer (the β-factor) during an impact, and help mature the technology required for a kinetic impactor mission, both of which are important precursor measures for a future space mission to deflect an asteroid by collisional means in an emergency impact hazard situation

Dealing with Uncertainties in Asteroid Deflection Demonstration Missions: NEOTwIST

Deflection missions to near-Earth asteroids will encounter non-negligible uncertainties in the physical and orbital parameters of the target object. In order to reliably assess future impact threat mitigation operations such uncertainties have to be quantified and incorporated into the mission design. The implementation of deflection demonstration missions offers the great opportunity to test our current understanding of deflection relevant uncertainties and their consequences, e.g., regarding kinetic impacts on asteroid surfaces. In this contribution, we discuss the role of uncertainties in the NEOTwIST asteroid deflection demonstration concept, a low-cost kinetic impactor design elaborated in the framework of the NEOShield project. The aim of NEOTwIST is to change the spin state of a known and well characterized near-Earth object, in this case the asteroid (25143) Itokawa. Fast events such as the production of the impact crater and ejecta are studied via cube-sat chasers and a flyby vehicle. Long term changes, for instance, in the asteroid's spin and orbit, can be assessed using ground based observations. We find that such a mission can indeed provide valuable constraints on mitigation relevant parameters. Furthermore, the here proposed kinetic impact scenarios can be implemented within the next two decades without threatening Earth's safety.Comment: Accepted for publication in the proceedings of the IAUS 318 - Asteroids: New Observations, New Models, held at the IAU General Assembly in Honolulu, Hawaii, USA 201

ASIME 2018 White Paper. In-Space Utilisation of Asteroids: Asteroid Composition -- Answers to Questions from the Asteroid Miners

In keeping with the Luxembourg government's initiative to support the future use of space resources, ASIME 2018 was held in Belval, Luxembourg on April 16-17, 2018. The goal of ASIME 2018: Asteroid Intersections with Mine Engineering, was to focus on asteroid composition for advancing the asteroid in-space resource utilisation domain. What do we know about asteroid composition from remote-sensing observations? What are the potential caveats in the interpretation of Earth-based spectral observations? What are the next steps to improve our knowledge on asteroid composition by means of ground-based and space-based observations and asteroid rendez-vous and sample return missions? How can asteroid mining companies use this knowledge? ASIME 2018 was a two-day workshop of almost 70 scientists and engineers in the context of the engineering needs of space missions with in-space asteroid utilisation. The 21 Questions from the asteroid mining companies were sorted into the four asteroid science themes: 1) Potential Targets, 2) Asteroid-Meteorite Links, 3) In-Situ Measurements and 4) Laboratory Measurements. The Answers to those Questions were provided by the scientists with their conference presentations and collected by A. Graps or edited directly into an open-access collaborative Google document or inserted by A. Graps using additional reference materials. During the ASIME 2018, first day and second day Wrap-Ups, the answers to the questions were discussed further. New readers to the asteroid mining topic may find the Conversation boxes and the Mission Design discussions especially interesting.Comment: Outcome from the ASIME 2018: Asteroid Intersections with Mine Engineering, Luxembourg. April 16-17, 2018. 65 Pages. arXiv admin note: substantial text overlap with arXiv:1612.0070

In-Space Utilisation of Asteroids::“Answers to Questions from the Asteroid Miners”

The aim of the Asteroid Science Intersections with In-­Space Mine Engineering (ASIME) 2016 conference on September 21-­‐22, 2016 in Luxembourg City wasto provide an environment for the detailed discussion of the specific properties of asteroids, with the engineering needs of space missions that utilize asteroids.The ASIME 2016 Conference produced a layered record of discussions from theasteroid scientists and the asteroid miners to understand each other’s key concerns and to address key scientific questions from the asteroid mining companies: Planetary Resources, Deep Space Industries and TransAstra. These Questions were the focus of the two day conference, were addressed byscientists inside and outside of the ASIME Conference and are the focus ofthis White Paper.The Questions from the asteroid mining companies have been sorted into the three asteroid science themes: 1) survey, 2) surface and 3) subsurface and 4)Other. The answers to those Questions have been provided by the scientists with their conference presentations or edited directly into an early open-­‐access collaborative Google document (August 2016-­‐October 2016), or inserted byA. Graps using additional reference materials. During the ASIME 2016 last two-­‐hours, the scientists turned the Questions from the Asteroid Miners around by presenting their own key concerns: Questions from the Asteroid Scientists. These answers in this White Paper will point to the Science Knowledge Gaps (SKGs) for advancing the asteroid in-­‐space resource utilisation domain

Possible physical and thermodynamical evidence for liquid water at the Phoenix landing site

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/95444/1/jgre2665.pd