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

Small-body deflection techniques using spacecraft: techniques in simulating the fate of ejecta

We define a set of procedures to numerically study the fate of ejecta produced by the impact of an artificial projectile with the aim of deflecting an asteroid. Here we develop a simplified, idealized model of impact conditions that can be adapted to fit the details of specific deflection-test scenarios, such as what is being proposed for the AIDA project. Ongoing studies based upon the methodology described here can be used to inform observational strategies and safety conditions for an observing spacecraft. To account for ejecta evolution, the numerical strategies we are employing are varied and include a large N-Body component, a smoothed-particle hydrodynamics (SPH) component, and an application of impactor scaling laws. Simulations that use SPH-derived initial conditions show high-speed ejecta escaping at low angles of inclination, and very slowly moving ejecta lofting off the surface at higher inclination angles, some of which re-impacts the small-body surface. We are currently investigating the realism of this and other models' behaviors. Next steps will include the addition of solar perturbations to the model and applying the protocol developed here directly to specific potential mission concepts such as the proposed AIDA scenario.Comment: 19 pages, 11 figures, accepted for publication in Advances in Space Research, Special Issue: Asteroids & Space Debri

The NEOShield-2 EU project: The Italian contribution

The NEOShield-2 (2015-2017) project has been recently approved by the European Commission in the framework of the Horizon 2020 programme with the aim i) to study specific technologies and instruments to conduct close approach missions to NEOs or to undertake mitigation demonstration, and ii) to acquire in-depth information of physical properties of the population of small NEOs (50-300 m), in order to design mitigation missions and assess the consequences of an impact on Earth. The Italian scientific community is widely involved in this project

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

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

The European Union funded NEOShield project: a global approach to near-Earth object impact threat mitigation

Although discussions are underway within the Action Team 14 of the United Nations COPUOS, there is currently no concerted international plan addressing the impact threat from near-Earth objects (NEOs) and how to organize, prepare and implement mitigation measures. We report on a new international project to address impact hazard mitigation issues, being the subject of a proposal submitted to the European Commission in response to the 2011 FP7 Call “Prevention of impacts from near-Earth objects on our planet”. Our consortium consists of 13 research institutes, universities, and industrial partners from 6 countries and includes leading US and Russian space organizations. The primary aim of the project, NEOShield, is to investigate in detail the three most promising mitigation techniques: the kinetic impactor, blast deflection, and the gravity tractor, and devise feasible demonstration missions. Furthermore, we will investigate options for an international strategy for implementation when an actual impact threat arises. The NEOShield project was formally accepted by the European Commission on 17 November 2011 and funded with a total of 5.8 million Euros for a period of 3.5 years. The kick-off meeting took place at the DLR Institute of Planetary Research, Berlin, in January 2012. In this paper we present a brief overview of the planned scope of the project

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