International defence against asteroids
The project was appropriately called NEOSHIELD (A global approach to near-Earth object impact threat mitigation). This EU-funded initiative brought together an international group of scientists and engineers to investigate methods of defence against asteroids. There are thousands of known near-Earth objects (NEOs), leading researchers to posit that a dangerous collision could occur as often as every few hundred years. However, it is possible to stop an asteroid from hitting Earth. The ultimate aim of the NEOSHIELD project was to develop a plan to knock a threatening massive asteroid out of its Earth-bound orbit. One way to do this is to have a spacecraft impact the asteroid and impart enough force to change its orbit. The NEOSHIELD team evaluated a wide range of promising methods for deflecting NEOs, which may only mean providing a nudge in the right place at the right time. The so-called kinetic impactor – a large space probe hits an asteroid at very high relative speed creating an impact sufficient to change its orbit – is feasible using today's technology for objects with diameters of less than 1 km. But, there are many unanswered questions concerning this method. NEOSHIELD partners dealt with various aspects of the problem, from astronomical research into the physical properties of NEOs, laboratory experiments and computer modelling to investigate how an asteroid would respond to a deflection attempt, to the development of technologies needed for a deflection mission. Technologies developed included ways to guide the spacecraft to the moving target at the right angle with the right velocity. The most powerful but least appealing technique explored during the NEOSHIELD project relies on explosive power to divert or break up an Earth-bound asteroid. However, breaking up a large asteroid could be disastrous if it were to result in the Earth being showered with many large fragments. NEOSHIELD provided detailed space mission plans that could form the basis of a proposal to national and international space agencies for a mission to investigate or demonstrate NEO deflection techniques. Project work has generated over 20 peer-reviewed publications in major international journals, in addition to many conference papers. Full details are available on the project website.
Keywords
Asteroids, NEOSHIELD, near-Earth object, impact hazard, kinetic impactor
