Using several methods together to prevent an impact
Often, when reading about different ways to change the course of asteroids, people tend to think about one method versus another. Which way is best given what circumstance? It is probable that given the large number of interesting ideas that have many advantages and disadvantages, there could well be benefits in combining some methods together to make best use of these benefits. Some mission ideas which will be looked at during the study are as follows.
Combined gravity tractor solutions:
The gravity tractor has a great deal of potential, particularly when fine control of an asteroid’s course is needed. Often, the bulk of a deflection can be done with another method, such as a kinetic impact, with a gravity tractor being used to tweak the position of an asteroid into its final desired orbit.
(Image courtesy Airbus Defence and Space)
Combined kinetic impactor and standard explosive:
A significant amount of energy is delivered to an asteroid when a kinetic impactor hits it. Given that a great deal of the mass delivered to the asteroid is ballast – or dead weight – what if some of that mass were to be replaced with an explosive material? It is known that the more material that can be ejected from an asteroid on impact, the more effective the deflection. Perhaps using an explosive material will improve the deflection by increasing the amount of ejecta. This will be examined during the NEOShield project.
Other combined methods:
A host of combinations exist, and a large trade-off study will be conducted during the NEOShield project which will consider a range of possibilities. Many of the concepts will consider combining impulsive methods, such as kinetic impacts and explosives with slower push methods, such as laser ablation or ion beam propulsion.