Turning an asteroid away from the Earth “at the last minute” is difficult, but possible

Engineers from the Spanish company GMV claim that it is possible to prevent an asteroid collision with the Earth not only months and years before it happens, but also much later. But this requires new navigation and control systems.

Deflection of the asteroid at the last moment. Source: news.mit.edu

How to shoot down an asteroid near the Earth

The recently conducted DART mission demonstrated the ability to change the orbit of asteroids. This is a key technology to protect the Earth from collision with them. But the experiment carried out by NASA is designed primarily to influence celestial bodies which orbit is determined for many years to come.

At the same time, there is a possibility that a potentially dangerous asteroid will be detected just a few months before it collides with Earth. Traditionally, it is believed that in this case we will not be able to do anything. However, engineers from the Spanish company GMV, specializing mainly in satellite control and navigation systems, recently published a study in which they proved that this is still possible.

Three options for how to deflect an asteroid

They considered three possible options for changing the asteroid’s orbit: gravitational impact, nuclear explosion at the surface and kinetic impact. The first of them involves placing a spacecraft next to the celestial stone, which will affect its trajectory. But this method is too slow to apply it when there are only a few weeks left before the collision.

A nuclear explosion has not yet been tested as a means of changing the asteroid’s orbit. It is so strong that it makes sense to use it only when the diameter of the body is measured in kilometers. And the orbits of such objects are usually known in advance. The danger is mainly represented by smaller stones.

In addition, the use of nuclear weapons in space is prohibited by international agreements. Therefore, the kinetic influence remains, which was used in the DART experiment. The researchers focused on it.

Control system of the device

According to the authors of the study, the main problem with the deviation of a space stone in terms measured in days is the inability to determine the exact parameters of its orbit and rotation in such a short time.

That is, it is possible to launch a projectile like DART quickly enough. But in order to understand how to adjust its orbit so that the impact is effective, scientific research is needed, which can last for years.

However, if we develop an autonomous control and navigation system that is more efficient than the SMART Nav used on DART, then the effective impression of an asteroid becomes quite real. This system can work according to one of two principles: proportional navigation and intelligent feedback.

The first one is usually used. The computer of the firing probe determines its position and the position of the target every second and corrects the trajectory with the engines. However, such an approach in conditions when the geometry and parameters of the target are clarified only during the mission, leads to fuel overspending.

Therefore, GMV experts suggest applying the second principle — intelligent prediction of the target’s behavior. In accordance with it, the computer first builds for itself a model of the geometry and rotation of the object, that is, it performs all the work that specialists usually do on the Earth. And already coming out of it, it builds a course so that the engines turn on only when it is really necessary.

According to phys.org

Follow us on Twitter to get the most interesting space news in time