How a satellite hijacking could save the world

An asteroid is hurtling towards the Earth. The end of the world is imminent. What can be done to avert the danger? The solution: fearless renegades jump into a spaceship, race off into space and eliminate the danger, blasting the asteroid into a thousand pieces on the spot. The stuff of novels and Hollywood films. And the reality?

The threat of a catastrophic impact of an asteroid on Earth is real. Not today. Not tomorrow. But given that up to ten new asteroids - on top of the 26,000 or so already known and observed - are discovered every day, the question is no longer whether such an impact could happen, but only when.

And it would not be the first: in 1908, precisely on 30 June, in the vastness of the Siberian taiga, the most devastating impact to date took place. In the so-called Tunguska event, more than 2100 square kilometres - roughly the size of the holiday island of Tenerife - were razed to the ground. An estimated 80 million trees were destroyed.

Since 2016, the UN has held ’Asteroid Day’ in commemoration of this event.  And for at least 20 years, space engineers have been investigating possible solutions to prevent an asteroid from colliding with Earth. Because, among other things, the idea of renegades to the rescue doesn't work because of a lack of ready-to-go spaceships.

Therefore various technical approaches are being investigated worldwide. One possibility, which Airbus is also investigating, is the Kinetic Impactor - a kind of interplanetary battering ram. This involves sending a heavy satellite on a collision course to the approaching asteroid. The kinetic energy transferred during the impact is intended to cause the celestial body to deviate minimally from its course. At a great distance and well in advance, the deflection is then - so the thinking goes - great enough so that the Earth is ultimately missed.

In a global asteroid deflection effort, multiple parallel kinetic deflection missions would be required to ensure successful deflection of the asteroid and gather the required deflection momentum. Therefore, all space agencies worldwide are expected to build and launch multiple deflection missions. At the initiative of the United Nations, space-faring nations have already joined forces in the ‘Space Mission Planning and Advisory Group’ (SMPAG) to prepare for such a demanding undertaking.

But how quickly do you have to react when there is a threat? How and where can such a satellite be built, how must it be technically designed and how quickly can it be launched? The space experts at Airbus also got to the bottom of all these questions as part of studies for the European Space Agency (ESA).

The requirement: a defence mission must be capable of launch in just six months.

The solution: ’Hijacking a satellite’ - at least that's how the Airbus space experts titled their study results.

The idea is not to hijack a satellite, but rather to repurpose it. This would involve modifying a telecom satellite currently under construction - these are built regularly and are therefore frequently available, have the required mass and thus the necessary penetration power - and adding a special kinetic deflection (KD) module and a small ‘piggyback’ satellite.

The special KD module has a separate propulsion system to enable the final and precise approach to the asteroid, deep space communications functionality and a dedicated navigation system for target detection. A camera-equipped mini-satellite flies on the module, separating just before impact with the celestial body to observe and confirm the success of the mission.

"If you calculate the overall scenario," explains Albert Falke, who led the Fast Kinetic Deflection (FastKD) study at Airbus, "with an asteroid still three years away from possible impact, we have a whole six months to react and launch the mission - including political decision-making." After the launch, there is a six to eighteen-month flight phase to reach the asteroid at a great distance from Earth, ram it and thus deflect it.

"The 'hijacking' scenario would deliver the fastest possible launch readiness, but at the same time requires a great deal of preparation," Falke continues. For example, a tested impactor module must already be available and stored ready for use.

Ad-hoc solutions without preparation are reserved for science fiction movies.