Space: Faced with the potential threat of an asteroid, the defense is organized


SpaceFaced with the potential threat of an asteroid, the defense is organized

The UN’s International Planetary Defense Legal Group is working on the best way to redirect an asteroid’s trajectory in the event of danger to humanity. Interview with his manager.

NASA will lead the DART experimental mission in September, which aims to deflect an asteroid from its orbit.


How would humanity react if one asteroid heading straight for land and putting him in enormous danger? This is the question that the UN’s International Legal Group for Planetary Defense is working on, led by the French scientist Alissa Haddaji. Its role is “to decide on the best possible scientific mission to push this forward asteroid», says the scientist who also leads the Harvard & MIT Space Consortium, invited this summer to the Fleurance Astronomy Festival (Gers). This reflection under the auspices of the UN is carried out in parallel with NASA’s experimental DART missionwhose ship will hit an asteroid at the end of September, to deviate its orbit.

What risks should planetary defense address?

“Planetary defense is about knowing what to do in the event of a threat from an asteroid or comet. If we detect an object that is more than 50 meters in diameter and has more than a 1% chance of impacting the Earth, we activate the SMPAG (editor’s note) Space mission planning advisory group, approved by the Scientific Committee of the Council United Nations Space Affairs and composed of space agencies from different countries. If the asteroid is more than 300 meters, we are talking about a continental impact, and if it is more than one kilometer, 25% of living species would be extinct. If it is 50 metres, we therefore have a national risk in the broadest sense,” replies the French scientist Alissa Haddaji.

What methods are considered in the event of an asteroid threat?

“It’s definitely not ‘Armageddon’, blowing up the asteroid, because it’s undesirable to create more pieces. It would be possible to hit it and push it thanks to this effect, like the DART missions from NASA and Hera from European Space Agency (ESA) will test very soon. If the asteroid is very large or you go very late, it would be possible to cause an explosion of a nuclear charge next to the asteroid, thus melting some of the rock, which would break off and would push him to the other side by reaction.”

Within what legal framework will such an intervention take place?

“It is stipulated in the space treaty that it is forbidden to send a weapon into space. In addition, the Partial Nuclear Test Ban Treaty prohibits any nuclear explosion. If it turns out that there is a need to send a nuclear warhead, the UN Security Council will have to temporarily override these rules by allowing a waiver from this treaty. We then follow the rules specific to the UN Security Council with 15 members, five possible vetoes. Of the 15 members, there must be at least nine who agree without a veto.

How would the decision be made?

“Decision-making systems have been drawn up. The IAWN (International Asteroid Warning Network, ed. note) group, which is responsible for detecting asteroids and assessing risks, will alert the UN and the SMPAG group, as well as the politicians of the country or countries that may be affected. The decision will be taken at a political level following the advice of SMPAG.”

Is the space affected by current international tensions?

“This is where we see the role of space. This is an area where basically everyone needs everyone. This is one of its most valuable features. The fact that we have a great space treaty of 1967, adopted by 111 nations, which says that space belongs to no one, that it is there for scientific freedom of exploration, makes it possible to find solutions even when there are tensions. The principle of the International Space Station, where all countries work together towards a common goal of understanding the universe, is inspiring. With the current international tensions, maybe things will change, for now we don’t know. But we are in a field where knowledge guides and where scientific experts influence decisions.


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