How would humanity react if an asteroid headed straight for earth, putting it in immense danger? This is the question on which the United Nations International Legal Group for Planetary Defense, led by French scientist Alissa Haddaji, is working.
Her role is “to decide on the best possible scientific mission to push this asteroid”, says the scientist who also heads the Harvard & MIT Space Consortium, invited this summer to the Fleurance Astronomy Festival (Gers).
This reflection under the aegis of the UN is carried out in parallel with NASA’s DART experimental mission, whose ship must hit an asteroid at the end of September, to deviate its trajectory.
Question: What risks should planetary defense allow us to face?
Answer: “Planetary defense aims to know what to do in the event of a threat from an asteroid or a comet. If an object is discovered that is more than 50 meters in diameter and has more than 1% chance of impacting the earth, the SMPAG advisory group (Space mission planning advisory group, editor’s note) is activated, approved by the scientific committee of the United Nations space affairs council and composed of space agencies from different countries. more than 300 meters, we are talking about a continental impact, and if it is more than a kilometer, 25% of living species would be eradicated. If it is 50 meters, we therefore have a broad national risk.
Q: What methods are considered in the event of an asteroid threat?
A: “It’s definitely not +Armageddon+, blowing up the asteroid, because creating more pieces is not desirable. It would be possible to ram it and push it through this impact, which the DART missions from NASA and Hera from the European Space Agency (ESA) will test very soon. If the asteroid is very large or if we start very late, it would be possible to cause an explosion of a nuclear charge next to the asteroid, thereby melting some of the rock which would break off and push it to the other side, as a reaction.”
Q: In what legal framework would such an intervention take place?
A: “It is stipulated in the Outer 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 there is Should we need to send a nuclear warhead, the United Nations Security Council would have to temporarily override these rules by authorizing a derogation from this treaty. We then find ourselves following the rules specific to the Security Council of the UN with 15 members, five possible vetoes. Of the 15 members, there must be at least nine who agree without a veto.”
Q: How would the decision be made?
A: “Decision-making schemes have been developed. The IAWN (International Asteroid Warning Network, editor’s note) group, responsible for detecting asteroids and assessing the risks, would warn the United Nations and the SMPAG group as well as the policies of the or possibly affected countries. The decision will be taken at the political level on the advice of SMPAG.”
Q: Is space affected by current international tensions?
A: “This is where we see the role of space. It is an area where, in essence, everyone needs everyone. This is one of its most valuable features. The fact that we have a marvelous Space Treaty dating from 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 for a common goal of understanding the universe, is inspiring. With the current international tensions, perhaps things will change, for At the moment we don’t know. But we are in a field where knowledge guides, and where scientific experts have a say in decisions.”