11-02-2025
What we know about possible Nasa mission to ‘deflect' asteroid heading for Earth
Scientists will begin to debate in the coming weeks whether they will need to send a mission to intercept an asteroid that may hit Earth in 2032.
It might sound like the plot of a Hollywood fiction film, a European Space Agency (ESA) scientist told Yahoo News that one option available to scientists is to crash a satellite into the space rock and divert it off course.
Last week, the ESA has raised the odds of the asteroid designated '2024 YR4' hitting Earth to 2.2% following updated data from telescopes in recent days.
If the asteroid still poses a threat and it is above 50 metres (164ft) wide, scientists will begin to debate sending a mission to intercept it in May.
Juan L Cano, of the ESA's Planetary Defence Office, told Yahoo News: 'We could start discussing in May whether there is any merit in sending a mission there. The problem is that we have just seven and a half years by that point to do something and develop and construct a satellite. It will be very constrained.'
The object is travelling away from Earth and scientists are aiming larger and larger telescopes at it to get a clearer picture of both its path and its size.
The object's 'aphelion' – its most distant point from the sun – is close to Jupiter, and it was spotted when it passed Earth coming from the sun. It will only be in reach of telescopes for a short time.
Cano said: 'We need to keep observing this object as much as possible. The object is receding from us and getting more away every time we need target telescopes for that. We are now at a limit where we need telescopes of the order of two metres in diameter in order to be able to observe the subject.
'By next month, we will be needing four metres and later, the ones that are eight metres in size. Finally, the largest ones, for example, the Gran Telescopio Canarias which has a 10-metre diameter.'
The ESA has requested to use the James Webb Space Telescope to observe the asteroid until mid-May.
By May, Cano hopes, scientists will have enough information to decide both whether the object will hit Earth, and how big it is.
Depending on the size of the object, scientists will either debate sending a mission to deflect the object – or simply evacuate the area where it might hit.
Cano told Yahoo News: "We have two scenarios here, if we see that the impact probabilities have not gone down in April and the object is bigger than 50 metres, the Space Mission Planning Advisory Group will decide whether to suggest a deflection mission or not.
"If it is not, the suggested solution is evacuation of the impact area."
By the time the asteroid returns, its trajectory will be well enough understood for scientists to evacuate.
NASA and the European Space Agency have conducted research into how the trajectory of an asteroid can be changed by ramming it with a spacecraft.
NASA's Double Asteroid Redirection Test (DART) mission impacted the asteroid Dimorphos in September 2022.
The collision changed Dimorphos's orbit successfully, and now scientists hope to study the space rock close-up to understand how to launch similar missions.
The ESA's Hera spacecraft will enter the orbit of Dimorphos and its larger companion Didymos in October 2026. By analysing the results of DART, Hera will offer information which could be used to repeat the feat with other objects.
Astronomer Dr David Whitehouse told Sky News that another potential option would be launching a nuclear weapon at the asteroid.
The asteroid was spotted on 27 December by NASA's Asteroid Terrestrial-impact Last Alert System (ATLAS).
ATLAS is a warning system for asteroid impacts consisting of four telescopes. It is designed to offer a minimum of 'several weeks' of warning before the impact of a 300ft asteroid like 2024 YR4.
As telescope technology has improved, the number of asteroids spotted has increased, although the number of space rocks remains the same.
The ESA estimates that the asteroid is between 40 metres and 100 metres wide. That would potentially make the space rock's width similar to the height of Big Ben in London, which is 96 metres high.
It is difficult to accurately predict any potential damage. NASA says that an 100-metre wide asteroid has 10 times the destructive force of the 2021 Tonga volcanic eruption, which caused a large explosion and tsunamis in several countries.
The damage caused by such an explosion would vary depending on where the asteroid hit.
"An asteroid this size impacts Earth on average every few thousand years and could cause severe damage to a local region," the ESA has said. NASA says that the impact could kill up to a million people, "averaged over all possible impact locations".
"These deaths could result from a direct hit or by tsunami (tidal wave) in the event of an ocean strike," it adds.
An asteroid thought to have been around 18 metres wide across 'blew up' over the Russian town of Chelyabinsk in 2013.
During the 2013 Chelyabinsk event, 1,500 people were injured and 7,300 buildings damaged by the intense overpressure generated by the shockwave at Earth's surface.
The time of closest approach to Earth (when it could potentially impact) is the 22 December 2032.
The asteroid has been ranked as 'level 3' on the Torino Impact Hazard scale, but NASA says this is likely to drop.
NASA describes level 3 asteroids as a "close encounter, meriting attention by astronomers. Current calculations give a 1% or greater chance of collision capable of localised destruction."
It adds: "Most likely, new telescopic observations will lead to re-assignment to Level 0. Attention by public and by public officials is merited if the encounter is less than a decade away."
