Artist's impression of the asteroid (99942) Apophis. Image: The Planetary Society (CC BY-NC 3.0)
The ESA plans to launch a spacecraft at the ‘god of chaos’ asteroid when it flies past the Earth in 2029, to learn more about how to prevent large asteroid collisions.
Have you ever looked up at the night sky, bustling with activity and wondered: what if an asteroid is heading straight towards us?
It’s a morbid thought, but not beyond the realms of possibility. A massive asteroid wiped out the dinosaurs around 65m years ago, smaller collisions have occurred since and various asteroids have narrowly missed a collision with the Earth in recent years. There is even an annual Asteroid Day to highlight the threat these space rocks present and the importance of monitoring them.
But if we did spot an asteroid that presented that sort of threat, the next question is clear: How we would stop it?
NASA managed to successfully test a planetary defence concept in 2022, by successfully altering the path of an asteroid by crashing a rocket into it. But there is still much to learn about large asteroids and the best ways humanity could avert this sort of disaster.
To understand more about dangerous asteroids – and how to defend against them – the European Space Agency (ESA) has announced a new mission called Ramses, which will fly up to meet the notorious Apophis asteroid when it passes very near to the Earth in 2029.
Learning from a chaos god
Apophis was spotted in 2004 and instantly causes a stir, being identified as the asteroid most likely to strike Earth. Named after the Egyptian god of chaos and taller than the Eiffel Tower (around 375m across), Apophis will pass within 32,000 km of the Earth’s surface on 13 April 2029.
Luckily, astronomers have ruled out the possibility that Apophis will crash into the Earth, at least for the next 100 years. But the upcoming fly-by presents a unique opportunity to monitor a large asteroid this close – there are estimates that one this large comes this close to Earth only once every 5,000 to 10,000 years.
“There is still so much we have yet to learn about asteroids but, until now, we have had to travel deep into the solar system to study them and perform experiments ourselves to interact with their surface,” said Dr Patrick Michel, director of research at the French research centre CNRS.
“For the first time ever, nature is bringing one to us and conducting the experiment itself. All we need to do is watch as Apophis is stretched and squeezed by strong tidal forces that may trigger landslides and other disturbances and reveal new material from beneath the surface.”
The ESA is working on the Ramses spacecraft, which will meet up with Apophis and monitor it as it flies past the Earth in 2029 to observe how it is altered by the planet’s gravity.
The spacecraft will conduct a before-and-after survey of the asteroid’s shape, surface, orbit, rotation and orientation. By learning how the Earth’s gravity alters the Apophis asteroid, researchers can learn the best approach for knocking a hazardous asteroid away from a collision with the Earth.
The ESA said the Ramses spacecraft needs to launch in April 2028 to allow for an arrival at Apophis in February 2029, two months before its approach. The ESA has been granted permission to begin preparatory work on the spacecraft, but we won’t know if the ESA will fully commit to the mission until November 2025.
Richard Moissl, head of the ESA’s Planetary Defence Office, said the Ramses mission would demonstrate that humanity can “deploy a reconnaissance mission to rendezvous with an incoming asteroid in just a few years”.
“This type of mission is a cornerstone of humankind’s response to a hazardous asteroid,” Moissl said. “A reconnaissance mission would be launched first to analyse the incoming asteroid’s orbit and structure. The results would be used to determine how best to redirect the asteroid or to rule out non-impacts before an expensive deflector mission is developed.”
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