In 2029, an asteroid larger than the Eiffel Tower will fly past Earth in an event scientists until recently feared could predict a catastrophic collision.
Now researchers hope to closely examine 99942 Apophis as it makes its close encounter in an effort to bolster our defenses against other space rocks.
The European Space Agency (Esa) has announced funding for preparatory work on the Rapid Apophis Mission for Security and Safety (Ramses) in which a spacecraft will be sent to the asteroid to gather information about its size, shape, mass and the way it spins as it orbits. rush through space.
The mission will also shed light on the composition and internal structure of Apophis, as well as its orbit, and explore how the asteroid changes as it moves within 20,000 miles (32,000 km) of Earth – about one-tenth the distance to the moon – on Friday 13 April 2029.
“The flyby it does with the Earth is absolutely unique,” said Dr Holger Krag, the head of the ESA’s space safety program office, adding that no asteroid is expected to come this close for several thousand years. “If the sky is clear, you should be able to see it with your naked eye.”
Apophis will pass closer to Earth than the geostationary satellites used for TV broadcasts, GPS navigation and weather forecasting. At that distance, Krag said, the asteroid would begin interacting with Earth.
“It’s the gravitational field of the Earth that will basically reshape the asteroid slightly, causing it to change its shape,” he said, adding that the gravitational force could also cause landslides on the asteroid’s surface.
Krag said the insights from Ramses will help scientists understand the asteroid, and the risk such space rocks pose. “Our goal in planetary defense is not to do science on asteroids, but it’s to characterize them in a way that we can one day distract them when they become dangerous,” he said.
Prof Monica Grady of the Open University said that while most asteroids were in fairly safe orbits and did not come close to our planet, Earth-crossing asteroids such as Apophis were a different matter.
“They are coming close to the Earth, and there is potential that one day one of them will hit the Earth and cause a major disaster. We believe it happened 65 million years ago, when the dinosaurs were all wiped out,” she said. “And if it is a large asteroid and it hits us, it will be a catastrophe that will destroy humanity.”
After its discovery in 2004, Apophis kept scientists awake at night with concerns that it could collide with Earth as it orbits the Sun. While Nasa ruled out an impact as Apophis approaches Earth in 2029 and 2036, it wasn’t until 2021 that experts said a bang be off the charts for at least the next 100 years.
However, space agencies are not leaving the safety of the planet to chance, but are exploring ways to tackle Earth-bound asteroids.
Among such projects are Nasa’s Dart missionin which a spacecraft was crashed into the asteroid Dimorphos to test if it was possible to deflect a space rock. Launching this year, ESA’s Hera planetary defense mission will study the aftermath of that accident.
“What the Dart experiment showed is that it’s very important to understand everything about the target asteroid before you hit it,” Krag said. “Because its composition matters, the spin rate matters, the mass matters. So, in principle, before you engage with an asteroid, you need to be able to do a very, very quick inspection.”
Ramses offered scientists the chance to practice just such a rapid exploration, he added. “You can’t just go hit [a target asteroid] because then you cannot predict the outcome. And you can make it worse.”
Prof Alan Fitzsimmons of Queen’s University Belfast, who is on the science advisory team for Ramses, said the data collected by the Ramses mission could also help scientists extend the window for which they can look for potential collisions with Apophis for many hundreds years can predict. “Our posterity still has to worry about this thing right now,” he said.
Krag said the new funding from Ramses will enable the team to purchase the first hardware for the mission – although the final decision on whether Ramses will continue will not be made until the end of next year.
As well as wear An asteroid frame cameraKrag said other potential instruments could include a seismometer to monitor activity as the asteroid experiences Earth’s gravity.
Should Ramses be approved, the plan is to launch the spacecraft in early 2028. “So we have a little under four years, which is very fast for a spacecraft,” Krag said.
Ramses is not the only mission preparing to investigate Apophis: after Nasa’s successful Osiris-Rex mission last year, which recovered 4.6 billion-year-old chunks of space rock from the asteroid Bennuthe same spacecraft will rendezvous with Apophis in 2029 under a new mission title, Osiris Apex.
While Ramses will arrive at Apophis before his close encounter with Earth, Osiris-Apex is expected to arrive afterwards.
Prof Terik Daly of Johns Hopkins University, who is involved in the Osiris-Apex mission, said: “What Ramses is going to be able to do is document Apophis before the asteroid’s close encounter with Earth. So then [Osiris-Apex] can really look and see what this natural experiment has done. How did it change Apophis?”
Daly said the set date of Apophis’ close encounter with Earth was significant. “There’s nothing we can do to change that date – and that’s what will happen in a situation where an asteroid hits the Earth. We cannot negotiate with the asteroid. What we can do is prepare to respond in an effective way.”
Grady said that while such missions were interesting to scientists, they also had a larger appeal. “It’s very exciting as a member of the public to realize that we can actually do something to prevent the earth from a catastrophic extinction,” she said.
