In 2004, American astronomers found an invisible spot in the sky: it is a new asteroid, which in itself is not a strange thing. But this asteroid is special: preliminary calculations show that there is a 2.7% chance that it may fall to Earth in April 2029. Everything came clear only two years later, thanks to more accurate observations. The 350-meter-wide asteroid, now called Apophis, would not miss Earth, albeit hardly.
“Apophis will pass the Earth in a geostationary orbit at a distance of 30,000 km. You will be able to see it, for example from the Middle East or from Eastern Europe. It will be relatively bright, which means you can see it with the naked eye or with binoculars”, says Vishnu Reddy , a participant in the Apophis T minus seven conference.
Can small objects infiltrate the monitoring network?
Although the effect is now considered impossible, astronomers prepared for the event with simulation games. Reddy is one of a group of 100 researchers around the world who are now discussing for the third time how Earth can detect and defend potentially dangerous asteroids. The result: Only if current research telescopes continue to receive sufficient funding is there a chance of discovering smaller fragments.
“We have tools and technology to detect celestial bodies the size of Apophis. Smaller objects are a challenge. A 140-meter asteroid can destroy large parts of a country or completely wipe out a small country. We have to find these pieces! And then we need to study them in sufficient detail to calculate their orbits afterwards. A hundred years into the future.”
Osiris Rex on a flying visit
While large portions of asteroids within the 300-meter class of Apophis are known today, astronomers know only an estimated ten percent of all objects that are only half that size. In order to better understand the mechanical properties of these asteroids in the event of an emergency, NASA would like to observe Apophis directly during its flyby in 2029: the US space agency will send the OSIRIS-REx space probe to Apophis, which is still operating its way back from another asteroid.
Michael Nolan is leading the science team for the mission: “We rarely get to experience something of this magnitude. Above all, we want to understand how sunlight changes the asteroid. The surface can be slightly exposed during flight. While we don’t think the shape of Abiba will change dramatically, it has Small landslides happen.”
What countermeasures might work?
The spacecraft is scheduled to arrive at Apophis after three oscillating maneuvers on Earth in April 2029, soon after its close flyby. OSIRIS-REx is designed to take pictures and possibly etch into the surface with a robotic arm to answer an important question: How strong is the material? How would an asteroid like Apophis react if explosives or nuclear weapons were detonated in an emergency? These questions are still open.
Michael Nolan: “As far as we know today, we have to be very careful because we don’t understand asteroids very well yet. Once we study them closely, we may one day be able to distract them with simple, non-violent actions.”
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