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Scientists are preparing for the near-collision of the largest asteroid to pass near the Earth in recent history.
The object, known as 99942 Apophis, will only appear on April 13, 2029. But when it does, it will pass about 33,000 kilometers from the surface of the Earth – slightly closer than satellite orbits Communication.
It is close enough for him to sail in the skies of Australia and Africa, he will be almost as bright as the stars of the Southern Cross.
"An object of this size arrives at this point nearly once every 1000 years," says Richard Binzel, an asteroid researcher at the Massachusetts Institute of Technology in the United States.
He was one of the scientists at the upcoming Global Defense of Astronautics Conference in 2019 in Maryland, USA.
And shortly after it was discovered a few years ago, it was feared that the 350 meter rock – a rock 100 times larger than the largest asteroid known to have hit the Earth in recorded human history – could have an impact on the planet. it's not going to happen.
"Earth will be missed, Apophis," says Binzel. "It will be do not hit us. We will shave closely [but] again, I will miss him.
This will provide an unprecedented search opportunity, including space missions that can do anything from quick flyby to rendezvous.
It is even possible to make a landing in which instruments could be deployed on the surface of the asteroid to monitor what happens when it meets the gravity field of the Earth.
According to Binzel, the Holy Grail would consist of placing a seismometer on the surface to measure the shock waves created by the constraints of the Earth's much greater gravity.
According to him, measuring how these waves propagate could provide clues to the inner strength and structure of Apophis.
He compares it to NASA's InSight Mars lander, who is now looking to probe the interior of the Martian planet via marsquakes.
"We can have InSight Apophis," he says.
Jeffrey Plescia, a global scientist at the Laboratory of Applied Physics (APL) at Johns Hopkins University, also in Maryland, believes it is possible to search for shock waves generated by the impact of small meteorites.
It may even be possible to place small explosive charges on the surface, similar to those used to separate the rocket stages at launch, to generate additional seismic waves, he said.
It is also possible to use an impactor fired on the asteroid from above, similar to the one used by the Japanese in their current explorations of the 162,173 Ryugu asteroid, says researcher Jakob Deller. of Asteroids at the Max Planck Institute for Solar System Research, Göttingen. Germany.
It is also useful to measure the extent to which flyover constraints change Apophis rotation rate and if they cause landslides on sloping portions of its surface.
The first of these measures would provide additional information about the interior of the asteroid, says Daniel Scheeres of the University of Colorado. The latter would help to understand the strength of its surface materials.
Several mission concepts are already under design. They focus primarily on the use of inexpensive CubeSats, which are lightweight probes that can leave the Earth via "shared actions" in other more important missions.
For example, says Fazle Siddique, a design and navigation engineer for space missions at APL, a ship weighing only 180 kilograms can do a lot, using solar electric thrusters that, with relatively small amounts of propellant, can allow it to continue Apophis. far into its orbit, and rendezvous with it well before it crosses the Earth.
"You can [do] Apophis has an appointment with about 40 kilograms of propellant, "he explains.
Visit Apophis on foot, however, does not have a purely scientific interest.
The rock is classified as potentially dangerous – and depending on where its trajectory was taken in 2029, there is a small chance for it to receive the correct gravitational (or erroneous) kick in order to to collide with Earth next time. close, in 2068.
At the moment, the risk seems to be extremely low. But this is not zero, and the more we learn about it as the 2029 flyby approaches, the more we know if we have something to fear 39 years later.
More importantly, Apophis seems to be similar to most other potentially dangerous asteroids.
This means that even though we never have to worry about trying to divert this one from the Earth, all that we will have learned about it will help to better understand how to divert one's loved ones, if the need actually feels.
"What we learn about Apophis will be broadly applicable to the entire population of potentially dangerous asteroids," Binzel said.
Not to mention that, with the approach, it will attract a lot of public attention.
"It will be visible to two billion people," Binzel said. "Two billion people will see this asteroid cross the night sky. The world will look, [and] it's up to us to be ready. "
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