Space: A NASA spacecraft collides with an asteroid and deflects it

A few minutes ago, the asteroid Dimorphos, located about 11 million kilometers from Earth, grew progressively larger in spectacular images broadcast live on board. Before the images stop at the moment of explosion, we can clearly distinguish pebbles on its gray surface.

“We’re entering a new era where we have the ability to protect ourselves from a potentially dangerous asteroid impact,” said Lori Glaze, NASA’s director of planetary science.

“Planetary Defense” mission

Dimorphos is about 160 meters in diameter and poses no danger to our planet. It is actually a satellite of the large asteroid Didymos, which has so far orbited in 11 hours and 55 minutes. NASA is trying to shorten Dimorphos’ orbit by 10 minutes, which means bringing it closer to Didymos.

It will take a few days to a few weeks for scientists to confirm that the asteroid’s path has indeed been altered. They will do this with telescopes on Earth, which will observe the variation in brightness as the smaller asteroid passes before and behind the larger one.

This “planetary defense” mission, named DART (DART in English), was the first to test such a technique, if the target is modest compared to the cataclysmic scenes of science fiction films such as “Armageddon”. This allows NASA to train in case an asteroid threatens to one day hit Earth.

scrutinized

The ship had been sailing for ten months since setting sail in California. To hit a small target like Dimorphos, the last stage of the flight was fully automated like a self-guided missile.

Three minutes after impact, a shoebox-sized satellite called LICIACube was launched aloft by the spacecraft, about 55 km from the asteroid to capture images of the plume.

The event will be monitored by the Hubble and James Webb Space Telescopes, which will be able to detect the bright cloud of dust and thus help estimate the amount of ejected material.

All this makes it possible to better understand the composition of dimorphoses, representative of the most common asteroid population, and therefore to measure the exact effect that this technique, called dynamical impact, can have on them.

The European Hera probe, due to launch in 2024, will take a closer look at Dimorphos in 2026 to assess the effects of the impact and, for the first time, calculate the asteroid’s mass.

Unknowns

Asteroids have surprised scientists in the past. In 2020, the American probe Osiris-Rex sank deeper than expected into the surface of the asteroid Bennu. Likewise, the composition of Dimorphos is currently unknown.

“If the asteroid responds to a Dart impact in a completely unexpected way, it could lead to rethinking the extent to which kinetic impact is a common technique,” chief scientist Tom Stadler warned last week.

About 66 million years ago, the dinosaurs became extinct after an asteroid about 10 kilometers across collided with Earth. Nearly 30,000 asteroids of all sizes have been cataloged near Earth (they are called near-Earth objects, meaning their orbits cross the orbit of our planet).

Today, none of these known asteroids threaten our planet for the next 100 years. Except that not all of them are listed yet. According to scientists, almost all were found a kilometer or more. But they estimate that they only know about 40% of asteroids that are 140 meters or larger — capable of destroying an entire region.

“Our most important job is to find missing people,” said Lindley Johnson, NASA’s planetary protection officer. The earlier they are detected, the more time professionals have to put in place a mechanism to protect themselves from them. According to Lindley Johnson, the DART mission was an important first step in this direction: “This is a very exciting time for the history of space, and even for the history of mankind (…).”

AFP

Did you find an error?Please let us know.

0 comments