00:00Hundreds of millions of rocks gravitate around the sun in the asteroid belt between Mars and Jupiter.
00:07But only a few of them are relatively close to Earth.
00:11NASA ranks asteroids in orbit less than 48 million kilometers from our planet,
00:17in the category of geocruisers.
00:20In this group, some objects are particularly worrying.
00:24They are so big and orbit so close to our planet
00:27that they could be a real threat to the world in the event of a direct collision.
00:32At present, NASA closely monitors an asteroid named Bennu.
00:37It is a relatively large space object that could hit our planet in 159 years.
00:44According to experts, the asteroid, which was spotted for the first time in 1999,
00:51is likely to drift into the orbit of our planet.
00:54If this happens, it could collide with Earth on September 24, 2182.
01:01It is thought that the asteroid Bennu is larger than the Empire State Building.
01:05If it came to hit our planet, the collision would release 1,200 megatons of energy.
01:10It's a huge amount of energy.
01:13Nothing built on Earth can produce as much.
01:17NASA scientists think that during its flight of the 22nd century,
01:22the asteroid could pass through a gravitational lock hole.
01:26This area would place our space traveler on a certain trajectory,
01:30which could lead him to crash on Earth.
01:34Bennu approaches our planet every six years.
01:37It has hit Earth three times, in 1999, 2005 and 2011.
01:45Today, scientists estimate at 1 in 2,700,
01:48the probability that the asteroid will hit our planet by 2182.
01:53A person is five times less likely to be hit by lightning.
01:57Even if the collision risks between Bennu and Earth are for the moment quite low,
02:02this space rock has still been classified as a potentially dangerous asteroid.
02:08All this because it could approach 7.5 million kilometers from Earth.
02:14This is why it is also classified as a geocruiser.
02:19Bennu is a carbon-rich asteroid,
02:22which formed during the first 10 million years of the history of the Solar System.
02:26That is to say, about 4 or 5 billion years ago.
02:30It is therefore not surprising that this space body contains precious clues
02:34about the origin and development of the rock planets of our Solar System,
02:38namely Mercury, Venus, Earth and Mars.
02:43Even better, it could contain organic molecules
02:46similar to those that are essential to the appearance of life.
02:50In 2020, NASA's Osiris-Rex probe
02:53managed to briefly touch the surface of the asteroid.
02:57It collected some samples and then moved away.
03:00For NASA, this was the first mission of this type.
03:04But you will probably not be surprised to learn
03:06that Bennu is not the only asteroid we should worry about.
03:10Asteroid 929.9 Fang 42 Apophis is another space body that we must be wary of.
03:17It is a geocruiser object about 335 meters in diameter.
03:22It was discovered in 2004 and was first considered
03:26as one of the most dangerous asteroids ever detected.
03:30Apophis quickly gained notoriety.
03:33It was thought to be a serious threat to Earth.
03:37Experts predicted that it would dangerously approach our planet in 2029.
03:42Fortunately, after a more in-depth examination of Apophis and its orbit,
03:47astronomers concluded that there was no risk
03:49that the asteroid would collide with our planet before at least a century.
03:54The risk of impact of 2029 has been completely ruled out,
03:58as has the potential impact that could be caused
04:01by the asteroid's approach in 2036.
04:05It is interesting to note that until March 2021,
04:08there was still a small risk of collision in 2068.
04:13But Apophis then overflew Earth,
04:16and astronomers took advantage of it to use powerful radars
04:20to more precisely estimate the orbit of the asteroid around the Sun.
04:24This allowed them to rule out any risk of impact for the next 100 years at least.
04:30The reason why such discoveries worry us so much
04:33is that even a relatively small asteroid,
04:36the size of a house,
04:37could wreak havoc by colliding with our planet.
04:41So, when an asteroid is more than 1 km in diameter,
04:45we are talking about a planet destroyer.
04:48The energy released by the impact of such an asteroid would be devastating.
04:52This is why it is essential to know where these asteroids are located
04:56and in which direction they are moving.
04:58The problem is that our ability to protect the planet from asteroid impacts
05:02is not yet optimal.
05:04If such a disaster was about to occur,
05:07we would need a lot of time to prepare.
05:10A collision with an asteroid was something serious.
05:14The crater of Chicxulub is probably the most famous asteroid impact site.
05:19It bears witness to the terrifying collision that led to the extinction of dinosaurs.
05:23Curiously, this crater is not very visible, but others are.
05:27For example, the Barranger crater in Arizona,
05:30which is also called the Meteor crater.
05:32When we think about the collision that caused it,
05:34we get chills down our spine.
05:37Anyway, we now know that space rocks have not only hit the Earth,
05:43but also the Moon, Mercury and Mars.
05:47No rocky planet in the solar system is sheltered from asteroid impacts.
05:53This is why there is a whole scientific enterprise
05:56whose goal is to find and catalog the asteroids of the solar system.
06:01This may seem a little scary,
06:03but there are about 25,000 asteroids of more than 140 meters in diameter
06:08near the orbit of our planet.
06:10Such an asteroid is big enough to scratch an entire city on the surface of the Earth.
06:16So far, less than 50% of these asteroids have been detected.
06:21There are also 230,000 objects of equal or greater than 49 meters in diameter.
06:28These objects are capable of destroying a concentrated urban area.
06:32And yet, less than 8% of them have been detected.
06:37There are also tens of millions of smaller geocruisers.
06:42They measure more than 10 meters in diameter and can cause damage to the surface.
06:47Less than 1% of these small spaceships have been discovered so far.
06:53Our internal solar system poses enormous problems for the search for asteroids.
06:58Every night, there are only two 10-minute clocks
07:01during which astronomers can observe the region.
07:05The reason is that the sun creates a dazzling background light.
07:09In addition, the atmosphere of our planet deforms and blurs the images.
07:13Detecting asteroids in such conditions exceeds the capabilities of most telescopes.
07:18We need a truly unique instrument to accomplish this task.
07:22The preferred tool is the Dark Energy Camera
07:25of the Inter-American Observatory of Cerro Tololo in Chile.
07:29This device was not designed to search for asteroids.
07:32Researchers have built it to detect something even more unspeakable.
07:37The dark energy, the mysterious force that governs the expansion of the universe.
07:42The Dark Energy Camera is supposed to observe hundreds of millions of galaxies.
07:46It is therefore both large and deep.
07:49Thus, it can observe the universe in depth and capture a wide field of vision.
07:55This allows it to record the movements of galaxies
07:58and to inform us about the conditions that prevailed at the beginning of the universe.
08:03But this also means that the Dark Energy Camera is perfectly adapted
08:06to locate asteroids near the sun.
08:10Interior asteroids are rare and deep images are necessary
08:15because these objects are not very bright.
08:18Scientists must be able to fight both the brightness of the twilight sky near our star
08:24and the distorting effect of the Earth's atmosphere.
08:27And the DECAM can help them in this task.
08:30The Dark Energy Camera was built to study dark energy.
08:34A mission that was completed in 2019.
08:37Today, astronomers can use the power of this device for other missions.
08:42They claim that the DECAM survey is the most precise ever carried out
08:47in terms of objects located near the orbits of Venus and our planet.
08:52Thanks to it, we will be able to know what types of objects move inside our solar system.
Comments