Speed: 22,530 km/h The spacecraft deliberately hit an asteroid Humanity's first asteroid defense test successfully implemented a "kinetic collision"

In science fiction movies, there is often an "asteroid hitting the earth", and in reality, there is a "spacecraft sent by the earth to hit an asteroid".

On the 26th, a NASA spacecraft deliberately hit an asteroid to test the "asteroid impact with the Earth" defense technology and change the asteroid's orbit. This is called a kinetic collision.

NASA said it was the world's first test mission to protect Earth from an asteroid impact. "What an amazing day for humanity," said Bobby Braun, director of the space exploration division at the Johns Hopkins Applied Physics Laboratory.

The main players in this mission are the DART spacecraft, the DRACO navigation camera, the LICIACube cube satellite and the asteroid Dimorphos.

DART:

Ten months in space

A lifetime just for that one collision

At a speed of 22,530 kilometers per hour, it aimed at the asteroid Dimorphos and slammed into it head-on. The sky and the earth were instantly silent, and I didn't even hear the sound of the impact.

If it were on Earth, such a speed would cause a loud bang and burn into a fireball, but in space, there is no air and no such sound.

I am a bit square, 1.2m x 1.3m x 1.3m, but I have two wings, 8.5m in spread, and use new solar cell array technology.

At the time of impact, I weighed 570 kg.

Dimophos is a hundred times bigger than me, with a diameter of 160 meters and an estimated mass of 4.8 million tons. This collision was like a chicken hitting a mortar.

The moment of impact was also my last moment:

September 2022, 19:14 Eastern Time on the 26th, 07:14 Beijing Time on the 27th.

My nickname is DART, which is conventionally a combination of the initials of the full name Double Asteroid Redirection Test. DART means dart, or dash.

I departed from Vandenberg Space Force Base in California, USA on November 23, 2021. I was sent into space by SpaceX's Falcon 9 rocket, using a new technology solar ion propulsion system during the flight. Humans have been testing it for 7 years. Now, the climax has arrived.

I have been in space for 10 months. My only mission in life is to run to Dimophos, which is 11 million kilometers away from the earth, and hit it head-on.

This collision was the first attempt by humans throughout history to deflect the movement of a natural celestial body.

An indescribable moment of splendor.

DRACO:

Accompany you, DART, and die with you

We crashed into Dimorphos at the same time and were smashed into pieces at the same time. DART and I, who had been flying in space together for 10 months, perished together in an instant.

My job was navigation and positioning, using new technology with autonomous real-time navigation algorithms to guide DART toward the asteroid, determine the impact site and geological conditions, and capture high-resolution images of the surface of Dimorphos before impact and transmit them back to Earth.

My nickname is an abbreviation of a long name: Didymos Reconnaissance and Asteroid Camera for Optical navigation.

When DART spreads its wings, I am its big round eyes. I am a narrow-angle camera with an aperture of 208 mm and a field of view of 0.29 degrees. My eyes are focused. DART is focused on hitting the asteroid, and I am constantly taking pictures, one per second, which are connected like a video. The asteroid I took an hour before the impact was just a point of light, and then it became bigger and bigger.

The picture of the pebble beach on the asteroid was taken by me 2 seconds before impact, 12 kilometers away from the asteroid. The last picture was taken 1 second before impact, showing only a small pebble beach. At this time, at the mission control center at the Johns Hopkins Applied Physics Laboratory in Maryland, the signal was lost, the screen was red, and the excited people were clapping and shouting.

LICIACube:

You guys go ahead and hit me, I'll jump out of the car first

DART weighed 570 kg when it impacted, but weighed 610 kg when it was launched last year. This was because I jumped out of the vehicle on the 11th, 15 days before impact.

I was sent by the Italian Space Agency, and it's called the Light Italian CubeSat for Imaging of Asteroids (nicknamed LICIACube).

I have very good eyesight and can take both black and white and color photos because I have two eyes, which are two cameras. One is called LEIA, which is a narrow-field panchromatic camera, and the other is called LUKE, which is a wide-field RGB camera.

LEIA and LUKE are the names of the protagonists in the movie "Star Wars", and they are also the abbreviations of my name.

Jumping before the impact was of course planned in advance. I needed to observe the impact effect from a safe distance: 3 minutes after the impact, I flew over Dimophos from 40 to 80 kilometers away, photographing the jet plume and the crater left by the asteroid.

The Webb Space Telescope, the Hubble Space Telescope and NASA's Lucy probe also watched from afar.

Although I didn't break into pieces, I was destined to be disposable. I would wander around in space doing nothing, and people would call me "space junk." The European Space Agency would send the spacecraft Hera to replace me.

Dimorphos:

I thought it would be like this forever

Who would have thought that I would be hit in the waist?

I am the protagonist of this film.

My name is Dimorphos. I have always been a supporting role. I revolve around Didymos, and we revolve around the sun. Didymos is 780 meters in diameter, while I am only 160 meters. It is said that our names both mean twins.

Since ancient times, we have been turning quietly like this, thinking that we would keep turning in this posture, silently until the end of time.

But on April 11, 1996, Joseph Montagnier, a space observation fellow at Kitt Peak National Observatory in the United States, spotted us.

I went from a supporting role to a leading role because humans decided to crash into me.

Humans have an obsession that asteroids will hit the Earth. Research shows that the mass extinction of dinosaurs was the terrible consequence of an asteroid hitting the Earth. Humans have come up with various ways to deal with it, such as changing the direction of asteroids flying towards the Earth or destroying them.

The orbit I travel may occasionally approach the Earth's orbit, but space is infinite, and the probability of my threat to the Earth is infinitesimal. Perhaps it is precisely because there is no threat that humans chose me. Of course, it is also because my body is smaller than Didymos, so I may be able to hit it.

It will knock out my original orbit and shorten it by 1%. So I can only go around Didymos on the new orbit. It used to take 11 hours and 55 minutes to go around once, but it may be shortened by 10 minutes in the future. Then, I will have to go around more times in the future. I feel dizzy.

It is said that humans will use ground-based telescopes to observe the bright and dark cycles of Didymos to verify the effect. When I pass by, it will be dark. This is also the reason why humans choose to hit the twin asteroids. NASA scientist Statler said that I am a "perfect natural laboratory."

Asteroids with a diameter greater than 140 meters and orbits within 7.5 million kilometers of the Earth's orbit are considered potential threats by Earthlings. NASA believes that no asteroids will pose a real threat in the next 100 years. If an asteroid hits the Earth in the future, I wonder if humans can deal with it by using the "hit me" trick.

Reporter Zhong Songjun comprehensive report