In 10 days, a "dart" 11 million kilometers away will hit an asteroid. Do you want to watch it?

On September 26, the DART spacecraft, nicknamed "Dart", will sacrifice itself for the future of mankind. At that time, it will use its 550 kg body to hit an asteroid 11 million kilometers away from us at a speed of 6.6 kilometers per second. The impact energy is equivalent to 5.7 tons of TNT, enough to shatter itself and leave a crater with a diameter of about 10 meters on the asteroid.

The purpose of this kind of suicide attack is noble and of great significance.

Asteroid impacts are one of the biggest threats to human survival and continuation. Many mass extinctions in history have been caused by asteroid impacts. There are countless asteroids in the solar system, and there are tens of thousands of near-Earth asteroids that pose a major threat to the Earth. These asteroids pass by the Earth from time to time. Once they hit the Earth, humans will be in big trouble.

In 1994, a comet called Shoemaker-Levy 9 hit Jupiter with an impact energy of 40 trillion tons of TNT equivalent, equivalent to the power of 3 billion Hiroshima atomic bombs. If it hits the earth, even if humans are not extinct, they may return to the Stone Age. Therefore, responding to and preventing the threat of asteroid impacts is a major issue for all mankind.

The United Nations and many countries in the world are developing plans and tests to prevent asteroids, and China is no exception. These preventive measures are mainly based on monitoring and early warning. For asteroids that may threaten the earth and human beings, nuclear explosions, impacts, ablation, power drag, particle beam traction, mass drive and other means are used to destroy the structure of asteroids, or deviate the orbit of asteroids to avoid collision with the earth.

Among them, gravity impact is a relatively simple but effective method. Many developed space countries are conducting this research and experiment, and China is no exception. According to relevant sources, my country is likely to carry out a space asteroid physical impact test around 2025 or 2026.

As early as 2005, the United States conducted a space impact test. The object of the collision was a comet. A small spacecraft called Deep Impact was launched, which traveled 430 million kilometers and approached the "target" - the Stamp 1 comet, which was about 12 kilometers long and 5 kilometers wide, at a distance of 130 million kilometers from the earth. It hit the target at a speed of 10.2 kilometers per second, completing the "first impact" mission of mankind on an asteroid in space.

DART mission is the first-ever test of asteroid defense

The impact with an icy comet 17 years ago was to clarify the composition and structure of comets, while this mission is the first collision with a rocky asteroid. The name of the mission is "Double Asteroid Redirection Test", referred to as DART. It is the first mission in history to study and demonstrate the method of asteroid deflection. The main process is to deliberately collide with the target asteroid by DART without posing a threat to the Earth, so as to change the speed and path of the asteroid.

The mission has been planned since 2012, led by NASA and participated by ESA. It was not until November 24, 2021 that the DART spacecraft (nicknamed "Dart") was successfully launched with a launch weight of 610 kilograms.

The asteroid that was hit is called "Didymos", a binary asteroid combination. The main star is called Didymos, with a diameter of about 780 meters and a rotation period of 2.26 hours; the secondary star is called Dimorphos, with a diameter of about 160 meters and a distance of about 1 kilometer from the main star. It can be understood as a satellite orbiting the main star, revolving once every 11.9 hours.

It is that secondary star that DART is meant to hit.

This group of asteroids will not hit the Earth. According to their trajectory, they will pass by the Earth at a distance of 11 million kilometers at their closest. It is precisely because the test is safe that they were selected as targets for the impact test by NASA. "Dart" has been tracking and chasing "Ditimos" in space for 10 months. It will approach "Ditimos" before September 26, and will wait for an opportunity to collide with the secondary star between September 26 and October 1.

The ideal result of the impact is to shift the orbit of the secondary star by 1%. Based on the actual data obtained from the impact, it is possible to calculate what mass, speed, and angle of impact spacecraft can be used to knock an asteroid of what size, mass, and speed off its orbit. In this way, when an asteroid hits the Earth in the future, it can be deflected by gravity impact to save humanity.

This kind of impact test may have to be carried out many times before detailed and accurate technical parameters can be obtained to evaluate the feasibility of changing the orbit of an asteroid through impact. Eventually, humans can prepare several impactors, and when an asteroid is found speeding towards the earth, such an impactor can be launched in time to save humans from disaster.

This impact test will have a profound impact on future defense against asteroid threats

Of course, if we want to deflect an asteroid by impact, we must have early warning of the threat of an asteroid, at least discover the danger months or years before the asteroid hits the Earth, so that we can take this approach to save it. If an asteroid is close to the Earth and is about to hit the Earth, with the current technological capabilities of mankind, it is impossible to escape.

In addition, this kind of impact may only be effective against relatively small asteroids. If the asteroid is too large, such as several kilometers or even dozens of kilometers, this method will be useless. With the current capabilities of mankind, we can probably only wait for the Day of Judgment to come.

In order to prevent all the eggs of humanity from being smashed in one basket on Earth, far-sighted scientists are trying to create conditions for interstellar migration, which is another topic and I will not go into it here. In short, asteroid impact tests are of great significance to human survival and reproduction.

In order to observe the effects of the impact in detail, the DART spacecraft also carries a small cubic satellite LICIACube, manufactured and operated by the Italian Space Agency. It is nicknamed the "mini photographer" and is equipped with a high-definition camera and signal transmission system. When the spacecraft approaches "Ditimos", this small cubic satellite will pop out.

According to the operation team, the "Mini Photographer" was successfully released on September 11 and is now closely monitoring DART's flight status, waiting for the shocking collision on September 26. At that time, it will faithfully carry out the mission entrusted by humans - and transmit the image data of the impact to the eyes of humans on Earth in a timely manner.

At that time, some telescopes on Earth will also be aimed at the mission target to film the entire impact process. Will the Hubble Telescope and the Webb Telescope, which are currently performing missions in space, participate in it? There is no news on this yet. But NASA has said that the entire impact drama will be filmed and broadcasted in real time.

Given well-known factors, it is unlikely that some of my country's major media will broadcast the event live, so from which channels can we watch this wonderful drama? You should still look for it yourself. If Time and Space Communication has any news, we will inform you in the comment section as soon as possible.

Further reading: Introduction to the "Mini Photographer" LICIACube

Team members of NASA's Double Asteroid Redirection Test (DART) -- the world's first planetary defense test mission -- confirmed that the spacecraft's own "mini-photographer" LICIACube (Italian acronym for Lightweight CubeSat Imaging) was successfully ejected from its spring-loaded box on Sept. 11.

When the signal was sent to release LICIACube at 7:14 p.m. Sunday evening — exactly 15 days before DART was scheduled to impact the asteroid Dimorphos — DART team members watched with bated breath for a signal confirming that the CubeSat had been safely deployed. When the signal finally came nearly an hour later, cheers rang out.

"We are very excited about this - it is the first time that the Italian team operates its national spacecraft in deep space!" exclaimed Simone Pirrotta, LICIACube Project Manager at the Italian Space Agency, which contributes to and manages LICIACube. "The whole team is fully involved in the activity, monitoring the satellite status and preparing for the phases approaching the asteroid flyby. We expect to receive the first full-frame images and process them within a few days after DART's impact. We will then use them to confirm the impact and add relevant information about the generated plume - a truly invaluable asset to our photographs."

LICIACube (pronounced LEE-cha-cube), designed, built and operated by Italian aerospace company Argotec, with participation from the National Institute for Astrophysics and the Universities of Bologna and Milan, is programmed to record DART's September 26 impact. It will collect unique images of the asteroid's surface as well as debris ejected from the newly formed crater, providing valuable information to inform computer models of satellite-asteroid impacts and provide a spectacular demonstration of the mission's success.

The CubeSat carries two optical cameras: LUKE (LICIACube Unit Key Explorer) and LEIA (LICIACube Explorer Imaging of Asteroids). Each will capture scientific data that will inform the microsatellite's autonomous systems by finding and tracking the target asteroid Dimorphos throughout the DART encounter. The LICIACube team is now calibrating the spacecraft and its payload by capturing images of the celestial body at different rates and integration times.

The team will later load command maneuvers for the satellite's final trajectory, which will fly over Dimorphos about three minutes after DART's impact. This slight delay will allow LICIACube to confirm the impact, observe the evolution of the plume, possibly capture images of the newly formed impact crater, and view the opposite hemisphere of Dimorphos that DART will never see.

Importantly, these images will complement those from DART's own high-resolution imager, DRACO (Dimorphos Reconnaissance and Asteroid Camera for Optical Guidance), helping to better characterize DART's effectiveness in deflecting Dimorphos' impact.

"We're excited to have LICIACube on the way -- our intrepid little reporter, which we hope will make valuable contributions to DART," said DART's principal investigator, Andrew Cheng, a planetary scientist at the Johns Hopkins Applied Physics Laboratory in Laurel, Maryland. "What it will witness and record will provide us with unique and important information that we wouldn't be able to see otherwise."

The LICIACube project is managed by ASI's Robotic Exploration Missions Office, with the industrial contractor Argotec SrI and a scientific team from the National Institute for Astrophysics, Politecnico di Milano, University of Bologna, University of Naples Parthenope and CNR-IFAC.

Johns Hopkins APL manages the DART mission for NASA's Planetary Defense Coordination Office as a project of the agency's Planetary Missions Program Office. DART is the world's first planetary defense test mission, intentionally kinetically impacting Dimorphos to slightly change its motion through space. While the asteroid does not pose any threat to Earth, the DART mission will demonstrate that a spacecraft can autonomously navigate to a kinetic impact with a relatively small asteroid and prove that this is a viable technology to deflect an asteroid on a collision course with Earth, if one is found. DART is due to reach its target on September 26, 2022.

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