The article was published at The Conversation.
Gail Iles is a senior lecturer in physics.
A NASA craft the size of a golf cart has been directed to hit an asteroid with the intention of knocking it off course. In case an asteroid threat is detected in the future, the test aims to demonstrate our technological readiness.
The Double Asteroid Redirection Test will arrive at the target asteroid system in September of next year.
Didymos is a member of the Amor group of asteroids. Didymos is seen by a mini-moon every 12 hours. DART's target will be the smaller half of the pair.
What would a planetary defense mission look like?
Are we facing a threat from asteroids?
We've all seen disaster movies in which an asteroid hits Earth and causes an extinction event like the one that killed off the dinosaurs millions of years ago. Is that possible now?
Small asteroids ranging from 1-20 meters in diameter are bombarding Earth frequently. Most asteroids of this size are harmless.
There is a relationship between the size of the object and the number of impact events. We get hit more often by small objects than larger ones because there are more of them in space.
Small asteroid impacts show day and night time impacts. The size of each dot is determined by the impact's optical energy. The image was taken by NASA JPL.
On average, asteroids with a 1 km diameter strike Earth every 500,000 years. The Tenoumer impact crater is thought to have been formed 20,000 years ago by the most recent impact of this size. Earth is hit by asteroids about once every 20 million years.
The Chelyabinsk meteoroid, which hit Russia in July of last year, was estimated to be 20m in diameter.
Assessing the risk.
NASA's DART mission was sparked by the threat and fear of a major asteroid hitting Earth in the future.
The Torino scale is a method for estimating the impact hazard associated with a near-Earth object. It uses a scale from 0 to 10, with 0 meaning there is a small chance of collision, and 10 meaning the object is large enough to cause a global disaster.
The extinction of non-avian dinosaurs is believed to have been caused by the Chicxulub impact. Torino Scale 8 shows the impacts that created the Barringer Crater.
asteroid "near-misses" tend to generate fear in the public with the increase of online news and individuals' ability to film events. NASA is keeping a close eye on asteroid Bennu, which is the object with the largestcumulative hazard rating. You can keep up to date as well.
Bennu is capable of creating a 5 km crater. There is a chance that the asteroid will miss us.
Be prepared for impact.
Didymos and Dimorphos come within about 5.9 million km of Earth at one point in their elliptical path around the sun. DART will hit Dimorphos when it is very close to our moon.
When DART is close to Didymos, it will change direction and crash into Dimorphos at a speed of about 6.6 km per second.
DART is shown in this animation around the Sun. Pink, Didymos, Blue, Earth, and Gold are the colors of the DART. The image is from NASA.
The larger Didymos is a better target for DART to aim for. DART can make a last-minute course correction to collide with the moonlet once it has detected the smaller Dimorphos.
The mass of Dimorphos is over five million tons and the mass of DART will be over 500 tons. DART is expected to change the moonlet's position around Didymos by transferring a huge amount of momentum to Dimorphos.
Within weeks or months, this change will be detected by ground telescopes. 1% is actually a promising shift, even though it doesn't seem like a lot. If DART were to slam into an asteroid, it would only change its position around the sun by a small amount.
The DART mission dates are listed. The image was taken at the University of JohnsHopkins.
We will be able to detect the 1% change from Earth, and the pair will continue along its path around the sun. A small satellite will be deployed ten days before the impact.
NASA's first mission is to demonstrate a planetary defense technique. It's relatively cheap in space mission terms, at a cost of US$330 million. Next month, the James Webb Telescope will be launched.
There won't be any debris from DART's impact. Imagine a train parked on the tracks with no brakes on, it's like that on Earth. A train collides with it.
The trains won't break apart or destroy each other, but will move off together. The stationary one will gain speed, and the one impacting it will lose speed. The trains combine to make a new system.
We won't experience any effects from the DART mission.
Some asteroids can pass close to Earth, but they are usually between Mars and Jupiter. The image is from Pearson.
Is the effort worth it?
The results of the mission will show us how much mass and speed is needed to hit the asteroid. We already track most of the asteroids that come close to Earth, so we would have an early warning of any such object.
We have missed objects before. In October of 2021, A asteroid passed over the ocean. We missed it because it was in the direction of the sun. It wouldn't have caused much damage, but we should have seen it coming.
It would be difficult to build a system for a major asteroid threat. We would have to hit the target quickly.
SpinLaunch is a US company that has designed technology to launch satellites at rapid speeds. The device could be used to fire mass at asteroids.
meteorites come from where? We were able to find out how many fireballs were in the sky.
The Conversation's article is a Creative Commons licensed one. The original article can be found here.
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