It sounds like a movie.
NASA will soon be testing its ability to divert an asteroid from Earth. NASA will launch a spacecraft about the size of an ATM into a space rock that is the size of an Egyptian pyramid.
DART, or Double Asteroid Redirect Test, is the name of the sci-fi-like mission. The spacecraft will launch very soon, on the 23rd of November 2021 at the earliest. This is humanity's first attempt to move an asteroid intentionally. Dimorphos is not an asteroid threat, but it is an experiment to determine how civilization can alter the course of an asteroid that is on collision course with Earth.
Although no known asteroid at least 460 feet in diameter is considered a threat over the next century, it is possible for an asteroid to strike at some point. The $330 million mission is therefore crucial.
Markus Wilde, associate professor of aerospace, space science and physics at the Florida Institute of Technology, stated that "we are currently defenseless against any asteroids aiming for Earth." Wilde is not part of the mission.
Johns Hopkins APL engineers build the DART spacecraft. Credit: NASA/Johns Hopkins APL/Ed Whitman
It may sound impressive to ram a spacecraft into Dimorphos. The goal is to give Dimorphos some nudge. This nudge could occur many years, if not decades before the collision. Andrew Rivkin, a planetary astronomer from Johns Hopkins University Applied Physics Laboratory who is also one of DART’s leading scientists, stated that this gives enough time for the asteroid to miss Earth. A small change in an asteroid’s trajectory can make a huge difference over the course of years.
This strategy requires that you know what's coming. Good news: Astronomers have detected more than 27,000 objects near the Earth and have found approximately 1,500 every year since 2015.
"We are currently defenseless against any asteroids aiming for Earth."
In the next few decades, however, there will be many more rocks to find: Astronomers believe that thousands of large asteroids greater than 460 feet in diameter remain unknown. Astronomers have found over 90% of the larger rocks, some measuring up to a mile in width -- the type that could cause catastrophe on large areas of Earth. The smaller and more obscure rocks have the potential to sneak up on our attention. In 2019, a rock measuring 187-427 feet in size swooped upon Earth and shocked scientists. This kind of impact could prove to be catastrophic. A 600-foot-deep crater was created in Arizona by an asteroid measuring 100- 170 feet in diameter, some 50,000 years ago. NASA's David Kring, an impact expert from the Lunar and Planetary Institute, stated that a similar-sized impact event could decimate a city as large as Kansas City today.
"We must be able to locate these things early," stressed Cathy Plesko, a Los Alamos National Laboratory scientist who studies asteroid impacts and works on the DART mission. We're making progress, but we are not there yet.
Barringer Meteor Crater, Arizona, a 50,000-year-old landmark. Credit: USGS / NASA / Joshua Stevens
The Impact
The DART spacecraft, located at 6.8 million miles away from Earth, will reach the Dimorphos 525-foot-wide Dimorphos around October 1, 2022. Dimorphos will not be the only one. It is actually orbiting a larger sibling, the Didymos, which measures half a mile in width.
Astronomers consider Dimorphos a perfect collision target. Scientists on Earth will use telescopes after the impact to measure the effect of the collision (or "nudge") on Dimorphos orbit around Didymos. The crux of the experiment is: How much space rock did we move? Scientists are hoping to slow the orbit of the space rock by several minutes or even 10 over the course a 12-hour orbit.
NASA will record extreme footage of the 15,000 mph impact. The DART spacecraft will launch a small, toaster-sized "CubeSat" 10 days before the strike. The tiny box will follow DART for a few minutes so astronomers can see what happens when a plume is blasted through the space.
An illustration of the DART spacecraft, and the Didymos system of asteroid systems. Credit: Johns Hopkins APL
The Future
NASA's success in slowing down Dimorphos will not be an extraordinary, deep-space achievement. This is proof that the planetary defense technique works. The same mission will not work if an asteroid larger is found heading towards Earth in 2077. Space agencies can better plan for deflecting the space rock. Plesko suggested that two spacecraft might be required to send the asteroid.
It's the same principle. She said that scaling it up would be the only thing.
NASA will need to conduct a series of DART-like collisions to understand how to deflect the various asteroids that are out there, Wilde of Florida Institute of Technology said.
A radar image of Dimorphos and Didymos. Credit: Naidu et al. / AIDA Workshop
One thing is certain. It is possible to deflect an asteroid many years ahead of its arrival, which can be a great solution for protecting Earth from an imminent threat. We don't want an emergency. This could lead to the need to resort to dangerous defensive measures such as launching a nuclear weapon into space to destroy a 700-foot-wide rock. Computer simulations have shown that a nuclear explosion could eliminate most of the threat. Plesko noted that there are likely unintended consequences and unknowns, such as the possibility of spawning bullet-like micrometeorites, which could cause a runaway tsunami of debris and satellite collisions. This would result in the destruction of civilization's valuable communications, weather, scientific satellites, and other satellites.
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Space scientists are excited that the mission will launch with a well-calculated asteroid Deflection. They say the $330 million cost is worth it.
Wilde said, "It's definitely worthwhile its money."
