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NASA’s mission to deliberately crash into an asteroid: What you need to know


An illustration of the DART spacecraft.


NASA/John Hopkins APL

Very soon, aboard SpaceX’s Falcon 9 rocket, NASA’s DART spacecraft will blast off into the cosmos. But this isn’t any old spacecraft. Unlike beloved robotic explorers Lucy and the Parker Solar Probe, DART isn’t going to send back scientific secrets of the universe. It’s programmed to crash.

DART, which stands for Double Asteroid Redirection Test, is NASA’s test run of a futuristic planetary defense system that’ll protect Earth from incoming asteroids by literally slamming spacecraft into them.

Asteroids collide with our planet more often than you might think, ranging in size from refrigerators to automobiles. Usually, they aren’t too menacing because most of the rock burns up in the atmosphere. But as you may recall, dinosaurs were wiped out nearly 66 million years ago by a massive one called Chicxulub

The goal of the DART mission is simple: NASA wants to understand if we can crash into an asteroid to prevent such a calamity from wiping us out.

As a proof of principle, the spacecraft will strike a little asteroid called Dimorphos that’s orbiting a larger asteroid, Didymos. The target asteroid is about as big as the Washington Monument is tall, and on impact, it’s hoped the rock’s trajectory and speed will be altered.

This particular floating rock doesn’t pose a threat to our planet. But if DART is successful at knocking Dimorphos slightly off course, we’ll know we may have a workable tactic for one day fending off asteroids that are actually dangerous.

How to watch NASA launch the DART mission

You can watch the first liftoff attempt online on NASA TV. Its launch window opens on Nov. 23 at 10:20 p.m. PT (Nov. 24 at 1:20 a.m. ET). Note, this isn’t necessarily the launch time. It’s window is open for a few months, so make sure to check CNET Science for exact timings.

Here’s how that time translates to different zones:

  • US: Nov. 23, 10:20 a.m. PT / Nov. 24, 1:20 a.m. ET.
  • Brazil: Nov. 24, 3:20 a.m. (Federal District).
  • UK: Nov. 24, 6:20 a.m.
  • South Africa: Nov. 24, 8:20 a.m.
  • Russia: Nov. 24, 9:20 a.m. (Moscow).
  • United Arab Emirates: Nov. 24, 10:20 a.m. 
  • India: Nov. 24, 11:50 a.m.
  • China: Nov. 24, 2:20 p.m.
  • Japan: Nov. 24, 3:20 p.m.
  • Australia: Nov. 24, 5:20 p.m. AEDT.

Until then, be sure to check out CNET Highlights for updates, clips and more inside news on the mission. For now, here are a few crucial mission specs to know about in preparation for launch day.

Target acquired: Dimorphos 

Somewhere in our solar system lies a grayish space rock about a half mile wide known as Didymos, which, with a gentle gravitational pull, keeps a companion asteroid on a leash. That second, smaller fragment orbiting Didymos is DART’s target: Dimorphos.

In late 2022, the DART spacecraft is poised to autonomously navigate toward and collide with Dimorphos when it’s about 7 million miles from Earth — their closest point to Earth.

Basically, scientists behind DART selected Dimorphos for the test because its orbit around Didymos mimics how potentially threatening near-Earth asteroids orbit around the sun. Asteroids are gravitationally bound to our star, which could put them on a collision course with the Earth. 

But Dimorphos’s orbit isn’t locked to Earth or the sun but rather to Didymos. This makes it a perfect testing ground for NASA. They can try to crash DART into the tiny rock and see how that changes its orbit around its larger companion.

NASA predicts the crash will be strong enough to adjust Dimorphos’s orbital period by a few minutes. Calculations show the impact will bring Dimorphos closer to Didymos. 

The take-home message is this is a technology demonstration — a way for NASA to get valuable data on how we may one day deflect a super scary asteroid that’s on a collision course with Earth. The scientists behind the mission want to learn just how much we can affect asteroid orbits with a spacecraft crash that barely nudges the rock.

“Mostly, what we’re looking to do is change the speed of the incoming object by a centimeter per second or so. That’s not very fast, but if you do it enough seconds in advance, you can cause it to miss the Earth entirely,” according to the mission overview by Johns Hopkins University’s Applied Physics Laboratory.

dart-image-2

After moving DART to SpaceX’s payload processing facility at Vandenberg Space Force Base in California, DART team members carefully removed the spacecraft from its shipping container and moved it to a low dolly.


NASA/Johns Hopkins APL/Ed Whitman

This approach is one of many ideas for saving humanity from asteroids, and it’s known as “deflection by kinetic impactor.” According to the team, this is the first time the method will be employed intergalactically.

“This technique is thought to be the most technologically mature approach for mitigating a potentially hazardous asteroid,” NASA’s planetary defense officer, Lindley Johnson, said in a statement. “It will help planetary defense experts refine asteroid kinetic impactor computer models, giving insight into how we could deflect potentially dangerous near-Earth objects in the future.”

The way it works is pretty intuitive.

Quick, throw something at it!

Let’s say your buddy is riding a skateboard extremely fast and is headed toward your dog. One (chaotic) way for you to save your dog is to run into your skateboarding friend. When you collide with your friend, the energy you’ve built up changes their direction and lowers their speed. You’ve just become a kinetic impactor — designed to throw your skateboarding buddy off-course and save your dog.

If the skateboarder was a planet-destroying asteroid and your dog was Earth, you’d be playing the role of a future spacecraft.

DART works in a similar way, but it’s not trying to protect the dog, it’s just trying to knock a skateboarder off course. The spacecraft, which is about the size of a school bus, will fly into Dimorphos at a speed of about 4.1 miles per second. That’s roughly 14,760 miles per hour (23,760 kilometers per hour). 

machine

Illustration of the DART spacecraft with its Roll Out Solar Arrays extended. 


NASA/John Hopkins APL

On impact, NASA says, the small asteroid’s, or moonlet’s, orbital speed should change by a fraction of a percent, which leads to an orbital period that’s several minutes slower. 

Though Dimorphos poses no threat to Earth, Earth-based telescopes can easily catalog the bump’s effects, because at just 7 million miles away, the impact is close enough for scientists to observe any changes in the rock’s orbit around its companion, helping them to perfect future planetary defense weapons based on valuable information retrieved from DART’s prototype.

The brave spacecraft’s specs

DART is rather simple. It’s a relatively inexpensive metal box with two roll out, extended solar arrays for power, a single camera and a smaller satellite, or CubeSat, that’ll be deployed right before impact. The sparse tools make sense, as the spacecraft is doomed to die in a suicide mission. 

pd-dart-spacecraft-bus.png

Two different views of the DART spacecraft.


NASA

Here are some specifics:

Cost: $308 million.

Weight: 1,345 pounds (610 kilograms) at launch / 1,210 (550 kilograms) pounds at impact. 

Box dimensions: 3.9 by 4.3 by 4.3 feet (1.2 by 1.3 by 1.3 meters).

Solar array dimensions: 27.9 feet each (8.5 meters).

Extra instrumentation: DRACO camera and one CubeSat.

Engine: Ion propulsion technology/Xenon thrusters.

licia-cube-bench-check-7373

DART team engineers lift and inspect the CubeSat. The miniaturized satellite will deploy 10 days before DART’s asteroid impact, providing essential footage of the collision and subsequent plume of materials. Here, one of the solar panel arrays on the satellite’s wings is visible.


NASA/Johns Hopkins APL/Ed Whitman

While DART’s spacecraft payload is hyper-minimal, the team’s programming behind the course is highly advanced. That’s because the brave little craft is going to behave autonomously throughout the mission. 

Until the end, DART

The spacecraft’s tools may be few, but they’re key. The Didymos Reconnaissance and Asteroid Camera for Optical navigation, or DRACO, device is an ultra-high-resolution camera that can measure the size, shape and geologic composition of asteroids in its vicinity. 

DART also has a metal-oxide semiconductor and image processor that’ll help the spacecraft determine the precise positioning of Dimorphos and stream information back to Earth in real time by way of an antenna attached to the machine.

In addition, DART will be armed with a special navigational toolkit with state-of-the-art directional coding, including the star tracker, which is my personal favorite NASA tool, to ensure it hits Dimorphos at exactly the right moment — ding, ding: the 7 million miles (11 million kilometers) checkpoint. Ten days before DART smacks into its target, it’ll send its CubeSat out. That offshoot will preserve the kinetic impact’s chronicle long after DART turns to rubble.

DART will toil in the line of duty right up until the end. NASA hopes to catch the collision’s juicy details before, after and during impact, so “in its final moments,” the Johns Hopkins University overview says, “DART’s DRACO camera will help characterize the impact site by providing high-resolution, scientific images of the surface of Dimorphos.”

Then: boom.

Mission over — until step two of our intergalactic defense system commences.



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