NASA spacecraft will soon intentionally crash into a tiny asteroid

[Buster's Uncle]

NASA spacecraft will soon intentionally crash into a tiny asteroid
Ashley Strickland - Yesterday 6:35 PM
CNN


A NASA spacecraft that will deliberately crash into an asteroid is getting closer to its target.

The DART mission, or the Double Asteroid Redirection Test, will have a rendezvous with the space rock on September 26 after launching 10 months ago.

The spacecraft will slam into an asteroid’s moon to see how it affects the motion of an asteroid in space. A live stream of images captured by the spacecraft will be available on NASA’s website beginning at 5:30 p.m. ET that day. The impact is expected to occur around 7:14 p.m. ET.

The mission is heading for Dimorphos, a small moon orbiting the near-Earth asteroid Didymos. The asteroid system poses no threat to Earth, NASA officials have said, making it a perfect target to test out a kinetic impact – which may be needed if an asteroid is ever on track to hit Earth.

The event will be the agency’s first full-scale demonstration of deflection technology that can protect the planet.

“For the first time ever, we will measurably change the orbit of a celestial body in the universe,” said Robert Braun, head of the Johns Hopkins University Applied Physics Laboratory’s Space Exploration Sector.

Near-Earth objects are asteroids and comets with orbits that place them within 30 million miles (48.3 million kilometers) of Earth. Detecting the threat of near-Earth objects, or NEOs, that could cause grave harm is a primary focus of NASA and other space organizations around the world.

Collision course
Astronomers discovered Didymos more than two decades ago. It means “twin” in Greek, a nod to how the asteroid forms a binary system with the smaller asteroid, or moon. Didymos is nearly half a mile (0.8 kilometer) across.

Meanwhile, Dimorphos is 525 feet (160 meters) in diameter, and its name means “two forms.”

The spacecraft recently caught its first glimpse of Didymos using an instrument called the Didymos Reconnaissance and Asteroid Camera for Optical navigation, or DRACO. It was about 20 million miles (32 million kilometers) away from the binary asteroid system when it took images in July.

On the day of impact, images taken by DRACO will not only reveal our first look at Dimorphos, but the spacecraft will use them to autonomously guide itself for an encounter with the tiny moon.

During the event, these images will stream back to Earth at a rate of one per second, providing a “pretty stunning” look at the moon, said Nancy Chabot, planetary scientist and DART coordination lead at the Applied Physics Laboratory.

At the time of impact, Didymos and Dimorphos will be relatively close to Earth – within 6.8 million miles (11 million kilometers).

The spacecraft will accelerate at about 15,000 miles per hour (24,140 kilometers per hour) when it collides with Dimorphos.



NASA spacecraft will soon intentionally crash into a tiny asteroid
© Provided by CNN
The light from asteroid Didymos and its moonlet Dimorphos is visible in a composite of 243 images taken by DRACO on July 27. - NASA JPL DART Navigation Team


It aims to crash into Dimorphos to change the asteroid’s motion in space, according to NASA. This collision will be recorded by LICIACube, or Light Italian CubeSat for Imaging of Asteroids, a companion cube satellite provided by the Italian Space Agency.

The briefcase-size CubeSat hitched a ride with DART into space. It recently deployed from the spacecraft and is traveling behind it to record what happens.

Three minutes after impact, the CubeSat will fly by Dimorphos to capture images and video. The video, while not immediately available, will be streamed back to Earth in the weeks and months following the collision.

Protecting the planet
Dimorphos was chosen for this mission because its size is relative to asteroids that could pose a threat to Earth. The spacecraft is about 100 times smaller than Dimorphos, so it won’t obliterate the asteroid.

The fast impact will only change Dimorphos’ speed as it orbits Didymos by 1%, which doesn’t sound like a lot – but it will change the moon’s orbital period.



NASA spacecraft will soon intentionally crash into a tiny asteroid
© Provided by CNN
An illustration shows NASA's DART spacecraft and the Italian Space Agency's LICIACube before the collision with Dimorphos. - Steve Gribben/Johns Hopkins APL/NASA


“Sometimes we describe it as running a golf cart into a great pyramid or something like that,” Chabot said. “But for Dimorphos, this really is about asteroid deflection, not disruption. This isn’t going to blow up the asteroid; it isn’t going to put it into lots of pieces.”

The nudge will shift Dimorphos slightly and make it more gravitationally bound to Didymos – so the collision won’t change the binary system’s path around the Earth or increase its chances of becoming a threat to our planet, Chabot said.

Dimorphos completes an orbit around Didymos every 11 hours and 55 minutes. After the impact, that may change to 11 hours and 45 minutes, but follow-up observations will determine how much of a shift occurred.

Astronomers will use ground-based telescopes to observe the binary asteroid system and see how much the orbital period of Dimorphos changed, which will determine if DART was successful.

Space-based telescopes such as Hubble, Webb and NASA’s Lucy mission will also observe the event.

In four years, the European Space Agency’s Hera mission will arrive to study Dimorphos, measuring physical properties of the moon, and look at the DART impact and the moon’s orbit.

No asteroids are currently on a direct impact course with Earth, but more than 27,000 near-Earth asteroids exist in all shapes and sizes.

The valuable data collected by DART and Hera will contribute to planetary defense strategies, especially the understanding of what kind of force can shift the orbit of a near-Earth asteroid that could collide with our planet.


https://www.msn.com/en-us/news/technology/nasa-spacecraft-will-soon-intentionally-crash-into-a-tiny-asteroid/ar-AA11UT3u?rc=1&ocid=winp1taskbar&cvid=568d9acee2724ea0e8917eb0efbff3b9

[Unorthodox]

So, remember the spongey asteroid/sinking lander surprise a few weeks ago, I wonder what such a makeup might do to this type mission.  Or if we can predict the spongey type...

[Buster's Uncle]

It'd probably make for a more efficient/complete momentum transfer.

[Unorthodox]

See I think it would hamper transfer. 

Smashing into a pit of sand theoretically causing more ejecta/lateral momentum transfer. 

[Buster's Uncle]

That blows the projectile up better, sure, but I'd think a soft landing spot transfers more energy along the intended vector.

[Unorthodox]

Take a basketball. 

Dribbling on pavement it bounces well because the momentum is directed the same direction as it fell.  Dribbling on sand, that momentum gets spread to the sides by the sand particles thus the ball doesn't bounce back.  I know the ball is the 'projectile' but the resulting impact is only different because the momentum get's 'lost' by all the sideways transfer on the sand thus less momentum in the direction you want is lost.   

BUT fluid physics don't work the same, and sometimes 0 g [poop] works closer to fluids. 

[Unorthodox]

It'd probably make for a more efficient/complete momentum transfer.

So, because I can, I asked some of the people with the papers that prove they're smart this question. 

It more or less boiled down into both sides presented here.  Some think it would actually BENEFIT the transfer of momentum, some think it would cause a loss of transfer as it's deflected to different vectors. 

With that said, those with the papers more specifically oriented to zero g stuff tended to agree with you that it would result in and increased change in momentum of the target but not because it was more efficient transfer on the initial impact, but because the ejecta would actually act as additional sources of thrust both when they left the surface and again when they eventually fell back to the asteroid, but also warned this would likely not be even so could cause spinning or slightly angular changes. 

(the more terrestrial papered folks tended to be adamantly opposed to this idea, which kind of leads me to believe it boils down to the level of gravity of the target object to really matter one way or another, but it's unlikely any target would ever hit that breaking point)

Either way it sparked a nice argument that got fairly heated at times and was generally amusing. 


All thought landing even a tiny engine would be more efficient for redirect...

[Geo]

All thought landing even a tiny engine would be more efficient for redirect...

Maybe a tiny engine, but I doubt the fuel/propellant storage would be tiny...

[Unorthodox]

There is DEFINITELY some level of ask a rocket guy to solve a problem and they're going to suggest rockets involved, but the whole idea behind an engine is they provide more thrust than their mass, thus would be better at providing deltaV to the asteroid than an equivalent mass into it.  A small xenon ion engine could provide a lot of thrust over time provided you found the asteroid far enough out to give it that time.