What are you doing on September 26? It’s Monday, but it’s going to be the worst Monday ever for asteroid Dimorphos, as it will collect a projectile sent from Earth since last November. It’s a revenge gesture on our part, if you will, for all the dinosaurs killed 65 million years ago (yes, I know it’s been a while, but that’s about it).

Usually, when NASA launches something into space, we’re used to thinking of complex missions with millions and millions of dollars of complex instruments, spectrometers and all sorts of complex things to study either the Martian soil or the light of distant stars, but the DART mission is not like that at all.

Her mission is to collide with an asteroid. This is it. Okay, so it has some cameras, sensors for navigation so it knows where to go, radio antennas so it can get instructions and report back to us, and some engines so it can be sure to hit the damn Dimorphos.

What, Dimorphos, he has done nothing to us, he is truly innocent. For example, we also don’t immediately go for Apophis’s neck (it’s really worth the bobber, let’s make sure he doesn’t hit us first in the next few centuries, but that’s another story).

Dimorphos, the length of which does not exceed 200 meters, goes about its business and calmly revolves around another, slightly larger asteroid Didymos, the diameter of which is almost 800 meters. Please, the diameter is a bit incorrect to say, because they are small, they are not really spherical, they are a bit like a potato, but you get the idea.

The DART probe weighs about 600 kilograms, which may not seem like a lot compared to a 200-meter asteroid that weighs almost 5 million tons, but it would be wrong to compare masses only: DART is heading for Dimophos at a relative speed of 6.6 km/s, which means a significant impulse sufficient for a measurable effect.

Why do we do this?

To learn how to defend against asteroids with real danger. In the coming decades, NASA promises that no massive asteroid will fly by to throw our civilization into chaos, but do you know what will happen in a few centuries? I mean the dinosaurs didn’t have a space program and look what happened to them

We have a space program, and if we don’t use it wisely, we might as well perish. And it is not easy with these asteroids, because they are not the only ones in the solar system, there is also Jupiter, which is large enough to influence their orbit and complicate our calculations, especially if we want to know where a certain asteroid is for 2-3 decades. It is as difficult as trying to predict the likely weather for the next month.

But going back, we kind of have an idea of ​​what’s going to happen after the impact, but at the same time we want to be sure. One is the calculations we do at home on paper (or on mainframes), the other is perhaps reality. What if this asteroid is just a pile of boulders and space dust, and our projectile will go right through it like cheese? What if its density is different from the density of the models NASA uses? We’ll see on September 26 if NASA got it right or not. And for the sake of all of us, let’s hope he got it right.

It’s actually going to be a while before we can clearly see the effects of this strike, because the European HERA mission hasn’t launched yet, which is also going to pass through the Didymos-Dimorphos system and take some pictures, let’s see what they – went to the Americans. Well, those who are in a hurry can look at the trajectory of the asteroid, because after the impact, NASA is betting that the change in trajectory will be visible from Earth.

As it turned out, for the first time in our history we managed to change the trajectory of an asteroid. Not bad for a mammal species that didn’t even know how to write 7,000 years ago. What I like about the HERA mission is that Romania is also involved through several research institutes, as well as private companies that have tested or assembled the components that are now on their way to Dimorphos. We are also involved, in a small way, in efforts to protect the planet from future asteroids.

Can it be done with just a knock?

Thank God Dimorphos didn’t get a nuclear uppercut, but such a mission was much more expensive and difficult. There are other ways to protect against asteroids. For example, we can cover them with a reflective film, changing their albedo, which is their brightness, meaning they will absorb less sunlight, reflect more light, and actually allow the sun to do its job of changing its path around us.

Because even though photons have zero rest mass, they never stand still, which means they have momentum, and with the billions and billions of photons hitting a hidden asteroid, the momentum could be enough to force its trajectory to bypass us by at least several thousand kilometers. That is, we don’t just hit it once, we allow photons of light to hit it billions and billions of times over several years.

And there is another method tested by the same mission: the gravitational attractor. It looks like some kind of device invented by Jordy LaForge in the belly of the USS Enterprise, but a gravitational attractor is actually an object with enough mass that, when placed near an asteroid, it changes its trajectory over time under the influence of gravity. .

It’s pretty hard to launch new thousands of ton probes right now, but… Dimorphos already has a natural gravitational attractor on Didymos! Once on Dimorphos, we’ll see what effect its new trajectory will have on another asteroid. Come on, it’s not for nothing that the engineers who designed this mission work at NASA and the European Space Agency, it’s really clever what they’re doing there.

In general, mark somewhere on the calendar the date of September 26, when humanity will give the asteroid a hard time.