NASA and ESA are going to slam a spacecraft into an asteroid to deflect it | Hacker News Reader

NASA and ESA are going to slam a spacecraft into an asteroid to deflect it

technologyreview.com

86 pointscarlsborg58 comments

The asteroid will abruptly turn and fly into Venus.

The asteroid's orbit will decay and will collide with its orbiting object, breaking it into pieces and sending a much bigger chunk directly back at Earth.

In understand the first reference, but not yours. What's it from?

I've just started Persepolis Rising, please don't spoil anything rubbingalcohol!

lol I've never even heard of that. I'm just a little fearful of playing games with asteroids. Probably because I suck at Star Fox.

Do watch The Expanse though. The show is amazing, and I hope the books are even better.

Ah, it's book 7 of The Expanse series. They are worth reading and the show is worth watching.

Or we fuck up and make it an earth asteroid rather than a near earth asteroid ... lol. With the way events have been shaping recently I say there’s a 50/50% chance of success

They are hitting a moonlet of a near-earth asteroid. Even after they hit it, the moon will still be in orbit of the (still) near-Earth asteroid.

Think of the poor Adam Savage just trying to survey the impact site!

"If it works, it will be the first time in history humans have physically changed the orbital trajectory of a space-based object."

They could have done a bit better with this quote ... we change the orbit of space-based objects all the time! So far, they've only been man-made space-based objects though. One thing the article leaves out is whether Bruce Willis will be on-board again.

I think that something manufactured on Earth is an Earth-based object.

Great to see NASA and ESA working together in this selfish era. The world needs more collaboration between people.

Like this?

An American, a Russian and the first Arab astronaut from the UAE all just headed into space together:

https://time.com/5686017/international-space-station-uae-ast...

... I've always admired the capacity for various Space Agencies to put any current (geo)political, social etc. issues aside in the pursuit of science. This isn't a new thing, but you are right - we can all take a page from their book.

Another idea for deflecting an asteroid:

https://en.wikipedia.org/wiki/Gravity_tractor

Seems strange to have an observational cubesat on the first vehicle and still launch a second vehicle to arrive five years later instead of building a second cubesat into the first.

Stop trying to reduce their budget.

If you're curious about how big is the asteroid we'll target (from Wikipedi): it's a moonlet orbiting another asteroid; "It measures approximately 0.17±0.03 kilometers in diameter compared to 0.75±0.1 kilometers for its primary"

No mention about mass though, maybe because we don't know what the asteroid is made of?

Knowing the asteroid's composition isn't required to calculate the mass. This can be derived by the orbit. So, the total mass of the binary system (main and moonlet) is known, but the mass contribution of each isn't. Assuming though that they have the same bulk density, M2/M1 = (D2/D1)^3 ~ 0.0116 and considering Σ Mi = M, then M2 ~ 0.0115M.

Thank you. I searched better online, the total mass is estimated at 52.7 billion kg, so the mass of the moonlet should be around 606,000 metric tons.

Will this work without any Huge Materia?

Yeah, but the asteroid might pause in its orbit for a couple months before releasing hurricanes.

Space is always so fascinating and unknown to me in so many ways. I've never really thought about the endless amount of ways space could wind up killing me, it just seems so far away from my daily life that I don't need to worry about it. I really hope this experiment works for them, or they learn a good bit from it, but I also really hope we never have to use it.

Much more reasonable than NASA’s ARM which was cancelled (https://www.nasa.gov/content/what-is-nasa-s-asteroid-redirec...). But I hope we bring it back

> Get ready for humans to change the orbit of another rock in space for the first time in history

I don't understand. Change the orbit of another rock

and

for the first time in history.

How can changing an orbit of another rock be the first in history?

My english is not a native level.

"Another" here doesn't mean we've done it before. You're supposed to interpret it as "Change the orbit of a rock".

I'm assuming "Another" refers to "A rock that is not earth." Though that does seem rather confusing.

Hmmm. The vast majority of space object's orbits are stable enough in orbits avoiding us:

1. We wouldn't be here if it weren't the case 2. They would have already collided.

Do we really want to destabilize an otherwise random asteroid's orbit unless it's certain it's on a collision course?

1. There are millions (billions?) of other asteroids that come close to us. What makes this one so special? Deflecting this one, even if the deflection works with no unintended consequences, does nothing to improve our odds against getting hit (P = P_one_asteroid * N_asteroids; N_asteroids - 1 ~ N_asteroids). 2. If the deflection destabilizes the orbit, where will the asteroid go but to a nice heafty attractor ?

The only value of this is if we're certain its on a collision course. But if we are, then it too late to deflect!

First off, why wait until we have an actual emergency to test out a theory?

Second, your statement #2 is true, it caused a mass extinction event and probably paved the way for humanity to evolve. If we however get hit by an asteroid of that size again, chances are high that most of the population will die out.

The Earth has already swept it's region of the solar system clean with prior collisions causing the mass extinctions.

There are not an infinite amount of asteroids, and in large time frames you can reduce their numbers. Therefore, we have a large hit once a century. Large, but largely inconsequential (The Earth is empty. Try this: Pick random coordinates and look them up on a map. Repeat. How long before you end up w/ 10 km of an inhabited area?)

Theories are infinite, funds are not. This is an ineffective solution (we can only deflect small and well predicted orbits) to an unlikely problem: mass extinction from asteroids hasn't happened in a very long time (millions of years) -> Bayesian inference -> very low probability of occurring soon. It will happen. But in a millions years

Compare that with the plethora of reasons we might die out in the next 10, 20, or 100 years.

The last mass extinction event caused by an asteroid was probably only about 66 Mya, about 1% of the Earth's lifetime.

So very rare.

Mass extinctions, from your number, appear to be a once in a 132 Mya event. [0]

Humans have been on Earth 0.1 Mya, 0.2Mya; statistically we'll be around for a total of 0.2 to 0.4 Mya in total. [0][1]

Therefore, there is a 1-330 chance of the two time lines overlapping.

[0] Assuming the present time is random, I believe the best estimate of event frequency is that we're in the middle of two occurrences; hence the doubling. [1]I'm being generous here. I don't think we have 0.2 Mya left in us, primarily because for the first time in history we have the ability to kill ourselves off. Therefore the assumption that out present in at a random position of the human experience used in [0] is invalid. Since we probably only have 100 years left, that's a 1-1E6 possibility facing us.

>First off, why wait until we have an actual emergency to test out a theory?

I think the theory is deflection of this object from its orbit could have all sorts of unintended consequence like a domino effect that cause either a chain reaction of events that lead this object or others on a collision course with Earth.

If you read the article, you'll find out that this specific asteroid was chosen because it's a binary asteroid with some specific characteristics. We'll only hit the moonlet orbiting around the main body, which will make it much easier to measure the deviation even from Earth based observations.

Can we shoot down distant asteroids with a missile?

No, for much the same reasons that you can’t shoot down an incoming KE shell fired at you from the main gun of a tank on a ridge half a mile above you with a bang-snap you fire from a child’s elastic catapult.

Sure, technically asteroids come in many sizes, but for dangerous ones you are talking about shooting a thing the size of a mountain that is falling towards you in a way that makes it stop falling towards you.

It'd be hilarious due to some universal physics that cannot be understood, the asteroid slams into Earth due to the interference

The physics of irony :)

Or maybe a metric/imperial mixup

I think this particular rock is about 800m in diameter. That would probably not kill us completely, just be the most catastrophic natural disaster in the history of humanity.

But jokes aside, I think the probability of altering the orbit to hit the earth practically non-existent, especially if you hit it when it is relatively close. You would want to hit it when it is the furthest away from earth to maximize your impact, so something > than 2AU or > than 300,000,000km.

Would pushing large enough asteroids into one another generate gravitational waves?

Yes, but they will be very very very … very very very tiny, and we will not be able to detect them with LIGO+Virgo.

I'm not sure if the formula to estimate the energy we receive from the waves is (Mass1+Mass2) * SomeConstant / distance^2 or it is Mass1 * Mass2 * SomeConstant / distance^2. I'm assuming that it is the first formula. If the second one is the correct one, you must add more "very" in my first paragraph.

Everything generates gravitational waves. They're just far too small to detect unless the masses involved are enormous.

Any form of acceleration generates gravitational waves. The point is how strong they are. Two black holes sized ~200km (or ~30 solar masses) merging at distance ~10000km would be detected through an interferometer by a shift in one part in 1000, that is a change of ~2mm. Those are objects many order of magnitudes more massive than asteroids. So you will get gravitational waves but you wouldn't be able to detect them similar to not being able to detect the waves responsible for the orbit decay of planets.

This is true but we’re detecting that type of interaction a billion lightyears away. I bet if you did the stubby pencil work you would find that the sensitivity is there. I just don’t think the search algorithms would find the signature.

Yes, everything creates gravitational waves. Though at this scale we don't have equipment large enough to detect it.

Technically yes. Also, technically this is wrong:

« If it works, it will be the first time in history humans have physically changed the orbital trajectory of a space-based object. »

...because that happens every time we launch a rocket or land one.

Will this add a bunch of debris to the already crowded near earth space?

No, this is not in earth orbit.

And the solar system is anyway full of flying gravel. The environmental impact is similar if you went to an open mine pit and hammered at a small rock for a while.

I think the concern is that near earth orbit one day will be impassable without some garbage collection.

The acceleration of objects in near earth orbit is vastly greater than the particles from a mine. Space ships collaring with super fast particles in the orbit could spell disaster for the spacecraft.

Hopefully we find ways to make the rock impact negligible if we ever get to the stage of unable to leave orbit due to collisions with space particles (Not saying subatomic particles I just mean debris)

I don't think anybody shares that concern. Not even for LEO, where the wildest fear is not being able to stay in a stable orbit there for years.

Not exactly https://www.nytimes.com/2019/04/02/world/asia/nasa-india-spa...

Thank you for this article! I would post kurgezstat video but their credibility went down recently so NOPE

I think you’re both missing marcosdumay‘s point. If you just want to say go to Mars then you can very quickly got far from earth and easily avoid space junk. The IIS is huge and most days has no problem with space debris. It’s only when you start talking about spending months and years in earth orbit that Kessler syndrome becomes a real concern.

Put another way, if you had 1,000 tons of mass to spread around earth orbit it would be difficult to effectively block rockets from leaving. Try to do the same thing with random orbits and it’s even less of a concern.

I think you are missing the point of years of space debris being added will eventually cause Kessler syndrome to be a lot more accessible from short space travel

Didymos has an orbit that only very occasionally brings it anywhere near Earth. Only within a few million kilometres every hundred years or so. The small amount of debris produced will continue along the slightly altered orbit, so won't be a hazard to local space traffic until such time as the larger asteroid comes close enough to hit Eartch, at which point the tiny debris is a lesser concern.

It's happening! I hope they make a movie out of it.

Would be nice if we could care this much about the actual ongoing mass extinction event we are perpetuating on earth.

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