Hacker News Board Hacker News, browsed like a classic message board
Live data from Hacker News

NASA's DART spacecraft changed an asteroid's orbit around the sun

sciencenews.org

Post reply on HN
Print view View original

61–70 of 100 posts

Re: NASA's DART spacecraft changed an asteroid's orbit around the sun

#61

Post by ryan_j_naughton »

bdamm wrote: post #51
Ajakks wrote: post #46

Earlier quoted context omitted.

Why exactly? I think the US ought to spend a few trillion on an actual space battleship - one that never comes down to the surface, just sits in orbit. There was a project regarding dropping telephone pole sized pieces of metal from space as an offensive weapon - put something like that on the space battleship and... That is simply "Assured Destruction" with absolutely no mutual drawbacks or lingering consequences li…

You've described a space station, which three countries have already done independently (Mir, SkyLab, Tiangong). But dropping rods from an orbiting platform makes no sense. There's a reason that "Rods from God" didn't pan out, and it has to do with orbital dynamics. Neither Bezos nor Musk can do it, because it actually doesn't work.

> There's a reason that "Rods from God" didn't pan out, and it has to do with orbital dynamics. Neither Bezos nor Musk can do it, because it actually doesn't work.

Can you say more on this? Thanks!

Re: NASA's DART spacecraft changed an asteroid's orbit around the sun

#62

Post by wongarsu »

Ajakks wrote: post #46
redman25 wrote: post #31

Earlier quoted context omitted.

First things first, we have to colonize the rest of the solar system before we can terrorize Earth.

Why exactly? I think the US ought to spend a few trillion on an actual space battleship - one that never comes down to the surface, just sits in orbit. There was a project regarding dropping telephone pole sized pieces of metal from space as an offensive weapon - put something like that on the space battleship and... That is simply "Assured Destruction" with absolutely no mutual drawbacks or lingering consequences li…

> That is simply "Assured Destruction" with absolutely no mutual drawbacks

Nuclear countries would simply declare that they will launch nukes if any rod comes down on their territory. Even if you had thousands of projectiles in orbit (at considerable cost per projectile) this would not be significantly different from 60s-style MAD: put nukes in bunkers, in the air and in the sea to ensure they can't all be taken out. We might see the return of strategic bombers that stays in the air for weeks at a time.

Alternatively they can just shoot down your battleship with anti-satellite weapons. The risk of retaliation might be worth preventing the disadvantaged position in the long term

Re: NASA's DART spacecraft changed an asteroid's orbit around the sun

#63

Post by Daneel_ »

Rexxar wrote: post #44
Daneel_ wrote: post #23

Earlier quoted context omitted.

Exactly! The only logical way out of the flammable/inflammable mess is to use 'flammable' and 'non-inflammable', which makes me so mad.

It's just a parsing error. "in-" is also a prefix to create verbs from a name or another verb like inhume, inflame, induce, incite, inject, infiltrate. Inflammable is (inflame)-able and not in-(flammable)

I agree, but it’s ambiguous, hence the problem.

There are many counter-examples to your examples, such as “direct” and “indirect”, “humane” and “inhumane”.

The words used should be clear in their meaning. “Inflammable” is ambiguous, and it makes a great deal of difference which meaning is intended.

Flammable is unambiguous, as is non-inflammable. I’m forced to use these. Personally, I’m more in favour of flammable (able to catch fire) and inflammable (not able to catch fire).

Re: NASA's DART spacecraft changed an asteroid's orbit around the sun

#64

Post by jjk166 »

mikeyouse wrote: post #41
infinitewars wrote: post #39

> slowed the orbit of a pair of asteroids around the sun by more than 10 micrometers per second Or in other words, 1 meter per day Why not say that?

Because the SI unit is meters per second, so maintaining the “second” gives people with that understanding a basis in which to compare the delta-V.

Okay but they didn't give it in meters per second, they gave it in micrometers per second. Converting to micrometers per second is exactly as much arithmetic as converting to meters per day.

Re: NASA's DART spacecraft changed an asteroid's orbit around the sun

#65

Post by m4rtink »

Ajakks wrote: post #46
redman25 wrote: post #31

Earlier quoted context omitted.

First things first, we have to colonize the rest of the solar system before we can terrorize Earth.

Why exactly? I think the US ought to spend a few trillion on an actual space battleship - one that never comes down to the surface, just sits in orbit. There was a project regarding dropping telephone pole sized pieces of metal from space as an offensive weapon - put something like that on the space battleship and... That is simply "Assured Destruction" with absolutely no mutual drawbacks or lingering consequences li…

The story of Footfall is basically about that - and alien space invasion force with torch drive powered space battleship in orbit.

There are ways to battle that - balistic missile submarines for one and then "Project Michael" which would be a massive spoiler to elaborate on. ;-)

Re: NASA's DART spacecraft changed an asteroid's orbit around the sun

#66

Post by m4rtink »

Ajakks wrote: post #55
bdamm wrote: post #51

Earlier quoted context omitted.

You've described a space station, which three countries have already done independently (Mir, SkyLab, Tiangong). But dropping rods from an orbiting platform makes no sense. There's a reason that "Rods from God" didn't pan out, and it has to do with orbital dynamics. Neither Bezos nor Musk can do it, because it actually doesn't work.

I doubt it was seriously considered at the time it was discussed. Space Stations are in orbit - the space battleship doesn't have to be, that is very significant. Earth is spinning in a giant circle around the sun. Thats facts. "aiming an asteroid" is less of making a rock a missile - and a lot more of tug-boating it into the exact right spot, in the way of earth, so that earth hits the asteroid - not anything compli…

Any realistic space warship design will need propellant - sure you can avoid ground based interceptors and kill sats but it will eat into your propellant reserves over time.

You will need to replenish from somewhere & that somewhere might as well get nuked instead of the ship, rendering it useless.

Re: NASA's DART spacecraft changed an asteroid's orbit around the sun

#67

Post by Tuna-Fish »

jjk166 wrote: post #64
mikeyouse wrote: post #41

Earlier quoted context omitted.

Because the SI unit is meters per second, so maintaining the “second” gives people with that understanding a basis in which to compare the delta-V.

Okay but they didn't give it in meters per second, they gave it in micrometers per second. Converting to micrometers per second is exactly as much arithmetic as converting to meters per day.

No, it is not. It is in fact no arithmetic at all, if you understand how SI works.

Re: NASA's DART spacecraft changed an asteroid's orbit around the sun

#68

Post by m4rtink »

wongarsu wrote: post #28
jl6 wrote: post #24

Earlier quoted context omitted.

Or offense.

You know what they say: the best planetary offense is a good asteroid redirect program It's also the best planetary terrorism, going by the plot of The Expanse

It only worked in the Expanse because they expertly choose a special trajectory that made the rocks hard to detect and some questionable (but plot necessary) "stealth coating".

By this point UN and MCR have been in cold war for 100+ years staring each other down with region killer nuke arsenals and an absurd amount of interceptors always ready. See than one time Mars actually fired a barrage - only like two warheads got through, only due to shitload of decoys and overall numbers.

A dumb rock would totally get vaporized without the plot armor in a safe distance.

Re: NASA's DART spacecraft changed an asteroid's orbit around the sun

#69

Post by fc417fc802 »

Daneel_ wrote: post #63
Rexxar wrote: post #44

Earlier quoted context omitted.

It's just a parsing error. "in-" is also a prefix to create verbs from a name or another verb like inhume, inflame, induce, incite, inject, infiltrate. Inflammable is (inflame)-able and not in-(flammable)

I agree, but it’s ambiguous, hence the problem. There are many counter-examples to your examples, such as “direct” and “indirect”, “humane” and “inhumane”. The words used should be clear in their meaning. “Inflammable” is ambiguous, and it makes a great deal of difference which meaning is intended. Flammable is unambiguous, as is non-inflammable. I’m forced to use these. Personally, I’m more in favour of flammable (a…

There's an inconsistency but no ambiguity, only ignorance. Inflammable only ever means one thing regardless of how ridiculous english might be.

The historically correct term would be non-inflammable. The modern variant is non-flammable.

Similarly, inflammable is the historic term and flammable is the modern variant.

The confusion arises when people are exposed to the word flammable and then attempt to apply the usual rules to construct a word they've never actually used before.

This isn't the usual sort of inconsistency introduced by our fusing multiple incompatible languages. It's from the original Latin and I'm unclear what led to it. For example consider inflammable versus inhumane. It seems Latin itself used the prefix to mean different things - here on(fire) versus not(human). But confusingly it's ex to indicate location, despite ex also being the antonym of in. So ex equo means you are on horseback, not off it as I would have guessed.

Re: NASA's DART spacecraft changed an asteroid's orbit around the sun

#70

Post by adriand »

gatreddi wrote: post #16

Wild that we went from "can we even deflect an asteroid" to measurably changing a solar orbit. 150 milliseconds sounds tiny until you realize compounding over decades makes that a meaningful trajectory shift. The engineering confidence this gives for actual planetary defense is massive.

> The engineering confidence this gives for actual planetary defense is massive.

Is it? Isn’t it the case that we can’t even detect the vast majority of objects on a potentially problematic intersection path with earth? I feel like the most likely scenario is that by the time we realize we’re about to get slammed by an asteroid, it’s way too late.

Post reply on HN