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I hate websites still stuck in late-2000s internet pages with a gajillion ads meant to distract old people

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Sir your moon is upside down

^(/s)

Great shot! Need me a telescope like this. Got a cheap one, had too much zoom to even be usable...

Yes, that part is completely wrong. Nuclear rockets still use propellant. Nuclear thermal rockets use about half as much by mass as the best chemical rockets, but they only get their peak performance with LH2, which takes up about 5 times as much volume for the same amount of mass. A nuclear thermal spacecraft will be a big pile of propellant tanks (likely drop tanks so you don't have to carry empty tank mass around) strapped together with a nuclear rocket engine at the back and a small payload tacked onto the front.

The "45 days" claim appears to be in reference to the "wave rotor" stuff that's been getting massively overhyped. Basically, as described, they propose sticking a widget between the nuclear reactor and the nozzle that somehow doubles the specific impulse while halving the flow rate.

This means doubling the power output of the reactor. Since the power output of the reactor is already limited by the need to keep it from melting, and the reactor is cooled by the propellant flow which you've just cut in half, it's not clear how this doesn't result in the reactor, well, melting. Also, even if it worked, doubling the specific impulse isn't nearly enough of a gain to allow a 45 day trip to Mars.

They then throw in nuclear-electric propulsion, which requires heat exchange loops, many megawatts of electrical generation capacity, giant radiator arrays, and arrays of ion thrusters. They assume all this can be done "with minimal addition of dry mass", and this is how they double the performance again to get their 4000 s number. However, it doesn't actually appear to have anything to do with the wave rotor.

NASA's giving one guy $12500 to look at it. It's not taking anyone to Mars any time soon.

Does this mean the scify art where spaceships emit little rings from their exhaust isn't that far off?

On smartphones that's not so straightforward

Don't ever be ashamed of watching a show you like, and don't shame others for watching a show they liked. Big Bang Theory was incredibly popular. I really hate the show myself but I can see the appeal.

Astronomy is just a game of “spot the difference” on extreme difficulty

I enjoy this with you are sharing and it’s high quality! Minor man made rule hurdles are just an inconvenience. Thanks

Is that another one of Jupiters moons faintly visible to the far left?

The best part about this discovery?

They used existing tech that had been assumed not to work... & made it work better than anyone had ever thought.

Discovery oft comes in simply finding the assumptions others missed.

>blows my mind we can calculate the trajectory of a “random” ass asteroid

It is High School physics. Stay in school kids, pay attention, and you mind will be able to handle basic, explainable things unlike most Americans.

Shame anything earth-like is hundreds of lightyears away :/

Early calculations for solid core engines could be as high as 800-1000 seconds using hydrogen as the propellant.

Edit: nevermind, I didn't realize this article was about rotating detonation engines, I thought it was about nuclear-thermal engines

Again, the juice is simply not worth the squeeze. You're adding nuclear complexity to every launch (nobody wants a dirty bomb going off in the sky) and you're just not getting significant benefits. You're still going to run out of propellant after an X minute burn. And now you're stuck with a super complex, hazardous, expensive boat anchor on your space craft that's VERY hard to cool because you only have radiation as conduction and convection don't exist in space.

Also

>Lighter molecules go faster at a given temperature, and H2 is much lighter than H2O. So you get roughly twice the exhaust velocity/specific impulse.

Oh, twice huh. H2 weighs 2 grams per mole, it will need to be ejected at nine times the velocity of a water molecule at 18 g/mol to have equal the force.

You know when I was editing and creating it. I didn't really think about it like that. But your right, and I think that's why I like it so much. It does have a nostalgic feel to it. Glad you enjoyed it as well.

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Oh, alright, thanks for the info ! Still pretty cool .

This is the real danger to our civilization. We should be funneling money into observing NEO rocks. Last I heard, the program was canceled or defunded.

SMH 🤦‍♀️

> Bakugo's Howitzer Impact

Not familiar enough with manga physics to answer your question. I only do physics for this world :-).

8 meter diameter. No mention of speed, but zero consequences if it hit.

> What is the point of adding the danger of a nuclear energy source

Because a nuclear-thermal engine can use pure hydrogen rather than a hydrogen-oxygen mix. Lighter molecules go faster at a given temperature, and H2 is much lighter than H2O. So you get roughly twice the exhaust velocity/specific impulse.

(This one was too small to warrant trajectory calculation, since it would be harmless if it hit, but...)

Isn't it still the case that, if there is a potentially disastrous impact detected, knowing doesn't do much good? Its not like you can evacuate a city within a short time frame.

I guess what I mean to ask is - how does knowing about an impact help save us when we can't stop them?

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