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Artemis II Launch Day Updates

nasa.gov

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Re: Artemis II Launch Day Updates

#781

Post by brabel »

marcus_holmes wrote: post #721
p1mrx wrote: post #715

Earlier quoted context omitted.

According to general relativity, you (and the ground) are accelerating at 1g, and feel weight because your inertia resists that acceleration. If you jump off a cliff, you'll stop accelerating for a bit, until the ground hits you. Edit to reply: > I am standing on the ground. I feel 1G acceleration. My speed is not changing. How much am I accelerating? You are accelerating at 1g through curved spacetime. Newtonian "sp…

I am standing on the ground. I feel 1G acceleration. My speed is not changing. How much am I accelerating?

You say later that you think gravity and acceleration look the same but cannot be the same , which is funny since that’s exactly what relativity says: if two things are indistinguishable from each other even in principle, then they must be the same. Which is what led Einstein to realize that gravity really is just a curvature in space time. Hard to wrap your head around that! But if you study relativity, you eventually understand what being relative actually means.

Re: Artemis II Launch Day Updates

#782

Post by JumpCrisscross »

palata wrote: post #774
hn_acc1 wrote: post #241

Earlier quoted context omitted.

The space program has created some great technology we use every day now.

That we probably could have developed without the space program for a fraction of the cost, if we're being honest.

> That we probably could have developed without the space program for a fraction of the cost, if we're being honest

I don't think so. Some people are good at small tasks and stewardship. Some people want to ambitiouslyl build. If there isn't a space program, the engineers who were inspired to join NASA cannot be assumed to have gone into semiconductors or material science. They probably wound up, in the alternate timeline, bureaucrats or financiers.

Re: Artemis II Launch Day Updates

#783

Post by JumpCrisscross »

palata wrote: post #775
discardable_dan wrote: post #257

Earlier quoted context omitted.

Bro, of all the stupid shit we spend taxes on ($50 billion on corn subsidies), you're mad about space exploration?

I will guess that farm subsidies go to... well, farming. Doesn't sound completely ridiculous at first sight. > you're mad about space exploration? Exploration? It's not exploration at all: it's sending 4 humans for a 10 days trip around the Moon. I wish they used the money for actual space exploration, though.

> will guess that farm subsidies go to... well, farming

Or not farming. Lots of CRE. Also constant bail-outs because e.g. the soybean farmers got tariffed. Also ethanol.

Re: Artemis II Launch Day Updates

#784

Post by JumpCrisscross »

ActorNightly wrote: post #767
glenstein wrote: post #678

Earlier quoted context omitted.

That's not even remotely true. They talked in great detail about heat shield fragmentation Artemis I, it's failure modes, the prospect of it getting worse with new designs and a number of other things at much greater detail than you are. Your comments show a fraction of the effort and detail of the thing you're criticizing and you could have made your best argument five comments ago if you were ever actually going to…

You are obviously very invested in the fact that someone who is going against the grain of the obviously bad, overly buerocratic government agency MUST be correct (otherwise, in the case you actually gave a fuck about the truth, you would be researching statements from NASA and comparing the reports) If that is so, put your money where you mouth is and place a bet on polymarket. If you are too scared to do so, then a…

> place a bet on polymarket

Aww, it would make me sad if people were betting on astronauts dying.

Re: Artemis II Launch Day Updates

#785

Post by palata »

ActorNightly wrote: post #767
glenstein wrote: post #678

Earlier quoted context omitted.

That's not even remotely true. They talked in great detail about heat shield fragmentation Artemis I, it's failure modes, the prospect of it getting worse with new designs and a number of other things at much greater detail than you are. Your comments show a fraction of the effort and detail of the thing you're criticizing and you could have made your best argument five comments ago if you were ever actually going to…

You are obviously very invested in the fact that someone who is going against the grain of the obviously bad, overly buerocratic government agency MUST be correct (otherwise, in the case you actually gave a fuck about the truth, you would be researching statements from NASA and comparing the reports) If that is so, put your money where you mouth is and place a bet on polymarket. If you are too scared to do so, then a…

> place a bet on polymarket

Isn't that a platform for insider trading? Not sure it qualifies here.

Re: Artemis II Launch Day Updates

#786

Post by magicalhippo »

marcus_holmes wrote: post #761
BDPW wrote: post #748

Earlier quoted context omitted.

You're conflating coordinate and proper acceleration.

I don't think I understand the difference. I have always been told that acceleration is change in velocity over time. Is that wrong? Are there other types of acceleration?

> I have always been told that acceleration is change in velocity over time. Is that wrong?

Not per se, but it's more complicated when relativity gets involved.

Wikipedia has some decent starting points:

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

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

https://en.wikipedia.org/wiki/Four-acceleration

Re: Artemis II Launch Day Updates

#787

Post by tsimionescu »

JumpCrisscross wrote: post #741
p1mrx wrote: post #715

Earlier quoted context omitted.

According to general relativity, you (and the ground) are accelerating at 1g, and feel weight because your inertia resists that acceleration. If you jump off a cliff, you'll stop accelerating for a bit, until the ground hits you. Edit to reply: > I am standing on the ground. I feel 1G acceleration. My speed is not changing. How much am I accelerating? You are accelerating at 1g through curved spacetime. Newtonian "sp…

> According to general relativity, you (and the ground) are accelerating at 1g I don't believe this is correct. If I lock two rockets in opposition to each other, they aren't accelerating. They're pushing at each other. And their propellant is accelarating away. But their displacement and orientation are unchanging, which means their velocity is zero which means acceleration isn't happening. Similarly, the normal for…

It is correct, and you're also right that two rockets tethered to each other would not feel acceleration. The acceleration we feel in Earth's gravitational field is affecting our speed, though - it's slowing down the speed at which we move towards the future.

Re: Artemis II Launch Day Updates

#788

Post by tsimionescu »

marcus_holmes wrote: post #721
p1mrx wrote: post #715

Earlier quoted context omitted.

According to general relativity, you (and the ground) are accelerating at 1g, and feel weight because your inertia resists that acceleration. If you jump off a cliff, you'll stop accelerating for a bit, until the ground hits you. Edit to reply: > I am standing on the ground. I feel 1G acceleration. My speed is not changing. How much am I accelerating? You are accelerating at 1g through curved spacetime. Newtonian "sp…

I am standing on the ground. I feel 1G acceleration. My speed is not changing. How much am I accelerating?

You need to take into account your entire 4-vector for speed. You don't just have a speed in the 3 spatial coordinates, you're also moving thorough the "time" coordinate, and that is happening at a slower pace near a large mass like the Earth than it would of you were far away from here.

Re: Artemis II Launch Day Updates

#789

Post by Animats »

InexSquirrel wrote: post #303
xnx wrote: post #83

Earlier quoted context omitted.

Truly. I'm not sure why anyone needs to be on the rocket at all, let alone our best and brightest.

I suspect it's the optics of it. If you can fly people around the moon, then landing people on the moon is a more reasonable next step. I agree that it may not be entirely logical, but keeping public and funding opinion positive & invested _is_ important. edit: I thought RocketLab flew their elecron rocket around the moon a few years ago? So it's definitely doable... so again I think it's about the optics.

> I suspect it's the optics of it.

That's probably the justification for sending four people. First test flight probably could have been done with one or two pilots.

Re: Artemis II Launch Day Updates

#790

Post by jve »

FabHK wrote: post #725
casefields wrote: post #719

Earlier quoted context omitted.

A Dodge Challenger SRT Demon can also reach 10,000mph in 4 minutes if it held its 0-60 acceleration over the whole span. So yes, you can buy a car today that'll let you feel the G's like you're a space pilot.

One fact that I found unintuitive (while we're at cars doing things they can't): If you could drive your car straight up vertically, you'd have to cruise just for an hour or so at 100 km/h (<65 mph) until you reached space. It's not that far.

However space is not orbit. Space is easy, orbit is hard. https://what-if.xkcd.com/58/
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