Artemis II Launch Day Updates • Hacker News Board

Re: Artemis II Launch Day Updates

#741

Post by JumpCrisscross » Thu, Apr 02, 2026, 4:42 AM UTC

p1mrx wrote: post #715

marcus_holmes wrote: post #708

Earlier quoted context omitted.

I am in a gravitational field. I have no idea what my acceleration is, I just know that I feel 1G (I could be falling in a stronger gravity and only feel 1G, or I could be climbing in a weaker gravity and feel 1G). The only way of determining it is to see if I'm moving relative to the stuff around me. Even then, that's not definite - I could be in an elevator and everything around me is also accelerating. I'm not dis…

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 force resists your gravitational force to produce zero net acceleration. (An object at rest in a gravity well is its own local frame.)

> If you jump off a cliff, you'll stop accelerating for a bit, until the ground hits you

I don't believe this is correct. In GR, free fall is still inertial motion. You're just free of fictitious forces and thus following the curvature of spacetime.

Re: Artemis II Launch Day Updates

#742

Post by mullingitover » Thu, Apr 02, 2026, 4:42 AM UTC

bdangubic wrote: post #617

mullingitover wrote: post #574

Earlier quoted context omitted.

> That's per 100k No, it's a plain headcount. Your first link is a chart of non-inflation adjusted spending. Your second link is all government, not just federal employees so it's not really germane to the discussion, and your third link includes things like Social Security, and frankly... good . Without the government stabilizing spending the economy would be even more of a dumpster fire of random investor panics. I…

> No, it's a plain headcount > They're brilliant, they do great work and they aren't paid what they're worth The headcount of such wonderful people you are describing has been reduced but then replaced by 3x+ times the rates Gov is paying for the contractors that were hired (I am one of them). so this headcount being low is a nothing more than political smokescreen that will probably be used in campaigns leading up t…

I am willing to concede that it would be more financially responsible for the United States to greatly increase the size of the permanent federal workforce, and to stop making its size a political football.

Re: Artemis II Launch Day Updates

#743

Post by DubOfWeek » Thu, Apr 02, 2026, 4:53 AM UTC

That was awesome!

it's better to invest in human progress than in war

Re: Artemis II Launch Day Updates

#744

Post by bryanlarsen » Thu, Apr 02, 2026, 4:57 AM UTC

casefields wrote: post #719

sd9 wrote: post #320

Minutes after launch they reached "ten thousand miles per hour". That's 2.78 miles per second. Nuts. No doubt the speeds go even higher later too. I'm sure people here are already familiar with the speeds these things go, but that's the first time I've confronted a fact like that and it blew me away.

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.

The acceleration of a rocket is slower than a normal car at lift off. It's pulling about 1.2G, but 1G of that is fighting gravity, so effective acceleration is only 0.2G. Almost any car can do that at low speeds.

But a car's acceleration slows almost instantly. The rocket just keeps accelerating faster as the tank empties and it gets lighter. By main engine cut off it might be pulling 5G.

Re: Artemis II Launch Day Updates

#745

Post by WalterBright » Thu, Apr 02, 2026, 4:59 AM UTC

tombert wrote: post #679

WalterBright wrote: post #377

Earlier quoted context omitted.

It's still a non-profit.

That's debatable. Musk bought his way into politics and shut down USAID very specifically because USAID was investigating him [1]. Oh, and he used his position in DOGE to assist in making sure that government contracts went to his companies, or licensing out his SpaceX workers when his idiocy led to a shortage of air traffic controllers [2], which was very obviously a publicity stunt if nothing else. So it's a produc…

Still non-profit

Re: Artemis II Launch Day Updates

#746

Post by kinematikk » Thu, Apr 02, 2026, 5:01 AM UTC

SyzygyRhythm wrote: post #681

JumpCrisscross wrote: post #300

April 6: flyby April 10: splashdown After that, the exciting work will be in Starship making LEO and testing propellant transfer (a humanity first) [1] and Blue Origin testing its rocket and lunar lander [2], both scheduled for 2026, to enable Artemis II (EDIT: III), currently scheduled—optimistically, in my opinion—for next year. [1] https://en.wikipedia.org/wiki/List_of_Starship_launches#Futu... [2] https://en.wiki…

Starship "making LEO" is not a significant challenge--the existing flights have explicitly targeted a (very slightly) suborbital trajectory. They could have done otherwise at any point, but for now it's more important to guarantee that the stage comes down immediately. None of their current objectives require more than ~1/2 of an orbit. Starship v3 flying will be a significant leap, though. It's the first with the Ra…

I was asking this myself just an hour ago, thank you

Re: Artemis II Launch Day Updates

#747

Post by 3RTB297 » Thu, Apr 02, 2026, 5:02 AM UTC

vjvjvjvjghv wrote: post #547

The camera work was just terrible. They really need to learn from SpaceX how to do this right. Minus the obnoxious cheering. SpaceX does these beautiful drone shots and live telemetry so well. Considering that each SLS launch costs in the billions it would be nice to do a little better on production I felt the commentary during the launch also wasn't good. And I am not too interested in hearing from some Hollywood pe…

I thought the same thing - hopefully by the time Artemis III launches they'll remember the gaps and blank screens from this launch. Even the live telemetry model at the core stage separation seemed to not match what the on-board cameras showed. Artemis I's camera work was better. Why???

Re: Artemis II Launch Day Updates

#748

Post by BDPW » Thu, Apr 02, 2026, 5:04 AM UTC

marcus_holmes wrote: post #708

layer8 wrote: post #538

Earlier quoted context omitted.

It’s absolute in the sense that you can determine your acceleration without any external reference. You feel a certain force (like what you feel in an elevator). That’s your acceleration. You don’t accelerate relative to Earth, or relative to anything else. You accelerate relative to when you wouldn’t be accelerating (your inertial rest frame, a state of free fall). If you are in space accelerating and the Earth woul…

I am in a gravitational field. I have no idea what my acceleration is, I just know that I feel 1G (I could be falling in a stronger gravity and only feel 1G, or I could be climbing in a weaker gravity and feel 1G). The only way of determining it is to see if I'm moving relative to the stuff around me. Even then, that's not definite - I could be in an elevator and everything around me is also accelerating. I'm not dis…

You're conflating coordinate and proper acceleration.

Re: Artemis II Launch Day Updates

#749

Post by ju571nk3n » Thu, Apr 02, 2026, 5:06 AM UTC

[flagged]

Re: Artemis II Launch Day Updates

#750

Post by mrexroad » Thu, Apr 02, 2026, 5:11 AM UTC

0xffff2 wrote: post #654

mrexroad wrote: post #458

Earlier quoted context omitted.

Have you talked to any actual NASA employees (not just contractors) that work in science? For what it’s worth, I watched today’s Artemis II launch with them. While proud of the mission, they’re likely in your “Doomer” category after a year being devastated and demoralized by having their science budgets slashed, grants/projects cancelled, having been forced to fire good contractors of 10+ years and then watching some…

Yep, I work with them every day, since I am myself a NASA contractor. I'm curious what you think the major distinction is between a contractor and a civil servant in the first place. I work directly as part of a division (used to be "on site" before 2020, but now I'm remote so that doesn't quite fit) doing 80% the same job as any of my civil servant colleagues. I really don't think the range of opinions is all that d…

Fair question—I probably overly delineated the two as I currently only know people on the civil servant side at NASA. Decades ago (!) I worked in the DC, hung out some folks, and often the ones who had strong opinions related to policy were the ones at risk of losing/keeping/winning a contract, not the government employees. That was probably in the back of my head when I made the distinction. I don’t really have a strong opinion either way now, but I felt it was only fair to answer you as best I could. Either way, I’ll try to be cognizant of that potential bias in future.

With that said, and while I haven’t had much exposure to what folks on the internet are saying, all I know is I’ve never seen this group of friends this worried or impacted. Most of them are also the type to just keep their heads down, focus on the mission, and wait for the winds shift.