Recent comments in /f/space

NomDePlume007 t1_j9n3d8i wrote

Reply to Honest question, what if we accepted the assumption that God created the universe 6,000 years ago, could this explain away dark matter and galaxy rotation? by DrMilzie

You're comparing magic (belief) and science (fact). If you believe in magic, you can make up anything you like, whether or not it's even internally consistent.

I think many scientists are also religious. But they know the difference between reality and a belief system.

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Draemeth t1_j9mz6rt wrote

Reply to comment by dirtydrew26 in Starship greenlit for launch after static fire test by DevilsRefugee

It’s easier to consistently hit satellites than people, actually. Satellites have a fixed trajectory, a public location and can’t exactly hide. People are small, annoying, constantly moving, intelligent, underground, hidden, etc. I’d bet Russia could easily take out satellites, but so could a lot of countries

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rocketsocks t1_j9mrfhg wrote

Reply to comment by nic_haflinger in DARPA is Reigniting the Nuclear Engine by Afrin_Drip

The primary advantage of early-generation NTRs is that they can operate with pure hydrogen, that's it. Doing that allows them to have an exhaust velocity of around 9 km/s. And because the rocket equation is exponential with respect to the ratio of delta-V and exhaust velocity NTRs start to look really good for single digit or low double digit delta-V. With a stage mass ratio of 5:1 you can achieve a delta-V of 14.5 km/s, which is a lot to work with. In contrast, with the same stage mass ratio you'd achieve maybe 40% of that delta-V with a LOX/methane stage.

However, things stop looking so rosy very rapidly. Because NTRs use a heavy reactor and rely on low-density hydrogen it is very challenging to achieve high stage mass ratios, which limits performance. Also, because liquid hydrogen is super cryogenic and has a high boil-off rate it is very challenging to build a high efficiency NTR which has significant longevity for deep space propulsion. Even if you can bring boiloff rates under control with thermal control systems and active cooling all of that stuff adds mass which again cuts into the stage mass ratio.

All of which conspires to make the most compelling use of a first generation NTR something like a trans-lunar (or interplanetary) kick stage for crewed missions. Which might be fine, but is still pretty limiting, and likely results in only a small number of NTRs ever being built.

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Makhnos_Tachanka t1_j9moxog wrote

Reply to comment by Bewaretheicespiders in Relativity Space on Twitter: You’ve asked, “Wen Launch?” and to that, we say...👇 Catch us live at Launch Complex 16 in Cape Canaveral, FL on March 8, 2023 to watch the world’s first 3D printed rocket fly. 🚀 #GLHF by allforspace

I'm sure it'll have plenty of impact, just as falcon 1 did, as a technology demonstrator. Really, terran 1 is a demonstration of their ability to print the rocket, stick all the avionics together with their engines, and get to orbit. For them to have any chance of securing the funding for terran r, which actually does take advantage of the 3d printing process, they kinda have to start small. And ultimately, what they're really building here is the ability to build rockets on the moon and mars, which is a big deal in and of itself. Same goes for spinlaunch, for that matter. They're both building launch vehicles with technologies that don't make that much sense on earth, but do make a ton of sense once you get off it.

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