valuearb

72 ms·

781.
by valuearb 6y ago
Messinian Salinity Crisis.
782.
by valuearb 6y ago
Doggerland.
783.
by valuearb 6y ago
I’m fine with adding more originalists to the Supreme Court. We have democratic mechanisms to modify the constitution.
784.
by valuearb 6y ago
Didn’t I cover both groups?
785.
by valuearb 6y ago
I’m not saying you shouldn’t lock down these amazing rates for the long run. I’m saying that when mortgage rates double, the cost of buying homes will effectively double. Buyers simply won’t be able to afford to pay as much and prices will
786.
by valuearb 6y ago
Ever heard of inflation? How can mortgage rates stay below inflation rates after massive money supply increases?
787.
by valuearb 6y ago
Pure ice would require a 2,500 times increase in water proportions. That’s a big increase. It does seem reasonable that sub soil not heated to 260 degrees every two weeks for two weeks at a time would contain a lot more water. But when Luna
788.
by valuearb 6y ago
I’m thinking the author knows just a bit more about it than you.
789.
by valuearb 6y ago
Eventually those mortgage rates will go back above 4%, and what happens to housing prices when they do ?
790.
by valuearb 6y ago
You can’t replace Raptors with NTRs because of size/thrust mismatch. A NTR with the same vacuum thrust as a Raptor would weigh at least 80 times more, and likely be far larger. Then you have shielding and radiators, it’s never gonna be
791.
by valuearb 6y ago
You need heavy radiators or your entire ship quickly becomes uninhabitable when the engine is running. We’ve never built a NTR capable of shedding all its heat through its propellant. In fact, we’ve never operated one in space, only on Ear
792.
by valuearb 6y ago
Those already take the slow boat Hohmann transfer orbit to maximize payload capacity. Starship might be able to send 150 tons that way to the surface itself. And building bigger starships is easier than building NTRs.
793.
by valuearb 6y ago
Scaling up low thrust to weight engines with large cooling and shielding requirements doesn’t create many mass efficiencies. Maybe in the shielding, but that’s the least of your concerns. The other problem is that low thrust to weight means
794.
by valuearb 6y ago
Who is we?
795.
by valuearb 6y ago
Did we really need to go to the Americas? When first discovered by Europeans North America was nearly uninhabitable. Did we ever need to criss the Bering land bridge? Or leave Africa?
796.
by valuearb 6y ago
The increase in cancer rate for a two year trip to Mars and back is about 4% over your lifetime. The only actual radiation risk is from solar storms, which can be ridden out in storm shelters aboard ship and in Mars habitats.
797.
by valuearb 6y ago
You want to be careful to avoid heating your hydrogen fuel, it’s slowly evaporating through the tank even when near absolute zero, any significantly higher temperature is going to increase that rate.
798.
by valuearb 6y ago
Heavy radiators are definitely needed if you don’t want your space ship becoming uninhabitable. And running extra propellant through the engine to cool will further reduce usable ISP.
799.
by valuearb 6y ago
Not really. An 85 ton Starship fueled in LEO can use Oberth effect, get to Mars just as fast, and land directly on Mars. Your deep space NTR has engines that weigh way at least ten times more, while providing only a fraction of the thrust,
800.
by valuearb 6y ago
NTR is not competitive with chemical rockets in any actual application. Dry mass has to triple at a minimum, your propellant evaporates over long trips, and NTR engines don’t have enough thrust to land on Mars or even the moon, requiring th
801.
by valuearb 6y ago
I’m still skeptical. Nuclear just has too many characteristics that limit its ability to make use of that ISP. Starship will have a dry mass around 85 tons including about 9 tons of engines, payload of 100 tons, and 1,200 tons of methane&#x
802.
by valuearb 6y ago
Yea but NTR’s gains in ISP is mostly wasted by all its large dead mass requirements and its requirement to use hydrogen as a fuel.
803.
by valuearb 6y ago
Thrust to weight still will matter. NTR and NERs still have to drag all that dead mass of engine, radiators and shielding wherever they go.
804.
by valuearb 6y ago
I think STR is the best possible competitor to chemical rockets for trips inside Jupiter’s orbit. NTR is what we will need out past Jupiter unless a few brave souls use chemical rockets for the fame of being first to make those extremely l
805.
by valuearb 6y ago
Don’t be silly. Nuclear pulse rocketry is very well understood from an engineering perspective, the forces it generates are easily managed, and the radiation it produces easily shielded for. Without a doubt it’s by far the most practical ca
806.
by valuearb 6y ago
Starship can get to Mars in 3-4 months. It depends mainly upon how much payload you carry. Elon has discussed crewed Starships making the trip in 3-4 months to minimize radiation exposure, and cargo Starships maximizing payload mass and tak
807.
by valuearb 6y ago
Cooling is the Achilles heel of NTR, requiring massive radiators to remain functional over a long burn.
808.
by valuearb 6y ago
This is another shortcoming of NTRs, as Hydrogen is tiny and slippery, leading to significant amounts of leakage over long trips.
809.
by valuearb 6y ago
NTR is not anywhere near 2x chemical because of parasitic losses, in fact it may only barely offer higher net DeltaV. NTR requires heavy engines, heavy shielding and heavy radiators to keep cool. The final NERVA prototype was as close to a
810.
by valuearb 6y ago
Those options are already opening up without Nuclear Thermal. The problem with NTR is the engines are heavy, and the necessary shielding and heat radiators are very heavy. So the high ISP is mostly lost to higher dead mass requirements. If

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