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Forums - General Discussion - First mission to bring back samples from the moon since 1976 started successfully

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Nighthawk117 said:
SvennoJ said:

True, submarines have been nuclear powered since 1955. There must be a reason NASA hasn't jumped on that ship yet. Maybe it's all a PR problem or all the shaking during launch isn't very good for nuclear engines.

Ah I see they just got back on track. Scrapped in 1970, $125 million granted in 2019 to continue with the nuclear rocket program. Nice.

Yes, the NERVA program ended around 1970.  They had the Prometheus program in the 80s or 90s.  Not sure what the new name is now.

You don't want a nuclear powered rocket to get you off the Earth - hell people are scared enough of RTGs.  You want chemical rocket engines to get you off the Earth, but to go from Earth orbit to deep space, a nuclear powered engine is far away, the most efficient way to travel.

Are you sure? The main reason it takes so long to get to Mars is, that the probes aren't under full thrust the whole time. Because fuel would be needed, which in turn would need to be accelerated at first which needs more fuel to accelerate all the fuel. I don't see how nuclear propellants solve that problem.

If I look here, I see the proposed nuclear rocket engines, they are hypothetical: https://en.wikipedia.org/wiki/Rocket_engine#Nuclear



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Mnementh said:
Nighthawk117 said:

Yes, the NERVA program ended around 1970.  They had the Prometheus program in the 80s or 90s.  Not sure what the new name is now.

You don't want a nuclear powered rocket to get you off the Earth - hell people are scared enough of RTGs.  You want chemical rocket engines to get you off the Earth, but to go from Earth orbit to deep space, a nuclear powered engine is far away, the most efficient way to travel.

Are you sure? The main reason it takes so long to get to Mars is, that the probes aren't under full thrust the whole time. Because fuel would be needed, which in turn would need to be accelerated at first which needs more fuel to accelerate all the fuel. I don't see how nuclear propellants solve that problem.

If I look here, I see the proposed nuclear rocket engines, they are hypothetical: https://en.wikipedia.org/wiki/Rocket_engine#Nuclear

Go to Wikipedia and look at a Gas Core Nuclear Rocket (GCNR)

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

Last edited by Nighthawk117 - on 25 November 2020

Mnementh said:
Nighthawk117 said:

Yes, the NERVA program ended around 1970.  They had the Prometheus program in the 80s or 90s.  Not sure what the new name is now.

You don't want a nuclear powered rocket to get you off the Earth - hell people are scared enough of RTGs.  You want chemical rocket engines to get you off the Earth, but to go from Earth orbit to deep space, a nuclear powered engine is far away, the most efficient way to travel.

Are you sure? The main reason it takes so long to get to Mars is, that the probes aren't under full thrust the whole time. Because fuel would be needed, which in turn would need to be accelerated at first which needs more fuel to accelerate all the fuel. I don't see how nuclear propellants solve that problem.

If I look here, I see the proposed nuclear rocket engines, they are hypothetical: https://en.wikipedia.org/wiki/Rocket_engine#Nuclear

You need a lot less nuclear fuel to go the distance, thus you take a lot less weight.

From google:
One uranium fuel pellet (about 10 grams) creates as much energy as one ton of coal, 149 gallons of oil or 17,000 cubic feet of natural gas.

You can be under full thrust until the halfway point and reverse



SvennoJ said:
Mnementh said:

Are you sure? The main reason it takes so long to get to Mars is, that the probes aren't under full thrust the whole time. Because fuel would be needed, which in turn would need to be accelerated at first which needs more fuel to accelerate all the fuel. I don't see how nuclear propellants solve that problem.

If I look here, I see the proposed nuclear rocket engines, they are hypothetical: https://en.wikipedia.org/wiki/Rocket_engine#Nuclear

You need a lot less nuclear fuel to go the distance, thus you take a lot less weight.

From google:
One uranium fuel pellet (about 10 grams) creates as much energy as one ton of coal, 149 gallons of oil or 17,000 cubic feet of natural gas.

You can be under full thrust until the halfway point and reverse

You need some propellant. That you will lose in the effect. That is some advantage of chemical fuels: the exhaust gases are used as propellant. For nuclear rockets you need to take some gas with you, which will be heated to expand and propel the rocket.



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Mnementh said:
SvennoJ said:

You need a lot less nuclear fuel to go the distance, thus you take a lot less weight.

From google:
One uranium fuel pellet (about 10 grams) creates as much energy as one ton of coal, 149 gallons of oil or 17,000 cubic feet of natural gas.

You can be under full thrust until the halfway point and reverse

You need some propellant. That you will lose in the effect. That is some advantage of chemical fuels: the exhaust gases are used as propellant. For nuclear rockets you need to take some gas with you, which will be heated to expand and propel the rocket.

It all depends on the velocity of the exhaust. Ideally you shoot out particles at near relativistic velocities and collect them on the way (Bussard ramjet)

Nuclear gas rockets are more efficient than liquid hydrogen plus liquid oxygen anyway. I imagine fuel / propellant for the way back will be send ahead to refuel at Mars.



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I really hope we get to Mars and start taking some more series steps forward in terms of space travel in my lifetime.
While some cool stuff has been done in my life like probe missions to Jupiter and Saturn's moons and rovers on Mars, it's going too slowly for my liking.

Last edited by curl-6 - on 26 November 2020

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curl-6 said:

I really hope we get to Mars and start taking some more series steps forward in terms of space travel in my lifetime.
While some cool stuff has been done in my life like probe missions to Jupiter and Saturn's moons and rovers on Mars, it's going too slowly for my liking.

There basically was a 40 year gap in space travel. Just recently things got picked up again. So recently we had: multiple mars rovers, first mission to a comet, first mission to the backside of the moon. Also a lot of stuff that wasn't done since many years got recently on course, like again a bigger spaceship to the ISS, so that it can operate with full manpower again soon and this one to get moon soil samples back. Also we have way more participants in the space right now, not only the US and Russia. So that all looks promising.



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my greatest games: 2017, 2018, 2019, 2020, 2021

10 years greatest game event!

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Ka-pi96 said:

Where's the positive news?

Billions of dollars wasted to get a piece of rock while millions of people around the world live in abject poverty? Even if there were any decent scientific progress made from this I'd have to question whether it was worth it. But I doubt there will be. Going to the moon is just for "bragging rights" and to me spending billions of dollars of tax payer money for "bragging rights" is a reprehensible thing to do.

Compared to some of things governments spend money on, space travel is downright cheap. Even at its peak in the 1960s, NASA represented less than 5% of the U.S. federal budget. The Apollo program cost less over its entire run than some military programs. Today, NASA is less than 1% of the budget. But during the Apollo days, as today, there were people saying that the money spent on space exploration would be better spent fixing problems here on Earth. Well, we cancelled Apollo, cut NASA's budget, and, well, how'd that work out for us? Here were are nearly 50 years later with no material gains to be had from the money we supposedly "saved" by no longer sending people to the moon. Poverty, joblessness, homelessness, and other problems are still with us, this despite NASA still not even having any non-privatized means of its own to get astronauts into orbit nearly a decade after the the final space shuttle flight.

Space exploration, manned or unmanned, does yield actual benefits. Those benefits might not always be immediate, or immediately obvious. Advancing the frontiers of human knowledge is always beneficial. Much of the time, the insight gained can and does help us solve problems here on Earth. Sometimes it results in new inventions. And even when it doesn't yield any material benefits to mankind beyond satisfying our intellectual curiosity, I'd still say bettering our understanding of physical reality is always worth it. If anything, we should be spending more on space exploration. I still wonder where humanity would be at in terms of manned space exploration had we not simply abandoned Apollo and stuck to LEO.

If we were going to cut something in the budget to spend on solving social maladies like poverty, then maybe we ought to focus on that 500-pound gorilla in the room that is the military budget. The U.S. spends more on defense than China, India, Russia, Saudi Arabia, France, Germany, the UK, Japan, South Korea, and Brazil combined. In terms of per capita spending, we are surpassed only by Israel and possibly Saudi Arabia. As a percent of GDP, we spend more than any other advanced nation besides Israel. The F-35 fighter program by itself is estimated to cost over a trillion dollars over the course of its lifespan. The United States government seems to struggle to find money for or justify spending money on social programs that can help lift Americans out of poverty, but it always seems to have plenty of cash lying around to splurge on newer and more efficient ways of killing people and lining the pockets of the corporations that sell them the means to do so and pad their election campaign coffers in the process.



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Mnementh said:
curl-6 said:

I really hope we get to Mars and start taking some more series steps forward in terms of space travel in my lifetime.
While some cool stuff has been done in my life like probe missions to Jupiter and Saturn's moons and rovers on Mars, it's going too slowly for my liking.

There basically was a 40 year gap in space travel. Just recently things got picked up again. So recently we had: multiple mars rovers, first mission to a comet, first mission to the backside of the moon. Also a lot of stuff that wasn't done since many years got recently on course, like again a bigger spaceship to the ISS, so that it can operate with full manpower again soon and this one to get moon soil samples back. Also we have way more participants in the space right now, not only the US and Russia. So that all looks promising.

That's true I suppose; in the last 20 years we've also had the first re-landable rocket, first rover on an asteroid, and first encounter with Pluto. It's manned exploration I wish would pick up the pace. Like I say, it'd be awesome to put a human on Mars in the next few decades at least. One can hope I suppose.



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Speaking of future missions here's one I'm excited about; the Dragonfly program, launching in 2026, aims to put an aerial drone on Titan in 2034, where it will search for signs of life.

https://www.nasa.gov/press-release/nasas-dragonfly-will-fly-around-titan-looking-for-origins-signs-of-life



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