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GarunixReborn t1_j6kpnr0 wrote

Took them long enough, good god 50 years without any development at all

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Radioactiveglowup t1_j6kr388 wrote

Indeed. Nuclear space propulsion is the only option for meaningful space exploration and industrialization, just like how Nuclear power generation is the only carbon-free, long term solution on Earth that is really feasible at scale.

It's staggering how much damage to the environment has been caused by well-meaners who established the kneejerk anti-nuclear culture.

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GarunixReborn t1_j6krklm wrote

Hall thrusters are also great, hope to one say see them both in action

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OlympusMons94 t1_j6m0720 wrote

Hall effect thrusters so far almost always use solar/battery power, but could also use nuclear. The Soviet Kosmos 1818 and 1867 had nuclear powered hall thrusters.

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GarunixReborn t1_j6ktcak wrote

Also the fact that we've been sending up plutonium for decades already without a single failure

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The_Solar_Oracle t1_j6lcoqk wrote

Ehhhhh . . . That's kind of misleading. While the risks of nuclear fuel dispersal is generally overblown (coal plants are hard to beat in this regard), there is not a zero risk of dispersal and there have been historic releases of fissile material.

In the 1970s, the Soviet Union's US-A radar imaging satellites (often known as RORSAT) depended on nuclear reactors to power them in lieu of RTGs and Solar panels. An unnamed launch failed to reach orbit in 1973 and resulted in the reactor entering the Pacific Ocean. Kosmos 954 and Kosmos 1402 had their cores reenter the atmosphere in 1978 and 1983 respectively, with the latter dispersing its debris over Canada. More recently, the Russia Federation's Mars 96 launch failure resulted in the reentry of its onboard plutonium-238.

The United States also had plutonium-238 enter the Earth's atmosphere during Apollo 13. As this material was originally intended to remain on the Moon to power surface instruments, it remained onboard since a landing attempt was aborted.

Only a small handful of launch providers can claim a 100% success rate, and nuclear reactors for man rated thermal rockets or electric rockets must inevitably much larger than any of those involved in the beforementioned incidents.

I also caution against people arguing that nuclear fission is the only way forward for space travel. There have been very encouraging developments in Solar electric propulsion in recent years, and nuclear power for spacecraft comes with engineering headaches that tend to be ignored more often than not. Nuclear reactors must have heavy shielding to protect the crew, and this shielding increases their already large minimum engine mass. Reactors generating electricity must also have significant mass dedicated to generating said electricity and then shedding the large amounts of waste heat produced as a result.

Moreover, nuclear reactors can only be reused so many times before they accumulate too many poisons and can no longer produce useful levels of energy. Once a reactor has also been used, they will also continue to generate radiation. This can make docking in particular very problematic, as economical shielding can only cover a certain 'cone' in front of the reactor and thus forcing other vehicles to enter via that safe zone once they've come within a certain distance of the nuclear-armed target.

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urmomaisjabbathehutt t1_j6mctb8 wrote

i love they start nuclear propulsion in space specially things like the dual NTP/NEP design they were posting a few days back because the best that NTP alone can do is twice as better than chemical and we need better than that

this post is about nuclear propulsion the rest of your comment smacks of acolites of the church of the fissiontology pushing propaganda created by fossil fuel to slow the adoption of clean energy and doesn't belong to this discussion

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coffeesippingbastard t1_j6ldvf2 wrote

>The two agencies had been separately pursuing NTP projects. DARPA started DRACO with three Phase 1 awards in April 2021 to teams led by Blue Origin, General Atomics and Lockheed Martin to work on preliminary designs of reactors and spacecraft.

You hear nothing out of them and the social media consensus is that they're doing nothing but then you see their name pop up in stuff like this.

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ShedDoor2020 t1_j6o7eys wrote

ELI5 The way I understand it, nuclear ships and power plans basically use the heat from the nuclear reaction to power a steam engine and thus turn a turbine or drive-shaft. So how does nuclear power create thrust without a propeller or other mechanical aid? Are they controlling and focusing a series of miniature nuclear explosions to create thrust???

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gaunt79 t1_j6ooewc wrote

Liquid hydrogen takes the place of water in a terrestrial reactor. The hydrogen is pumped into the reactor core (cooling the nozzle and reactor casing on its way) where it is superheated. It then passes to the nozzle, where it expands and is focused into the thrust plume that propels the spacecraft.

This diagram may make more sense.

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ShedDoor2020 t1_j6p362x wrote

Thank you for the explanation. So, do you have to replenish/refuel the hydrogen periodically? Or is it a closed system like a car radiator?

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gaunt79 t1_j6p5hdo wrote

It would need to be replentished, but it would theoretically be easier/safer to refill only hydrogen propellant than to refill both a fuel and an oxidizer. I don't think that refueling is in DRACO's mission parameters, though. Future NTP spacecraft may be reusable in that manner.

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