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dirtballmagnet t1_j6qyvgt wrote

Man, I just looked at one of the project abstracts and felt like I came in fifteen minutes late to a science fiction disaster film. Do what now?

>To address the urgent need for advanced propulsion solutions, we propose
the development of a nuclear fission fragment rocket engine (FFRE) that
is exponentially more propellent efficient than rocket engines
currently used to power today's space vehicles and could achieve very
high specific impulse (>100,000 sec) at high power density
(>kW/kg). ... NIAC work will provide detailed mission analysis of fast transit to SGL
for direct imaging and high-resolution spectroscopy of a habitable
exoplanet at a distance of up to 100 light years. The FFRE propulsion
system could provide delta-V to reach the SGL in less than 15yrs and
provide the slowdown and maneuvering capability at SGL.

A hundred thousand second Isp, you say? Let me just plug that into Kerbal Engineer Redux.

And sorry, I don't know what the urgent need is. Nor do I know what SGL is, or why you'd want to floor it to get there.


yongedevil t1_j6r2d67 wrote

>Nor do I know what SGL is, or why you'd want to floor it to get there.

Solar Gravitational Lens. We can use the sun's gravity to focus light like a telescope. However the sun doesn't bend light much so the focal point is something around 500 AU out. For reference, the Voyager probes are only around 150 AU out.


_WardenoftheWest_ t1_j6rp6ah wrote

It takes a comment like this to make me realise there are people somewhere who understand this, and then I can extrapolate just how fucking dumb I am


1992PlymouthAcclaim t1_j6sceys wrote

A couple years ago, I used parallax to triangulate the absolute depths of my own fucking ignorance. I don't recommend it.


Bipogram t1_j6sm777 wrote

I'm a chartered physicist, and that just means that I can plot my ignorance on a chart with fancy-pants axes, such as log-linear space.

And it's still a straight line vs. time.

The older I get, the less I know as a fraction of all that is knowable.


SimbaOnSteroids t1_j6scasn wrote

Well that’s still pretty good then. Remember there are only two groups of people.

Those that can extrapolate from incomplete data


NecroAssssin t1_j6uv0hw wrote

But binary teaches us there are actually 10 people. Those who understand binary.


Warrior_and_reader t1_j6snpwp wrote

It’s great to discover things we don’t know; it gives us the opportunity to learn more.


TheLemmonade t1_j6twj9i wrote

Using an observatory at the SGL, we could potentially resolve 100x100px images of exoplanets


yongedevil t1_j6v0p8d wrote

And then there are the people who come up with these ideas. Ideas like this, that could be dismissed out of hand as being impractical for any number of reasons. But thanks to people like Von Eshleman who sat down and did the math we know roughly what we need to achieve to make these crazy ideas real.

A solar gravitational lens is still in impractical territory, but pieces like blocking out the sun's light, precise spacecraft positioning, and now high performance engines are developing. Who knows, if one of our other telescopes finds a planet that we really really want a closer look at maybe we'll get an actual image of it showing continents and oceans in our lifetimes.


ackermann t1_j6uwotz wrote

Could we use Jupiter instead, or, is its focal point even farther away, since it bends light even less? Not sure how that works.


Elias_Fakanami t1_j6r7h0k wrote

Other comments have said what an SGL is, but don’t properly convey just what one would be capable of. A solar gravitational lens can be used to image relatively near astronomical objects with extraordinary resolution. If we could get a spacecraft to ~500 AU it could be used to observe an exoplanet that is ~100 light years out at a 25 km resolution.

Someone looking at the Earth from 100 LY with that kind of resolution would probably be able to see signs of life.


1nv4d3rz1m t1_j6rug1t wrote

Each project get $175000 and 9 months to do further studies on their project. Doesn’t sound like NASA considers this particularly urgent when they spend billions of dollars on other projects. 175 thousand dollars over 9 months is probably just enough to keep a couple researchers employees.


zeeblecroid t1_j6sjiiv wrote

All of those multibillion-dollar projects start with a handful of researchers poking at an idea for a few months.


Ds1018 t1_j6z5hks wrote

I wonder how many amazing multibillion-dollar projects were not funded because the 2 or 3 researchers that were poking at it for a few months were lazy or incompetent. I mean... every field has some.


SeaSaltStrangla t1_j6tdhy1 wrote

As a person working on one of these NIAC projects literally right now (im on reddit at work), they are primarily proof of concept ideas. The first phase funding is for demonstrating basic technology so you can get either Phase II or other external funding


dirtballmagnet t1_j6stnq3 wrote

Yes, it wasn't properly abstracted, but others have explained that the urgency here is that the point in space they're trying to reach is half a trillion miles away and to return science in the lifetime of the scientists they want to try to reach it in 15 years. Get it done in my lifetime sort of urgency, heh.


WarriorSabe t1_j6rb9f4 wrote

Fission fragment engines are being looked at? That's cool, those are actually some of my favorite high-performance engine designs, because they can achieve efficiencies in the realm of fusion rockets but are far more feasible.

In essence, what they do is have an exposed nuclear reactor core, and funnel the radiation emitted by it through magnetic fields and use it directly for thrust. The reason for that being, the radiation moves at a very high speed, and specific impulse is directly proportional to how fast your exhaust is. Biggest downside is the extremely low thrust, but it can run for ages to build up speed.

The main challenges for building one is managing the heat to avoid a meltdown and explosion, since for optimal performance the reactor needs to be designed in a way that is difficult to keep cool, and you want it as powerful as possible while also using highly-enriched fuel (and an expendable coolant will just make it into a much less efficient nuclear thermal rocket and defeat the purpose)


_WardenoftheWest_ t1_j6rp8yg wrote

How long can they theoritically run for before the emission run out


WarriorSabe t1_j6sg583 wrote

Well, it depends on just how much you put in the reactor. The half-life is millions of years, so it's not really going to decay on its own (that is, you have to have the reactor turned on for it to do stuff, using its equivalent of control rods) meaning you can treat it basically like any other fuel.

And for how much you can get out of that fuel, it is theoretically to our best ion drives what those best ion drives are to average chemical rockets - so think running for months or years on end and capable of eventually reaching hundreds of kilometers per second.


Genji_sama t1_j6stfat wrote

Imagine a nuclear disaster on Mars. Could we even colonize at that point? Fallout cleanup is already so expensive on earth...


toothpastetitties t1_j6t2ysf wrote

I mean you really don’t have much of an option. Much like on earth.

It’s nuclear energy or bust.


bathroomheater t1_j6rnqjg wrote

They spent 175k to fund think tanks on how to do a bunch of really difficult things and you’re acting like it’s an active project.


dirtballmagnet t1_j6ssjnv wrote

I'm acting like the dumbasses who wrote the abstract included an acronym without defining it, thus producing an abstract that makes no sense to the public... who is paying for it.


Ukulele_Maestro t1_j6uf7if wrote

so a telescope that is using gravitational lensing, with a nuclear propulsion device to reach the required spot in 15 years.

you are right does sound like science fiction! Wild to think about this.

direct imaging of planets 100 light years away?! my god, I hope to live to see this.


FHPirates_21 t1_j6vl8gc wrote

Wow at that speed we could reach Proxima Centauri in a brief 3,500 years! Lol everything is so far away


akman_23 t1_j6thxhl wrote

>nuclear fission fragment rocket engine

At that point you might as well develop a nuclear salt water rocket. Might be a bit less efficient but hey, if you're gonna get irradiated, you might as well have high thrust.


the6thReplicant t1_j71l4je wrote

Note you don't use this to leave Earth. This is for travelling in the vacuum of space and I don't even think it can be used to escape orbit either.

Small acceleration over large time scales means fasty-fasty.


dirtballmagnet t1_j72ptfl wrote

Yes, one of the most exciting spacecraft ever was Dawn, which couldn't accelerate faster than a feather falls, but it fired for months and went from Vesta to Ceres... eventually. That was a huge change in velocity.


Banthe t1_j72sdwq wrote

Yeah I thought we decided against fission rockets so we don’t accidentally spew radioactive material everywhere on the off chance of a failed launch. What is this urgent need that they speak of? Mildly concerning but I’ll just assume the best ig.


dirtballmagnet t1_j72uhh9 wrote

So the way around the radioactive accident problem is fairly well solved now. A reactor would be assembled and activated on orbit after the parts were carefully shipped to that the components could not easily disintegrate on launch.

Others here have taught me that he urgency here comes out of the undefined acronym, which was "Solar Gravitational Lens." That is a point--the focus of the lens made by the sun--somewhere 3 times farther out than our current farthest spacecraft, the Voyagers. It's taken them almost 50 years to get that far so they'll want to reach that focus ten times faster than our current vehicles, then it has to slow and maneuver around that point.


youkmowwhatyouarefor t1_j6twgtp wrote

According to this instead of 80,000+ years to get to Proxima Centauri it would only take 8000+. Huge improvement.


smolDreee t1_j6u1p12 wrote

Are they hoping to build an ekranoplan on Titan or something?


Airplanesteve t1_j6vdw99 wrote

Ngl I like NASA returning to Apollo era projects. Hopefully we’ll see a sea dragon 2 project.


Commander_Amarao t1_j6u6xzr wrote

The drawing almost looks like a Handley page Victor (except for the tail) A beautiful plane IMHO.


Nemo_Shadows t1_j6sw5ry wrote

What IF I was tell you that there is a better way to do it?

N. S