[dongobongo]

A company I work with recently started design and development for space craft to catch Borisov or Omouamoua, the other extra solar object that recently passed by, using a nuclear decay heat source and Hall effect thrusters. It's pretty realistic and doable - no bleeding edge technologies. Very high power density, very high isp, very fast space craft. Apparently, they can achieve 100km/s + velocity delta for a very small payload: https://www.nasa.gov/directorates/spacetech/niac/2021_Phase_...

The same system could do a Mars visit and return to Earth for small payloads in 50 days.

This stuff needs to get funded! They are funded for initial studies and design with NASA, but I know they are looking for extra funding to pull off the mission faster without being tied to NASA's timelines and mercurial objectives.

[_Microft]

Do you know how these chargeable atomic batteries („CAB“) which are mentioned on the NASA webpage work? A web search does not return anything useful.

[dongobongo]

The typical radioisotope generator is a Plutonium-238 source like the MMRTG on the Mars rovers. The Plutonium decays by alpha emission with a half life of 80+ years. The problem is there is a very limited supply of Plutonium-238 - we use the entire supply for Mars Rover - and it's very controlled material.

The CAB starts with a non-radioactive material like Cobalt-59 spheres placed in a ceramic matrix. It is then put into a nuclear reactor where it turns into Cobalt-60, which releases energy by beta and gamma emission with a half life of 5 years. This charging can be done every couple years to generate more Cobalt-60 inside the device. Such a power source is something like 40x as power dense as the Pu-238 source and since it's made of high temperature ceramics, it can go to very high temperatures which is very useful for space generators where you have to reject heat using blackbody radiators.

[_Microft]

Thanks, so "charging" means activating stable cobalt to radioactive cobalt by neutron capture. This sounds very doable and is in line with what I expected for a project selected for the program.

I asked because of an experiment conducted by a german research institute at an accelerator in France. They modified nuclear states by using "shaped" x-ray pulses. I wondered if it were possible to store energy by making a nucleus undergo a transition to a meta-stable state (spontaneous emission is forbidden by a selection rule) but which could eventually be triggered by another pulse to extract energy again.

I hope my description of the process I imagine is not too far off, it has been a while since my nuclear physics course ;)

Here is the article and some discussion:

https://www.mpg.de/16449701/coherent-nuclear-excitations

https://news.ycombinator.com/item?id=26190965

[marshmallow_12]

if it's what i think they are, they are essentially batteries with a radioactive source. It relies on the gradual decay of the source to create energy which is somehow harnessed and used as a power source. I have learnt here on HN that they last many years, are used on space projects such as the voyager probes, and more recently, the mars rover. They are impractical for other uses, such as powering your fridge and home. And their price is.... astronomical.

[_Microft]

Atomic batteries are a thing; I was wondering how they could be made chargeable.

[addaon]

One thing that comes to mind is Hafnium 178m2, but (for understandable reasons) there's basically zero public information about the feasibility of charging and induced discharging of any nuclear isomer, let alone one so energy dense.

[_Microft]

Cool, thanks for pointing that out! This is basically what I was thinking about in my reply to user dongobongo.

[jhgb]

I wonder, has anyone seriously considered employing the Oberth effect as close to the Sun as possible? Combined with using solar power for propulsion energy, that could get interesting.

[the8472]

I could swear I have seen a video on building a test chamber with an intense light source to test a heat shield similar to the parker solar probe but with hydrogen or helium piped through it for a solar thermal thruster. But I can't find it now.

[kortilla]

There isn’t a way to use solar power for propulsion energy. The issue isn’t an electrical source, the problem is emitting mass.

[dragonwriter]

> There isn’t a way to use solar power for propulsion energy

That’s...demonstrated to be false.

https://en.m.wikipedia.org/wiki/Solar_sail

[bawolff]

What about a photon rocket? https://en.m.wikipedia.org/wiki/Photon_rocket

[jhgb]

Solar electric propulsion and solar thermal propulsion seem to work just fine.

[totetsu]

Byebye Americas cup and f1, hello solar drag racing

[TheBlight]

How would you locate their precise position?

[postalrat]

What sort of science could be done flying by Omouamoua at some crazy high speed?

[lrem]

Why?

I appreciate the coolness factor. But, unless the payload can be enough to pull off a 1998 Bruce Willis, what's the immediate benefit? Or, would this be fundamental to some research?

[dongobongo]

Regarding Omouamoua, we just observed for the first time in human history, a cylinder or plate shaped object from another star flying through our solar system with questionable orbital velocities (we are not quite sure how to explain a small acceleration it had). A cylinder/plate is not a low energy geometry (things like to turn into spherical type objects over time), it's from another solar system, we don't know very much about it. How could you not want to visit it?

It's an opportunity to pull off a speed and distance record, visit something from another solar system, resolve big research questions about its shape, composition, origin and rule out any theories of its possible intelligent origin. They are also pursuing it to showcase the benefits of nuclear heat for space.

[sneak]

Sol is the name of our star, so there is only one Solar system.

[codeulike]

solar system (noun)

earth science - the sun and the group of planets that move around it, or a similar system somewhere else in the universe

(Definition of the solar system from the Cambridge Academic Content Dictionary © Cambridge University Press)

https://dictionary.cambridge.org/dictionary/english/solar-sy...

[vmception]

This is a more of an etymology issue than what you think, if you need to look up the word etymology, I'm referring to the the history of the words and not suggesting any changing meaning

[Fordec]

Let's see..

Search for evidence of life outside the solar system. Unless you're planning a trip to another star system this is all we've got in our lifetimes.

Hitching a fast ride to the outer edges of the solar system since it's on a hyperbolic trajectory.

What is the asteroid made of? That shape of asteroid is not normal. Usually they're rubble piles, these were different. Is there formation methods we don't yet know? Were they fragments of a planet's destruction?

On an engineering level, we've never had to rendezvous with something on this trajectory before. Can we?

[pyuser583]

Dont underplay the “coolness factor.” The moon landing was pretty cool. Not practical, but freaking cool.

We need more coolness in public policy.

[mynegation]

That is how progress works. Lots of things were researched or invented before progress in other areas (materials, economics, society, other scientific finds...) made these findings useful or even feasible. You never know when and why you will need this, the only thing you know - it will be used eventually. Maybe this will give some important clues into the future interstellar travel, maybe the tricks and technologies invented for this mission will be used elsewhere, maybe sample will give important clues into the origins and probability of life.

[azernik]

It would be absolutely helpful to astronomy and planetary science research. We have never in history looked at extrasolar material up close.

And if it is indeed relatively cheap, it doesn't need to be "fundamental".

[throwaway3699]

People often claim commerce and free markets are the driver of innovation. That's true, but they're not the only driver. Industry and national "moonshots" play off each other very well.

[dvh]

Because oumuamua had aspect ratio 10:1

[dboreham]

Like the bounty hunter's ship.

[cambalache]

It didnt. It had a perceived dimming factor of 10:1 which suggests (but does not prove) a "weird" shape

[walrus01]

what is the constant wattage output of the RTG on that? 20kW steady state all the time?