Hacker News Reader

Comment by myrmidon | Hacker News Reader

There is no "building" such a thing. All we could do right now is send the "telescope probe" >500AU away, on the opposite side of the sun from the observation target, then hope it still works 80 years later or so when it gets there.

Edit: My point is that you can't "build" such a thing and later point it somewhere-- you have to fly the camera part of the "telescope" about 3 times as far as voyager 1 went, exactly opposite of your observation target, and it is not gonna stay there for too long either.

As long as we improve rapidly at both drone-building and exoplanet target selection, it is not really gonna be worthwhile because both the drone hardware and the target will be hopelessly obsolete before we even get halfway to the observation point.

View on HN

Well, there is a way to do it slowly, the probe(s) just need to be in a 500AU circular orbit. At that distance power and thrust are an issue, and RTGs seem like a better choice than solar. Certainly, takes longer to get to orbit than fly through a point for a pic, but you would get a lot more pics.

First: Orbital period out there is over 10000 years.

And if you circularize (which is expensive to do in delta-v), you minimize the time window you have for observation (because you're basically pointing your speed vector straight to outside of your observation cone).

The orbital velocity at this distance is around 1 km/s, so you can fairly trivially (compared to anything else) zero it out. Then you can just hover in place, the solar gravity acceleration at this range is in _microns_ per second squared.

For all intents and purposes, you'll be in the interstellar space.

In order to get something there fast enough it would be traveling out very fast. Getting something there to orbit I think is not realistic for us any time soon.

I guess the point he's making is that the orbital velocity is pretty slow, so it's not too different to "get there" and "orbit there".

Of course, the rocket equation often makes "just add a few percent more delta V" pretty hard ;)

> so it's not too different to "get there" and "orbit there".

But to "get there" within any reasonable timespan requires going really fast - which is currently highly impractical. And then once you get there, you have to them cancel pretty much all of that velocity which is not just a "few percent more delta V".

We can do 7-8 AU per year right now using tech we have. Voy 1 and Voy 2 are moving at 3.59 and 3.25. A starship sized rocket could also possibly get a small payload that separates to 15 AU. This is all using conventual propellent. If you consider using nuclear explosive as a prepulsion technique the math starts to change substantially and you can achieve even 25 AU / year.

https://ntrs.nasa.gov/api/citations/20140013260/downloads/20...

Sure. But then how do you go from 7-8 AU/yr (33-38 km/s) to whatever the orbital speed is at that distance and also point that velocity vector in the correct direction for the orbit?

Technically, you don't need to stop. Gravitational lensing does not work like regular lenses, there is no "focal distance".

You have to be so far because that's the minimal distance where the Einstein ring becomes larger than the Sun's apparent diameter.

If time is no object, sure.

an ort cloud of eye peices comes to mind

Reply on news.ycombinator.com