3I/ATLAS: Probably NOT an alien interstellar probe

[Jarhyn]

I would say you need significantly less material than most of y'all are thinking to survive the impact.

You need a computer capable of calculating the impact forces within margins, a computer you could conceivably later use as ablation or reaction mass, and then a number of small events.

This is because in space, things like the hydrophobic ejection of spore capsules happens at insane velocities and does not get the ejection "broken" by the thickness of the atmosphere.

Imagine a spore container several "spores" thick. The outer container uses hydrophobics to eject an inner container that contains some water and spore containers, and suddenly you have the means to get going well beyond the speed of sound with an utterly tiny package.

Remember that there's a cube/square problem going on, where the smaller you can make the interception device, the less energy it takes to intercept at speed.

Then, having an impactor made to take the structural collapse and damage for the internal payload would complete the journey.

I will maintain that having several hundred thousand tons of material to add to or modify and which is already going somewhere, anywhere, is a much better way of having several hundred thousand tons of material launched from a planet and accelerated yourself.

Then in a few hundred thousand years (what does it matter to the probe systems? They hibernate!) when something happens you wake up and check if you have found yourself somewhere interesting, maybe shed some probes, and continue on through the universe.

In fact this particular interstellar object has its own 'coma' or micro-atmosphere as well as frozen gassy deposits which would be VERY nice to have for future probe applications, since not only are they easily accessed reaction mass, they are also useful hydrocarbon sources for whatever other features might need to be farmed up.

1) Tyranny of the rocket equation. Booster to payload is exponentially linked to desired velocity vs reaction mass ejection velocity. Hydrolox running rich is the best chemical propulsion that can exist. (Using fluorine produces a higher binding energy, but it binds only one atom of hydrogen. More energy per molecule but less energy per gram. Likewise, you run hydrolox rich not only to protect your engines but because hydrogen is lighter--you actually end up with a higher exhaust velocity than if you provided enough oxygen.) Innovations come from reducing weight and reducing power consumption.

2) You still haven't addressed the problem of supersonic impact.

Position a launch vehicle maybe the size of a brick with a payload of less than a gram. Maybe a single milliliter of payload?

I keep saying the best information to density ratio we have for constructing some manner of 'truth machine' is something resembling biology.

I really do think that it is much easier to get something very small launched out of a system on an exit path than it is to get something large on that same exit path, and it's useful to have a lot of mass on an exit path.

The best exit path is therefore one that some other object is already on.

I'm not saying it's ever going to be easy to catch or direct such an object.

I acknowled that it's hard.

... But it's the best ticket we have to having something to build from and launch off of later, especially when we've used up a lot of the available resources trying to do even more wasteful shit like launching cans full of air into space to preserve hungry, cold, hairless, heavy apes.

At some point in the far future, when humans have gotten our asses into space and discovered that there's not really much to do or build from or survive with out there, even though it's the only place we have left that isn't completely fucked, and we're desperate enough to try to attach to anything on its way through or out, you can be sure that we're going to be trying even the crazy shit some asshole on an internet forum suggested before we give up trying to exist elsewhere.

Knowing how things tend to happen, I'll bet that the first couple tries will be half-assed and the payload will be a dud, or something bound to that object and unable to leave, trapped to live out eons in the cold of space, to never actually make an effective way to get off the rock, and to wander endlessly until it's too cold and doesn't pass anything warm enough to keep a semblance of activity going.

I think that if we can engineer life that can shit out hominid things that remember what it's like to be us, slap it on a thing we launch out of the system using slingshot maneuvers, and then litter into a new system.

In fact I'm not the only person who has this sort of idea for how life could be jury rigged; a much more simplified version is 40k Space Orks, apparently, where they are born of spored that germinate into a space-orkoid-creature producing womb.

So I'm not the only one thinking about doing that and it's apparently a popular idea. People will probably be suggesting it at some point of only because apparently, one in a popular grimdark space setting that will possibly outlive humanity with the profusion of junk that advertised it.

 

[Loren Pechtel]

1) Tyranny of the rocket equation. Booster to payload is exponentially linked to desired velocity vs reaction mass ejection velocity. Hydrolox running rich is the best chemical propulsion that can exist. (Using fluorine produces a higher binding energy, but it binds only one atom of hydrogen. More energy per molecule but less energy per gram. Likewise, you run hydrolox rich not only to protect your engines but because hydrogen is lighter--you actually end up with a higher exhaust velocity than if you provided enough oxygen.) Innovations come from reducing weight and reducing power consumption.

2) You still haven't addressed the problem of supersonic impact.

Position a launch vehicle maybe the size of a brick with a payload of less than a gram. Maybe a single milliliter of payload?

Ran some numbers through a calculator. Finding delta-v to intercept was hard, I'm using Google's AI answer of 24 km/sec.

Hydrolox--the launcher weighs 230x the payload. Note that the engines and tanks must be considered part of the payload! Reality is more like your booster is 5% rocket and 95% fuel and thus many stages will be needed. This equation is so extremely sensitive to the exact ratio that I'm not even going to try to ballpark it. Instead, let's look at the real world: What is the most energetic mission NASA has ever tried to do? Single spacecraft to the moon. 17.62 km/s. They gave up, decided they couldn't do it! Apollo only worked because they parked their return equipment in orbit rather than taking it down to the surface. A paper that's behind a paywall has in it's intro that the minimum mass ratio for the moon is 500. Same paper, minimum mass ratio for Mars (18.91 km/s needed) is 5,000. Note how rapidly it's going up. And note that NASA's plans to get Curiosity's samples home is to launch one mission that can land on Mars and lift the samples into orbit. And a separate mission that can grab them in orbit and bring them home. Because it's cheaper to build a whole second mission than it is to give the lander 2.1 km/s (Low Mars orbit to Earth injection) more delta-v and what's needed to survive the landing.

But you're talking biological. No idea on exactly how good this can be made, I'll use the most energetic stuff we actually use for numbers (which is almost certainly better than anything you can do biologically). Using the same initial calculation instead of 230x I'm getting 3,500x. And using a more realistic number (a steam rocket) I'm getting 200,000x.

 

[Jarhyn]

1) Tyranny of the rocket equation. Booster to payload is exponentially linked to desired velocity vs reaction mass ejection velocity. Hydrolox running rich is the best chemical propulsion that can exist. (Using fluorine produces a higher binding energy, but it binds only one atom of hydrogen. More energy per molecule but less energy per gram. Likewise, you run hydrolox rich not only to protect your engines but because hydrogen is lighter--you actually end up with a higher exhaust velocity than if you provided enough oxygen.) Innovations come from reducing weight and reducing power consumption.

2) You still haven't addressed the problem of supersonic impact.

Position a launch vehicle maybe the size of a brick with a payload of less than a gram. Maybe a single milliliter of payload?

Ran some numbers through a calculator. Finding delta-v to intercept was hard, I'm using Google's AI answer of 24 km/sec.

Hydrolox--the launcher weighs 230x the payload. Note that the engines and tanks must be considered part of the payload! Reality is more like your booster is 5% rocket and 95% fuel and thus many stages will be needed. This equation is so extremely sensitive to the exact ratio that I'm not even going to try to ballpark it. Instead, let's look at the real world: What is the most energetic mission NASA has ever tried to do? Single spacecraft to the moon. 17.62 km/s. They gave up, decided they couldn't do it! Apollo only worked because they parked their return equipment in orbit rather than taking it down to the surface. A paper that's behind a paywall has in it's intro that the minimum mass ratio for the moon is 500. Same paper, minimum mass ratio for Mars (18.91 km/s needed) is 5,000. Note how rapidly it's going up. And note that NASA's plans to get Curiosity's samples home is to launch one mission that can land on Mars and lift the samples into orbit. And a separate mission that can grab them in orbit and bring them home. Because it's cheaper to build a whole second mission than it is to give the lander 2.1 km/s (Low Mars orbit to Earth injection) more delta-v and what's needed to survive the landing.

But you're talking biological. No idea on exactly how good this can be made, I'll use the most energetic stuff we actually use for numbers (which is almost certainly better than anything you can do biologically). Using the same initial calculation instead of 230x I'm getting 3,500x. And using a more realistic number (a steam rocket) I'm getting 200,000x.

And 200,000x is... 200 litres of fuel for a milliliter final payload all the way from ground. The harder part is getting a small enough computer attached to each to do the on-fly adjustment.

The idea is to eject all the need for mass beyond some small payload long before you need to launch it.

Only that last milliliter is biological, though. Everything else is fuel and staging computers.

Most of it would be with hydrolox for getting close.

All that said, for yeeting a rock initially, planning a slingshot on something we purposefully huck down from the oort cloud might do a better job of hucking out a serviceable mass?

Granted, I would want to hitch-hike on an intruder if only because someone else might have already done that.

I really do think we can and should seek to "tag" some of these passers-by with some long term mission using engineered life, and that in the long run, it will be valuable to consider how.

 

[Loren Pechtel]

1) Tyranny of the rocket equation. Booster to payload is exponentially linked to desired velocity vs reaction mass ejection velocity. Hydrolox running rich is the best chemical propulsion that can exist. (Using fluorine produces a higher binding energy, but it binds only one atom of hydrogen. More energy per molecule but less energy per gram. Likewise, you run hydrolox rich not only to protect your engines but because hydrogen is lighter--you actually end up with a higher exhaust velocity than if you provided enough oxygen.) Innovations come from reducing weight and reducing power consumption.

2) You still haven't addressed the problem of supersonic impact.

Position a launch vehicle maybe the size of a brick with a payload of less than a gram. Maybe a single milliliter of payload?

Ran some numbers through a calculator. Finding delta-v to intercept was hard, I'm using Google's AI answer of 24 km/sec.

Hydrolox--the launcher weighs 230x the payload. Note that the engines and tanks must be considered part of the payload! Reality is more like your booster is 5% rocket and 95% fuel and thus many stages will be needed. This equation is so extremely sensitive to the exact ratio that I'm not even going to try to ballpark it. Instead, let's look at the real world: What is the most energetic mission NASA has ever tried to do? Single spacecraft to the moon. 17.62 km/s. They gave up, decided they couldn't do it! Apollo only worked because they parked their return equipment in orbit rather than taking it down to the surface. A paper that's behind a paywall has in it's intro that the minimum mass ratio for the moon is 500. Same paper, minimum mass ratio for Mars (18.91 km/s needed) is 5,000. Note how rapidly it's going up. And note that NASA's plans to get Curiosity's samples home is to launch one mission that can land on Mars and lift the samples into orbit. And a separate mission that can grab them in orbit and bring them home. Because it's cheaper to build a whole second mission than it is to give the lander 2.1 km/s (Low Mars orbit to Earth injection) more delta-v and what's needed to survive the landing.

But you're talking biological. No idea on exactly how good this can be made, I'll use the most energetic stuff we actually use for numbers (which is almost certainly better than anything you can do biologically). Using the same initial calculation instead of 230x I'm getting 3,500x. And using a more realistic number (a steam rocket) I'm getting 200,000x.

And 200,000x is... 200 litres of fuel for a milliliter final payload all the way from ground. The harder part is getting a small enough computer attached to each to do the on-fly adjustment.

The idea is to eject all the need for mass beyond some small payload long before you need to launch it.

Only that last milliliter is biological, though. Everything else is fuel and staging computers.

Most of it would be with hydrolox for getting close.

All that said, for yeeting a rock initially, planning a slingshot on something we purposefully huck down from the oort cloud might do a better job of hucking out a serviceable mass?

Granted, I would want to hitch-hike on an intruder if only because someone else might have already done that.

I really do think we can and should seek to "tag" some of these passers-by with some long term mission using engineered life, and that in the long run, it will be valuable to consider how.

Did you not notice the part where I said 5% for the hardware? Let's look at the Falcon 9. Kerolox will degrade the overall performance but won't have much effect on the stages. The second stage is about 20% the weight of the first stage.

You seem to think you can make a magic rocket with neither tanks nor engines.

 

[Bronzeage]

AvI Loeb tbinks everything that falls from the sky or is in the sky is an alien probe. AvI Loeb says he has found alien probes at the bottom of the ocean.

AvI Loeb is a fraud now.

If alien probes have ever reached Earth, the chances it would land in the ocean are very high. This is thinking only in terms of fairly recent history. A lot of what was once ocean bottom is now above sea level, but buried under many layers of rock. The chances of discovering an alien probe in a fossil bed is very small, but not zero.