Energy and Other Constraints on a 3I/Atlas Type Object, if it is of Artificial Origin

There have been speculations that the interstellar object 3I/Atlas might be of artificial origin, rather than being a natural object. This is obviously highly contentious, but I thought it would be interesting to see just how likely it would be for a civilization much like the Earth’s to send an object on an interstellar journey.

Even now, we know that Earth has already sent an interstellar object or two on their way out of the solar system. These are rather small probes, such as Voyager, Pioneer or New Horizons, that were sent to study the outer planets and as a result of those missions, are now proceeding out of the solar system. So, clearly it can be done, though it must be kept in mind that gravity assists (so called sling-shots) increased the velocity of these craft, such that they were significantly faster than they would have been with launch energy alone. That required some very specific orbital manoeuvres and planetary alignments – those conditions would not necessarily exist for other hypothetical journeys out of our solar system or out of any similar solar system.

Energy Constraints

So, I did a very high-level (i.e. approximate) analysis of the energy budget possible for a craft, using the energy various sources that we now have or could soon have, here on Earth. Those are:

Energy Available

Fuel Mass Density (Kg/M3) Energy Density MJ/Kg

Methalox (Methane/Oxy) 810 10

RP-1 with Oxidizer 2074 12

Hydrogen, Liquid & LOX 641 17

U-235 (25% enriched) 4000 3,900

Hydrogen, Fusion (DT) 4000 15,600

Here are the escape velocities from some points within the Solar System.

Energy Required to Escape the Solar System

Initial Point Escape Velocity (km/sec)

Earth 42.1

Mars 34.1

Ceres 25.3

Jupiter 18.5

Saturn 13.6

Uranus 9.6

Neptune 7.7

Pluto 6.6

The basic idea is simple (below is the example of a 10 km radius "spacecraft", similar to the 3I/Atlas speculations):

given a radius for the object, calculate the volume (assuming a sphere)
make some of this the fuel mass and some of it the object mass, using representative densities for both.
This example postulates a very high porosity in which a metholox (liquid methane and liquid oxygen mix) fuel supply could be contained.

Radius

- km 10

- m 10,000

Volume (assuming sphere)

- km3 4,189

- m3 4.19E+12

Mass (kg)

Fuel Methalox

- mass density (kg/m3) 810

- porosity 90%

- total fuel mass 3.05E+15

Non-Fuel (rock/metal)

- mass density (kg/m3) 3,000

- pct non-porosity 10%

- total non-fuel mass 1.26E+15

Total Fuel & Non-Fuel Mass

- porosity 90%

- Mass 4.31E+15Energy

Energy density (MJ/kg) 10.0

- Total (max avail, MJ) 3.05E+16

- porosity 90%

- Total, given porosity est. (MJ) 2.75E+16

For a very rough estimate of the velocity that could be obtained by burning this much fuel, given the mass of the object, a simple kinetic energy calculation is used. This assumes that all of the available energy could be "somehow" converted to the kinetic energy of the object:

Escape Velocity (km/sec)

- from solar system

Starting at Pluto

- km/sec 6.6

- m/sec 6,600

Escape Velocity – Kinetic Energy Required

- from solar system

Earth

- 6.65E+16 MJ

So, about 6.6 X 10E16 megajoules would be needed, but only about 2.8 X 10E16 megajoules would be available, even given simplistic and unrealistically optimistic estimates of the theoretically available energy. That gives an Energy Available/Required ratio of only about 0.41, not even half of what is needed to escape the solar system, even from the distance of Pluto.

Perhaps a significant payload could be launched out of a sun-like star’s solar system with a long series of gravity assists, though that would probably be extremely complicated and time consuming. Perhaps a long series of "stepping stones" might work, moving slowly to the outer parts of the system, always making use of local resources, such as dwarf planets, comets and asteroids.

However, if nuclear energy could be used, the situation would be dramatically different, due to the huge energy density of nuclear energy sources. Even from Earth distance, it could probably be done if enough enriched uranium was available and the object was assembled far from the Earth’s gravitational influence. I think the surface or near-surface of the object would have to be festooned with nuclear reactors, at least of the power of hundreds of nuclear submarines. At any rate, the energy would potentially be there, if it could be converted into kinetic energy (maybe by accelerating ions in a strong electric field).

The case is improved further, if the object was powered by fusion energy from deuterium-tritium reactors, should those actually be feasible. The main advantage would be availability of fuel. That would be even more true for deuterium- deuterium reactors. Again, the object’s surface and near-surface would probably have to contain hundreds of such reactors and devices for accelerating ions in strong electrical fields.

Detailed calculations for several fuels and several solar system distances from the sun are given in an appendix at the end of the blog.

Other Constraints

The next obvious question is "who would want to do this, given the vast expenses and the long time scales involved?". After all, even at fantastic velocities (e.g. 1000 km/sec) it would take millennia to get anywhere interesting. (e.g. at about 30 billion km per year, it would take about 1000 years to get to Alpha Centauri).

I think it would have to be a long-lived species, very possibly a non-organic one, that could make plans and then execute those plans on time scales like this. That assumes that members of a machine species could actually exist without breakdown for those kinds of time scales. On Earth, I don’t think we have kept any machine running for even centuries, let alone millennia.

So, my conclusion is that something like 3i/Atlas could conceivably be artificial, but it would indicate many technologies that we have still not achieved and planning horizons and motivations that we can’t even begin to comprehend.

That said, I suppose if something is possible, it might well be done, eventually.

Appendix

Below is a table with back-of-the-envelope calculations for various types of fuel and various distances from the sun-like central star.

Assuming Asteroid Radius=10 km
Starting from 1 AU (Earth Distance)
Initial Point	Earth	Earth	Earth	Earth	Earth
Initial Point escape Velocity	42.1	42.1	42.1	42.1	42.1
Fuel	Methalox	RP-1 with Oxidizer	Hydrogen, Liquid & LOX	U-235 (25% enriched)	Hydrogen, Fusion (DT)
Porosity	90%	90%	90%	90%	90%
Energy Available:	2.75E+16	8.47E+16	3.68E+16	5.29E+19	2.12E+20
Energy Required:	2.71E+18	6.93E+18	2.14E+18	1.34E+19	1.34E+19
Energy Index (Avail/Required)	0.010	0.012	0.017	3.96	15.84

Starting from 1.52 AU (Mars Distance)
Initial Point	Mars	Mars	Mars	Mars	Mars
Initial Point escape Velocity	34.1	34.1	34.1	34.1	34.1
Fuel	Methalox	RP-1 with Oxidizer	Hydrogen, Liquid & LOX	U-235 (25% enriched)	Hydrogen, Fusion (DT)
Porosity	90%	90%	90%	90%	90%
Energy Available:	2.75E+16	8.47E+16	3.68E+16	5.29E+19	2.12E+20
Energy Required:	1.78E+18	4.55E+18	1.40E+18	8.77E+18	8.77E+18
Energy Index (Avail/Required)	0.015	0.019	0.026	6.04	24.15

Starting from 2.77 AU (Ceres Distance)
Initial Point	Ceres	Ceres	Ceres	Ceres	Ceres
Initial Point escape Velocity	25.3	25.3	25.3	25.3	25.3
Fuel	Methalox	RP-1 with Oxidizer	Hydrogen, Liquid & LOX	U-235 (25% enriched)	Hydrogen, Fusion (DT)
Porosity	90%	90%	90%	90%	90%
Energy Available:	2.75E+16	8.47E+16	3.68E+16	5.29E+19	2.12E+20
Energy Required:	9.77E+17	2.50E+18	7.73E+17	4.83E+18	4.83E+18
Energy Index (Avail/Required)	0.028	0.034	0.05	10.97	43.87

Starting from 5.2 AU (Jupiter)
Initial Point	Jupiter	Jupiter	Jupiter	Jupiter	Jupiter
Initial Point escape Velocity	18.5	18.5	18.5	18.5	18.5
Fuel	Methalox	RP-1 with Oxidizer	Hydrogen, Liquid & LOX	U-235 (25% enriched)	Hydrogen, Fusion (DT)
Porosity	90%	90%	90%	90%	90%
Energy Available:	2.75E+16	8.47E+16	3.68E+16	5.29E+19	2.12E+20
Energy Required:	5.23E+17	1.34E+18	4.14E+17	2.58E+18	2.58E+18
Energy Index (Avail/Required)	0.05	0.06	0.09	20.51	82.05

Starting from 9.6 AU (Saturn)
Initial Point	Saturn	Saturn	Saturn	Saturn	Saturn
Initial Point escape Velocity	13.6	13.6	13.6	13.6	13.6
Fuel	Methalox	RP-1 with Oxidizer	Hydrogen, Liquid & LOX	U-235 (25% enriched)	Hydrogen, Fusion (DT)
Porosity	90%	90%	90%	90%	90%
Energy Available:	2.75E+16	8.47E+16	3.68E+16	5.29E+19	2.12E+20
Energy Required:	2.82E+17	7.23E+17	2.23E+17	1.39E+18	1.39E+18
Energy Index (Avail/Required)	0.10	0.12	0.16	37.95	151.82

Starting from 19.2 AU (Uranus)
Initial Point	Uranus	Uranus	Uranus	Uranus	Uranus
Initial Point escape Velocity	9.6	9.6	9.6	9.6	9.6
Fuel	Methalox	RP-1 with Oxidizer	Hydrogen, Liquid & LOX	U-235 (25% enriched)	Hydrogen, Fusion (DT)
Porosity	90%	90%	90%	90%	90%
Energy Available:	2.75E+16	8.47E+16	3.68E+16	5.29E+19	2.12E+20
Energy Required:	1.41E+17	3.60E+17	1.11E+17	6.95E+17	6.95E+17
Energy Index (Avail/Required)	0.20	0.24	0.33	76.17	304.69

Starting from 30.0 AU (Neptune)
Initial Point	Neptune	Neptune	Neptune	Neptune	Neptune
Initial Point escape Velocity	7.7	7.7	7.7	7.7	7.7
Fuel	Methalox	RP-1 with Oxidizer	Hydrogen, Liquid & LOX	U-235 (25% enriched)	Hydrogen, Fusion (DT)
Porosity	90%	90%	90%	90%	90%
Energy Available:	2.75E+16	8.47E+16	3.68E+16	5.29E+19	2.12E+20
Energy Required:	9.05E+16	2.32E+17	7.16E+16	4.47E+17	4.47E+17
Energy Index (Avail/Required)	0.30	0.37	0.51	118.40	473.60

Starting from 39.5 AU (Pluto)
Initial Point	Pluto	Pluto	Pluto	Pluto	Pluto
Initial Point escape Velocity	6.6	6.6	6.6	6.6	6.6
Fuel	Methalox	RP-1 with Oxidizer	Hydrogen, Liquid & LOX	U-235 (25% enriched)	Hydrogen, Fusion (DT)
Porosity	90%	90%	90%	90%	90%
Energy Available:	2.75E+16	8.47E+16	3.68E+16	5.29E+19	2.12E+20
Energy Required:	6.65E+16	1.70E+17	5.26E+16	3.28E+17	3.28E+17
Energy Index (Avail/Required)	0.41	0.50	0.70	161.16	644.63

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The Magnetic Anomaly – A Science Fiction Novel

The novel version of The Magnetic Anomaly is now available onAmazon (ebook, print version to come soon, also audible version).

This novel began life as a short story, similarly by not exactly titled The Magnetic Anomaly – A Science Fiction Story (note “the novel” vs “story”). Some reviewers were interested to know where the short story would go, once it was turned into a novel.

To be honest, I didn’t know myself, until I started writing it. But often the process of writing takes on a life of its own. I think it turned out quite nicely, in my humble but obviously not disinterested opinion. Fortunately, my beta readers agreed with that assessment. I hope other readers agree as well.

Summary

Below is an excerpt from the short story, which is also the first chapter of the novel:

“A geophysical crew went into the Canadian north. There were some regrettable accidents among a few ex-military who had become geophysical contractors after their service in the forces. A young man and young woman went temporarily mad from the stress of seeing that. They imagined things, terrible things. But both are known to have vivid imaginations; we have childhood records to verify that. It was all very sad. That’s the official story.”

As the summary above indicates, the main characters, geophysicist Alex and geologist Mary, survived their ordeal in the northern exploration camp. However, there was much more involved, behind the scenes, than they could imagine at the time.

The novel version of the story expands greatly on this.

Alex and Mary get caught up in a vast conflict and exciting adventure, one of literally cosmic proportions. During this time, they encounter a variety of enigmatic persons, as well as other entities, all of whom are also engaged in this struggle. With some of them they end up allying; with others, they contend in deadly conflict. The struggle takes them around the world, and eventually to the far reaches of the solar system.

During this time their relationship continues to evolve and deepen. Circumstances demand that they grow in courage and confidence, though within the scope of (mostly) normal people, as has been the case for countless people throughout history.

The story also showcases some historical events, relating to different versions of what went on in Antarctica, shortly after World War 2. Several versions of these events, official and unofficial UFO lore are given. This becomes a springboard to much of the action. Some philosophical and scientifica ideas are also explored, though not in such a way as to get in the way of the action for long.

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