The series of fortunate astrophysical events that gave us Ceres | Hacker News Reader

The series of fortunate astrophysical events that gave us Ceres

nautil.us

89 pointsdnetesn19 comments

Original title: How Ceres, the Largest “Dark Asteroid,” Survived the Inner Solar System

A better title, for sure. 1) gives the name of the body, 2) doesn't imply it's near us -- "inner solar system" is still pretty dang far, and 3) gives a better idea what it will be about, namely how this asteroid is still around.

Ceres is considered a "dwarf planet", now that it's known to have pulled itself into a rather good sphere. It's surprising that 0.03g is enough to do that.

Wow: “Meanwhile they were heating up, mainly from the radioactive element Aluminum-26. The amount of energy this element released during the first 2 to 3 million years of solar system history amounts to more than all of the heat released by all other sources over the past 4.5 billion years (except for the sun, of course).”

I was surprised to see that such a silly, narrow-minded, and misleading statement actually came from one of the authors of the paper, and not an editorializing pop-science writer.

First of all, it's obvious that it amounts to more than all the heat released by all other sources that we know of. How is it that we discover this new interesting way heat could have been released, and it doesn't occur to us that maybe there are other new interesting ways heat could have been released that we haven't discovered yet? The very discovery of that mechanism is exactly evidence that we have not yet discovered all possible sources of heat in the early universe. It's crazy that I need to point this out.

Secondly, it's worded extremely misleadingly. The article goes "Ceres did this; Ceres did that; it's a member of this type of body; these bodies involved this element; this element was the source of a tremendous amount of heat". What produced all that heat? Not Ceres. Not carbonaceous asteroids. Aluminum-26 around the entire solar system. Most of that heat generation could have occurred (and probably did occur) in the core of Jupiter, not in Ceres. Yet it makes it sound like early Ceres was a huge source of heat in the solar system. This is a pretty extreme amount of carelessness from this author.

The wording seemed fairly straightforward given the given the context.

The sentence itself speaks about the "solar system history," mentioning the sun for comparison, and the paragraph after that attributes the heating of planetesimals to Aluminum-26 specifically. Ceres is not even mentioned in the two paragraphs that describe heating.

Regarding the remarkable points about AL-26,

"Meanwhile they were heating up, mainly from the radioactive element Aluminum-26. ... this hot stuff’s radioactivity is short-lived: With a half-life of 700,000 years, it was basically all used up, or extinct, within 2 or 3 million years."

So why was there a significant amount of it in the young Sun? Wiki[1] says it "is mainly produced in supernovas ejecting many radioactive nuclides in the interstellar medium." So are they guessing that the Sun condensed from a cloud of material that was _recently_ ejected by a supernova? (Because if it wasn't recently produced, there wouldn't have been any AL-26 left.) Something of a violation of the Mediocrity principle[2].

[1] https://en.wikipedia.org/wiki/Aluminium-26

[2] https://en.wikipedia.org/wiki/Mediocrity_principle

They mention using Dyneema for the space elevator tether, a material I hadn't heard about.

https://www.gearpatrol.com/outdoors/a462827/everything-you-n...

It's used on sailboats. Shows very low stretch under load. https://www.landfallnavigation.com/boats-parts/sailing-lines...

It's used very widely in climbing as a lighter-weight alternative to nylon

Probably the most valuable real estate in the solar system. See

https://arxiv.org/pdf/2011.07487.pdf

This is amazing.

And probably step three to being a multiplanetary species!

If you take that paper seriously it points out serious deficiencies in all the other space colonization schemes like the O'Neill cylinders.

I like, however, the idea that interstellar travelers who'd mastered D-D fusion and could live (for a while) independently of stars could cut an object like Pluto up. The outer layers of Pluto contain huge amounts of nitrogen and carbon monoxide not to mention water and would be good for making organic chemicals, plastics, bodies, cattle, etc. but it seems you'd have to dig in pretty deep to find metal oxides and stones. In the case of Pluto you could probably get rock to tide you by from Charon but as that paper points out there's a strong motivation to not waste volatiles with rockets but rather do all as much transportation by cable and rail.

Even if aliens like that were "grabby" they might have little interest in dry inner solar system worlds that are good for very little living area. If "grabby" aliens had come to our solar system, however, they probably would have consumed Ceres and/or Pluto.

I hope I live long enough to see the mission to 16 Psyche, a massive mostly-metal asteroid, which has enough resources (theoretically) to propel humanity into a space-based species. Seriously.

I could imagine we send 3d printers to 16 Psyche and get Starships landing in return. We could do this - we have the ability - we just don't have the moral/ethical motivation.

Nevertheless, I hope I see the results of the mission, one of these days. Its truly exciting.

I have great news for you. https://psyche.asu.edu/

only have to last to 2029

Yes, I have my eyes on that mission. Only 6 short, uneventful years to go ..

> I could imagine we send 3d printers to 16 Psyche and get Starships landing in return.

Where would the starships get their fuel?

Harvesting the interstellar medium? Transfer ships from Earth? Some random comet redirected to the area? I dunno, let science work it out. I just wanna dream.

https://archive.is/DzoJd

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