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Astronomical engineering: a strategy for modifying planetary orbits

D. G. Korycansky, Gregory Laughlin, Fred C. Adams

2001 · arXiv

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From the abstract

The Sun's gradual brightening will seriously compromise the Earth's biosphere within ~ 1E9 years. If Earth's orbit migrates outward, however, the biosphere could remain intact over the entire main-sequence lifetime of the Sun. In this paper, we explore the feasibility of engineering such a migration over a long time period. The basic mechanism uses gravitational assists to (in effect) transfer orbital energy from Jupiter to the Earth, and thereby enlarges the orbital radius of Earth. This transfer is accomplished by a suitable intermediate body, either a Kuiper Belt object or a main belt asteroid. The object first encounters Earth during an inward pass on its initial highly elliptical orbit of large (~ 300 AU) semimajor axis. The encounter transfers energy from the object to the Earth in standard gravity-assist fashion by passing close to the leading limb of the planet. The resulting outbound trajectory of the object must cross the orbit of Jupiter; with proper timing, the outbound object encounters Jupiter and picks up the energy it lost to Earth. With small corrections to the trajectory, or additional planetary encounters (e.g., with Saturn), the object can repeat this process over many encounters. To maintain its present flux of solar energy, the Earth must experience roughly one encounter every 6000 years (for an object mass of 1E22 g). We develop the details of this scheme and discuss its ramifications.

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In the conversation

Original HN comments, with labels from simple text rules. A label describes the whole comment and may miss context or irony. Read the discussion to make up your own mind. About the labels

4 selected excerpts · 4 total mentions

ben_w
Neutral mention · rule
> How do you know? It's not far fetched to think that, if humans don't go extinct in the meantime, they will continue to find ways to shape the world according to their needs. I'd say it's pretty far-fetched to imagine humans caring about things 7 generations into the future, let alone 3e7 generations. > By the time the Sun goes red giant, we may well have found a way to alter the orbit of Earth. By the time the Sun goes supernova, we may be able to move to another star. Who knows. We already know how to meaningfully alter Earth's orbit over such timescales[0], the sun won't go super-nova anyway (too small)[1], and we know what it would take to increase its lifetime by a…
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few orders of magnitude even if organising ourselves on the numerical and time scales required is beyond us[2]. But even maximally extending the lifespan of Sol would take us to perhaps 100 trillion years if we're very lucky, and that's if we actually engage in the exact kind of long-term thinking that people currently criticise the Longtermism movement for even daring to consider. [0] https://arxiv.org/abs/astro-ph/0102126 [1] https://en.wikipedia.org/wiki/Supernova#Core_collapse [2] https://en.wikipedia.org/wiki/Star_lifting#Stellar_husbandry
Original comment 'More than a hint' that dark energy isn't what astronomers thought
jwm1
Neutral mention · rule
Cycling a large asteroid between Earth and Jupiter could be used to slowly shift the orbit of Earth, most of the energy coming from Jupiter. Astronomical engineering: a strategy for modifying planetary orbits [https://arxiv.org/abs/astro-ph/0102126]
Original comment Why does it take so long to get to Mercury?
FiatLuxDave
Neutral mention · rule
Here is a relevant paper which may answer some of your questions: https://arxiv.org/abs/astro-ph/0102126 I've been slowly writing a paper about how to move planets by using repeated gravitational assists from masses moving in orbits which repeatedly cycle between inner and outer planets, conveying momentum from one planet to another. Unfortunately, I just don't have time to finish it right now. Feel free to email me if you want to discuss this stuff in more depth.
Original comment Ask HN: What would it take to move the Earth out of its orbit?
ben_w
Neutral mention · rule
That question is definitely unknowable in advance, because our intelligence level leads to radical changes in the environment in which we exist. If we really, really, cared, we could set up a momentum exchange between Earth and Jupiter mediated by an asteroid, moving Earth further out and Jupiter (slightly) further in, chasing the outward drift of the Sol habitable zone: https://arxiv.org/abs/astro-ph/0102126 Also, we could (in principle, not saying we will or we should) engage in selective breeding or genetic engineering of ourselves; and while mind-uploading is currently SciFi, it’s in the category of “we recon this is eventually possible” rather than “convenient plot device”.
Original comment The future lifespan of Earth’s oxygenated atmosphere

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