Moving a moon

It's encouraging, sort of, that in these fraught times there is still stuff like this being done: https://www.sciencenews.org/article/asteroid-moon-name-nasa-course-deflection-mi....

Looks like that asteroid would be a good candidate for another deflection method proposed; where they connect 2 asteroids orbiting each other to make a bolo of some sort which is supposed to change the center of gravity of the system and consequently change its path.

>2 DugsBooks: Got a reference for that idea? I can’t see how that would affect the system’s common centre of gravity. Wouldn’t you need to change the energy of one body somehow (as the NASA suggestion does)?

I'm wondering if you could do something like join them together with a length of rather strong stuff, then winch them closer to each other and/or apply a gradual force to speed up the rotation. Releasing the tether at a suitable point might then cause them to lose their gravitational connection, and fly off in opposite directions. Possibly. Details left as an exercise for the reader...

>3 haydninvienna: Here ya go. I read this probably 2am one restless eve.

"I can’t see how that would affect the system’s common centre of gravity. Wouldn’t you need to change the energy of one body somehow (as the NASA suggestion does)?

My thoughts exactly when I read the article, my slide rule is in the shop or I would have challenged them certainly. ;-)

https://futurism.com/the-byte/deflect-killer-asteroids-tie-shoelaces-together

>5 DugsBooks: Not clear that we are talking about the same thing here. The Science News article is about a proposal to change the orbit of the smaller body by, basically, bumping it. The original paper that your link talks about is here. Granted that the style isn't crystalline, and that I don't do partial differential equations, but what I think they're talking about is shifting the orbit of a hazardous body by tethering it to a smaller body. In other words, not starting with two mutually orbiting bodies but creating one: "This paper presents a tether assisted methodology to deflect a PHA by connecting a smaller asteroid, altering the center of mass of the system, and consequently, moving the PHA to a safer orbit.".

>6 haydninvienna: If I read it correctly, they are talking about using a tether at least 1000-3000 km long, without discussing what sort of material it might be made of (strength, elasticity), taking the tether's mass into consideration (Oh, wait, we don't know the material, so we don't know its mass.) or how it could be attached to the two bodies. Also "the logistics of capturing and transfering the smaller asteroid is not included in this study."

It's good to know that 101955 Bennu is not going to crash into the Earth in my lifetime, as the tether method is not going to functional in that period either.

>7 MarthaJeanne: Yup, all that too. I did read the whole paper, although I skipped the equations. In >6 haydninvienna: I was mainly concerned to point out that the experiment that I originally posted about wasn't the same as the one referred to in >2 DugsBooks: .

I think they could have at least calculated the necessary strength of the tether.

>6 haydninvienna: >7 MarthaJeanne: Thanks for clarifying that. I just browsed the article one late eve and assumed the two asteroids already had a gravitational relationship that tied them together - the thought of capturing one then securing it too another seemed to daunting to be what they intended in my hasty review.

None the less when you consider the possible consequences, no matter how remote, endeavors like >1 haydninvienna: are something humanity needs to keep putting effort into. The "near earth orbit" people have a mostly long and boring job but vital IMOHO.