Naked Science Forum

Non Life Sciences => Physics, Astronomy & Cosmology => Topic started by: chiralSPO on 06/11/2018 15:05:15

Title: Could Oumuamua be a light sail?
Post by: chiralSPO on 06/11/2018 15:05:15
Remember Oumuamua? (that interstellar thing that whizzed by us in 2017?) They're not saying it's aliens... (please be aliens! ...maybe?) but they are saying it is consistent with a light sail. (and "they" includes the chair of the astronomy department at Harvard)
https://arxiv.org/pdf/1810.11490.pdf

Part of the evidence is a previously published result that shows non-gravitational acceleration away from the sun with a statistical significance of 30 sigma (that's very high)
https://www.nature.com/articles/s41586-018-0254-4
Title: Re: Could Oumuamua be a light sail?
Post by: chris on 06/11/2018 21:12:45
Actually, some reports are selling it as a potential alien "visitation":

https://uk.yahoo.com/news/mystery-interstellar-asteroid-oumuamua-apos-170200169.html
Title: Re: Could Oumuamua be a light sail?
Post by: evan_au on 07/11/2018 08:30:06
Quote from: chiralSPO
a statistical significance of 30 sigma (that's very high)
But the statistical significance was not sufficient to confidently distinguish acceleration between forces proportional to 1/r or 1/r2...
Title: Re: Could Oumuamua be a light sail?
Post by: chiralSPO on 07/11/2018 15:30:27
Quote from: chiralSPO
a statistical significance of 30 sigma (that's very high)
But the statistical significance was not sufficient to confidently distinguish acceleration between forces proportional to 1/r or 1/r2...
True. They are certain that there was a non-gravitational acceleration, and that it was strongest when closer to the sun. But they did not have enough data (and/or precision) to distinguish the r1 from r2 relationships. I can't think of any force that goes as r1, and many that go as r2...
Title: Re: Could Oumuamua be a light sail?
Post by: guest46746 on 07/11/2018 19:42:34
Any rational person would consider if a solar wind was present in the vicinity and its velocity!  non gravitational acceleration is more fluff then story! lol

Title: Re: Could Oumuamua be a light sail?
Post by: yor_on on 08/11/2018 13:55:57
Very interesting, but considering that it took no active notice of us?
Why didn't it. Can't be that difficult to notice us existing.

" ʻOumuamua was compared to the fictional alien spacecraft Rama because of its interstellar origin. Adding to the coincidence, both the real and the fictional objects are unusually elongated and limited in size.[33] However, ʻOumuamua has a reddish hue and unsteady brightness, which are typical of asteroids.[34][35][36]

The SETI Institute's radio telescope, the Allen Telescope Array, examined ʻOumuamua, but detected no unusual radio emissions.[37] More detailed observations, using the Breakthrough Listen hardware and the Green Bank Telescope, were performed;[33][37][38] the data were searched for narrowband signals and none were found. Given the close proximity to this interstellar object, limits were placed to putative transmitters with the extremely low power of 0.08 watts.[39] " https://en.wikipedia.org/wiki/%CA%BBOumuamua

Also it is described as 'tumbling' through space.
Title: Re: Could Oumuamua be a light sail?
Post by: evan_au on 08/11/2018 21:15:40
The other implication of that paper was that if it was affected by light pressure, then it must have been hollow, with very thin walls.

I guess solar wind might have more momentum than light?
Title: Re: Could Oumuamua be a light sail?
Post by: yor_on on 09/11/2018 10:02:09
Yea, it should be blue shifted relative the Oumuamua, shouldn't it?
Title: Re: Could Oumuamua be a light sail?
Post by: Lance Canham on 10/11/2018 01:29:43
Im thinking that Maybe a Planet much like earth in that water flowed as a liquid created Shale or something and it got smashed to smithereens and it is a piece of Shale which is much more reflective than most Asteroids as we know them.  Since its not round it likely has a far greater surface area at times pointing toward the sun and also being more reflective added to probably lighter with less metal content. Therefore its's a natural solar sail. 

Dats my best attempt at it then Who knows
Title: Re: Could Oumuamua be a light sail?
Post by: guest46746 on 10/11/2018 15:09:42
Dats my best attempt at it then Who knows

I don't wish to detract from the seriousness of the discussion. One of my first impressions when seeing Oumuamua was that of an exhaust pipe. As such it would be hollow and extremely light as commented above. It would also allow for collected propulsion to be expelled from one if not both ends. A microwave infinity drive it you will!  lol
Title: Re: Could Oumuamua be a light sail?
Post by: David Cooper on 10/11/2018 20:36:19
How do we know what shape it is? From what I heard at the time, all they had was a regular brightening and darkening as it rotated, suggesting that we were getting more light from it when it's side on and less when it's end on, but it could simply be round with two bright spots on opposite sides.