Le 28/06/2018 23:13, jacobnavia a écrit :

Accelerating this thing?

And accelerating so fast that we can detect it?

If we are all serious and agree that spaceships do not exist, we will
never see one when it passes by.

A pity for us. Oumuamua is leaving us at great speed. Changing its
course for new endeavours.

jacob

[[Mod. note -- Yes, many of us have read "Rendezvous with Rama".


I didn't, that is one novel from Clarke I am missing. But it is fun now
that it is the VLT that is bringing the news... A much better novel.

Incredible things happen.

But it seems to me that for Oumuamua the "comet-like outgassing"
hypothesis is strongly favored by Occam's razor: we know that other
objects (comets) outgas in this way (many comets are observed to have
non-gravitational accelerations of this type),

Sure, this thing is outgassing. Comets can do it but... we do not see
any outgassing.

Strange isn't it?

Why not if this is a comet?

The "comet/inert rock from other solar system just tumbling around"
hypothesis could be true.

But the spaceship hypothesis has some traction in it too.

and if Oumuamua has
spent little time near a star it's quite plausible that its surface
still has plenty of volatiles (e.g., frozen water and/or methane)
which would vaporize (outgas) when heated by a close solar passage.


Sure. But then... we would see it isn't it?

We don't.

And, unlike Rama, Oumuamua's spin (tumbling) period seems to be a
lot longer than 4 minutes.
-- jt]]


Yes, but that is a detail. The idea behind this post is to discuss in
public scientific hypothesis. And the spaceship solution is one of the
solutions of this equation.

We know its mass, we know its acceleration, how much energy would be
necessary to make the observed delta v?

We can calculate the tons of material necessary to give the observed
thrust isn't it?

How much is that?

That would be one way of verifying the outgassing hypothesis.

How can the spaceship hypothesis be verified?

Well, if it is living, it can navigate. We use the mass of Jupiter to
point us in the right direction with an added boost. (The new Horizons
spaceship for instance).

If it is using the mass of the sun to get a boost, as we do, it is
accelerating in the direction of its next star.

We have just try to figure out where is it moving to.

Fun, isn't it?

What is this thing?