Oumuamua is leaving us at high speed.

Humans try to follow it with the VLT, and they report that the thing...
is accelerating.

Accelerating?

When I first saw the drawings I thought:

Gosh! This is a spaceship. It really looks like one.

Other humans tried to listen if it emits any comprehensible signals.
They got nothing in radio frequencies, the only ones we know about.

Accelerating?

But how?

Astronomers put forward the theory of some kind of "outgassing" from its encounter with the sun. Problem is, and they are honest enough to say
it, is that no outgassing is seen.

The surface of this thing was bombarded by the sun, no problem. But
since it is tumbling, there is no preferencial side that gets more
illuminated than any any other, and at most, that would produce a dust
grain cloud around the object. But that would not furnish any THRUST!

Acceleration needs a force vector. The outgassing must be concentrated
in one direction to make the desired effect.

This thing is moving, i.e. it can change its velocity vector. This a
clear sign of life.

"Spaceship" is making this thing human-like, and this tumbling object is
surely not. But we dreamed of it in our novels and stories.

Why?

Bceause of the evidence: if we aren't the only ones around, there are
beings more advanced than us that can travel around.

Is this velocity vector change just the result of random fluctuations of
the debris cloud?

And why the hypothetical invisible coarse grains that get off the
surface of this object (if they exist, as astronomers propose) should
have a special direction?

The object is tumbling. At least it was tumbling when it passed nearby.

And it is quite massive too. Km wide.

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".

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), 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.

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

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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?

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On 6/30/18 4:58 PM, jacob navia wrote:

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?

Trying to get a dimensional feel of the problem:
Oumuamua's dimensions:
230 x 35 x 35 m = 282,000 m^3 or 2.82x1a^11 cm^3
Assume 1 g/cc density
then mass = 2.82x1a^11 g
Nature Letter says anomalous non gravity acceleration
at 4.92x10^-6 m/sec^2 or 4.92x10^-4 cm/sec^2
Therefore sun based radial Force
= 2.82x1a^11 x 4.92x10^-4 = 1.39 x 10^8 dyne
Calculate ejected material by impulse momentum F = (m/t) x v
with hydrogen ejected at temperature 20 K
(perhaps there is a better temperature
sqrt(Boltzmann x 20K/hydrogen mass) = 41,000 cm/sec
with hydrogen mass ejected on a second basis
m/t = F/v = 1.39 x 10^8/41,000 = 3,400 g/sec or 3.4 kg/sec
This net radial ejection mass quantity rate
does not seem to be that much
considering the low temperature gas potential of an object that has been wandering in cold interstellar space for millions of years.

Richard D Saam

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Le 01/07/2018 à 19:37, Richard D. Saam a écrit:

m/t = F/v = 1.39 x 10^8/41,000 = 3,400 g/sec or 3.4 kg/sec

OK, but this thing has been accelerating for months... Suppose just 4
months. At this ejection rate we have

material=3.4*3600*24*30*4
35 251 200.0 Kg

For an object whose mass is 2.82e8 Kg this represents
mass=2.82e8 Kg

mass/material

7.999727

i.e. this object should have lost 1/8th of its mass in 4 months...

And we should somehow see something of those 35 thousand tons of ejected
gas.

But maybe is not a spaceship, we will never know.

There is a recent paper
"A possible flyby anomaly for Juno at Jupiter" https://arxiv.org/abs/1711.08893v2

a team of astronomers confirms the pioneer anomaly and other spacecraft mysterious accelerations.

Maybe this object is experiencing the same "problem"?

That would be also a big scoop, maybe more productive than just an
interstellar cargo ship passing by.

:-)

jacob

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On 7/2/18 12:08 AM, jacobnavia wrote:

Le 01/07/2018 19:37, Richard D. Saam a écrit:

m/t = F/v = 1.39 x 10^8/41,000 = 3,400 g/sec or 3.4 kg/sec

OK, but this thing has been accelerating for months... Suppose just 4
months. At this ejection rate we have

material=3.4*3600*24*30*4
35 251 200.0 Kg

For an object whose mass is 2.82e8 Kg this represents
mass=2.82e8 Kg

mass/material

7.999727

i.e. this object should have lost 1/8th of its mass in 4 months...

And we should somehow see something of those 35 thousand tons of ejected
gas.

But maybe is not a spaceship, we will never know.

There is a recent paper
"A possible flyby anomaly for Juno at Jupiter" https://arxiv.org/abs/1711.08893v2

a team of astronomers confirms the pioneer anomaly and other spacecraft mysterious accelerations.

Maybe this object is experiencing the same "problem"?

That would be also a big scoop, maybe more productive than just an interstellar cargo ship passing by.

:-)

jacob

My apologies, I made a mistake length m^3 cm^3 conversion
The ejection rate .034 kg/sec and not 3.4 kg/sec
*****************
Trying to get a dimensional feel of the problem:
Oumuamua's dimensions:
230 x 35 x 35 m = 282,000 m^3 or 2.82x10^9 cm^3
Assume 1 g/cc density
then mass = 2.82x10^9 g
Nature Letter says anomalous non gravity acceleration
at 4.92x10^-6 m/sec^2 or 4.92x10^-4 cm/sec^2
Therefore sun based radial Force
= 2.82x10^9 x 4.92x10^-4 = 1.39 x 10^6 dyne
Calculate ejected material by impulse momentum F = (m/t) x v
with hydrogen ejected at temperature 20 K
(perhaps there is a better temperature
sqrt(Boltzmann x 20K/hydrogen atomic weight) = 41,000 cm/sec
with hydrogen mass ejected on a second basis
m/t = F/v = 1.39 x 10^6/41,000 = 34 g/sec or .034 kg/sec
This net radial ejection mass quantity rate
does not seem to be that much
considering the low temperature gas potential of an object that has been wandering in cold interstellar space for millions of years.

Richard D Saam

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On 7/2/2018 7:08 AM, jacobnavia wrote:

Le 01/07/2018 à 19:37, Richard D. Saam a écrit:

m/t = F/v = 1.39 x 10^8/41,000 = 3,400 g/sec or 3.4 kg/sec

...

mass/material

7.999727

i.e. this object should have lost 1/8th of its mass in 4 months...

Yes, so after a few passages close to a star it would perhaps be
destroyed. But that is what happens to comets and asteroids all the
time (assuming that this is just an asteroid).

...

But maybe is not a spaceship, we will never know.

Maybe we could listen for EM interference with sharply beamed
receiver antennas? (Or actually not just noise but intentional
radio transmissions.. Has this been investigated?)

In any case it is wise of them to disguise their spaceship as
an asteroid. And to restrict their acceleration to small values
that could be caused by outgassing. That must be quite annoying,
never to be able to put their foot on the throttle (I mean their
tentacles, of course!)

...

a team of astronomers confirms the pioneer anomaly and other spacecraft mysterious accelerations.

Maybe this object is experiencing the same "problem"?

That would be also a big scoop, maybe more productive than just an interstellar cargo ship passing by.

If it is a real asteroid, just hollowed out to carry cargo, it
might be the cheapest interstellar transportation method. If it
could somehow control its outgassing for course corrections and
use a slingshot trajectory, delivering and picking up goods at
every passage of a star..

Perhaps Elon Musk should have sent up his Tesla car to Oumuamua!
Or better a whole shipment. Primitive artifacts from the natives
are always good merchandise. (Although not always a success for
the natives.. So maybe the President didn't allow him to, fearing
a new trade imbalance would develop?)

--
Jos

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On 30/06/2018 22:58, jacob navia wrote:

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.

If we see another two go past then we will know that ET is a big fan of
Arthur C. Clarke.

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?

It is probably a bit far from the sun now to see if there is any coma.

Why not if this is a comet?

It may be a comet with a nice sturdy thick crust of black sooty dust on
the surface and the heat from the sun has finally reached a volatile
layer deep inside it. The anomolous acceleration isn't really anything
to write home about - merely that it isn't slowing down in exactly the
way that basic gravitational mechanics would predict.

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]]

ISTR Rama was spinning along the central axis allowing fake gravity on
the inside rim. And they did everything in threes.

[snip]

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?

That is an interesting question though. Did the approach trajectory look planned to take advantage of the position of any of the gas giants to
get a slingshot assist? That *would* favour ET being involved.

--
Regards,
Martin Brown

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On Mon, 02 Jul 2018, Martin Brown wrote:

That is an interesting question though. Did the approach trajectory look >planned to take advantage of the position of any of the gas giants to
get a slingshot assist? That *would* favour ET being involved.

For interstellar travel, the Sun itself can be used for a slingshot
assist for (say) travelling outwards in the Galactic disk. The key
question, I think, is whether the object approached on a similar
vector as the Sun's but travelling a bit faster so as to catch up to
the Sun..

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On 6/28/18 11:13 PM, jacobnavia wrote:

The object is tumbling. At least it was tumbling when it passed nearby.

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

Yes, interstellar originated Oumuamua's spin (tumbling) period
is faster than Rama's 4 minutes
and has a ~8 hr spin commonality with a lot of asteroids.
Is that a coincidence?
Or how about a similar period observed
by gravitationally sensitive Pathfinder
and Gravity Probe B (outside their stated missions).
And then there are universal stellar core g-waves of the same period.
It all points to a universal Machian oscillation.
Is it alive? That is the question.

Richard D Saam

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On 7/9/2018 8:42 PM, Eric Flesch wrote:

On Mon, 02 Jul 2018, Martin Brown wrote:

That is an interesting question though. Did the approach trajectory look
planned to take advantage of the position of any of the gas giants to
get a slingshot assist? That *would* favour ET being involved.

For interstellar travel, the Sun itself can be used for a slingshot
assist for (say) travelling outwards in the Galactic disk. The key
question, I think, is whether the object approached on a similar
vector as the Sun's but travelling a bit faster so as to catch up to
the Sun..

The key question for the slingshot hypothesis is whether it
comes from the direction of a nearby star and leaves the solar
system into the direction of another nearby star.

If both directions would match a star within, say 100 psc
distance, then it is a slingshot trajectory for traveling
along three stars. (By definition it is such a trajectory,
whether it is *intentionally* so, or just by accident, is
then still not proven. but one could calculate how small
the chances for the latter would be..)

Of course one could always match the two directions to very
distant stars, but then there is a big chance that it is
accidental. There are 2 'uncertainty cones' around the
measured directions of arrival and departure and we could
ask: What are the nearest stars in those two cones and
how small (or big) is the combined chance of finding them
at those distances.

[And if nobody has published the result of that calculation
yet, that fact is of course good material for a conspiracy
theory! :-) ]

--
Jos

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Le 09/07/2018 à 20:42, Eric Flesch a écrit :

For interstellar travel, the Sun itself can be used for a slingshot
assist for (say) travelling outwards in the Galactic disk. The key
question, I think, is whether the object approached on a similar
vector as the Sun's but travelling a bit faster so as to catch up to
the Sun..

Obviously I thought about that. But wait...

The problem of spaceship Oumuamua is that is... VERY slow. It takes
thousands and thousands of years for a hop. At 38 Km sec, it takes 7894
years to make a single light year. Stars are about 5 or 6 ly from each
other, so each hop takes around 40 000 years.

You rather be patient in such a spaceship.

The oldest living being on earth (a pine tree in California) has around
5 000 years. Bacterial spores can survive 30 000 years (Wikipedia).
Living beings adapted to such an environment as this piece of rock could
do it, maybe.

There could be beings that arrive to steer their rock by outgassing a collimated beam of 340g of material, as R. D. Saam calculated.

But that is total speculation. Fact is, as a spacehip it is not very
fast. Faster than anything we can achieve now, but not fast enough for
an interstellar spaceship.

I think we will come back to it in some years.

A fast machine will start from earth and catch up with it. And resolve
its mystery.

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Oumuamua wasn't a "traditional" spaceship but it is a solar sail.

https://arxiv.org/pdf/1810.11490.pdf

This point of view is proposed by reearchers Shmuel Bialy and Prof.
Abraham Loeb.

Oumuamua would be then, a thin (1mm) sheet designed to reflect as much
as possible solar radiation. This would explain the acceleration that we
see as it leaves us.

[Moderator's note: They discuss a "width" of 0.3--0.9 mm for the sheet.
I would use "thickness" here. -P.H.]

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On Thursday, June 28, 2018 at 5:13:18 PM UTC-4, jacobnavia wrote:

Oumuamua is leaving us at high speed.

snip
Easily explained.

Earth is a local stop; Oumuamua is long-distance (LD) express
(like Amtrak). Probably had a stop not too far back and is
now accelerating to it's next station.

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

That's how you know it's an LD express.

mj horn

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