APOD: 'Oumuamua: Interstellar Asteroid (2017 Nov 22)

[APOD Robot]

'Oumuamua: Interstellar Asteroid

Explanation: Nothing like it has ever been seen before. The unusual space rock 'Oumuamua is so intriguing mainly because it is the first asteroid ever detected from outside our Solar System -- although likely many more are to follow given modern computer-driven sky monitoring. Therefore humanity's telescopes -- of nearly every variety -- have put 'Oumuamua into their observing schedule to help better understand this unusual interstellar visitor. Pictured is an artist's illustration of what 'Oumuamua might look like up close. 'Oumuamua is also intriguing, however, because it has unexpected parallels to Rama, a famous fictional interstellar spaceship created by the late science fiction writer Arthur C. Clarke. Like Rama, 'Oumuamua is unusually elongated, should be made of strong material to avoid breaking apart, is only passing through our Solar System, and passed unusually close to the Sun for something gravitationally unbound. Unlike a visiting spaceship, though, 'Oumuamua's trajectory, speed, color, and even probability of detection are consistent with it forming naturally around a normal star many millions of years ago, being expelled after gravitationally encountering a normal planet, and subsequently orbiting in our Galaxy alone. Even given 'Oumuamua's likely conventional origin, perhaps humanity can hold hope that one day we will have the technology to engineer 'Oumuamua -- or another Solar System interloper -- into an interstellar Rama of our own.

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[Wayne Jepson]

Oumuamua is far smaller than Rama, however... it is much closer in size to a Klingon vessel, or at least the wreckage of one - with its engines blasted off, leaving it with the quasi-cigar shape that this alleged asteroid apparently has :~)

[RocketRon]

Any resemblance between reality and an "artists illustration" is purely conjectural ?

are consistent with it forming naturally around a normal star many millions of years ago

Millions of years ??

With the distance it has to have come from - from even the closest possible star, and its (relatively) low speed,
it would more likely have been billions of years ago ?

Possibly even before our Solar System formed, in fact.
So it was purely an accidental vistor ?

[pckozy]

Love the reference to Rama. A wonderful story by one of the best scifi writers of all time. Remeber Ramans do things in threes.

[bystander]

http://asterisk.apod.com/viewtopic.php?t=37698

[RocketRon]

&
https://apod.nasa.gov/apod/ap171103.html

Could this object be from the "Solar System" that was 'here' before ours ?
More of a time traveller than a distance traveller, perchance ??

[Spif]

That 6 to 1 aspect ratio looks suspiciously unnatural?

No ice or dust ejecta near the sun. Hmm.

Comes out of nowhere and pulls a nice tight slingshot maneuver well inside Mercury's orbit?

I'm starting to wish that maybe this thing just blew the Fermi Paradox away

If its incoming and outgoing trajectories seem to aim at the same star, that could be a somewhat convincing clincher.

But then that speed of 26kps is just not practical for interstellar anything... 50k years just to cover the distance of Alpha Centauri.

[Boomer12k]

Maybe its intelligent riders don't consider TIME to be a factor....Muuahhhhahahaha!

IT would be COOL!!!! To put a SUIT OF CAMERAS and a bunch of SENSORS ON IT.....maybe next time....

Bon Voyage...
:---[===] *

[JohnD]

Assuming that 1I's shape can be approximated by an ellipsoid, the amplitude constraint implies that 1I has an axial ratio of 4.1 to 6.9, which is strikingly elongated. Assuming that 1I is rotating below its critical break up limit, our results are compatible with 1I having a density > 1.0 g cm−3, or having modest cohesive strength (Bolin, et al)
ʻOumuamua has a rotation period of 7.3 to ~8.10 (± 0.42) hours (Wiki - sorry, I'm doing this quickly!)
length is about 800 meters. (Science website - again, improper ref)

So that's smaller than 67P/Churyumov–Gerasimenko, but rotating faster, so the 'critical break-up limit' is a real concern, but the picture looks like a slab of slate, not the rock pile that is the only asteroid we've ever seen up close. And a density of "less than 1gm/cm^3" is low compared to other estimates of asteroids. So is Oumuamua a solid slab?

Spif, the projected trajectory change is through about 90 degrees. No question of a hairpin turn and back where it came.

John

[RocketRon]

If its incoming and outgoing trajectories seem to aim at the same star, that could be a somewhat convincing clincher.

incoming and outgoing trajectories are not consistent with this statement.

https://www.nasa.gov/sites/default/file ... k=178v74Z7

(If it was only sighted rather late, how was this path extrapolated ?)

[JohnD]

This one extrapolates further:
https://www.eso.org/public/images/eso1737c/

John

[heehaw]

"passed unusually close to the Sun for something gravitationally unbound." I've never understood how it can be that so many comets come so very close to our sun. Can anyone explain it to me?

[BDanielMayfield]

Very nice to see that this wonderfully unique newly discovered object gets an[other] APOD nod.

"passed unusually close to the Sun for something gravitationally unbound." I've never understood how it can be that so many comets come so very close to our sun. Can anyone explain it to me?

The explanation involves things you already know sir, so your question is a bit baffling. The Sun's large mass is a strong gravitational attractor, and there are a great many bodies under the influence (within the range) of that attractor.

That 6 to 1 aspect ratio looks suspiciously unnatural?

No ice or dust ejecta near the sun. Hmm.

Comes out of nowhere and pulls a nice tight slingshot maneuver well inside Mercury's orbit?

I'm starting to wish that maybe this thing just blew the Fermi Paradox away

6 to 1? I've read that it has an even more extreme length to width of 10 to 1. If true, that would even bolster Spif's conjecture.

I don't believe in UFOs, but ... Nah, it's gotta be natural.

But then again, the shape and density could be consistent with a spent stage of some kind of an interstellar propulsion device...

Nah. No way. I absolutely do not think that this is an artifact. But I'm wrong sometimes.

Bruce, covering both bases.

[hamilton1]

"passed unusually close to the Sun for something gravitationally unbound." I've never understood how it can be that so many comets come so very close to our sun. Can anyone explain it to me?

The vast vast majority of comets come nowhere near the Sun... it's because thousands of comets do come near the Sun that we know the Oort cloud exists, which must contain trillions of comets to produce the numbers that we actually see.

[neufer]

Click to play embedded YouTube video.

Comes out of nowhere and pulls a nice tight slingshot maneuver well inside Mercury's orbit?

I'm starting to wish that maybe this thing just blew the Fermi Paradox away

If its incoming and outgoing trajectories seem to aim at the same star, that could be a somewhat convincing clincher.

But then that speed of 26kps is just not practical for interstellar anything... 50k years just to cover the distance of Alpha Centauri.

Well...of course they came out of hyperspace in order to examine our solar system.

[Zoomer]

" ...because it is the first asteroid ever detected from outside our Solar System -"
How is this possible unless Voyager1 somehow reported it?
Or is this just a simple and too common grammatical error?

[Chris Peterson]

Millions of years ??

With the distance it has to have come from - from even the closest possible star, and its (relatively) low speed,
it would more likely have been billions of years ago ?

It could be any long length of time. But millions of years is perfectly reasonable. We're talking about a body which is approximately co-orbiting with our own Solar System within the Milky Way. That means both us and it make a complete orbit around the center of our galaxy every 250 million years or so, passing or being passed by countless stars, rogue planets, rogue asteroids in similar orbits.

[neufer]

Millions of years ??

With the distance it has to have come from - from even the closest possible star, and its (relatively) low speed,
it would more likely have been billions of years ago ?

It could be any long length of time. But millions of years is perfectly reasonable. We're talking about a body which is approximately co-orbiting with our own Solar System within the Milky Way. That means both us and it make a complete orbit around the center of our galaxy every 250 million years or so, passing or being passed by countless stars, rogue planets, rogue asteroids in similar orbits.

Hundreds of millions of years might be reasonable but billions of years is more reasonable.

(Just sagan...)

[Spif]

If its incoming and outgoing trajectories seem to aim at the same star, that could be a somewhat convincing clincher.

incoming and outgoing trajectories are not consistent with this statement.

https://www.nasa.gov/sites/default/file ... k=178v74Z7

Local stars move relative to our own solar system. Those relative motions tend to be on the order of tens of km/s (except for halo stars, and "rogue" stars generally).

So that snapshot of the object's trajectory is not inconsistent with the speculative idea of a probe originating from and returning to the same star. (Although why someone would devise a mission for a probe to fly by and then return to the home system, I don't know. A more likely behavior would be to transmit findings back home and then move on to another nearby star. So if that outbound trajectory is aimed to intercept another star ... that would be a pretty impressive indicator of unnatural origin as well.)

(If it was only sighted rather late, how was this path extrapolated ?)

Technically, it only takes three observed data points to determine the orbital trajectory of an object. You need four dimensions on those points: for example, two angles, range, and time. Generally you want to make the three measurements with a significant time separation to increase the accuracy of your projection. This is because time separation helps to decrease sensitivity to errors in your positional measures. Making more than three observations further increases accuracy of the projection. I'm guessing that we have hundreds of such data points.

[Fred the Cat]

Talk about a cat box survivor. It would be a giant “cat ass trophy” if the mess-enger "escaped" from a society of giant felines.

Scoop up that asteroid.

[InfinitiesLoop]

Someone mentioned it in this thread already, but I think it deserves discussion -- what is the feasibility of a mission to outfit a visitor like this with sensors? Why build a probe when nature has provided one?

We'd have to match its speed to be able to land on it, perhaps at that point you don't even need to land on it anymore. So I suppose the trick would be in getting something onto it without having to match its speed, like a snare or something. The more I think about it the more untenable it sounds, but there's gotta be something to it. Plenty of comets and asteroids with predictable orbits to practice on.

[neufer]

Someone mentioned it in this thread already, but I think it deserves discussion -- what is the feasibility of a mission to outfit a visitor like this with sensors? Why build a probe when nature has provided one? We'd have to match its speed to be able to land on it, perhaps at that point you don't even need to land on it anymore. So I suppose the trick would be in getting something onto it without having to match its speed, like a snare or something. The more I think about it the more untenable it sounds, but there's gotta be something to it. Plenty of comets and asteroids with predictable orbits to practice on.

<<Off on a Comet (French: Hector Servadac) is an 1877 science fiction novel by Jules Verne. The story starts with a comet that touches the Earth in its flight and collects a few small chunks of it. Some forty people of various nations and ages are condemned to a two-year-long journey on the comet. They form a mini-society and cope with the hostile environment of the comet (mostly the cold). The size of the 'comet' is about 2300 kilometers in diameter - far larger than any comet or asteroid that actually exists.>>
----------------------------------------

---

The 36 inhabitants of Gallia include a German Jew, an Italian, three Frenchmen, eight Russians, 10 Spaniards, and 13 British soldiers. The main characters are:

* Captain Hector Servadac of the French Algerian army
* Laurent Ben Zoof, Servadac's aid
* Count Wassili Timascheff of Russia
* Lt. Procope, the commander of Timascheff's yacht, Dobrina
* Isaac Hakkabut, a German trader
* Nina
* Pablo
* Colonel Heneage Finch Murphy and Major Sir John Temple Oliphant of Britain's Gibraltar garrison.
* Palmyrin Rosette, the French discoverer of the comet and previously Servadac's teacher.
----------------------------------------
<<From the beginning Verne had problems with this novel. Originally he intended that Gallia would crash into the earth killing all on board. This may have been the motivation for his ghoulish and rather unfunny joke naming the hero "Servadac" with the mirror of the French word cadavres (="corpses"), predicting all would die on the "return". His publisher Hetzel would not accept this however, given the large juvenile readership in his monthly magazine, and Verne was forced to graft a rather unsatisfying ending onto the story, allowing the inhabitants of Gallia to escape the crash in a balloon.>>

[JohnD]

InfinitiesLoop
Just THINK for a moment.
This object was moving faster than anything else in the Solar System, 315,000 kilometres per hour.

67P/Churyumov–Gerasimenko's maximum velocity was 135,000 km/h, and the Rosetta mission was launched in 2004, to meet it in 2014, TEN YEARS LATER. It needed all that time for several 'sling-shots', three past the Earth and one past Mars to achieve rendezvous. There's a smashing animation of the process here: https://www.youtube.com/watch?v=ktrtvCvZb28

Now, how long have we known about Oumuamua? Since October 19th, this year. And it's moving more than twice as fast as 67P. Now, you answer your own question. Could we have set up a mission to catch, land on it and set up an obsevation post?
John

[Wayne Jepson]

My understanding, from the various articles I've read about this object so far, is that the only arguments supporting this being a natural 'asteroid' are:

1) it's trajectory can be defined solely by it's initial velocity and direction of motion, as influenced by the gravity of our sun during its close pass
(i.e. there is no evidence that its path is influenced by any sort of active, on-board propulsion system; it is adrift / tumbling in space)
2) it is red; and,
3) of course its natural, there's no such thing as aliens.

On the other hand, arguments for it not being "natural" include:

1) we are tracking over half a million asteroids in our solar system, none of them are known to have an aspect ratio as great as 10:1.
2) a spacecraft that is no longer functional could easily have a similar observed trajectory, you can speculate on how and when it achieved its observed velocity; and,
3) it is red. Why not paint your spacecraft red?

Anyone else have any further insights to add to either side of the debate?

[InfinitiesLoop]

InfinitiesLoop
Just THINK for a moment.
This object was moving faster than anything else in the Solar System, 315,000 kilometres per hour.

67P/Churyumov–Gerasimenko's maximum velocity was 135,000 km/h, and the Rosetta mission was launched in 2004, to meet it in 2014, TEN YEARS LATER. It needed all that time for several 'sling-shots', three past the Earth and one past Mars to achieve rendezvous. There's a smashing animation of the process here: https://www.youtube.com/watch?v=ktrtvCvZb28

Now, how long have we known about Oumuamua? Since October 19th, this year. And it's moving more than twice as fast as 67P. Now, you answer your own question. Could we have set up a mission to catch, land on it and set up an obsevation post?
John

The first thing you need to do when solving a difficult problem is identify the things that make it difficult. No reason to stop there. I never claimed it would be easy -- in fact, suggesting one of the problems being matching its speed. Yes that is difficult, but not impossible. Knowing when one is coming is another problem, but early detection of things like this is bound to get better, hence my statement about having predictable objects to practice on. I think it'd be interesting to explore the possibilities, however difficult or crazy they may be.