Foreign object now leaving solar system

[e-FTW]

EDIT: Not even close to correct on speed of light, apologies. Still plenty fast though.

This is a little off-topic, but I can't imagine a better group of folks with which to wonder at this thing:
News | Small Asteroid or Comet 'Visits' from Beyond the Solar System

Came in at 25.5 km/s, leaving at 44, or about half the speed of light (90 km/s)... Wow. This sucker is going places.
What kind of forces can make an object go that fast? Some pretty massive gravity-induced slingshots, like the one it just pulled around the Sun I suppose, but stronger, or repeated multiple times?

 

[oneday]

Speed of light is 299,000 km/s

Edit: or a little more precisely 299,792,458 m/s

 

[e-FTW]

Speed of light is 299,000 km/s

Edit: or a little more precisely 299,792,458 m/s

Yup, totally spotted that and edited my post seconds after posting. But I could not edit the thread title.

 

[S4WRXTTCS]

Is there any reason why we couldn't land a probe on it or a similar one to get a ride?

 

[Doug_G]

I’ve changed the thread title. It sounded whack-a-doodle before lol.

 

[dhanson865]

Is there any reason why we couldn't land a probe on it or a similar one to get a ride?

If you could get a probe up to the speed needed to land on it you wouldn't need to. There is no friction in space so there is no advantage of "getting a ride".

 

[S4WRXTTCS]

If you could get a probe up to the speed needed to land on it you wouldn't need to. There is no friction in space so there is no advantage of "getting a ride".

It's not absolutely zero friction, but yeah I suppose for all practical purposes it is.

I just like the idea of something really small like a probe hitching a ride mostly for protection.

But, apparently I've been watching way too many movies about spacecraft hitting things in space.

From a quick web search.

"We can track asteroids down to 50 km or so in size, and objects down to 1 cm in size in low Earth orbit. Of course, smaller, undetectable rocks are more numerous. However, even in the asteroid belt, they are spread out over such a large area that the likelihood of a collision with a rock large enough to end the mission is very, very small, and we must simply accept it as one of the risks of spaceflight."

How do unmanned space probes avoid running into things? (Beginner) - Curious About Astronomy? Ask an Astronomer

 

[dhanson865]

It's not absolutely zero friction, but yeah I suppose for all practical purposes it is.

I just like the idea of something really small like a probe hitching a ride mostly for protection.

But, apparently I've been watching way too many movies about spacecraft hitting things in space.

From a quick web search.

"We can track asteroids down to 50 km or so in size, and objects down to 1 cm in size in low Earth orbit. Of course, smaller, undetectable rocks are more numerous. However, even in the asteroid belt, they are spread out over such a large area that the likelihood of a collision with a rock large enough to end the mission is very, very small, and we must simply accept it as one of the risks of spaceflight."

How do unmanned space probes avoid running into things? (Beginner) - Curious About Astronomy? Ask an Astronomer

The thing is that it takes more energy to match a position and velocity than it would to just achieve that velocity going another path (even if you went generally to the same part of the solar system)

That wasted energy would far out way any minimal momentum lost to space dust (which isn't really friction as much as it is repeated micro collisions spaced out between periods of no friction). There is photonic friction Vacuum has friction after all but it's effect is so small it matters less than the random space dust you'll hit going out of or across the solar system.

End result you better have a very very good reason to rendezvous because it costs greatly.

Still nice thought experiments. Breaks up my day of non technical activities.

 

[Grendal]

To get something to land on an object moving at the half the speed of light that probe would need to get close to the same speed. It sure wouldn't be something easy to do. If we could do such a thing we'd probably be doing it now. Maybe a very small object powered by a number of nuclear explosions. Any thing moving at a speed we could generate normally would just go splat on this object.

It was a fairly small object. We're lucky it didn't hit the Earth. This is definitely the type of object that could severely damage the biosphere. It is moving way too fast to have it burn up in the atmosphere. A 400 meter rock striking the planet at half the speed of light would cause a huge amount of damage. It may reach the level of extinction event but I think it is a little too small for that.

An object like this is a good reason to have a successful colony on Mars

 

[RubberToe]

Rendezvous With Rama...

Rendezvous with Rama - Wikipedia

 

[RDoc]

"No intelligent life in this system, beam me up"

 

[Electroman]

Why do many folks in this thread keep saying 'half the speed of light?". This object is going less than 1/100 thousand the speed of light maybe ?

 

[jkn]

For planetary defense this was not a successful exercise. They noticed it too late. We can map asteroids (not done yet) and verify none will hit us in next hundred years. We cannot map interstellar objects. We need much better system to at least detect incoming projectiles before hit.

 

[ggr]

44000 m/s / 3x10^8 m/s ~= 0.00015c. It's a simple calculation. Why are we bouncing between 1/2 and 1/100 thousand?

 

[e-FTW]

Why do many folks in this thread keep saying 'half the speed of light?". This object is going less than 1/100 thousand the speed of light maybe ?

Because I, the OP, messed up, and quickly corrected half of my assertions. The a mod kindly removed the wacky part of the messed up thread title.

If anyone cares as to how I made that half-the-speed-of-light mistake, it is called “it's been a long week” and “I barely know what I'm talking about, I'm just a fan”: I had never looked at the speed of light in km/s, and a quick Wikipedia later, I was quoting 90 km/s. That figure actually refers to the delta between the speed of light in a vacuuum and the speed of light in air.
So that interstellar object is now leaving our solar system at half of the speed delta between the speed of light in a vacuum and the speed of light in air. Not a great thread title. ;-)

 

[e-FTW]

Here are some (hopefully) accurate numbers that blow my weekend mind:

Object arrival speed: 25.5 km/s
Object departure speed: 44 km/s

It got a 72.5 % boost from that slingshot around the sun. I knew this is how things end up going fast, but that is a lot! Makes me want to know how it ended up going that fast, and how many other meetings with stars it had to have. But without knowing what got it going in the first place, that would be hard.
#orbitalMechanicsRookie

Hey, can Kerbal Space Program reproduce this orbit? I really need to get KSP...

Welp: it wasn't that fast. Turns out the Helios probes hold the spacecraft record at 70.22 km/s... Or a quarter million km/h. Or Mach 205.71. Take that, um, visitors. ;-)
Edit: And Helios hit 0.0002357 times the speed of light.

 

[e-FTW]

This says the Juno might have gone faster than the Helios probes.
The Fastest Spacecraft Ever?

It is all relative! ;-)

 

[Topher]

For reference the Sun is traveling through the (local part of the) galaxy (i.e. not including the galaxy's speed toward Andromeda, or the Great Attractor) at 20 km/s. So a non-solar rock would only need 5 km/s to appear to be going 25 km/s if it was just the right direction.

Alternatively, if it was coming in the opposite direction, so 'catching up with the sun', then it was moving at 45 km/s and is now at 65 km/s (with respect to the local portions of the galaxy).

Cool any way you think about it.

Thank you kindly

 

[e-FTW]

For reference the Sun is traveling through the (local part of the) galaxy (i.e. not including the galaxy's speed toward Andromeda, or the Great Attractor) at 20 km/s. So a non-solar rock would only need 5 km/s to appear to be going 25 km/s if it was just the right direction.

Alternatively, if it was coming in the opposite direction, so 'catching up with the sun', then it was moving at 45 km/s and is now at 65 km/s (with respect to the local portions of the galaxy).

Cool any way you think about it.

Thank you kindly

Great point, it is always infinitely relative I guess.
Now, we know the angle at which it came in, and from which direction. And I saw that the Solar System is traveling while tilted at an angle relative to the Milky Way's disc. Pretty sure someone smart can figure out the speed of that object relative to other bodies and stars.
https://www.jpl.nasa.gov/images/comet/20171026/comet20171025-16.gif
The 72% increase from 25.5 to 44 km/s is all relative to the Sun, so those numbers stand on their own.

 

[Topher]

Pretty sure someone smart can figure out the speed of that object relative to other bodies and stars.

Yeah, but that's not me... The math isn't too tough, but looking up all those relative velocities? No thanks. Perhaps Bad Astronomer will do it.

so those numbers stand on their own.

Yup.

Thank you kindly.