Or did they accidentally leave the thrust on for too long?
From [this news article](Or did they accidentally leave the thrust on for too long? From), the line “But now it seems that engine ignition worked a little too well.” might suggest that it was unintentional, but I have not seen any explicit statement anywhere.
Wrong text in your link.
I can’t remember where I read it, but the final burn was to depletion, so there was perhaps more fuel left than predicted.
Your link is broken. Is this the article?
Yes
Musk tweeted last night “Third burn successful. Exceeded Mars orbit and kept going to the Asteroid Belt.” This makes it sound like it was not accidental, they just pushed it as far as they could (as suggested by Baron Greenback). The goal was to get it out to Mars orbit, and they exceeded their goal.
We’ll probably get clarification when SpaceX releases a statement.
What a waste of a totally rocking car! 
The asteroid belt is a crowded place with a plethora of complex gravitational interactions keeping everything in alignment. It would be sheer luck if the Tesla simply settled into place without some kind of collision.
Never tell me the odds!
it’s safe to assume everything except the loss of the core booster was intentional.
It would be more lucky if it did collide. There’s lots of asteroids out there (compared to the surrounding area), but there’s far more empty space than rocks.
One can only wonder what some future explorers, a hundred million years from now, of whatever species, will think when they find it.
Will the car stay out there, or is this still a heliocentric orbit with high eccentricity?
The asteroid belt isn’t like Star Wars. It’s mostly empty. Estimates of collisions all point to them being exceedingly rare, although they do happen (Hubble captured one a few years ago). We’ve sent numerous objects through the belt without collisions.
What is the plethora of gravitational interactions you refer to? I thought Jupiter was the primary, if not only, gravitational force that impacts the belt (other than the Sun, of course).
Also, the Tesla won’t be settling into orbit with other asteroids. Its orbit will be highly elliptical with its apogee extending into the belt but its perigee still close to Earth.
Well, anything with mass has a gravitational field, so each asteroid has one, albeit a weak one. In fact, asteroids known as “rubble piles” were once solid asteroids that were fragmented by some kind of collision but, because of the mutual gravitational attraction of each fragment, drew slowly back together to form a seemingly solid mass.
It shows that even weak gravitational fields have a noticeable effect given enough time. Modest though they may be, I believe they qualify as “gravitational interactions”.
That I didn’t know. I’ll leave it to the scientists to figure out how that will all play out over time.
The rubble piles in the belt are the result of larger asteroids that were broken apart, so the material in the pile was already in close proximity and traveling with the same velocity. Extremely weak gravitational forces might keep them close, but it isn’t drawing them back together over any kind of distance. The Tesla’s orbit might be impacted by Jupiter, but it’s not going to be affected by an asteroid.
Rule of rockets. If you make a burn, then you will end up coming back to the same place that you made that burn, eventually.
(Unless you make a further burn later, obviously, and does not apply at all to hyperbolic orbits.)
So, to answer, yes, unless they make another burn when they are out past mars to circulate the orbit, it will be back in the vicinity of earth orbit at some point.
It never sounded like there was a honest effort to get to mars, just to get out to mars orbit, though it did mention a hyperbolic mars orbit, which is just another name for a flyby, so perhaps close enough to be in mars’ sphere of influence was a hope. But this launch seemed more about testing the F’n heavy rocket and what is needed on the earth side for such a launch, but not anything on the mars side. It shows we can get there, but not that we can stop there.
In some ways this makes sense as it does not require a tight launch window to mars, but can be launched whenever.
Nitpick: Aphelion and perihelion (or apoapsis and periapsis, if you want non-body-specific terms). Apogee and perigee refer to points on an orbit around earth, which this object is no longer in.
:smack: Right, thanks.
You want to show you can get to Mars…but you don’t want to actually go…they don’t want to contaminate Mars.
If they did such a burn…energy wise they mostly showed they could get there if they were serious about it.
They did mention there was a (small) chance of a collision with Mars, so worry about contamination does not seem on their radar. It does seem like they were all about the launch and after that F’ it.
And there’s no way for them to do that. It is (presumably) out of fuel, and the batteries wouldn’t last the months of coasting to get out past Mars, and even if they did, the oxygen would have boiled off long before then, etc. The third burn (after 6 hours or so of coasting) was experimental enough that it was an open question whether they’d be able to even do that or not. There’s no way a current Falcon second stage could coast for months through space and then do a burn.