<p>I'm going to say no, for a few reasons, but if anyone wants to give a more detailed answer, feel free.</p>

<p>1) Planets and moons that form inside the <a href="https://en.wikipedia.org/wiki/Frost_line_%28astrophysics%29">frost-line</a> have much less water and other ices than those that form outside.   Mars likely once had water and oceans but if it had formed outside the frost-line it should have a lot more water and a lower density.   The frost line moves away from the sun as the sun grows more luminous and planets move, so there is a degree of imprecision with this argument, but I believe this on it's own is a pretty good reason why it's not likely.</p>

<p>2) A moon that escapes Jupiter's orbit should enter a near Jupiter orbit initially, and at some point later, it could receive a gravity assist and be propelled either in towards the sun or away, but it's unlikely that Mars could have obtained it's relatively circular orbit had it originated as one of Jupiter's moons, unless Jupiter was much closer to the sun when Mars escaped.</p>

<p>3) it's difficult to see how the asteroid belt could have stayed around if Mars originated outside the asteroid belt and moved inside it.   Mars passing through the asteroid belt would have caused significant disruptions to it.   </p>

CC BY-SA 3.0
2015-11-16T08:31:37.143Z
2015-11-16T08:31:37.143Z
userLTK
<p>Yet another indication that Earth and Mars formed in the inner Solar System is that they have the same deuterium to hydrogen ratios. Primordial water trapped in 4.55 billion years old (0.017 bn years after Earth formation) lava from the deep mantle has been compared with Martian meteorites. The ratio should increase further out in the Solar System.</p>

<p><a href="http://www.abc.net.au/science/audio/2015/11/18/4354018.htm?topic=space" rel="nofollow">10 minutes radio interview</a></p>

<p><a href="http://www.abc.net.au/news/2015-11-13/origin-of-earths-water-found-in-ancient-rocks/6935928" rel="nofollow">News article</a></p>

CC BY-SA 3.0
2015-11-19T18:43:19.850Z
2015-11-19T18:43:19.850Z
LocalFluff
<p>Would more questions regarding the planet be answered if this was the case? </p>

CC BY-SA 3.0
2015-11-16T19:04:21.897Z
You could get better answers if you show us what you have have done to investigate this already. What sort of "questions" are you thinking of?
James K
<mars>
Is it plausible that Mars could have been one of Jupiter's natural satellites at one time?
user5434678
# Is it plausible that Mars could have been one of Jupiter's natural satellites at one time?

(Asked by: username_0 on 2015-11-16)

Would more questions regarding the planet be answered if this was the case?

**Tags:** mars
> **Comments:**
> **username_1**: You could get better answers if you show us what you have have done to investigate this already. What sort of "questions" are you thinking of?  

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## 2 answers

### Answer by username_2 on 2015-11-16. Score: 5

I'm going to say no, for a few reasons, but if anyone wants to give a more detailed answer, feel free.

1) Planets and moons that form inside the [frost-line](https://en.wikipedia.org/wiki/Frost_line_%28astrophysics%29) have much less water and other ices than those that form outside. Mars likely once had water and oceans but if it had formed outside the frost-line it should have a lot more water and a lower density. The frost line moves away from the sun as the sun grows more luminous and planets move, so there is a degree of imprecision with this argument, but I believe this on it's own is a pretty good reason why it's not likely.

2) A moon that escapes Jupiter's orbit should enter a near Jupiter orbit initially, and at some point later, it could receive a gravity assist and be propelled either in towards the sun or away, but it's unlikely that Mars could have obtained it's relatively circular orbit had it originated as one of Jupiter's moons, unless Jupiter was much closer to the sun when Mars escaped.

3) it's difficult to see how the asteroid belt could have stayed around if Mars originated outside the asteroid belt and moved inside it. Mars passing through the asteroid belt would have caused significant disruptions to it.


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### Answer by username_3 on 2015-11-19. Score: 2

Yet another indication that Earth and Mars formed in the inner Solar System is that they have the same deuterium to hydrogen ratios. Primordial water trapped in 4.55 billion years old (0.017 bn years after Earth formation) lava from the deep mantle has been compared with Martian meteorites. The ratio should increase further out in the Solar System.

[10 minutes radio interview](http://www.abc.net.au/science/audio/2015/11/18/4354018.htm?topic=space)

[News article](http://www.abc.net.au/news/2015-11-13/origin-of-earths-water-found-in-ancient-rocks/6935928)


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