How do they know it’s from Mars? Does it have “If found, please return to Marvin” inscribed on the bottom?
Of course, you couldn't be bothered to click the link and read any of the actual article.
They know it's from a planet because it's too young - asteroids are all over 4 billion years old, but this rock is about 2 billion years old.
And the composition closely matches that of rocks sampled by the Mars rovers on Mars.
This was all determined after 6 months of painstaking work.
I asked the same question. The following is from one site I went to.
“(SNCs) They are distinguished from other meteorites by their young crystallisation ages, down to 165 Myr. A young age implies formation on a body that was still active (i.e., not totally cooled and solidified) well after the initial accretion and aggregation of the Solar System ~ 4560 Myr ago. In other words, the SNCs must originate from a planet-sized body, not an asteroid.
The mechanism by which the meteorites reach the Earth is by impact ejection: as asteroids impact the martian surface, craters are formed. If the impactor enters the martian atmosphere at a sufficiently shallow angle and with a high enough velocity, then ejecta thrown from the surface can escape to orbit the Sun as small bodies in space, prior to landing on the Earth as meteorites.
The martian origin can be deduced through a process of elimination, by considering all the bodies in the Solar System in turn. Several of the planets can be rejected almost immediately. Mercury is too close to the Sun to allow ejecta to escape outwards to Earth. Jupiter, Saturn, Uranus and Neptune are gas planets, and not rocky. The satellites of the giant planets, although rocky in nature, are unlikely source objects, since any ejecta blasted from their surfaces will not escape from the gravitational attraction of their parent planet. Pluto is a mixture of rock and ice, as are comets, and are not thought to have been molten. So we are left with Venus, Earth and its Moon, and Mars.
Venus?
There is a low, but finite, possibility of Venus being the parent planet. Venus is about the same size and mass as the Earth, and so has a similar escape velocity.
But Venus has a very thick atmosphere with a high surface pressure (~ 96 atms). In order for ejecta to escape the planet, they must have very high energies when they are removed from the surface, such that by the time they have traversed the atmosphere, the ejecta still have sufficient velocity to escape. Similarly, the incoming impactor must be travelling at great speed, so that it is not decelerated so much that it is unable to impart sufficient energy to the ejecta to enable debris to escape.
And on top of all this, once material has escaped from Venus’ surface, it must have the correct orbital vectors to thrust against the gravitational tug of the Sun, and travel outwards to the Earth. Venus, therefore, is dynamically unfavourable as the parent of the SNCs.”