杏吧原创

The atmosphere of Mars may not聽contain much oxygen, but that doesn鈥檛 necessarily mean the planet itself聽lacks the stuff.聽聽A new calculation of how much oxygen could be dissolved in Martian brines shows that the dusty world may be hiding an abundance of oxygen under its surface 鈥� potentially enough to support life.

We know Mars has聽oxygen on its surface,聽which is why it looks red: iron in Martian dust reacts with oxygen to create red oxides.

Vlada Stamenkovi膰鈥� at NASA鈥檚 Jet Propulsion Laboratory in California and his colleagues calculated how much oxygen could be dissolved in salty brines just under the Martian surface. They found that, in certain types of brines under particularly cold conditions, there could be just as much oxygen as there is in Earth鈥檚 oceans 鈥� enough for microbes and even simple animals like sponges to survive.

But we鈥檙e not entirely sure that there are liquid brines on Mars. There have been hints, like recurring slope lineae 鈥� dark lines flowing down hills that appear to be liquid 鈥� but none of them have been definitively proven to be made of water or brine.

鈥淭here have been various different claims for where we may or may not have seen evidence for these brines existing,鈥� says Kirsten Siebach at Rice University in Texas. 鈥淪mall amounts of brines would be possible, but we aren鈥檛 sure that they鈥檙e really there.鈥�

Even if there is oxygen-rich brine on Mars, that鈥檚 not a guarantee of life, says Robin Wordsworth at Harvard University. 鈥淚t鈥檚 two sides of the coin in a way,鈥� he says. 鈥淚f you want respiration oxygen is good, but too much oxidation can be bad for life.鈥� Compounds like hydrogen peroxide can damage cells, which may be particularly bad for primitive lifeforms which don鈥檛 have that many cells to begin with.