Quick Fire Science: Exploring Mars

NASA's Curiosity rover landed on Mars in August 2012, and it has spent that past 15 months exploring a region of the planet called Gale Crater. This week the team running the rover reported on what they've found so far, and so here's your Quick Fire Science about our planetary next door neighbour with Dominic Ford and Hannah Critchlow.

• Today Mars is a barren and cratered world where temperatures commonly dip well below -100°C - cold enough for even carbon dioxide to form frost.
• To the unaided eye looking up at the night sky, Mars is strikingly red. This is because the Martian soil is littered with fine particles of iron oxide or rust.
• Low temperatures are not the only reason why Mars would be a harsh place to live. Its atmosphere is a hundred times thinner than the Earth's, and is composed mainly of carbon dioxide rather than breathable oxygen.
• What fascinates space scientists, though, is that ancient channels are carved into the Martian surface, which look like dried up rivers.
• Today, the pressure of Mars's surface is too low for liquid water to exist, so the presence channels imply that Mars's climate was radically different in the past, with a much thicker atmosphere.
• One of the Curiosity rover's aims is to work out how this change of climate happened. If there was once much more carbon dioxide gas in Mars's atmosphere, it's unclear where that carbon could have gone.
• The most likely answer is that it turned into carbon-rich limestone. Yet a big mystery is why very little limestone has ever been found on Mars.
• The Curiosity rover has also been measuring radiation on Mars's surface. Without a thick atmosphere to protect it, Mars's surface is blasted by the full brunt of radiation produced by the Sun.
• In fact, measurements from Curiosity's radiation sensors suggest that even the hardiest lifeforms on Earth could not withstand the irradiation the Martian soil receives.
• One of the next questions for Curiosity is whether microbial life might have been able to thrive on Mars in the distant past, even if not today.
• Space scientists are searching the Martian soil for large carbon-based molecules that are so complex that only ancient lifeforms could have assembled them.
• If Curiosity doesn't find any by 2018, the quest will then be taken up by the European ExoMars rover, which will arrive carrying the next generation of even more sensitive instruments.