News from the Red Planet Has Gotten Really Interesting Lately

July 28, 2018 – Mars this month is as close as it can get to Earth, or at least until September in 2035. As of yesterday, the planets were separated by a mere 57.5 million kilometers (35.7 million miles). Two days from now then Mars will be closer to us than at any time since 2003 and should be quite visible in the night sky shining at a magnitude of -2.8.

Magnitude in space refers to the brightness of an object seen from Earth. And you should be able to see Mars from Toronto at a point about 24 degrees above the southern horizon, midnight local time. For folks Down Under, Mars will be directly overhead when viewed from Brisbane. And about 70 degrees above the northern horizon if viewed in Wellington, New Zealand.

What you won’t see when you peer up into the sky is the planetwide dust storm that has enveloped Mars for much of this year. This dust storm may eventually cause the demise of NASA’s solar-powered rover, Opportunity. Curiosity, powered by plutonium, isn’t being affected.

Nor when you look at Mars will you see what was announced this week: the discovery of a salty body of water lying 1.5 kilometers below the south polar region of the planet, an announcement that got lots of press coverage because of the implications for finding life. But more on that further down in this posting.

In fact, observing Mars from Earth through a telescope, something I used to do when I was younger, doesn’t allow you to see all that much. I had a three-inch refractor when I was in my teens and at best I could make out a line or two on the Martian surface. That in hindsight was probably a faint impression of the Valle Marinaris, Mars’ supersized version of the Grand Canyon. If I really concentrated I sometimes could make out the polar ice caps. I never did see those Giovanni Schiaparelli canals that got people in the 19th century excited about a Martian civilization and led Percival Lowell’s to create elaborate drawings of cities connected by waterways, and of course to H. G. Wells 1897 serialized novel, “The War of the Worlds.”

The controversies of these 19th-century observations evolved into those of the late 20th and 21st. When two Viking landers reached Mars in 1976 they conducted soil analysis experiments that indicated life may have existed or exists on the planet today. NASA, in announcing the experiment results, erred on the side of caution at the time by stating they were inconclusive, or negative. It was said that Mars’ unique surface chemistry created false reads. But Curiosity in its exploration of Gale Crater over the last few years in its sampling has produced chemical results that suggest that what the Vikings discovered was likely biosignatures of past and possibly present life.

Then there is the publication of results from Martian orbiters which have tracked seasonal plumes of methane gas released into the atmosphere from the Martian surface. There can be two explanations for this observed phenomenon: biological or geological. On Earth, 95% of methane released from the surface comes from biological sources whether fossil organics or biomass. The fact that orbiters have continued to measure methane oscillations on Mars suggests an active source is continuing to replenish the gas. Curiosity has also detected methane emanations at Gale Crater described as burps that quickly dissipate. Again, the likely explanation beneath the Martian surface is past or present biology.

There’s more. Other research results from Mars from past landers and rovers including the Phoenix in 2008 have found perchlorates in the soil (chlorine and oxygen molecules). Here on Earth perchlorate is toxic to most life with the exception of extremophile bacteria. So perchlorate doesn’t eliminate Martian biology particularly when you consider its presence means water ice on Mars has a lower melting point than here on Earth. This suggests Martian water can be in a liquid state in bone-chilling temperatures.

This month on NASA’s website, an article appeared asking if the surface soil of Mars is perhaps too dry to sustain life. The article notes that Mars is 1,000 times drier than the driest place here on Earth, the Atacama Desert of South America. In the Atacama which infrequently gets rain, (I mean once every few years) there is evidence of past microbial activity dating back thousands of years. NASA scientists in the article speculate that the paradigm of the Atacama could be happening on Mars where life today may not be viable on the dry surface but may have been evident in the past leaving biological signatures like the ones Viking and Curiosity discovered.

And finally, we have the discovery of subsurface liquid water in the Planum Australe region of Mars at the South Polar Ice Cap, described as a lake. Mars Express, the European Space Agency orbiter, used subsurface radar to collect data from 2012 to 2015 that shows liquid water below ground in an area 20 kilometers wide and several meters in depth. This is not the first time subsurface water has been detected on Mars. Several sites have been found but none quite as large as this latest one. The Mars Express data and results are described in a journal article published this month in Science.

Other orbiter discoveries describe subsurface ice in “thick underground sheets” that get exposed on the rim edges of craters in the mid-latitudes of the planet. These observations are not isolated. The occurrence of ice just below the surface may explain the stria seen in images that appear as long thin dark lines cascading down from cliff edges and crater rims.

Mars is turning out to be much more than the barren world we once thought but yet far less than what 19th century astronomers perceived. So when you get the chance to go out and view the night sky over the next few days, factor all of the above as you search for and find that bright red dot of light.