A Trip Around Mars - Mud for Life and Young Glaciers

Orbital view of the north polar region of Mars

There is a fascinating aspect of Mars which we rather rushed over in the second part of A Trip Around Mars, now on BBC World Service.  This post seeks to address the issue.  It's about the periodic melting of the water ice in its north polar regions and the growth of glaciers elsewhere, every few million years.

In the programme, it cropped up towards the end with Chris McKay of NASA's Ames Research Center.  He was the principal investigator on the Phoenix lander mission which went to the far North in 2008.

Chris mentioned how the occasional warming of the permafrost just under the high northern plains might create a "muddy mix" of dirt and water in which Martian microbes might persist - if they exist.  My editing of the show left out the mechanism for the warming and melting.

Wayward Tilting

It turns out that the angle at which Mars' north and south poles tilt changes dramatically over a period of several million years.  The Earth's axis of rotation remains at an angle of about 24 degrees; it is stabilised over time by the presence of our Moon.  Mars lacks this stabilising influence, meaning there are times when its north polar region tilts right over and becomes significantly more exposed to the Sun's radiation each year.  Ice warms, melts and/or sublimes into the atmosphere.

Greg Crater and its Young Glaciers

We heard another fascinating story about Mars connected with this.  It concerns a crater called Greg.  Greg is 66 kilometres across, lies in the middling latitudes of the southern hemisphere (east of the Hellas basin) and was named after a Victorian romantic and proto-science fiction writer.  Most remarkable are what look like glaciers on the inner slopes of its northern rim.

The story of Greg's glaciers was told to us by another of our interviewees, the eminent planetary geologist and astronomical painter, Bill Hartmann of the Planetary Science Institute, University of Arizona.

Kevin Fong and Bill Hartmann

Here is an audio clip of Bill describing the initial discovery and the appearance of the glaciers on the northern slopes of the crater, and 'glacial' landforms in southern parts of the crater.



This image shows the tongue-shaped glaciers in more detail.  My understanding is that white ice is not exposed at the surface in these structures.  They have a covering of regular red-brown Mars dust and rock.

The next image shows the unusual landforms around the crater's south inner wall.

Bill Hartmann's count of small craters that have hit the glaciers since their formation suggests they are extremely recent in Martian geological history.  As he says, between 5 and 20 million years.

How could you get ice accumulating and then flowing as glaciers so recently in this region of Mars?  Answers emerged from a collaboration with scientists in France, including global climate modeller Francois Forget.  Forget took his computer climate model and plugged in the Red planet's parameters instead of terrestrial ones - Martian gravity, atmospheric pressures and composition, Martian topography et cetera.  Then they used the computer models to estimate climate variation around Mars at various tilts of the planet's north-south axis.  Bill Hartmann takes up the story in this next clip.



To sum it up: a few million years ago, Mars was tilted over more extremely than today.  Ice in the north evaporated and sublimed into the atmosphere.  The model suggests it was most likely to snow out and accumulate as ice in Greg crater's region of Mars.

Radar Evidence for Ice Flows in the Greg Neighbourhood

Greg's glaciers are too small for existing orbiters with ground-penetrating radar to confirm that they are made of ice.  But not so far away, there are larger landforms that are.  Here's Bill again plus an image showing an ice apron around a mountain, in the general 'neighbourhood of Greg.

 Bill Hartmann thinks this fascinating story has a lesson for us here on Earth - particularly for certain brands of politicians and commentators who pour scorn on anthropogenic climate change and global climate modellers. 


Ice on Canvas - Bill Hartmann's Latest Astronomical Painting

Science aside but continuing the ice theme, Bill showed us one of his astronomical paintings in progress - a view of Saturn from one of its ice moons, Enceladus (if my memory is correct).

A Trip Around Mars - Steve Squyres and the Mars Exploration Rovers

The image is a montage panorama from the Mars rover Spirit (RIP) at the summit of Husband Hill, looking into the floor of Gusev Crater.  It's known as the Everest pan and is a favourite of Steve Squyres, the lead scientist for both Mars Exploration rovers, Spirit and Opportunity.  Kevin Fong and I interviewed Steve at his office in Cornell University for the BBC Radio series A Trip Around Mars.  On this page, I have posted excerpts of this superb interview - much of which didn't make it into the broadcast programmes.

Steve and Kevin with part of the 20ft Everest pan as background

In this first clip, Steve talks about the making of the Everest pan.



"A Desolate Kind of Beauty"

Sand dunes at Gusev Crater

Another image taken by Spirit.  Both rovers far exceeded their expected working lives.  They landed in 2004.  Spirit lost power for good six years later.   Opportunity is still going.  In this next clip, Steve talks to Kevin about the harsh beauty of the landscapes through which both robots have trundled.

Victoria Crater from above

"Some Things on Mars are Just Uniquely Martian"

The point of the rovers' explorations has been to characterise the conditions under which the rocks in their paths formed.  Was there water there?  What kind of watery environments?  Could these have been places hospitable to Martian microbes?  As you can hear in this next clip, Spirit found a place suggestive of geysers and volcanic steam vents (possibly as long ago as 4 billion years) and Opportunity discovered evidence of something like a dessicating acidic salt pan.   Steve and Kevin then go onto discuss the wider evidence for a lot of water in the planet's deep past - catacylsmic floods and the controversy of Martian oceans.

Opportunity's view of the Meridiani Plains

"Humans very much belong on Mars - it can't happen soon enough"

The Columbia Hills were named after the lost space shuttle, and each peak is named for a crew member.
In this last clip Kevin asks Steve Squyres about his hopes and inspirations.  His daily hope is that Opportunity remains alive for at least one day longer.  Then talk turns to the search for evidence of life on Mars, how Steve came to spend his working life on Mars and the place of humans in the Martian landscape.

Victoria Crater from rim edge

Mars lander sites

A Trip Around Mars - Kim Stanley Robinson in conversation

How do you get people into the landscapes of Mars by radio, rather than by rocket?    Kevin Fong and I faced the challenge in our BBC radio project, A Trip Around Mars.  We were lucky to secure a stellar cast of planetary scientists –  William Hartmann, Chris McKay, Steve Squyres et al. "We should interview Kim Stanley Robinson," said Kevin.  Stan is the author of Red Mars, Green Mars and Blue Mars – collectively known as the Mars Trilogy.  The books were published in the late 1980s and early 1990s.

The three novels tell an epic story of colonisation, terraforming and the making of a new global society.  More importantly for our programmes, KSR takes the reader just about everywhere on Mars with his descriptions of the planet’s myriad landscapes.  The Martian terrain is the narrative bedrock.

We interviewed Stan at his home in Davis, California in February and most of the interview didn’t make it into the broadcast BBC programmes.  So here’s more of it in three segments. 

This first clip covers Stan’s synchronous interest in the images of Mars from the Viking missions and his own exploration of the Sierra Nevada mountains.  It then moves to Mars’ greatest volcano Olympus Mons and the topographic giganticism of the Red Planet.



Olympus Mons

KSR elaborates on why he chose to set his story on Mars – an explanation encompassing the Viking missions, the Sierra Nevada, the Vietnam war, utopias and the end of the Cold war.   He’s happy to confine his exploration of Mars to the imagination.



A Martian landscape by William Hartmann

In the last audio clip, Kevin and Stan talk about how data from Martian orbiters influenced the writing of the novels.   We hear that KSR was led astray by miscalculations of the topography of the Hellas basin.  It's the largest impact crater in the southern hemisphere.  Stan filled it with a sea.  Kevin and Stan also discuss the relationship between scientists and science fiction writers.

 

As an aside, it's said that the lowest region of Hellas is deep enough for liquid water to be stable at the surface.  There's enough atmospheric pressure to prevent water boiling away as it would do elsewhere on Mars (except at the bottom of Eos Chasma in Vallis Marineris).  On the warnest days, it would be liquid, say Pascal Lee of the Mars Institute and Margarita Marinova of NASA Ames Research Centre.



Chasma Borealis in the Martian north polar ice cap

Kim Stanley Robinson's next novel is set on the Earth during the last ice age, 20,000 years ago.  It's called Shaman and is out in September 2013.

The Sex Life of the Komodo Dragon

The most exciting interview I recorded last year was in the komodo dragon enclosure at London Zoo.  Part of the interview features in the latest part of the series Sexual Nature on the BBC World Service's science slot, Discovery, and first broadcast on BBC Radio 4 in January.  

The Komodo dragon is the world's largest lizard - the biggest recorded was a male 3.13 metres long (more than 10 feet long) and weighed 166 kilos.  Presenter Adam Rutherford and I met London Zoo's male dragon, Raja - a mere 7 feet long.  Senior reptile curator Ian Stephen introduced us and - as you can hear - answered every question that Adam could throw at him on dragon husbandry, virgin birth or parthenogenesis in these giant lizards, and courtship and sex in komodos.  Many of the gory details didn't make it into the broadcast programmes so on this page I've posted more of the audio we recorded.

A Tale of Two Penises

If you want to hear what happens when male and female dragons mate, this interview segment is for you.   Courtship involves several days of 'bipedal wrestling' and culminates with the likes of Raja revealing his hemipene (a sort of double-ended penis).  The image below shows those of another species of monitor lizard - just in case you are finding hard to picture...

Poor old Raja has yet to perfect his lurve technique so Ian and fellowkeepers have had to give him a helping hand.  All is revealed here.




Komodo Virgin Births

Under some circumstances, female komodo dragons can produce offspring without the wrestling, injuries and hemipenes.  Several zoos in the past ten years have documented instances of 'virgin births' or parthenogenic reproduction in komodos.  These were individuals who had not mated.  At London Zoo, they had a clutch of asexual eggs laid by a female called Sungai, most of which hatched.  All dragons produced this way are male.

Herpetologists speculate that a female dragon might use this male-making trick if the lizard comes ashore alone on a hitherto komodo-free island.  She produces some sons with whom she can then found a new breeding population.  Ian Stephen and Prof Jennifer Graves of La Trobe University in Australia explain in this slightly longer audio segment from the BBC programme.




Filming, Feeding and Fondling the Dragon

London Zoo's Raja is, in fact, a Bond dragon.  He was filmed for a CGI sequence in 'Skyfall' - the scene where 007 has a fight in a pit of komodo dragons in a casino in Macau.

Curator Ian told us that the celebrity reptile was not at his liveliest the morning in December we visited.  Raja had just downed 15 kilogrammes of horse carcass.

Raja was docile enough for us to creep right up to him and for Adam and Stephen to give him a stroke.

Close up, under the dried blood and dust, komodo dragons are colourful.

There is more on feeding komodos (including advice on avoiding a fat dragon) and the experience of being inches away from one of these magnificent reptiles in this segment of audio.

The Ants with Three Sexes

While making the recent BBC Radio 4 series, Sexual Nature: A Brief Natural History of Sex, I came across some research on North American ants with an extremely weird mating system.    They have three sexes  - sort of.

The strange sexual antics are going in at least two populations of seed harvester ant, Pogonomyrmex, which live in southwestern United States and northern Mexico.   'Sexual Nature' presenter Adam Rutherford interviewed Joel Parker who’d done some work on them a few years ago. 

Unfortunately the interview we recorded with Joel, at Plattsburgh University in remote New York State, didn’t make it into the final cut of the series.  But it is one of those Aren't-Ants-Amazing stories, deserving of more time than we had in the 'Sexual Nature' slot.   So I've posted a link to the audio of Joel's interview below. 

Before getting stuck in, it helps to be armed with the basics of who's who in a regular ant colony, and vanilla reproduction and parentage in ants. 

There is the queen ant of the colony who is the one reproductive female in the family.  She is the result of a mating between a male and female.

Pogonomyrmex queen

There are the workers who are also female but they are sterile.   They don't reproduce.  They  gather food for the colony, defend the nest, do nursery duties etc.  They are queen's daughters - the results of mating between female and male parents.

Pogonomyrmex workers

Third, there are males.  They have just one parent - a queen.  They hatch from her unfertilised eggs.  No fatherly input.  Males are made merely for their sperm and are only produced at mating time.  They don't live very long.

Male Pogonomyrmex being killed by a spider

To recap, in a regular colony, queens and workers are the result of matings between a female ant and a male ant.

But in these two strange Pogonomyrmex populations - one is red, the other is black -  Joel et al discovered that the queens need to mate with one kind of male to produce future queens and another kind of male to produce the workers.  The survival and future of an ant colony needs both queens and the worker caste so you can argue that the two types of males amount to two sexes.

What makes this situation even more intriguing is the two populations are dependent on each other.    Red queens mate with black males to make workers, and black queens need red males to make black workers.  New queens are made through red-on-red and black-on-black sex.  So the whole system actually needs four sexes. 

Here's Joel Parker talking about all this and how it might have come about.

Also, read more in this article by Joel Parker, published in 2004 in 'Trends in Ecology and Evolution'.  This piece from the Public Library of Science (Biology) is also good on the number of sexes in nature.

Ocean Acidification, Corals and Ken Caldeira

Image credit: The International Geosphere-Biosphere Programme and Globaia

This is a spin-off post from the radio series for the BBC World Service I am currently producing, Discovery: The Age We Made.  Presented by science writer Gaia Vince, it consists four programmes looking at the notion that humans have launched a new geological time period on the planet, the Anthropocene.  

Further down,  I have posted the audio of a great interview we did with leading climatologist Ken Caldeira on the seemingly likely fate of the world's coral reefs, because of the geologically extraordinary alterations we are making to the Earth's atmosphere.

We talk to leading earth and environmental scientists about the changes to the global environment our species is making which are so profound that they will leave physical, chemical and fossil marks in the rock strata forming today.  Homo sapiends is creating an assemblage of geological evidence that would tell any geologist in the far flung future (millions of years from now) that something forced the Earth into a new state - or down "a different trouser leg of geological time," as one of our interviewees put it.

The second part of The Age We Made focusses on climate change and the other consequences of our fossil fuel emissions, notably ocean acidification and its likely impact on the world's reef building corals.

About one third of the 10,000,000,000 tonnes of carbon we now put annually into the atmosphere as carbon dioxide dissolves into ocean waters.  Simply put, it forms a weak acid, carbonic acid.  Humans have been building up to this 10 billion tonnes per year emission output since the Industrial Revolution.   The acidity of shallow seawater has been creeping up, in step.  The latest measurements show that ocean acidity in the top levels has increased by about 30% on the last one hundred years - apparently, the most rapid rise measurable in Earth history.

This is a grim development for corals, and the millions of fish and other marine species that live in the reef ecosystems which the colourful, mineralising ones build.  Coral organisms make their skeletons from minerals, also dissolved in seawater.  The more acidic the waters, the harder it is for them to do this.   Some reefs in the Great Barrier recently measured are actually dissolving, such is the pH of the water now.

The finding about the dissolving corals of Australia's Great Barrier Reef came up in one of the interviews we did with Prof Ken Caldeira of the Department of Global Ecology at the Carnegie Institute for Science at Stanford.  So too did the suggestion that coral reefs would not be sustainable anywhere in the global ocean by 2050.  Cramming everything we wanted to put in the broadcast radio programme was impossible, so here you can listen to part of Ken's conversation with Gaia at greater and compelling length.   Prof Caldeira puts our CO2 emissions (particularly the rate of them) and their effects on the oceans into a stark geological time perspective.



There's a couple of minutes towards the beginning in which Ken talks about the processes in the normal long course of geological time which have kept ocean pH levels relatively stable.  Stick with it!  Because it helps to explain why what's happening today is so "extreme" to quote Prof Caldeira.

The last time anything comparable happened to the planet's oceans was about 60 million years ago, during the Paleocene-Eocene thermal maximum.  It was such a long time ago, that back then, horses were like the little one on the right.

This Google Earth video tour of ocean acidification is also excellent, in part because it shows graphically how acidification has increased and is projected to rise over the next few centuries.   It also nicely explains some of the basic science neglected by me here.