Posts Tagged ‘mars’
getting mildly excited about water
I’ve generally thought that the extraordinary volume of water on our planet’s surface was a problem, scientifically speaking, but I’m probably wrong. I used to think that the idea that water came to Earth in meteor showers (haha) couldn’t be right, because the days of Earth’s heavy bombardment came early in the planet’s history when everything was molten hot and the water or ice from meteors would’ve just boiled away. But what would I know? And why would meteors, or planetesimals, be so full of water?
As the astronomers are constantly telling me, water in solid, liquid and gaseous form is commonplace in our solar system, our galaxy, our universe. In the habitable zones of our universe it can exist in all three forms close together, and that’s what presumably makes those regions habitable. On Earth we have a hydrological cycle – evaporation and transpiration, condensation, and precipitation – involving the three forms of this precious stuff, more or less. Recently, some fuss was made about water found in the atmosphere of a not-so-distant exoplanet, and the female interviewer was seemingly excited about – hey, water, and maybe life!!! – but the scientist was much more impressed by the detection abilities we’ve developed for working out the chemical signature coming from distant bodies (this one was about 100 light years away – our galaxy is many thousands of light years across). Water in the atmosphere and even on the surface of these bodies is unsurprising, apparently.
When you (I mean I) consider that hydrogen is the simplest and most abundant element in the universe, and oxygen is also a relatively simple and abundant molecule, we shouldn’t be surprised that water is commonplace. As the above-mentioned scientist pointed out, water is found in the interstellar medium between star systems, amongst gas clouds, and within our solar system, especially in the material of the Kuiper Belt and in the ‘ice giants’, Neptune and Uranus. More excitingly for the possibilities of life, liquid, flowing water has been found on Mars – albeit highly salinated and mineral-rich. There’s still a possibility, though, that less ‘contaminated’ water may be found nearer the Martian poles. It’s also seen as a sign that Mars is drying up, water-wise, that it was once a much more watery world, and for a long time. Could it have seeded life on Earth?
Water worlds are being found elsewhere in the solar system too. The Cassini spacecraft has made major discoveries about Enceladus, a tiny, very bright moon of Saturn. Jets of water vapour, ice and surprisingly large quantities of organic chemicals burst out from below the moon’s icy crust at tremendous velocity. Some of the material is added to Saturn’s particulate ring system. The E ring’s particles, where the Enceladus material ends up, have been examined by Cassini, and in short, the examination suggests that there are hydrothermal vents beneath the icy shell of the moon, similar to those underneath the Pacific Ocean. Cassini’s analysis has also strongly indicated an ocean with a depth of around 10 kilometres underneath the thick ice (30-40 kms) at the southern polar region.
There are other promising watery discoveries too, and a relatively new theory about water on Earth, which I’ll leave for another post.
References
NASA discovers a water world in our solar system (mashable video)
https://imagine.gsfc.nasa.gov/features/cosmic/milkyway_info.html
https://solarsystem.nasa.gov/missions/cassini/science/enceladus/
How did Earth get its water?
Boots on Martian ground – crazy or brave?
Jacinta: Recently we attended a ‘Science in the Pub’ session, in which a group of three or four scientists/academics gives talks with Q&A on a topic of interest to the public. The topic the other day was indeed most topical, dealing with recent findings about the surface of Mars and future ventures to uncover more.
Canto: But we were most intrigued by the Q&A at the end, which was a friendly but passionate dispute about the wisdom of a ‘personned’ voyage to the Mars surface. Two of the speakers argued that we were far from ready, and possibly never would be (together with the ‘isn’t stuffing up one planet for us?’ claim) while the other suggested that we should really ‘go for it’.
Jacinta: Yes, and I was all for the more cautious approach, clapping my hands and nodding my head off at their caveats and their bemusement that such a suicide mission should be taken seriously at this stage…
Canto: And I tended to agree with you, but something the other speaker said really struck me. He compared this wild project to the Apollo mission, so daring and unlikely for its time, yet ultimately successful. And – this really caught my attention – that sixties adventure produced, in proportional terms, more PhDs in physics and engineering, in the USA and elsewhere, than has ever been experienced historically.
Jacinta: Need to fact-check that* but it’s more than plausible. So let’s look more closely at the pros and cons of this crazy idea of boots on Martian ground.
Canto: Okay, first we look at the problem of actually getting there. According to Mars One (a Dutch venture that recently went bankrupt but never mind) it takes about seven months, following the route known as the Hohmann Transfer Orbit. Now, we’ve obviously managed this trip with unpersonned vehicles, but a personned one…
Jacinta: Shit that’s a terrible word, but I suppose if ‘manned’ was once acceptable then ‘personned’ now has to be, politically.
Canto: Grin and bear it. A personned one would presumably have to be bigger and more accommodating in various ways. And of course we’ve never contemplated a return voyage for the Mars rovers…
Jacinta: But we’ve done return trips to the moon. We have the technology. But of course the journey to the moon took – what, a day or two? How are these colonists – a bus load of them perhaps? – going to endure, or survive, a months-long voyage?
Canto: We’ll get to that hopefully. First let’s look at any trip. There’s a period called a launch window, the optimum time for starting off. These periods come around every 26 months, but there are high-energy launch windows and low-energy ones, because the Mars orbit is quite eccentric, the second-most eccentric planetary orbit in the solar system. The low end requires only half the energy of the high end, and the next low-energy launch window comes round in 2033.
Jacinta: But Elon Musk says he’ll be ready to launch a humanned (is that better?) mission by 2024. He must have energy to burn.
Canto: A human mission, that’s settled. Actually Musk made that claim about a 2024 mission here in Adelaide just a few days ago. NASA is apparently keeping quiet on the issue – they’re planning a mission in the 2030s, very sensibly.
Jacinta: Or not, if you feel we’re far from ready.
Canto: Well let’s continue with the problems. The first one is radiation – not only on the planet Mars, but in deep space. We know that on the International Space Station, which is inside the protective magnetic field of the Earth, astronauts are exposed to 10 times the radiation that we have to deal with on the surface. I’m not sure if that means the ship is exposed to that radiation or the people inside it. I don’t know how radiation-proof you can make a spaceship, but I do know that exposure to these massive levels of radiation will increase risks of cancer, central nervous system damage, cardiac and circulatory problems, nausea, cataracts and no doubt much else. Presumably SpaceX is dealing with all this somehow or other. The plans seem to shift a bit, but it’s believed that they’re going to send a rocket out in 2022 (sans humans) – and presumably bring it back, so they can, inter alia, check out radiation levels inside and out.
Jacinta: The BFR, it’s called (Big Falcon Rocket). What about the astronauts that went to the Moon? Apollo 10 orbited the Moon about 30 times – that must’ve made them sick, if not from radiation. Apparently the best way to radiation-proof your ship requires adding mass, which requires using additional fuel on launch, etc.
Canto: The SpaceX launch vehicle is called Super Heavy, and that includes the upper-stage Starship, the part that makes the full trip and back, so presumably they’ve thoroughly planned for radiation effects. I do get the impression that Musk and his team are super-smart super-planners. It’s not pie-in-the-sky stuff, as Mars One seems to have been. And they have super-rich backing, I’m sure. Musk has said it’s not unlikely that some will die (just as some first-fleeters no doubt died back in 1788 – but they were only convicts, not cashed up adventurers), but I’m inclined to believe that the percentages will be low.
Jacinta: Humans appear to be more valuable these days, she said cynically.
Canto: The whole world will be watching, much more than in 1788. Anyway, another problem will be isolation. There won’t be a busload of adventurers on the first human trip. Just focusing on the SpaceX venture, they’ve got an ambitious plan to have something like a city on Mars by 2050. Again, this starts to remind me of the first fleet, and subsequent fleets. Think of Port Jackson in 1788, then think of Sydney Town thirty-something years later, with a population of 12-15 thousand. Hazardous voyages of many months’ duration, with many outbreaks of disease along the way…
Jacinta: Yeah mainly because of dodgy traders in ship supplies, disgusting treatment of convicts, cramped unsanitary conditions and the like…
Canto: So there’s no comparison. The human traffic will be a much more of a trickle, and the technology will be state-of-the-art. The proven successes of SpaceX, by the way, are what is bringing backers in. Which brings me back to isolation. It isn’t even known yet how many passengers will be on the first voyage, and they will have to get along extremely well, as they commence the incredibly arduous process of terraforming the region around their landing site – in the absence of ready food, water, and air! No lifeline to Earth. Terrifically hostile environment with massive dust storms, freezing temperatures, health issues due to low gravity and radiation…
Jacinta: It doesn’t so much sound like a problem of isolation as a problem of community and problem-solving…
Canto: Well it’s isolation from the basic stuff we need for survival and from expert treatment and procedure when things go wrong – health-care, technological fixes, raw materials and the means of transforming them and so forth…
Jacinta: Hmmm – can we look at the positives now?
Canto: Well – the food issue. The diet will have to be essentially vegetarian, based on hydroponics. They’ll be growing this stuff on the ship on the way over, presumably. Those first visitants and their followers won’t be in for a holiday – it’ll be work work work. But you can pack a lot of dehydrated stuff such as spices and sauces to taste things up. That would mean having a water supply of course, and that’s not clearly guaranteed.
Jacinta: Yeah but you’re looking at the practical life-and-death stuff. How boring haha. I’m thinking of the inspirational effect of having live human boots on the ground on another planet. I’ve read somewhere that humans could find out stuff about the planet – whether there’s actual life, what the atmosphere feels like, how actually manageable it might be to terraform the place and create a future there – thousands of times more quickly and effectively than any robot could. And in many ways I’d rather see SpaceX succeed in this than a national organisation like NASA. Okay SpaceX might be seen as quintessentially American, but Musk and his team won’t be looking at it that way I’m sure, they’ll be drawing their expertise from anyone around the globe who can contribute. One of the many things I love about science is its international collaborative character. It’s another bulwark against the petty nationalisms of Trump, Xi, Putin and co.
Canto: Okay, let’s stay healthy and watch what the future brings…
References
*https://www.theguardian.com/science/2012/dec/16/apollo-legacy-moon-space-riley
https://www.quora.com/What-are-the-pros-and-cons-of-living-in-Mars-planet
https://www.experiencesydneyaustralia.com/visitor-information/sydney-history-overview/
is there life on Mars? – encore
Don’t worry Davey, we’ll find out
The recent announcement about a large lake of water beneath the ice near the south pole of Mars has naturally engendered great excitement among those desperate to find life ‘elsewhere’, and with good reason. Mars, our closest planet, has long been a haven of hope for this sort of thing, but it has also engendered the ‘too good to be true’ response. It’s almost been seen as a lazy conjecture, as if we should expect to work really hard, and over unimaginably long distances, to find this precious and surely extremely rare stuff called life. But in recent decades we’ve managed to discover life surviving and even thriving under the most extreme circumstances in odd nooks and crannies of our own planet, which has widened our view of life’s diversity and tenacity. And the fact that we’ve been discovering new life on our own planet, is a testament to our developing skills and technology in the search for life – because, of course, the life we’re discovering isn’t new at all, what’s new is our technology and our deeper awareness of life’s range and possibilities.
And what we know about life on Earth is all about water. We’re full of the stuff, as are the plants and animals around us, and we now know that our ancestors emerged from the stuff, and we’ve never stopped being dependent on it. So it’s not surprising that the question about life on Mars is also all about water.
In previous centuries it was much speculated that water lay on the surface of Mars, in what appeared to be canals or waterways of some kind. Nowadays what we’ve learned about the atmosphere at Mars’ surface – low temperature and pressure – has rendered the possibility of liquid water increasingly unlikely. However, water below the surface is another matter. Lake Vostok, four kilometres below the surface in Eastern Antarctica, is just the largest of a number of subsurface lakes – at least 400 found under that continent – and they support thousands of living species.
So for some time there’s been a search for subsurface water on Mars. A radar instrument called MARSIS, orbiting the planet on the European Space Agency’s Mars Express, and purpose-built to search for underground water, has been sending out radio waves which are reflective to liquid water but not to ice or rock. A particularly reflective patch near the south pole appears to reveal a layer of water about 1.5 kilometres below the surface. However, MARSIS is limited in the data it can provide. The depth of the water, and what other material is mixed in with it, are not known – though we know that it’s about 20 kilometres across, and the the Italian research team that has published the findings estimates the water to be at least a metre deep, indicating a genuine lake rather than meltwater. It’s expected that the water will contain salts, which lower the freezing point of water, as would pressure from the material above the lake.
There are still many unknowns here, but the various Mars rovers and orbiters are building evidence, for example that Mars was once warmer and wetter, and that even now liquid water can still be found at periods on the surface. What we haven’t found so far is evidence of life. So how can we get this evidence? First, we need to look for life ‘as we know it’, carbon-based life, because that’s very likely the kind of life we’ll find on our nearest neighbour, and because we have no way of knowing how to look for completely alien life.
Mars’ Curiosity rover has already found organic molecules, specifically methane, which may or may not be produced by biological activity beneath the surface. The rover has been sampling the atmosphere and has found methane at varying levels as the seasons have changed. However, it’s generally believed that the thin atmosphere at Mars’ surface would be insufficient to deflect life-harming radiation. The discovery of a specific and more or less substantial body of water below the surface, perhaps sufficiently protected from radiation, provides a target for future researchers to aim at.
The next step would be to obtain samples from the lake, which is easier said than done. It would require some sort of robotic drill to be sent out there and operated remotely, a task beyond current capabilities. Meanwhile, a Chinese probe is set to be flown to Mars in 2020. It will have radar instrumentation similar to MARSIS, but operating at a slightly different frequency. It may confirm the MARSIS findings or discover other underground bodies of water, further piquing our interest in the very real possibility of life on the red planet.
Is it an underground lake? We can’t be entirely sure.
References
https://www.bbc.com/news/science-environment-44952710
is there life on mars?
good question, Davie
Back in 1975, NASA sent two space probes to Mars. Their landers touched down on the Martian surface less than a year later. The Viking 1 lander remained operational for more than six years, Viking 2 for three and a half. During this time, biological experiments were conducted upon Martian soil. As far as the general public is concerned, the results of these tests were negative, though for those in the know, it wasn’t quite that simple. Not that there was any great conspiracy or cover-up; the consensus amongst the cognoscenti was that the evidence tilted much more towards no-life than towards life, for the minute samples examined.
It seems, though, that exobiologists have long been intrigued by some of the findings in a particular batch of experiments, known as the Labelled Release experiments. As this Wikipedia article describes, these experiments involved a soil sample being inoculated with a weak aqueous nutrient solution. The nutrients were of the type produced in the famous Miller-Urey experiments of the fifties. Evidence was sought for metabolisation of these nutrients by micro-organisms in the soil, if any, and the first trial of these experiments produced surprisingly positive results. In fact, both the Viking probes produced initially positive results from different soil samples, one with a sample of surface soil exposed to sunlight, the other with a sample from beneath a rock. However, when the tests were repeated later, they produced negative results. Many other different types of biological tests were carried out during this mission, all of them yielding negative results. So it was all very inconclusive and mysterious.
Fast forward to April 2012, when a report was released by an international team of scientists suggesting that, after thorough analysis of the Labelled Release data, ‘extant microbial life on Mars’ may have been detected.
Researchers long ago abandoned the idea of multicellular life currently existing on Mars. Conditions for the maintenance of such life forms may have existed there billions of years ago – the Viking orbiters found evidence of erosion and the possible remains of river valleys – but those conditions have changed, though some have argued that the soil coloration and recent detection of silicate minerals indicates more recent signs of water, vegetation and microbial activity. All of this is highly contentious, but all good fun, and indicates that more research is required.
In 2008, a robotic spacecraft landed on Mars, in the polar region, and remained operational for about six months. The Phoenix lander had two principal objectives, to test for any history of water in the region, and to search for anything organic in the surrounding regolith [the surface layer of broken rock and soil affected by wind or water]. Preliminary data revealed perchlorate, an acid-derived salt, in the soil, which wasn’t a good sign. Perchlorate can act as an ‘anti-freeze’, lowering the freezing point of water. Generally, though, the pH levels of the tested soil, and its salinity, were benign from a biological perspective. CO2 and bound water were also detected.
We’ve only minutely scratched a few surface points of a huge beast, you might say. What we’ve found isn’t too promising, but it’s enough to keep us wanting to investigate further, just to make sure, or to know more. After all, there’s still plenty to learn about the surface of our own planet. Recently, for example, we learned how perchlorates can be formed from soils with highly concentrated salts, in the presence of UV and sun light. Chloride is converted to perchlorate in the process, which has been reproduced in the lab. Only in 2010, soils with high concentrations of perchlorate were discovered over a large section of Antarctica.
Between August 6 and August 20, that’s to say in two or three weeks time, the Mars Science Laboratory [MSL, also known as ‘Curiosity’] will land on Mars and look for further signs, past or present, of biological activity. It’s likely that whatever is discovered, not just in terms of life itself, but in terms of conditions for life, will be hotly debated. This Wikipedia article, covering the whole life-on-Mars search and debate, includes this intriguing para:
The best life detection experiment proposed is the examination on Earth of a soil sample from Mars. However, the difficulty of providing and maintaining life support over the months of transit from Mars to Earth remains to be solved. Providing for still unknown environmental and nutritional requirements is daunting. Should dead organisms be found in a sample, it would be difficult to conclude that those organisms were alive when obtained.
True enough, but even if dead, what a revelation it would be. Extra-terrestrial death means extra-terrestrial life, and so very very close to home in the great vastness of the universe. Another blow to our uniqueness, what terrible fun.