Showing posts with label Curiosity rover. Show all posts
Showing posts with label Curiosity rover. Show all posts

Monday 13 August 2018

Life on Mars? How accumulated evidence slowly leads to scientific advances

Although the history of science is often presented as a series of eureka moments, with a single scientist's brainstorm paving the way for a paradigm-shifting theory, the truth is usually rather less dramatic. A good example of the latter is the formulation of plate tectonics, with the meteorologist Alfred Wegener's continental drift being rejected by the geological orthodoxy for over thirty years. It was only with the accumulation of data from late 1950's onward that the mobility of Earth's crust slowly gained acceptance, thanks to the multiple strands of new evidence that supported it.

One topic that looks likely to increase in popularity amongst both public and biologists is the search for life on Mars. Last month's announcement of a lake deep beneath the southern polar ice cap is the latest piece of observational data that Mars might still have environments suitable for microbial life. This is just the latest in an increasing body of evidence that conditions may be still be capable of supporting life, long after the planet's biota-friendly heyday. However, the data hasn't always been so positive, having fluctuated in both directions over the past century or so. So what is the correspondence between positive results and the levels of research for life on Mars?

The planet's polar ice caps were first discovered in the late Seventeenth Century, which combined with the Earth-like duration of the Martian day implied the planet might be fairly similar to our own. This was followed a century later by observation of what appeared to be seasonal changes to surface features, leading to the understandable conclusion of Mars as a temperate, hospitable world covered with vegetation. Then another century on, an early use of spectroscopy erroneously described abundant water on Mars; although the mistake was later corrected, the near contemporary reporting of non-existent Martian canals led to soaring public interest and intense speculation. The French astronomer Camille Flammarion helped popularise Mars as a potentially inhabited world, paving the way for H.G. Wells' War of the Worlds and Edgar Rice Burroughs' John Carter series.

As astronomical technology improved and the planet's true environment became known (low temperatures, thin atmosphere and no canals), Mars' popularity waned. By the time of Mariner 4's 1965 fly-by, the arid, cratered and radiation-smothered surface it revealed only served to reinforce the notion of a lifeless desert; the geologically inactive world was long past its prime and any life still existing there probably wouldn't be visible without a microscope.

Despite this disappointing turnabout, NASA somehow managed to gain the funding to incorporate four biological experiments on the two Viking landers that arrived on Mars in 1976. Three of the experiments gave negative results while the fourth was inconclusive, most researchers hypothesising a geochemical rather than biological explanation for the outcome. After a decade and a half of continuous missions to Mars, this lack of positive results - accompanied by experimental cost overruns - probably contributed to a sixteen-year hiatus (excluding two Soviet attempts at missions to the Martian moons). Clearly, Mars' geology by itself was not enough to excite the interplanetary probe funding czars.

In the meantime, it was some distinctly Earth-bound research that reignited interested in Mars as a plausible source of life. The 1996 report that Martian meteorite ALH84001 contained features resembling fossilised (if extremely small) bacteria gained worldwide attention, even though the eventual conclusion repudiated this. Analysis of three other meteorites originating from Mars showed that complex organic chemistry, lava flows and moving water were common features of the planet's past, although they offered no more than tantalising hints that microbial life may have flourished, possibly billions of years ago.

Back on Mars, NASA's 1997 Pathfinder lander delivered the Sojourner rover. Although it appeared to be little more than a very expensive toy, managing a total distance in its operational lifetime of just one hundred metres, the proof of concept led to much larger and more sophisticated vehicles culminating in today’s Curiosity rover.

The plethora of Mars missions over the past two decades has delivered immense amounts of data, including that the planet used to have near-ideal conditions for microbial life - and still has a few types of environment that may be able to support miniscule extremophiles.

Together with research undertaken in Earth-bound simulators, the numerous Mars projects of the Twenty-first Century have to date swung the pendulum back in favour of a Martian biota. Here are a few prominent examples:

  • 2003 - atmospheric methane is discovered (the lack of active geology implying a biological rather than geochemical origin)
  • 2005 - atmospheric formaldehyde is detected (it could be a by-product of methane oxidation)
  • 2007 - silica-rich rocks, similar to hot springs, are found
  • 2010 - giant sinkholes are found (suitable as radiation-proof habitats)
  • 2011 - flowing brines and gypsum deposits discovered
  • 2012 - lichen survived for a month in the Mars Simulation Laboratory
  • 2013 - proof of ancient freshwater lakes and complex organic molecules, along with a long-lost magnetic field
  • 2014 - large-scale seasonal variation in methane, greater than usual if of geochemical origin
  • 2015 - Earth-based research successfully incubates methane-producing bacteria under Mars-like conditions
  • 2018 - a 20 kilometre across brine lake is found under the southern polar ice sheet

Although these facts accumulate into an impressive package in favour of Martian microbes, they should probably be treated as independent points, not as one combined argument. For as well as finding factors supporting microbial life, other research has produced opposing ones. For example, last year NASA found that a solar storm had temporarily doubled surface radiation levels, meaning that even dormant microbes would have to live over seven metres down in order to survive. We should also bear in mind that for some of each orbit, Mars veers outside our solar system's Goldilocks Zone and as such any native life would have its work cut out for it at aphelion.

A fleet of orbiters, landers, rovers and even a robotic helicopter are planned for further exploration in the next decade, so clearly the search for life on Mars is still deemed a worthwhile effort. Indeed, five more missions are scheduled for the next three years alone. Whether any will provide definitive proof is the big question, but conversely, how much of the surface - and sub-surface - would need to be thoroughly searched before concluding that Mars has either never had microscopic life or that it has long since become extinct?

What is apparent from all this is that the quantity of Mars-based missions has fluctuated according to confidence in the hypothesis. In other words, the more that data supports the existence of suitable habitats for microbes, the greater the amount of research to find them. In a world of limited resources, even such profoundly interesting questions as extra-terrestrial life appear to gain funding based on the probability of near-future success. If the next generation of missions fails to find traces of even extinct life, my bet would be a rapid and severe curtailing of probes to the red planet.

There is a caricature of the stages that scientific hypotheses go through, which can ironically best be described using religious terminology: they start as heresy; proceed to acceptance; and are then carved into stone as orthodoxy. Of course, unlike with religions, the vast majority of practitioners accept the new working theory once the data has passed a certain probability threshold, even if it totally negates an earlier one. During the first stage - and as the evidence starts to be favourable - more researchers may join the bandwagon, hoping to be the first to achieve success.

In this particular case, the expense and sophistication of the technology prohibits entries from all except a few key players such as NASA and ESA. It might seem obvious that in expensive, high-tech fields, there has to be a correlation between hypothesis-supporting facts and the amount of research. But this suggests a stumbling block for out-of-the-box thinking, as revolutionary hypotheses fail to gain funding without at least some supporting evidence.

Therefore does the cutting-edge, at least in areas that require expensive experimental confirmation, start life as a chicken-and-egg situation? Until data providentially appears, is it often the case that the powers-that-be have little enticement for funding left-field projects? That certainly seems to have been true for meteorologist Alfred Wegener and his continental drift hypothesis, since it took several research streams to codify plate tectonics as the revolutionary solution. 

Back to Martian microbes. Having now read in greater depth about seasonal methane, it appears that the periodicity could be due to temperature-related atmospheric changes. This only leaves the scale of variation as support for a biological rather than geochemical origin. Having said that, the joint ESA/Roscosmos ExoMars Trace Gas Orbiter may find a definitive answer as to its source in the next year or so, although even a negative result is unlikely to close the matter for some time to come. Surely this has got to be one of the great what-ifs of our time? Happy hunting, Mars mission teams!

Saturday 28 February 2015

Have spacecraft, will travel: planning the first manned Mars mission

As a space travel enthusiast since I was knee-high to a grasshopper it took me many years to appreciate robot probe missions with anything like the zeal engendered by manned spaceflight. As a schoolboy I watched the first space shuttle mission launch in 1981; no doubt like a multitude of others I initially considered this the start of the ‘casual' rather than pioneering phase of astronautics. Therefore it wasn't long before I asked myself the obvious question: when will there be a crewed mission to Mars?

Mars seems extremely familiar, no doubt due to the myriad of science fiction novels and films concerning the Red Planet. The last decade has seen a proliferation of news stories as various orbiters and rovers gather enormous amounts of - at times puzzling - data. However, none of the numerous projects of all scales that have investigated a manned mission have ever lifted off the launch pad. So here's a brief look at the state of play, not to say of course that this might not look woefully dated within the next few years.

1) Who will go to Mars?

Obviously the USA will supply the most funding so they will run the show. Or will they? The NASA budget available for planetary science is less than half that for International Space Station (ISS) operations, although of course the former are all unmanned missions. In fact, the Planetary Society has claimed that NASA spends less each year on interplanetary probes than the USA does on dog toys! A manned mission would have to negate this trend, as realistic estimates could be around US$500 billion for a single mission.

President Obama's announced half-billion dollar increase to the NASA budget is unlikely to be replicated by any Tea Party candidate who might (God forbid) achieve power. Unless that is we see a return to Cold War rivalries, with China offering a two-horse race to Mars. That might sound unlikely, but in 2006 the Chinese Government announced a long-term goal to land a crew there between 2040 and 2060. Since the US refused to allow them ISS involvement due to not wanting its technology to become available to Beijing, it is doubtful the Whitehouse would be any happier to cooperate in a Mars mission.

Either way, it's probable that some of the ISS partners would collaborate. However unrealistic it now appears in light of the financial crisis, back in 2001 the European Space Agency (ESA) announced its own plan for a crewed Mars landing in the 2030s. There was even a suggestion to include Russia as a minority partner, but the political situation there may prove prohibitive.

It doesn't just have to be other Western nations who participate in a NASA-led project, as numerous private companies are now involved in the commercial space programme. No doubt collaboration between some of the long-established aerospace giants and recent start-ups such as Space-X - whose long-term goal is to establish a Martian colony - with various Western governments would be more palatable to finance ministers. But it's still early days for the private sector: smaller infrastructure may shorten timescales compared to monolithic state enterprise, but as the Virgin Galactic SpaceshipTwo crash shows, developing even sub-orbital craft at this level still carries enormous risk.

So all in all, it could be the US and ESA, with or without substantial private investment, or China in a race with a Western bloc or (as an extreme longshot) Dutch engineer and entrepreneur Bas Lansdorp, whose Mars One mission plans to regularly send crews of four non-professional astronauts on a one-way trip to the Red Planet from 2025. So far he has raised about 1/8000th of the project's already shoestring budget, but that hasn't stopped thousands of would-be colonists from applying. In addition to the necessary privations, these volunteers would also be the subjects of a fund-raising reality television show. If doesn't sound even vaguely like the product of an insane society then I don't know what is. Perhaps we should just turn our backs on the rest of the universe and just spend our lives uploading selfies to social media sites?

2) What will happen?

In theory it sounds simple: a small group of professional astronauts with various scientific backgrounds will spend up to two years on a high-risk mission, exploring the Martian surface for perhaps a month or so, then bring back copious samples of rock, soil, atmosphere and ice for more detailed examination on Earth.

The BBC ‘s 2004 mockumentary Space Odyssey: Voyage to the Planets showed the deadly effects that ionizing radiation can have on interplanetary travellers. The Mars Science Laboratory, carrier of the Curiosity rover, spent the Earth to Mars transit recording the radiation levels. It confirmed that they were high enough to risk crew members contracting various serious conditions such as cataracts and cancer. Incidentally, female astronauts would apparently be more prone to radiation-induced cancers than male colleagues. A 2012 mission plan considered developing an electromagnetic anti-radiation shield, but most designs are looking to use traditional aluminium construction, perhaps with polyethylene shielding around the pressurised cabins. This definitely appears to be a case of fingers crossed as much as relying on advanced materials science.

The long duration spent in shipboard micro-gravity will also cause physical problems such as bone and muscle deterioration. The astronauts/cosmonauts/taikonauts (delete as preferred) will then have to adjust on Mars arrival to the one-third Earth gravity. As well as avoiding radiation on the Martian surface they will have to minimise contamination from the fine dust: minute particles suspended in the atmosphere could cause lung and thyroid problems if allowed into the lander cabin.

Besides the physical problems, the pioneering crew will also have to contend with the psychological effects of having travelled further from the Earth than any other humans - by an enormous margin. It's one thing to undertake a mission on the ISS - with a regular exchange of crew and a close-up view of the Earth via the cupola - but quite another to spend several years away from fresh air, blue skies, and all the other fantastic things we take for granted. The interplanetary distances would of course be exacerbated by the lack of real-time conversation: the one-way journey time for radio signals from the Martian surface is between four and twelve minutes.

There has been much research into astronaut's disturbed sleep patterns, which can obviously have deleterious effects on their work as well as their mental health. The claustrophobic conditions may contribute too: negative emotions blighted the small group of inhabitants of the Arizona-based Biosphere 2 sealed ecosystem in the 1990s. In addition, this experiment had distinct problems maintaining the environment, with a primary issue being the fluctuating oxygen and carbon dioxide levels. All in all, there are likely to be problems even the best planned mission won't have predicted.

3) When will it take place?

By comparison to low Earth orbit missions, a trip to Mars would be several magnitudes greater. If you want a pioneering aviation analogy I've just figured out that ratio of the Earth-Moon distance compared to the mean Earth-Mars distance is akin to the Wright Brothers' first flight of 36.5 metres being followed up by another spanning over 5 kilometres!

I can foresee two main issues to consider when planning mission timelines, which should ideally coincide to suggest an ideal launch window. The first is the relative orbital mechanics of the two bodies, which can be exploited so as to utilise a minimum fuel trajectory. The second relies on the eleven-year solar cycle: maximal solar activity helps to block interstellar cosmic rays and so reduce the risk of radiation poisoning. Although the sun's output would be at its peak, the astronauts would be safe from solar flares and coronal mass ejections providing they didn't need to undertake any spacewalks or surface EVAs for their duration.

There are several research projects that if one were to prove successful, could reduce by several decades the time before humanity is ready for its first manned Mars flight. The University of Washington and Lockheed Martin are both working on nuclear fusion technology suitable for such a mission. By reducing the journey time from between six and eight months to just three months there would be far less health risk to the crew, as well as presumably considerable weight savings on air and consumables.

Therefore it may become feasible as early as the 2040s but I doubt any earlier, regardless of how much advance is made in fusion technology. On top of all the usual political and socio-economic fluctuations there are just too many important longer-term issues that need resolution here first.

4) Where will it take place?

Mars, of course! The planet has a wide variety of locales (hint of travel brochure there), some rather more interesting than others. If the public get to vote on sites for exploration - bearing in mind that taxpayers will no doubt be funding the majority of the mission - conspiracy theorists and assorted nutbars might promote the curious tetrahedrons (note, not pyramids) of Elysium. Presumably they're enormous ventifacts, but they still appear to be very interesting geological features.

Then there's the great canyon system of Valles Marineris, over 4000 kilometres long and up to 7 kilometres deep. Or how about the 25 kilometre high Olympus Mons and its surrounding escarpment? In Pale Blue Dot: A Vision of the Human Future in Space, Carl Sagan suggested that it might be fruitful to explore the slopes of the Martian volcanoes in case they are scattered with diamonds ejected from the carbon-rich mantle!

Other locations that are just begging for detailed exploration are the polar caps, now thought to be mostly composed of water ice rather than frozen carbon dioxide, and caves or caverns, which would not only be a good place to search for native microbes but also to hide from radiation or dust storms.

5) Why will it happen?

This is perhaps the most difficult question to answer. Carl Sagan argued that the mission would fulfil the deep-seated need for exploration that our species - only recently converted from a nomadic existence - still feels. There is something to be said of this provision of a surrogate for human wanderlust, as identified in Bertrand Russell's 1959 quote: "a world without war need not be a world without adventurous and hazardous glory." This form of argument seems fairly mainstream in astronautic circles: even NASA's budget estimate for 2016 includes the phrases ‘reveal the unknown' (very likely) and ‘benefit all humankind' (which seems rather less obvious, except for Earth resources and weather satellites).

Against this notion are rather more pragmatic motives such as a combination of accelerated technological development and national prestige. But if nuclear fusion power is acquired in time for the first mission it's difficult to see what else will be gained from spending say half a trillion US dollars on a single crewed flight: wouldn't it be wiser to spend such vast sums on environmental stabilisation or medical research here on Earth? I've already commented on the potential white elephant of the ISS and there are no doubt many who don't consider any manned space exploration a suitable use of such enormous resources.

It's obvious that there are distinctive practical advantages to having humans on the spot rather than relying on robots. One issue that a single manned mission might be able to resolve that countless probes wouldn't is the question of life on Mars. The haze and plume seen in 2012 and the seasonal methane suggest some very interesting meteorological phenomenon if there isn't a biological explanation, but if there is any Martian bacteria then surely the mission could be deemed worthy of its immense budget? Somehow, I have my doubts…

One day in the next few centuries there could well be - unfortunately - branches of Starbucks and McDonalds on Mars and the Red Planet will be an alien frontier no more. But until then, any humans who undertake such an incredible journey will be pioneers in the Yuri Gagarin/Roald Amundsen/Edmund Hillary mould. However, I doubt the first human to step onto the Martian surface will use the latter's keen Kiwi phraseology: "we knocked the b***d off!"

Wednesday 27 February 2013

An index of possibilities: is science prognostication today worthwhile or just foolish?

A few evenings ago I saw the International Space Station. It was dusk, and walking home with the family we were looking at Jupiter when a moving bright light almost directly overhead got our attention. Too high for an aircraft, too large for a satellite, a quick check on the Web when we got home confirmed it was the ISS. 370 kilometres above our heads, a one hundred metre long, permanently crewed construction confirmed everything I read in my childhood: we had become a space-borne species. But if so few of the other scientific and technological advances I was supposed to be enjoying in adulthood have come true, has the literature of science prediction in these areas also changed markedly?

It is common to hear nowadays that science is viewed as just one of many equally valid methods of describing reality. So whilst on the one hand most homes in the developed world contain a myriad of up-to-date high technology, many of the users of these items haven't got the faintest idea how they work. Sadly, neither do they particularly have any interest in finding out. It's a scary thought that more and more of the key devices we rely on every day are designed and manufactured by a tiny percentage of specialists in the know; we are forever increasing the ease with which our civilisation could be knocked back to the steam age - if not the stone age.

Since products of such advanced technology are now familiar in the domestic environment and not just in the laboratory, why are there seemingly fewer examples of popular literature praising the ever-improving levels of knowledge and application compared to Arthur C. Clarke's 1962 prophetic classic Profiles of the Future and its less critical imitators that so caught my attention as a child? Is it that the level of familiarity has led to the non-scientist failing to find much interest or inspiration in what is now such an integrated aspect of our lives? With scientific advance today frequently just equated with cutting-edge consumerism we are committing an enormous error, downplaying far more interesting and important aspects of the discipline whilst cutting ourselves off from the very processes by which we can gain genuine knowledge.

Therefore it looks as if there's somewhat of an irony: non-scientists either disregard scientific prognostication as non-practical idealism ("just give me the new iPad, please") and/or consider themselves much more tech savvy than the previous generation (not an unfair observations, if for obvious reasons - my pre-teen children can work with our 4Gb laptop whilst my first computer had a 48Kb RAM). Of course it's not all doom and gloom. Although such as landmark experiments as the New Horizons mission to Pluto has gone largely unnoticed, at least by anyone I know, the Large Hadron Collider (LHC) and Mars Curiosity rover receive regular attention in popular media.

Perhaps the most regularly-occurring theme in science news articles over the past decade or so has been climate change, but with the various factions and exposé stories confusing the public on an already extremely complex issue, could it be that many people are turning their back on reading postulated technological advances as (a) technology may have greatly contributed to global warming; and (b) they don't want to consider a future that could be extremely bleak unless we ameliorate or solve the problem? The Astronomer Royal and former President of the Royal Society Martin Rees is one of many authors to offer a profoundly pessimistic view of mankind's future. His 2003 book Our Final Hour suggests that either by accident or design, at some point before AD2100 we are likely to initiate a technological catastrophe here on the Earth, and the only way to guarantee our species' survival is to establish colonies elsewhere as soon as possible.

But there are plenty of futurists with the opposite viewpoint to Rees and like-minded authors, including the grandly-titled World Future Society, whose annual Outlook reports are written with the aim of inspiring action towards improving our prospects. Most importantly, by including socio-economic aspects they may fare better than Arthur C. Clarke and his generation, whose space cadet optimism now seems hopelessly naïve.

One way near-future extrapolation may increase accuracy is for specialists to concentrate in their area of expertise. To this end, many scientists and popularisers have concentrated on trendy topics such as nanotechnology, with Ray Kurzweil perhaps the best known example. This isn't to say that there aren't still some generalist techno-prophets still around, but Michio Kaku's work along these lines has proved very mixed as to quality whilst the BBC Futures website is curiously old school, with plenty of articles on macho projects (e.g. military and transport hardware) that are mostly still in the CAD program and will probably remain that way for many years to come.

With so many factors influencing which science and technology projects get pursued, it seems worthwhile to consider whether even a little knowledge of current states and developments might be as useful as in-depth scientific knowledge when it comes to accurate prognostication, with luck instead playing the primary role. One of my favourite examples of art-inspired science is the iPad, released to an eager public in 2010 some twenty-three years after the fictional PADD was first shown on Star Trek: The Next Generation (TNG) - although ironically the latter is closer in size to non-Apple tablets. In an equally interesting reverse of this, there is now a US$10 million prize on offer for the development of a hand-held Wi-Fi health monitoring and diagnosis device along the lines of the Star Trek tricorder. No doubt Gene Roddenberry would have been pleased that his optimistic ideas are being implemented so rapidly; but then even NASA have at times hired his TNG graphic designer!

I'll admit that even I have made my own modest if inadvertent contribution to science prediction. In an April Fools' post in 2010 I light-heartedly suggested that perhaps sauropod dinosaurs could have used methane emissions as a form of self-defence. Well, not quite, but a British study in the May 2012 edition of Current Biology hypothesises that the climate of the period could have been significantly affected by dino-farts. As they say, truth is always stranger than fiction…