Wednesday, 31 August 2011

Talking down Mars life and NASA's Curiosity-lander

Jeffrey Bada, co-organizer of a special two-day symposium on the Red Planet, during the 242nd Meeting of the ACS in Denver, talked down the likelihood of NASA's Curiosity lander nailing down life on Mars. The landing site shows recent activity, yet he talked of billions of years radiation. Can it be that the 2016 ExoMars Trace Gas Orbiter will lose much of its rationale when Curiosity comes up trumps in a year or two?
The Curiosity Mars Science Laboratory will land next August, to start a 2 year-investigation. Curiosity will analyze dozens of samples drilled from rocks or scooped from the ground with far more powerful scientific instruments than the earlier Mars rovers. Solid evidence of life-chemicals will surely be found by the gas chromatograph, mass spectrometer and tunable laser spectrometer, with combined capabilities to identify a wide range of organic compounds and isotopes.
So why downgrade Curiosity's mission as only “to determine if conditions are favorable for life” and claim that missions need to search rocks as deep as 1 metre?

Tuesday, 30 August 2011

Asteroid impacts likely seeded Mars, icy moons and exo-systems

Impacts likely to have sent Earth-seeds to icy moons and exo-planet systems

The idea that Chixculub-sized impacts would eject life-bearing debris from Earth to the outer planets and beyond is being increasingly validated by computer orbit simulations. 
Mars is quite accessible via direct ejection or after sling-shot acceleration by the Moon.  The timescale to reach Jupiter and its moons via further sling-shots is ~1Myr.  Seeding planets beyond our Solar System as in our 2004 paper on interstellar panspermia had been dismissed, but the new calculations of longer-time orbits are supportive.  Gladman et al in 2006 considered seeding of Titan and Europa, now in 2011 Pennsylvania State Uni and NAU Mexico teams confirm it with the former running simulations as long as 10 Myr.  These calculations show greater transfer to the outer solar system because of higher ejection speeds assumed.  Their limitation is that they do not model the atmosphere’s strong effects on ejection, both the friction that throttles most ejecta and the impact vapour plume that blows out especially the smaller ejecta to higher speeds.
Delivery to icy satellites depends on survival in unbraked impact, whereas for delivery to embryonic exo-planets, Cardiff groups found impact fragmentation followed by gas friction slowing the seed-bearing fragments to be the most effective scenario.


Sunday, 28 August 2011

New claim to the earliest bacterial life

Fossils of sulphur-bacteria have been identified on ancient sand grains in 3.45 Gyr deposits in Western Australia. Hollow tubular structures clumping together and coating the grains resemble modern sulphate-reducing bacteria. Nitrogen-enriched carbonaceous walls, low in the C-13 isotope, provide chemical evidence. Also, associated pyrite crystals inferred to be the sulphurous metabolic by-product constitute circumstantial evidence. The Crawley-led team includes Oxford's Martin Brasier, who has previously cast doubt on claims of bacteria-shaped structures in the nearby 35Myr-older Apex cherts.
Claims to find earliest life evidently depend on what constitutes adequate 'evidence'.  Older sedimentary rocks are more strongly metamorphosed - making for weaker evidence - yet many would support Manfred Schidlovski's older claims (~3.8 Gyr) based on C-13 isotope data, which leaves relatively little time for evolution of DNA-based life on Earth.

Friday, 26 August 2011

"Snow White" becomes for Caltech an embarrassingly Red dwarf-planet

Caltech astronomers are embarrassed about naming a KBO “Snow White”, now it has turned out to be one of the reddest objects in the solar system. Other large (~1000km) KBOs - ie. dwarf planets orbiting beyond Neptune and similar to Pluto - are also known to be red.

Though its spectrum shows water-ice, they now (22 August) rush to say the red-colour means a methane atmosphere.   They are surely still misled by the paradigm that sees comets and icy moons as ice and snow, a fractured paradigm that still persists among some astronomers.

Outer solar system bodies like comets have been known tobe high in complex carbon compounds ever since the 1986 investigations of Halley’s comet.  That showed Halley to be one of the darkest objects in the solar system, rather than an ice-ball.  In 2005, the Deep Impact experiment on Tempel-1 showed a lot of fine organic-clay particles mixed with snow.  Both showed methane is minor, if present at all.

Halley’s dark crust is doubtless produced via strongly heated of carbonaceous regolith  by the Sun (at 0.6AU).  The colour in the KBO objects is much more likely to arise via radiation processing of organics at the surface.  However, radiation processing generally produces yellowish brown colours.  Purer colours are in general chromophores as exist in biological pigments.  The extended red emission of nebulae is a case in point.  So the astronomers should be looking to identify the red-colour with chromophores - giving far more interesting implications!

Saturday, 13 August 2011

Unscientific ambivalence over Panspermia

There is common disregard of panspermia by scientists and science commentators outside astrobiology, which is surely bolstered by shyness within the field, as evidenced by contributions to the Origins2011 conference in July. There several speakers were prepared to envisage life originating on Mars (more conducive early environment) and transferring to Earth borne by a meteorite (well-validated processes of meteorite ejection to space and landing from space).   
But why won't they go further and accept that life would similarly have arisen in planetary systems around earlier generations of exostars, say 10 Gyr ago, which similarly generated meteorites bearing spores that could have seeded our nascent solar system?
There are indeed questions around probability/frequency of transfer and viability of irradiated spores over the Myr timescales, but no issue of principle. Arguments over the probability and viability are up for debate – so we await responses to our appraisals of likely senarios: Interstellar transfer of planetary microbiota;  a mechanism for interstellar panspermia; comets and the origin of life. 

That's why panspermia has come of age, evolving from a hypothesis into a coherent theory. It’s pretty secure in terms of transfer of life between solar system bodies, though not (yet) for interstellar transfer. The ambivalence among astrobiology scientists appears to be psychological**, a relic of 20th century focus on Origin of Life on Earth, fuelled by over-confidence in the Urey-Miller approach and by a disproved belief that life could not survive space conditions.

** Why Do Some People Reject Panspermia?  by M  Burchell

Wednesday, 10 August 2011

Prof. Levin comments on Martian Water and Marc Kaufman

Gil Levin writes: the Washington Post ran a major story on water on Mars by science writer of Marc Kaufman (6 August 2011) which was widely sindicated through the USA. This new article ignores past history of evidence for water, particularly Viking's findings, my publications and implications for the Labelled Release experiment that found evidence for life. Yet Kaufman's book, "First Contact" published in March, included a quite favorable review of my work.

Levin's updated summary includes
  • rising soil temperature at Viking 2 under as Sun reaches zenith, paused at 273K
  • surface water vapour pressure measured at Viking sites exceeded the triple point
  • snow/frost landscape seen in Viking images
  • experiments at UC Berkeley in simulated martian conditions
  • Mars rover tracks and mud puddles (from bouncing airbag)
  • droplets on legs of Phoenix lander; two droplets seen to merge as on smooth metal
** (Ed.) In 2001, NASA covered Levin's arguments for liquid water on Mars “in limited amounts and for limited times” against the scientific consensus that liquid water cannot exist on the surface. What they called 'scientific consensus' has evidently changed, but no recognition is given to those who challenged the older consensus. They reported Chris McKay as stressing: "a biology explanation [for the Viking test results] is inconsistent, ecologically, with what we know about Mars' surface environment". 10 years on, we know of micro-organism ecologies that do live in periodically warmed antarctic environments. So another of the 'consensus' arguments against Gil Levin is defunct.

Repeated claims of discovery of Water on Mars

Yet another claim to discover water on Mars came out this month (August) – why jump to give it greater weight than previous evidence (Marc Kaufman)?

It's long accepted that channels and plains on Mars were sculpted by water early in the planet's history. Michael Carr described episodic flooding of underground water after initial oceans and seas had disappeared. The polar caps show that water moves to and from the polar caps, depending on changing orbital obliquity over millions of years (0.1 to several Myr). The first spacecraft (Viking) found diurnal frosting, indicating day-night movements of water.

NASA asked in 2001 does Water Exist on Present-day Mars?  Then scientific consensus held that liquid water cannot exist on the surface of Mars, the NASA story said. They counterposed Gil Levin's positive arguments for liquid water “in limited amounts and for limited times” with Chris McKay saying experiments show a layer of liquid could only be very short-lived.
Mars Express 2005 showed activity in modern times, with evidence of glaciers as recent as 20-30kyr ago, and sea-like horizontal terrain on Elysium Plantia formed by a sudden flood some 5 Myr ago (from few impact craters) leaving ice covered with a dirt/sand crust.
The Mars Orbiter's hi-res camera in 2008 showed a landform of dunes frosting and thawing  - as water sublimates, it leaves a dirty darker surface that being warmer in sunlight accelerates the thawing and erosion of the sand dunes. A similar feedback operates at Mars's north polar cliffs.

In Feb. 2009 we were told First liquid water may have been spotted on Mars, as drops on the legs of the Phoenix lander. This was followed in 2010 Liquid Water Found on Mars, whose author Richard A. Kerr reported Phoenix as showing liquid water has lately flowed on the frigid planet. The water may be liquid every martian spring or summer. Late in 2009, dark, finger-like features from a crater wall were interpreted as periodic flow.

Further HiRISE pictures of the features which appear and extend down some Martian slopes during the warmest months of the Mars year, show they fade in winter, then recur the next spring. Yet seasonal changes in colour can result not from flow but from diffusing water in the surface soil. Water in the pores is more stable against evaporation into the dry air and capilliary action can spread it as long as it stays mobile – which depends on temperature and salt or organic content (even live fungi or algae). Do the narrow features correspond to veins of salt – not to flowing water but damp enough to support pigmented photosynthesising organisms?

Marc Kaufman's “First contact”

Enthusiastic reactions a-plenty to this book, published in March. It's certainly a filip to the popular exposition of astrobiology science. The Space Review relays several – here are some extracts, followed by extracts from the Achenblog

Mike Brown in the Washington Post (April 8, 2011).
The range of this new field of astrobiology is exhilarating, and even though scientists are still learning how to sort out the hard science from the understandably infectious enthusiasm, getting to ride along with Kaufman is an expansive joy.

He concludes that our life-finding eureka moment could be just around the corner. I’m less sure, for I know — as Kaufman demonstrates time and time again — that we scientists will argue until our last breath over any data of such monumental import. Still, I’m willing to step back long enough to look at this new field as an enthusiast, rather than a typically skeptical scientist. It’s hard not to become infected by the clear passion and excitement that the search for life beyond the earth brings out.
Mike Brown is a professor of planetary astronomy at the California Institute of Technology and the author of “How I Killed Pluto and Why It Had It Coming.”

Michael D. Lemonick in Time Magazine (April 22)
E.T., Call Us Back! Making the Case for Alien Life
…. in 1996, for example, when scientists looked into a rock blasted from Mars to Earth and saw what they believed was evidence of fossilized bacteria, and earlier this year when an online journal announced a similar discovery in a meteorite that fell in the 1800s. In neither case were any real E.T. remains proved to exist. Back in the 1970s, the twin Viking probes landed on Mars and performed on-site tests of the soil, looking for life. Most came back negative, but one, designed by NASA scientist Gilbert Levin, showed suspicious activity. (See listening for aliens: what would E.T. do?)
In the end, Levin’s colleagues, including Carl Sagan, decided it was a fluke — but Levin himself still insists it wasn’t, and Kaufman is inclined to give him the benefit of the doubt. Kaufman also bends over backward for the folks who say that bacterial remains can be found in meteorites. “Research in the past decade into the worlds of extremophiles, microbes and fossils,” he writes, “has proven that what’s true today often is overturned tomorrow, and what’s rejected today may be accepted tomorrow.”

Jeff Foust in the Space Review (April 4)
There are now astrobiology conferences, astrobiology journals, and even a NASA Astrobiology Institute. It’s in that environment of increased acceptance that Marc Kaufman surveys the state of astrobiology’s quest to discover life elsewhere in the universe in First Contact.
One interesting portion of the book looks at those people who still work in—or have been exiled to—the fringes of astrobiology even as the field gains wider acceptance. “[P]erhaps because of its urge for legitimacy, or because the discipline itself so often enters terra incognita, astrobiology has shown a consistent need to enforce a consensus,” casting aside those who differ, Kaufman writes. These people include Gil Levin, who argues the Labeled Release experiment on the Viking landers did, in fact, detect life on Mars; David McKay, who led the team that discovered what they still believe is evidence of life in Martian meteorite ALH 84001; and Richard Hoover**, who claims to see similar evidence for life in other meteorites. All three get fair, if somewhat sympathetic, profiles in one chapter of the book; Kaufman goes so far to lament that the three, presenting in the same session of a conference, draw only a handful of people—never mind that they’re speaking at a conference run by SPIE, an organization better known for optics and related technologies.

** Foust shows he doesn't follow Kaufman's openness on astrobiology, with the disparaging comment that “Hoover has gained notoriety for publishing a paper in the quixotic, controversial Journal of Cosmology about his asteroid life claims, an event that generated some media attention but was widely rebuffed as containing nothing new to support his claims.” No willingness there to assess the evidence carefully assembled by Hoover, just a desire to associate with some disgraceful attacks on him and the Journal which has given space to a score of commentaries on the study (Ed.)

Q&A on “First Contact” Joel Achenberg and Marc Kaufman, on Achenblog 27 Apr 2011
Edited extracts from the lengthy blog – include Marc's views on the Sagan criterion (no longer excludes life on other solar system bodies, we could well be Martians), McKay's martian fossils (unlike those published) and panspermia (doesn't appreciate interstellar transport argument).

Joel to Marc: How’d you get hooked on this topic of extraterrestrial life (which I know from experience can be quite absorbing)?
Marc to Joel: several years ago at MIT; I was a relatively new science writer ..three-day course was on “The Universe” .. Sara Seager, one of the top people in the field of exoplanets and their atmospheres, told us unequivocally that life (or signs of life) would be detected in the next generation or so.... my reaction was: My God, what a story! And it took off from there.
What I found, as I quite literally circled the globe to meet with scientists doing related work, was that most of them share Seager’s conclusion. And they didn’t agree based on a wish or hope, but based on the science that was coming out of the field of astrobiology.
...what I learned is that the scientific logic that leads to the existence of ET life is strong and getting stronger... now science has many of the tools and much more of the needed knowledge to find what might really be out there. It won’t be easy, it won’t be quick, and it’s sure to be controversial -- most everything involving astrobiology sparks some controversy. But that’s the very exciting direction where things are headed.
Joel to Marc: .. the Sagan standard (“extraordinary claims require extraordinary evidence”) is a little too strict and impractical, that it makes it impossible to reach any conclusion; is that a fair interpretation of your point? Your book gives us the latest on the ongoing ALH84001 (Mars rock) controversy, and you seem to be generally sympathetic to McKay and Gibson without going quite so far as to say you think they’re right. ...I read Bob Hazen’s book “Genesis,” and he really lays out the backroom brawling and gives us a glimpse of the egos involved. But what’s your hunch?
Marc to Joel: First on McKay: His team really went out on a limb when they published. A key part of their discovery involved magnetites -- microbes that use and leave traces of planetary magnetism. At the time, there had been no finding of any magnetic field remnant on Mars. That came 6 or 7 years later. Their research also required the presence of water to form certain minerals. While the water on Mars discussion was already underway in 1995, it has picked up enormous strength since and now the idea that Mars had an early “wet and warm” phase is nearing consensus.
As for the mini microfossil, McKay pretty much told me he wished he hadn’t gone with that one. Subsequent research by others has found that mini microfossils can and do exists on Earth, but McKay says to forget them because he’s finding those bigger microfossils in clearly Martian meteorites. That research has not been sufficiently developed to pass the “is it terrestrial contamination?” test and has not appeared in mainstream science journals. McKay is convinced they were once alive and that they are not earthly contamination, but I’m agnostic on that one. Richard Hoover of NASA/Marshall famously believes he is finding similar microfossils in non-Martian meteorites, but his recent paper on that in the new journal Cosmology got trashed, and properly so.
Putting it all together, the case for life in ALH84001 is stronger now than it was in 1995. Nonetheless, the consensus view remains that McKay et al did not find life in the rock. I personally think the jury is still out, but the evidence is looking stronger for McKay. (The guy who reviewed my book, Mike Brown from Caltech) makes an aside that he is leaning more towards accepting McKay’s position.)
On “extraordinary claims requiring extraordinary evidence,” ...what’s so fascinating about astrobiology now is that much of the really important work is being done outside that realm of extraordinary claims.
Exoplanets -- and those in habitable zones -- presence throughout the cosmos of the elements and compounds we assume are needed for life - complex carbons are found in nebulae, amino acids come flying in on meteorites, CO2 and methane are in atmospheres of distant planets, as well as Mars. No real “extraordinary claims” here; just the building of a strong scientific logic in favor of ET life. The very much new and improved research on extremophiles strengthens the case, I believe, because it shows life to be phenomenally tenacious and able to survive in myriad environments we long assumed were uninhabitable.
As for the endless controversies... as you know well, scientific “discoveries” very seldom give final answers and are always being challenged... one of the great strengths of science, it seems to me.
And very final thought ...Carl Sagan was one of the reviewers of the McKay paper for Science. He clearly thought it either cleared the bar or that the bar was set higher than it should be. And despite all the scientific conflict that followed ALH84001, do remember that the finding was a (the?) catalyst for setting up the NASA astrobiology program.
Joel to Marc: How the heck did non-living stuff become alive? Are you a panspermia guy (I hope that’s not probing into too personal of a realm)?
Marc to Joel: Finding (a) second genesis would be revolutionary, but we can be almost 100 pc certain that any other life in our solar system would not have evolved beyond a microbial state. So we’d be left with this conundrum: We would know that life is most likely common beyond our solar system, but the vast distances would make it impossible to come into contact with that potential life (except through measurements of exoplanet atmospheres, etc.)
And regarding panspermia, we do know that Mars was far more hospitable to life than Earth back in the period of 3.8-4.5 billion years ago, and that Earth was definitely inhospitable for a good chunk of that time. Yet some scientists are convinced they have found evidence of microbial life on Earth from about 3.8 billion years ago, though others remain skeptical. But if that 3.8 billion year evidence becomes more solid and even confirmed, then life was present here not too long (in cosmic term) from the time when it was seemingly impossible. Did it come from Mars? We truly will never know**, because the evidence is long gone. But I probably would put my money on the theory that we are, in the final analysis, all Martians.

** uncharacteristic blinkered assertion (Ed.)