Thursday 28 July 2016

Out of this world

I got a handful of links from one of the very few post-graduate students at The Institute who has an interest outside his own research.  He should be in a university, he has the necessary curiosity. The links were all about the process of post-graduate education: should there be a viva? is an unpublished thesis a mere waste of shelf-space? One of the articles, has three accomplished scientists look back at their PhD thesis with a sense of the past is a different country.

Such is the absurd specialization in modern science that I'd only heard of one of these three spotlighted scientists. One of them was Sara Seager [Shown R with a prototype of her mini space telescope and a background to indicate "rocket-scientist"] who is currently the Class of 1941 Professor of MIT, but she spends a large part of her working life off-planet as an exobiologist.  If the 5 minute Nature interview tickles your fancy, maybe especially if you're a young woman in science, you should bite off another hour's worth of Prof Seager from the series Infinite History MIT. It's trying to produce a biographical sketch of one of MIT's stars but it can't help itself from bigging up MIT. In fairness, Seager maintains that MIT does the best for women-in-science, as a concept and individually, of all the places where she has worked. Those other places included U.Toronto (BSc), Harvard (PhD), Institute for Advanced Study Princeton (postdoc), Carnegie Institute (postdoc). As well as her contributions to understanding the universe, Seager devotes a significant part of her time towards mentoring young women; helping them to be more assertive, have bigger ambitions, and insisting on clearer acknowledgement for their contributions. In a way that's more important than the science direct. As a role-model, as a supervisor, as an external examiner she can make a new generation of scientists, especially the women, to fulfill their potential a little bit more. Not a lot different from Ireland's own source of potential energy.

But let's look at the science, although it may blow your bonce. You can get the easy picture in a 17 minute 2015 TEDx Vancouver talk. When she was a teenager, city-bred Seager went on a camping trip with her father and lost her heart to the stars when she saw them for the first time in their full deep-rural brightness.  She wasn't going to Med School after that. Instead she went to Harvard where she contributed to our understanding of the energetics of the Big Bang with a theoretical and methodological paper that was been widely cited. But you can have an impact in science even if you don't publish widely-cited papers. One way is to talk to others and help them get their half-baked ideas into the Do It oven. After her cosmology paper, Seagar moved sideways into looking for exoplanets because part of the tool-kit developed for the Big Bang project was finding ways of detecting minute signals in the noise of cosmic radiation. I've written about the discovery of the first exoplanet unsteadying the light of star 51 Pegasi by Mayor & Queloz in 1994. The early exoplanets were a) massive and b) near their sun; they had to be because the early detection techniques were crude. Seager reckoned that about 10% of these suns with planets would be so oriented that the crossing of the sun's face by one of its planets could be observed from Earth. Being the theoretician, she modelled the effect of light being distorted as it passed through the atmosphere of a planet before reaching a telescope on or near our own. She also nagged David Charbonneau, one of her colleagues, to get into the heap of data on his computer and actually observe the transit of an exoplanet across its sun. Grateful thanks for that but not authorship on Charbonneau's ground-breaking paper!

In her TEDx talk Seager makes the point that 'astronomers' no longer get their primary data by putting on a woolly hat and a fur coat at night in an observatory. Nope, like the rest of us they work mostly by e-mail and trawling through databases on the computer. Things have moved on since the days of Mina Fleming or Annie Jump Cannon or Jocelyn Bell Burnell whacking stakes into the ground with a sledge-hammer. It wasn't clear 20 years ago that there was much traction in exoplanets. First of all nobody believed they existed, then they thought the whole field was a waste of time and several senior and influential men advised Sara Seager against pursuing such distant and fuzzy objects.  But her take on it was that she and other, younger, star-watchers were on the track of Goldilocks planets: those that were close enough to being 'just right' for life. She has published her own take on the Drake Equation to calculate the probability that we are not alone. Things are looking promising, numerically, the average number of planets discovered per star observed is close to one. That's several thousand planets, now the trick is to winnow out those that might support life.

As we know from Gaia, planets do not just carry life; the two are in an intricate mutually modifying dialogue. There may be only 100+ elements but the number of chemical compounds is near infinite. The exoplaneteers have fingered ten biosignature gases which if present indicate that something living is making them: oxygen, ozone, methane, nitrous oxide, methyl bromide, methyl chloride, hydrogen sulfide, carbonyl sulfide, phosphine, and sulfur dioxide with a reserve list of sixteen acetaldehyde, acetone, benzene, carbon disulfide, dimethyl disulfide, dimethyl sulfide, dimethyl sulfoxide, ethanol, ethyl mercaptan, fluoroacetone, isoprene, methyl ethyl ketone, methyl mercaptan, methyl vinyl ketone, thioglycol, and toluene. Our atmosphere is close to 20% O2 by volume; a tad higher and we would all spontaneously combust. Without photosynthetic plants and cyanobacteria, there would only be a smidgeon of free oxygen detectable in our atmosphere by telescopes from the Planet Zorg.

How do you detect gases in inaccessible places? You do it by spectroscopic analysis of the light. Sodium burns with a characteristic yellow light that we can see radiating out from a street-lamp but equally from a distant star or distorted by passage through a distant planet's atmosphere. A sodium ion is absurdly small; to detect it at a distance of multiple light years is a technological feat that clearly invokes Clarke's third law (* see footnote). If only 10% of the ever-increasing catalog of exoplanets can be assessed for Goldilocksity during transit, then it's surely a good idea to design a technical fix to measure the other 90%.  Wouldn't it be some bummer, if we missed a distant earthly paradise simply because its solar system was a right-angles from our view-point? The exoplaneteers are developing multiple bread-box sized space telescopes [see above R and a snip a $1million each!] that can each clock data from a single distant star.  They are coupling this with a sunlight excluder called Star-shade [L with telescope] from which petals are deployed to occlude the sunlight which washes out any reflected signal of associated planets [explanatory youtube]. The picture [L] is distorted in that the effective distance between star-shade and telescope is not 50m but 50,000km and precisely in line with a known star-system of interest.  More engineering magic required there but I guess no more difficult than landing a man on the moon or docking with the International Space Station [prev].

Having a family doesn't seem to impact on the career of male scientists even if their wives are working full time. But children are a huge drag on the career progression of women-in-science.  It's not fair and we should do something about it. Sara Seager has managed against the institutionally stacked deck to get married and have two children. This in addition to making huge waves in her field. Her husband died, cruel young, in 2011 which left her a single mom with an additional layer of logistical difficulties. She is of the generation that will never be able to afford a home near to her place of work in Cambridge, MA, so a knackering commute is added to her daily life. In 2013, she secured a MacArthur Fellowship which augments her MIT salary by $650,000 as quarterly checks for 5 years. She is putting that all into servicing her home life: the cleaning, the school-run, the after-school, getting the car serviced and waiting for the plumber - so that she can continue to do effectively what she does best . . . be a scientist. Hats off to MacArthur, ditto with sweeping bow to Seager.

  • Clarke's first law When a distinguished but elderly scientist states that something is possible, he is almost certainly right. When he states that something is impossible, he is very probably wrong.
  • Clarke's second law The only way of discovering the limits of the possible is to venture a little way past them into the impossible.
  • Clarke's third law Any sufficiently advanced technology is indistinguishable from magic.
from Arthur C Clarke Hazards of Prophecy: The Failure of Imagination

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