Mak­ing alien worlds on Earth

Aus­tralian nu­clear sci­en­tists are find­ing fresh ways to un­cover the se­crets of space, writes BELINDA SMITH.

Cosmos - - Spectrum -

WANT TO GET UP CLOSE to the swirling meth­ane seas on Saturn’s satel­lite Ti­tan or check out the sub­sur­face salty oceans of Ganymede, Jupiter’s largest moon? For He­len Brand at ANSTO’S Aus­tralian Syn­chrotron in Mel­bourne and He­len May­nard-casely at the Aus­tralian Cen­tre for Neu­tron Scat­ter­ing in Syd­ney, there’s no need to wait for a probe to dive or drill in. The plan­e­tary sci­ence pair ex­plores alien worlds by mak­ing tiny bits of them on Earth.

Us­ing a tech­nique called pow­der dif­frac­tion, Brand and May­nard-casely mix the com­pounds that are thought to com­prise our com­pan­ions in the so­lar sys­tem, squash them to mimic those oth­er­worldly pres­sures and watch how their crystal struc­ture changes. For work such as this, Brand and May­nard-casely shared the 2017 ANSTO Early Ca­reer Award in Nu­clear Sci­ence and Tech­nol­ogy.

Their col­lab­o­ra­tion spans decades. They met at age 18 as un­der­grad­u­ates at Univer­sity Col­lege Lon­don. “We’ve known each other for a very long time!” May­nard-casely says. And even though both are Lon­don-born and work closely in Aus­tralia to­day, their jour­neys from child­hood through school to univer­sity took dif­fer­ent paths.

May­nard-casely grew up in ru­ral Cam­bridgeshire, her par­ents a me­chanic and a teacher. But she had her sights set on space early on. At eight years old, she watched chemist He­len Shar­man blast off and be­come the first Bri­tish as­tro­naut and first wo­man to visit the Mir space sta­tion. “Fam­ily leg­end is I walked up to dad and said, ‘I want to go to space be­cause that’s what He­lens do!’” May­nard-casely laughs.

That drive for outer space was brought back to earth when, not long af­ter, she dis­cov­ered vol­ca­noes. She be­came en­am­oured with the spate of vol­cano-disas­ter films of the time, such as the 1997 thrillers Vol­cano and Dante’s Peak. And at around 15 or 16 years old, she “found out about vol­ca­noes made of ice [on other plan­ets], and thought: ‘That’s where I want to be’.”

Af­ter high school, she en­rolled in a plan­e­tary sci­ence de­gree at Univer­sity Col­lege Lon­don, the first in her fam­ily to go to univer­sity. Mean­while, Brand – with a physics teacher

May­nard- Casely and Brand have forged paths us­ing data that didn’t ex­ist when they were at univer­sity.

mother and maths teacher fa­ther – “had no chance” of not be­ing a sci­en­tist, she says. Her dad, a hobby ge­ol­o­gist, “took a ge­o­log­i­cal ham­mer on his hon­ey­moon, much to my mum’s an­noy­ance!”

Luck­ily, the younger Brand liked ge­ol­ogy too – not to men­tion space. Grow­ing up in south Lon­don, she re­mem­bers fre­quent­ing the Lon­don Sci­ence Mu­seum. There, she ad­mired the bronze com­mand mod­ule of Apollo 10, which flew around the moon in a dress re­hearsal of the historic Apollo 11 land­ing in 1969.

It was a school trip to Ice­land, led around the bleak, icy, oth­er­worldly land­scapes by a ge­ol­o­gist teacher, that re­ally glued her love of rocks and space to­gether. She de­cided to ap­ply for the gen­eral phys­i­cal sciences de­gree at Univer­sity Col­lege Lon­don.

“On the first day, they give you a timetable and tell you to choose eight sub­jects,” she says. But af­ter around six weeks, she re­alised she was in the same classes as the plan­e­tary sci­ence stu­dents – in­clud­ing May­nard-casely – so she trans­ferred to their course.

Af­ter grad­u­at­ing, both em­barked on Phds. Brand stayed at Univer­sity Col­lege Lon­don, un­rav­el­ling the crystal struc­ture of hy­drated min­er­als in Jupiter’s four largest moons: Io, Europa, Ganymede and Cal­listo. May­nard-casely’s stud­ies took her to the Univer­sity of Ed­in­burgh in Scot­land, where she ex­am­ined how meth­ane’s struc­ture changes in the crush­ing pres­sures of gas gi­ants Uranus and Nep­tune.

When Brand moved to Aus­tralia in 2009 to take up a

po­si­tion at CSIRO in Mel­bourne, she worked on a prob­lem ex­tremely rel­e­vant to the min­ing boom of the time: how a hy­drated min­eral called jarosite forms.

Ore dug from the ground is of­ten a mix of loads of met­als and im­pu­ri­ties. To end up with pure zinc, for in­stance, a re­fin­ery must get rid of iron. This is done by mix­ing ore with wa­ter and adding an al­ka­line. The al­ka­line binds to iron, cre­at­ing jarosite, which “pre­cip­i­tates and blobs to the top, and can then be scooped off,” Brand says.

X-ray pow­der dif­frac­tion can tell min­ing com­pa­nies the best way to crys­tallise dif­fer­ent types of jarosite and do it more ef­fi­ciently.

“But the same thing hap­pens on Mars,” Brand says – not in mines, of course, but nat­u­rally (as it does on Earth). In 2004, the Op­por­tu­nity rover found jarosite on the Mar­tian sur­face – the first hy­drated min­eral dis­cov­ered on the red planet.

Jarosite needs lots of wa­ter to form. Its pres­ence was an­other piece of ev­i­dence that, at some point, Mars had vast liq­uid oceans.

When Brand moved to the Aus­tralian Syn­chrotron pow­der dif­frac­tion beam­line, she wanted to see how jarosite forms in con­di­tions like the Mar­tian crust and sur­face. The chem­istry could be plugged into ge­o­log­i­cal mod­els of Mar­tian evo­lu­tion and help plan­e­tary sci­en­tists re­veal the planet’s his­tory.

May­nard-casely made the move to Aus­tralia too, in 2011, first work­ing with Brand at ANSTO’S Aus­tralian Syn­chrotron be­fore mov­ing to ANSTO in Syd­ney. (“She fol­lowed me!” Brand laughs. “I was here first.”)

Among other things, May­nard-casely is look­ing at how the struc­ture of small hy­dro­car­bons and ices shift when placed un­der pres­sure. Re­cently, she’s taken an in­ter­est in the as­ter­oid belt – a ring of as­ter­oids and dwarf plan­ets be­tween Mars and Jupiter.

NASA’S Dawn space­craft swung by as­ter­oid Vesta be­fore set­tling into or­bit around Ceres, the largest body in the as­ter­oid belt, last year. There, it found the top­most me­tre of Ceres’ sur­face to be hy­dro­gen-rich, con­sis­tent with huge ex­panses of wa­ter ice tucked away be­low.

“We’ve gone from think­ing these bod­ies are com­pletely dry, there’s no wa­ter there, to the re­al­i­sa­tion that Ceres sits neatly on the ice line, which is the point where it got cold enough for wa­ter to con­dense straight away [when the so­lar sys­tem formed],” May­nard-casely says.

She’ll try dif­fer­ent com­bi­na­tions of salts to em­u­late Ceres con­di­tions and see what struc­tures ap­pear. Then, she’ll com­pare her data with that taken by Dawn (which, like all NASA re­search, is open-ac­cess). It might tell us about the wa­ter sit­u­a­tion on Ceres, she says, “but in re­al­ity, we’ll prob­a­bly make it a bit more com­pli­cated!” At the very least, she will have ac­cu­mu­lated a com­pre­hen­sive dif­frac­tion cat­a­logue of dif­fer­ent salty so­lu­tions from mi­nus 269 °C to room tem­per­a­ture.

Brand, too, has turned her at­ten­tion to as­ter­oids – but those that made it to Earth. Last year, a friend asked if she would use the X-ray diffrac­tome­ter to ex­am­ine sand-sized 2.7-bil­lion-year-old me­te­orites found em­bed­ded in limestone in the Pil­bara. What they found was ev­i­dence that the early Earth’s up­per at­mos­phere’s oxy­gen lev­els were sim­i­lar to that of to­day.

Since fin­ish­ing their de­grees, May­nard-casely and Brand have forged their own paths us­ing data that didn’t ex­ist when they were at univer­sity.

And while they’ve been in­ter­ested in sci­ence since child­hood, nei­ther had an idea of where it would take them – or the so­lar sys­tem’s se­crets they’d re­veal. They sim­ply pur­sued what they loved.

“When peo­ple say to me, ‘I don’t know what to do’, I say, ‘do what you en­joy’,” May­nard-casely says. “I tend to give that ad­vice to a lot of peo­ple.”

Brand agrees. When en­rolling in her gen­eral maths and physics un­der­grad­u­ate de­gree, “I didn’t re­ally know what I was do­ing or where I was go­ing to end up,” she says. “I just liked space and rocks – and here I am.”

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BELINDA SMITH is a sci­ence and tech­nol­ogy jour­nal­ist based in Mel­bourne, Aus­tralia.

IMAGES 01 Su­san Bogle / ANSTO 02 Nathalie Sal­dumbide / Sal­dumbide Pho­tog­ra­phy

He­len May­nard- Casely had her sights set on space early on. 01

02 He­len Brand has turned her at­ten­tion to­wards as­ter­oids.

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