Mighty Dons Of Science News

Sci­en­tists at a new re­search in­sti­tute are work­ing to find out how life might evolve us­ing chem­i­cals not found in Earth-based life forms.

They’re stu­dy­ing how organ­isms might emp­loy al­ter­na­tive sol­vents—that is, oth­er liq­uids that could play the role that wa­ter does in fa­mil­iar life forms.

The Un­ivers­ity of Vi­en­na es­tab­lished the re­search group Al­ter­na­tive Sol­vents as a Ba­sis for Life Sup­port­ing Zones in (Exo-)Plan­e­tary Sys­tems last May un­der the lead­er­ship of as­tron­o­mer Ma­ria Firneis. Re­search by the group was pre­sented at the Eu­ro­pe­an Plan­e­tary Sci­ence Con­gress in Pots­dam, Ger­ma­ny on Sept. 18.

Tra­di­tion­ally, plan­ets that might sus­tain life are sought in “hab­it­able zone,” the re­gions around stars in which Earth-like plan­ets with car­bon di­ox­ide, wa­ter va­pour and ni­tro­gen at­mo­spheres could main­tain liq­uid wa­ter on their sur­faces.

Sci­en­tists have been seek­ing chem­i­cal sig­na­tures pro­duced by ex­tra­ter­res­tri­al life with metabolisms re­sem­bling the ter­res­tri­al ones, where the build­ing blocks of life, ami­no ac­ids, are based on car­bon and ox­y­gen dis­solved in wa­ter.

But “it can­not be ruled out that life forms have evolved some­where that nei­ther rely on wa­ter nor on a car­bon- and ox­y­gen-based metabolis­m,” said re­search group mem­ber Jo­han­nes Leit­ner. “It is time to make a rad­i­cal change in our pre­s­ent ‘geo­cen­tric’ mind­set.”

A life-sup­porting sol­vent must re­main liq­uid over a large tem­per­a­ture range. Wa­ter is liq­uid be­tween 0 and 100 de­grees Cel­si­us, but some oth­er sol­vents are liq­uid over more than 200 de­grees. Such a sol­vent would al­low an ocean on a plan­et clos­er to the cen­tral star, re­search­ers say.

The re­verse sce­nar­i­o is al­so pos­si­ble – a liq­uid ocean of am­mo­nia could ex­ist much fur­ther from a star. Fur­ther­more, sul­phu­ric ac­id can be found with­in the cloud lay­ers of Ve­nus and lakes of meth­ane or eth­ane cov­er parts of the sur­face of the Sa­tur­ni­an moon Ti­tan.

The re­search group, with in­terna­t­ional col­la­bo­ra­tors, plans to study the prop­er­ties of a range of sol­vents oth­er than wa­ter, in­clud­ing their abun­dance in space, ther­mal and bio­chem­i­cal char­ac­ter­is­tics as well as their abil­ity to sup­port the or­i­gin and ev­o­lu­tion of life-sup­porting metabolisms. Al­though known most exoplan­ets, or plan­ets out­side our so­lar sys­tem, are com­posed of gas, “it is a mat­ter of time un­til smaller, Earth-size exoplan­ets are discov­ered,” said Leit­ner.