SCIENCE: Mysterious Quakes Never Detected Before on Mars.

It turns out that Mars is rum­bli­er than we knew. New tech­niques have revealed pre­vi­ous­ly unde­tect­ed quakes beneath the Mar­t­ian sur­face – and, sci­en­tists say, the best expla­na­tion so far is ongo­ing vol­canic activity.

The evi­dence seems to be mount­ing that Mars is far from dead, but hosts, under­neath its dusty, bar­ren sur­face, an inte­ri­or gur­gling away with seis­mic activity.

“Know­ing that the Mar­t­ian man­tle is still active is cru­cial to our under­stand­ing of how Mars evolved as a plan­et,” says geo­physi­cist Hrvo­je Tkalčić of the Aus­tralian Nation­al Uni­ver­si­ty in Australia.

“It can help us answer fun­da­men­tal ques­tions about the Solar Sys­tem and the state of Mars’ core, man­tle, and the evo­lu­tion of its cur­rent­ly-lack­ing mag­net­ic field.”

For a very long time, sci­en­tists believed that noth­ing much was going on inside Mars.

The plan­et has very lit­tle in the way of a mag­net­ic field. Plan­e­tary mag­net­ic fields are (usu­al­ly) gen­er­at­ed inside the plan­et, by some­thing called a dynamo – a rotat­ing, con­vect­ing, and elec­tri­cal­ly con­duct­ing flu­id that con­verts kinet­ic ener­gy into mag­net­ic ener­gy, spin­ning a mag­net­ic field out into space.

Mars’ lack of a mag­net­ic field sug­gests a lack of activ­i­ty. This is a big deal; in fact, a mag­net­ic field can mean the dif­fer­ence between life and death. Here on Earth, the mag­net­ic field pro­tects us from cos­mic radi­a­tion that might destroy life. On Mars, radi­a­tion lev­els are much high­er, even though it is more dis­tant from the Sun.

“All life on Earth is pos­si­ble because of the Earth­’s mag­net­ic field and its abil­i­ty to shield us from cos­mic radi­a­tion, so with­out a mag­net­ic field life as we know it sim­ply would­n’t be pos­si­ble,” Tkalčić explains.

But when NASA’s InSight lan­der arrived in Novem­ber 2018 and start­ed lis­ten­ing for Mars’ heart­beat, we learnt some­thing real­ly remark­able: Mars is rum­bling. To date, InSight has detect­ed hun­dreds of marsquakes – enough to give us a detailed map of the Mar­t­ian interior.

Tkalčić and his col­league, geo­physi­cist Wei­jia Sun of the Chi­nese Acad­e­my of Sci­ences, want­ed to look for quakes that might have gone unno­ticed in the InSight data. They used two uncon­ven­tion­al tech­niques, only recent­ly applied to geo­physics, to hunt seis­mic events in the InSight data.

Based on nine tem­plates of known marsquakes, the pair detect­ed 47 new seis­mic events, com­ing from a region on Mars called the Cer­berus Fos­sae – a sys­tem of fis­sures cre­at­ed by faults that have pulled the crust apart.

Most of those new seis­mic events resem­ble the wave­forms of two notable Cer­berus Fos­sae quakes that took place in May and July of 2019, sug­gest­ing that the small­er quakes are relat­ed to the larg­er ones.

Then the researchers sought to fig­ure out the cause of the quakes. Their analy­sis found that there was no pat­tern to be found in the tim­ing of the quakes, rul­ing out caus­es such as the influ­ence of Mar­t­ian moon Phobos.

“We found that these marsquakes repeat­ed­ly occurred at all times of the Mar­t­ian day, where­as marsquakes detect­ed and report­ed by NASA in the past appeared to have occurred only dur­ing the dead of night when the plan­et is qui­eter,” Tkalčić says.

“There­fore, we can assume that the move­ment of molten rock in the Mar­t­ian man­tle is the trig­ger for these 47 new­ly detect­ed marsquakes beneath the Cer­berus Fos­sae region.”

Pre­vi­ous analy­sis of fea­tures on the sur­face of Mars at the Cer­berus Fos­sae found that the region had been vol­cani­cal­ly active recent­ly, with­in the last 10 mil­lion or so years.

The activ­i­ty iden­ti­fied by Sun and Tkalčić, attrib­uted to the repet­i­tive move­ment of mag­ma in the Mar­t­ian man­tle, also sug­gests that Mars is more vol­cani­cal­ly and seis­mi­cal­ly active than we thought.

If this is the case, the results have impli­ca­tions for our under­stand­ing of the his­to­ry of Mars – and its future.

“The marsquakes indi­rect­ly help us under­stand whether con­vec­tion is occur­ring inside of the plan­et’s inte­ri­or, and if this con­vec­tion is hap­pen­ing, which it looks like it is based off our find­ings, then there must be anoth­er mech­a­nism at play that is pre­vent­ing a mag­net­ic field from devel­op­ing on Mars,” Tkalčić says.

“Under­stand­ing Mars’ mag­net­ic field, how it evolved, and at which stage of the plan­et’s his­to­ry it stopped is obvi­ous­ly impor­tant for future mis­sions and is crit­i­cal if sci­en­tists one day hope to estab­lish human life on Mars.”

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