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maven is a spacecraft that's orbiting

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Mars it's been there since 2014 maven in

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this case is an acronym that stands for

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Mars atmosphere and volatile evolution

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and this gives a clue as to what mavens

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real goal is it's to study the top of

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the atmosphere and how the gases in the

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top of the atmosphere might escape from

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Mars away to space so the atmosphere of

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Mars must have been a lot thicker but

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four billion years ago and today is very

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cold and dry and maven is meant to

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understand the atmosphere as it is today

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and how it has evolved into this current

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cold dry state one of the things we're

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trying to understand with maven is

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whether a magnetic field for a planet is

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important for regulating the climate or

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allowing the planet to keep an

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atmosphere earth has a global dynamo

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magnetic field Mars does not but Mars

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has an induced magnetosphere it has an

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induced magnetic field the upper

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atmosphere of Mars being ionized by

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solar radiation and so the electrons are

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being stripped from the atoms in the

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atmosphere when that happens it turns

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into what we call the state of plasma

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this plasma in the upper atmosphere is

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very conductive it leads electric

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currents to flow through it electric

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currents they shape the magnetic fields

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that are around them and that's actually

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how we see them with maven we take mean

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etic field data and we map it around the

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planet and from that the currents emerge

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we've known how the currents flow in the

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earth may need a sphere for decades but

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we don't know how that works around Mars

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we don't know how it influences the

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interaction with the solar wind because

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it determines how energy is flowing into

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the atmosphere it's transferred from the

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solar wind into the system and that's

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what we're trying to do with maven

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when you just look at the data as it

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comes down you're just seeing a little

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squiggly line essentially you're seeing

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the magnetic field strength in its

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direction vary as the spacecraft's

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flying through different regions and so

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what you have to do is you have to

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actually map it to the planets and to

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this interaction with the solar wind and

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then it starts to merge that the you

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have a drape situation where the the

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magnetic field the solar wind encounters

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the planet and it starts to wrap around

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it and the reason it wraps around the

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planet is those electric currents that

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we were seeing the magnetic field in the

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solar wind is straight lines you can

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think of straight spaghetti noodles and

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it's flowing towards the planet and

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those spaghetti noodles wrap around this

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basket ball shaped planet and that's

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indeed what we saw in the data the

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magnetic field lines draping around Mars

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as a planet one thing that wasn't so

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expected was the specific configuration

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of the electric currents that we derived

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from the magnetic field data if Mars is

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a ball here it's sort of this cup shape

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on the day side that loops back on

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itself maybe something that looks like

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this

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what wasn't so intuitive to me was the

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directions of those currents and the

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fact that it wraps continuously around

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to the night side and it makes this

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marvelously complex current system on

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the night side as well this is the first

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time that we've been able to actually

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map out the currents so we can see where

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the energy is being transferred we can

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see what actually forms the underlying

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mechanisms creating these induced

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magnetosphere that are not just common

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here in the solar system they're 50% of

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the planets that have them of the

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terrestrial planets and if you want to

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understand how the atmosphere of Mars

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and Venus why they're so different from

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the earth and why they're so different

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from each other despite both being non

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magnetized we need to understand they're

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induced many others first so knowing how

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these global current systems are

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configured teaches us about how charged

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particles near the planet are going to

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move both charged particles in the solar

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wind and charged particles from the

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atmosphere itself that are in the

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process of escaping to space so now we

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can understand better where those

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particles came from how they move near

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Mars and where they're going to go next

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that in turn teaches us about

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atmospheric escape from the planet and

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the history of the atmosphere over time

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how thick has it been how much has been