Sam Howell: ‘One day we might look for life directly on Europa’

the search for life in our universe is sort of one  of these intrinsic questions to humanity are we   [Music] alone when we look at Europa we see there  are ways to exchange Chemistry Between the space   environment in the ocean there are ways to keep  the body warm there are uh sources of chemical   energy and heat and all of this has probably  been going on for billions of years so all of a   sudden it starts to look like we maybe in our own  solar system have a second implausibly habitable   world and you know once you have two in one solar  system then they're probably all over the place   historically the NASA have sent three what we call  Flagship missions to the outer solar system three   two one we have ignition and as we look at that  tour and our progress through the solar system   having uh visited the planets with the Voyager  missions and gone to the Jupiter system with   Galileo and the Saturn system with Cassini we're  sort of stopping for a moment and going back to   Jupiter and the fourth outer solar system Flagship  Mission Europa Clipper is going to specifically   look at one of the largest four moons of Jupiter  Europa to understand if it has the conditions   necess necessary for planetary habitability europ  is about the size of our moon and most of its   Rock but the entirety of the world is covered in  about 100 kilm of water the top maybe 20 is Frozen   as solid ice and then there is a saltwater ocean  we think underneath that surface it has a really   unique orbital configuration where it interacts  with the other moons of Jupiter to continuously   dissipate frictional Heat at the interior  probably mostly within that icy shell keeping   the ocean liquid and warm on Earth we think that  a place life might have originally emerged is it   hydrothermal vents on the seafloor where water is  swept underneath and erupts outwards to deposit   um new sources of chemical energy uh that sort of  gives you one half of the terminal you need for   life and the other half at Europa could be made  by the radiation of Jupiter interacting with ises   the real insight it gives you is that you have a  second data point where if if you find a second   emergence of life in your own solar system  you can feel pretty confident and satisfied   that it's probably everywhere the eura Clipper  spacecraft is this large cylinder with two huge   solar panel Wings coming out it's solar panel  Wings span is just over 100 feet uh because   the sun is much dimmer at Jupiter than it is at  Earth and so you need a lot more surface area of   solar panels on board the spacecraft we have nine  instruments and one experiment that will observe   Europa in not only visible light with a narrow  and and wide angle cameras but and infrared and   thermal infrared and in the UV and even with an  active Source ice penetrating radar we'll have   Inu instruments that can measure the environment  directly we'll have dust analy that can pick up   material that's been sputtered off the Surface by  microm meteorite impacts and taste solid material   ejected from Europa directly we'll have mass  spectrometer capable of understanding the rarified   atmosphere of Europa we'll have uh magnetometer  capable of understanding the size and solinity of   europa's ocean by its interaction with Jupiter's  magnetic field but all of this is going to happen   from orbit around Jupiter with flybys of Europa  rather than orbit around Europa so we're going to   make about 50 flybys of Europa orbiting Jupiter  will come in as close as 25 km each time and the   reason we're doing this is Jupiter has a very  strong magnetic field anything coming through   the Jovian environment that's a Charged particle  particles from the Sun or the interstellar medium   particles erupted off the nearby volcanic moon  IO get trapped and sped up and make intense   ionizing radiation and so it's difficult to keep  a spacecraft alive in orbit around Europa because   of the radiation environment so we just dip our  toes in and fly out each time we're going to be   exploring what processes we think are active in  that ice shell today Central to habitability in   our story for Europa is that the salty ocean  interacting with the seaflo could produce a   lot of reducing chemistry and so that's chemistry  with electrons to give away and we believe that   the radiation environment at the Sur surface  interacting with water and even with sulfur   collected like bugs on a windshield from IO as  Europa goes around its orbit could produce strong   oxidants so things that want electrons and all  the life that we know of here on Earth uses the   transfer of an electron as its most basic energy  source for everything from cell maintenance to   mitosis basic functioning and so what we're really  interested in is the place where these oxidants   and reductants come together in the two terminals  of the battery close and the surface of Europa is   very young so there 's a plausible argument that  these oxidants made on the surface are coming down   to the ocean and it's important that we understand  you know the surface geology and land forms and   what those tell us about the exchange of material  from the surface to the ocean and the ocean to   the surface we're going to be looking for recent  incurrent activity everything from where there   might be tectonic faults active on the surface  today to where there might be eruptions of water   vapor from water trapped within the ice shell  we're going to be also probing the interior of   Europa we have an active Source ice penetrating  radar so we'll be able to image some structures   in the ice shell if you look at the surface of  Europa it looks like a yarn ball that's Criss   cut by slices there there's all of this tectonic  deformation going on in the surface that pulls   apart the ice shell and pushes it together  uh that's Central to Material Exchange and so   we're going to be looking at how those features  extend to depth maybe even possibly seeing the   ocean through radar on top of that we're going to  be probing the interior of the body by sending a   very stable radio signal back to Earth each time  we fly by Europa we can look at the Doppler shift   and the radio signal so in the same way a fir  truck driving by you gets really high frequency   as it gets close and low frequency as it goes away  as you accelerate flying by youropa you stretch   those waves out or compress them and it turns out  if you build up this web of fly eyes and you have   all of that Doppler data you can put back really  fine detail about how you accelerate it around   Europa and start to understand its gravity  field so then you can start to understand the   distribution of mass in the body and recover its  interior structure this is important because the   size of the ey shell relative to the ocean and  and the Deep interior structure all contribute   to how we understand the world to be habitable  as a system top of all of this we're also going   to be looking at the composition of the body  we have a across a variety of wavelengths the   ability to compositionally image the surface at  high resolution and so these are like cameras   that take pictures of light outside of the visible  spectrum and the light emitted and reflected and   transmitted by the material tells you something  about its composition and so we can survey the   composition of the surface we'll also be looking  at the temperature of the surface that can tell   us what tectonic features might be active or  where shallow subser water or even erupting   water we'll be scanning across the entirety of  Europa looking at its Edge for water vapor plumes   erupting into space going upward we're going to  be studying the material coming off of Europa   both sensing the chemistry of particles ejected  by microm meteorites in sensing the the very   tenuous Atmosphere by directly ingesting material  into Mass spectrometers on the spacecraft we'll   also be characterizing the magnetic field around  Europa this magnetic field of Jupiter that makes   the radiation environment so intense and makes  it difficult to explore Europa is also Central to   habitability because that radiation environment  creates half the chemistry that might be needed   for life but it also allowed us to detect europa's  ocean in the first place um Jupiter has a large   time varing magnetic field and as Europa goes  around it we noticed it produced a field that   was similar to but but offset from the Jovian  field uh that we call an induced field it's the   same way a wireless charger on your phone works  where you send a Time varying electrical current   through a loop of wire and it induces a magnetic  field you have a loop of wire on your phone and   that magnetic field then induces a current well as  Europa goes around Jupiter we notice this induced   magnetic field and similarly the only way that  that could be happening is if there was a large   Global conducting layer uh the most consist layer  that we understand is a large saltwater ocean and   so by sensing the magnetic field around Jupiter  and around Europa we can tease out properties   of that ocean like how salty it is and how deep  it is so all of these processes come together to   really help us close this test of the Europa  habitability hypothesis involving oxidants   produced at the surface and a reducing water Rock  interaction at the seafloor being brought together   by active geology in this thick icy shell to  potentially support a habitable ocean having   seen it go from really paper studies of how to  answer these science questions to Hardware that's   built and and sitting at the cape with a window  opening in October is indescribably exciting   these are missions that are National in scale or  really civilizational in scale that fundamentally   change our understanding of the solar system and  our own world it's exciting to think about what   might come next and what might ultimately result  in testing a life hypothesis but I really can't   overemphasize how exciting it is to be here in  this moment where we're testing the habitability   hypothesis because it really is a a new step  forward in how we think about the exploration   of astrobiology and so it's this really critical  moment where I feel like we're we're just coming   together to ask the question questions of what is  it we think life requires and and how to explore   that and how these processes interact and they're  really hard questions and yes it's exciting to   think about someday how we would do life detection  directly but the steper at and thinking about how   to close the problem and all of the variety of  people involved I I think is just as compelling