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Europa Clipper Moves to Next Stage

Europa Clipper stays on my mind, with the intent of digging deeper into the spacecraft as development moves forward. We are talking about a craft that is by necessity radiation-tolerant as it will make a series of close flybys of Europa during its long orbit of Jupiter. 45 such flybys are in the cards, at altitudes varying from 2700 to 25 (!) kilometers, with flybys of Ganymede and Callisto in the mix as well. The latter are considered gravitational maneuvers intended to refine Europa Clipper’s orbit, and while they should be productive, they are not science priorities.

Image: Because Europa lies well within the harsh radiation fields surrounding Jupiter, even a radiation-hardened spacecraft in near orbit would be functional for just a few months. Studies by scientists from the Jet Propulsion Laboratory show that by performing several flybys with many months to return data, the Europa Clipper concept would enable a $2B mission to conduct the most crucial measurements of the cancelled $4.3B Jupiter Europa Orbiter concept. Here we see how the mission can achieve global coverage during successive flybys. Credit: NASA/JPL.

NASA has now announced confirmation of Europa Clipper’s next mission phase, which means we proceed to completion of the final design, which will in turn be followed by construction and testing of the spacecraft and its science payload. NASA associate administrator for the Science Mission Directorate Thomas Zurbuchen frames Europa Clipper within the sequence of outer system missions that most recently has included Cassini’s operations at Saturn:

“We are all excited about the decision that moves the Europa Clipper mission one key step closer to unlocking the mysteries of this ocean world. We are building upon the scientific insights received from the flagship Galileo and Cassini spacecraft and working to advance our understanding of our cosmic origin, and even life elsewhere.”

Image: This artist’s rendering shows NASA’s Europa Clipper spacecraft, which is being developed for a launch sometime in the 2020s. Credit: NASA/JPL.

As the concept evolves, we’ll see how closely it tracks the image above, in which the ice-penetrating radar antennae are attached to the solar arrays extending from the spacecraft. The magnetometer boom and round high-gain antenna are visible on the side of the spacecraft, with a remote-sensing palette housing the rest of the instrument payload on the left.

The instruments NASA has selected to study Europa include nine of the thirty-three originally proposed. As you would imagine, they include a thermal instrument that will search the surface for recent eruptions of warmer water even as other instruments look for tiny particles in the thin atmosphere around the moon. It was back in 2012 that Hubble data indicated water vapor above the south polar region, giving us the possibility of water plumes linked to the subsurface ocean. As at Enceladus, that would open sampling options without drilling through the ice.

Ice-penetrating radar will be used to determine the thickness of the ice shell while also looking for the kind of subsurface lakes found beneath Antarctica. The matter has been the subject of controversy for years and clearly determines what is and is not possible in terms of ocean sampling from the surface, although collection of materials near Europa’s chaos regions, where the surface has been deformed, may one day allow a lander to study frozen ocean brines.

Long linear cracks on the surface seem to be the result of tidal forces causing the ice shell to flex. The constant gravitational interaction with Jupiter could provide enough heat energy to enable chemical reactions in the interior that, through volcanoes or hydrothermal vents, recycle nutrient-rich water between the ocean and the rocky interior. How well Europa’s different layers move material between them may determine whether living organisms can flourish here.

Image: This view of the Conamara Chaos region on Jupiter’s moon Europa taken by NASA’s Galileo spacecraft shows an area where the icy surface has been broken into many separate plates that have moved laterally and rotated. These plates are surrounded by a topographically lower matrix. This matrix material may have been emplaced as water, slush, or warm flowing ice, which rose up from below the surface. One of the plates is seen as a flat, lineated area in the upper portion of the image. Below this plate, a tall twin-peaked mountain of ice rises from the matrix to a height of more than 250 meters. The matrix in this area appears to consist of a jumble of many different sized chunks of ice. Though the matrix may have consisted of a loose jumble of ice blocks while it was forming, the large fracture running vertically along the left side of the image shows that the matrix later became a hardened crust, and is frozen today. Credit: NASA/JPL.

Europa Clipper will also carry cameras and spectrometers to produce high-resolution images and map surface composition, along with a magnetometer to measure the moon’s magnetic field, offering insights into the depth and salinity of the ocean. NASA announced in March that it was going to replace the earlier magnetometer designed for the mission — Interior Characterization of Europa Using Magnetometry, or ICEMAG — with a less complex (read ‘expensive’) instrument. The current list of instruments can be accessed here.

{ 28 comments… add one }
  • John walker August 21, 2019, 14:54

    The removal of ICEMAG angers me no end to this day. The magnetometer is central to this mission. It was always central to a Europa mission. I have read that the team believed they were on a good path to resolve the issues with the scalar vector helium sensors. Even if the instrument’s developmental cost had expanded to 100 million, that would still have represented less than 3% of the mission’s total cost. And if the SLS mandate is ignored and instead the Falcon/Star 48 option chosen, that could save as much as 1 billion dollars. The ICEMAG price tag is spare change in comparison. A terrible decision which I still (somewhat irrationally) hope will be reversed.

    • Ashley Baldwin August 21, 2019, 17:04

      Here,here. I couldn’t agree more. But given its hard road to get to this point. I guess that beggars can’t be choosers.

    • Ashley Baldwin August 21, 2019, 17:18

      Talking about development costs makes me wonder whether the delay due to SEIS on Insight may have had an impact. This came with a price tag of circa $150 million . An obvious direct effect. It also highlighted the risks of putting state of the art instrumentation on a cost capped mission. We have all witnessed the even greater consequences of this with the non capped JWST.

      • ljk August 22, 2019, 9:05

        So many things have to go right with the deployment of JWST that only a few wrong events can cripple the entire mission. And they have no in-space repair system set up!

    • Alex Tolley August 22, 2019, 0:06

      So this link is already out of date? (ICEMAG is one of the instruments included).


  • Coacervate August 21, 2019, 15:26

    Very exciting news, thank you. I hope this mission will include a lander with a petri dish. The current NASA vision seems to avoid a Viking/Beagle2 type direct effort to discover microbes. Maybe someday the Elon will muster the courage to risk failure and search for actual viable microbes in space.

    • violet August 21, 2019, 19:32

      This moon as well as any missions to Enceladus should have one priority . . . to search for life. Why waste all this money if the priorities are a magnometer . . . ?? I thought we have figured out there is water under that shell of ice. Why not a lander that can sniff the surface for organics. Time for the Organic Chemists to hold forth on these missions to complex ice covered ocean moons, Mars and Titan. It seems like the Planetary Geologists always win the grant battle and want to know why?

      • ljk August 22, 2019, 10:59

        They are being overly cautious because of what happened with the Viking Mars landers in 1976. They went there with a $60 million biology lab assuming they would detect native microbes in the surface. Instead they got back ambiguous readings and realized among other things that they should have better tried to understand the composition of the planet’s crust first.

        That being said, I agree if you are going to Europa or Enceladus or anywhere else life might exist, that you should look for it. We already know Mars had liquid surface water going back to the early 1970s. We confirmed it with the MERs in 2004. We also have more than a little evidence that Europa and Enceladus have global oceans of the liquid stuff. Time to move to the next logical steps.

      • VIY August 23, 2019, 11:42

        What if there’s (likely) no life elsewhere in the Solar system? Does this mean we should not explore anything? I believe that search for life should not be a primary goal – it’s more of a way to justify the large expense of those missions to the generally science averse public. The main goal should be to understand what is around us, how can it affect us, and how can we benefit or be aware of it. If we find life as a result, all the better.

        • Alex Tolley August 23, 2019, 13:41

          Finding whether there is ET life in the universe is a “big question”. Any of the answers – abundant|rare|none have great ramifications.

    • Coacervate August 24, 2019, 1:47

      Good science brings more questions than answers. The intriguing Viking results did exactly that because it was good science. Had NASA followed the trail thus blazed we would have learned about perchlorates, the nature of Martian geo/atmospheric chemistries and have answers for the “is there life after Viking” mysteries. Forty plus years later we are still arguing if we should even look for existing life. There are lessons there…Perhaps most important is what we learn about ourselves and what science means to societies at large. If the USA no longer wishes to explore strange new worlds, to seek out new life then stay home and watch it on YT. Everyone else is going, we’ll post a vid of our cat riding on a rover for you.

  • Laintal August 21, 2019, 17:50


    This is going to be one interesting mission to follow and hopefully set the stage for a lander in the future

  • Enzo August 21, 2019, 18:50

    About time.

  • Harry R Ray August 22, 2019, 9:39

    LET’S NOT FORGET ABOUT CERES! ArXiv: 1908.07731. “GAUSS – A Sample Return Mission to Ceres.” by Xian Shi et al. Joint Chinese-ESA mission. Departure: May 14, 2029. Mars gravity assist: June 7, 2032. Rendevous with Ceres: March 30, 2034. No set times for Ceres landing, sample return liftoff from Ceres, or Earth atmosphere re-entry. I hope and pray the lander and return capsule will be the ESA component, because I do not trust the Chinese to properly sterilize anything that will touch the surface of Ceres!

    • ljk August 22, 2019, 11:03


      GAUSS — A Sample Return Mission to Ceres

      Xian Shi, Julie Castillo-Rogez, Henry Hsieh, Hejiu Hui, Wing-Huen Ip, Hanlun Lei, Jian-Yang Li, Federico Tosi, Liyong Zhou, Jessica Agarwal, Antonella Barucci, Pierre Beck, Adriano Campo Bagatin, Fabrizio Capaccioni, Andrew Coates, Gabriele Cremonese, Rene Duffard, Ralf Jaumann, Geraint Jones, Manuel Grande, Esa Kallio, Yangting Lin, Olivier Mousis, Andreas Nathues, Jürgen Oberst, Adam Showman, Holger Sierks, Stephan Ulamec, Mingyuan Wang

      (Submitted on 21 Aug 2019)

      The goal of Project GAUSS is to return samples from the dwarf planet Ceres. Ceres is the most accessible ocean world candidate and the largest reservoir of water in the inner solar system. It shows active cryovolcanism and hydrothermal activities in recent history that resulted in minerals not found in any other planets to date except for Earth’s upper crust.

      The possible occurrence of recent subsurface ocean on Ceres and the complex geochemistry suggest possible past habitability and even the potential for ongoing habitability.

      Aiming to answer a broad spectrum of questions about the origin and evolution of Ceres and its potential habitability, GAUSS will return samples from this possible ocean world for the first time.

      The project will address the following top-level scientific questions: 1) What is the origin of Ceres and the origin and transfer of water and other volatiles in the inner solar system? 2) What are the physical properties and internal structure of Ceres? What do they tell us about the evolutionary and aqueous alteration history of icy dwarf planets? 3) What are the astrobiological implications of Ceres? Was it habitable in the past and is it still today? 4) What are the mineralogical connections between Ceres and our current collections of primitive meteorites?

      GAUSS will first perform a high-resolution global remote sensing investigation, characterizing the geophysical and geochemical properties of Ceres. Candidate sampling sites will then be identified, and observation campaigns will be run for an in-depth assessment of the candidate sites.

      Once the sampling site is selected, a lander will be deployed on the surface to collect samples and return them to Earth in cryogenic conditions that preserves the volatile and organic composition as well as the original physical status as much as possible.

      Comments: ESA Voyage 2050 White Paper

      Subjects: Instrumentation and Methods for Astrophysics (astro-ph.IM); Earth and Planetary Astrophysics (astro-ph.EP)

      Cite as: arXiv:1908.07731 [astro-ph.IM]
      (or arXiv:1908.07731v1 [astro-ph.IM] for this version)

      Submission history

      From: Xian Shi [view email]

      [v1] Wed, 21 Aug 2019 07:33:54 UTC (6,376 KB)


    • John walker August 22, 2019, 11:13

      Thanks. I wasn’t aware of this mission. It is only a proposal at the moment. 27 page description here https://arxiv.org/abs/1908.07731
      Post DAWN, Ceres has gained many advocates including those who see it as an intermediate target for human exploration before Mars. https://www.hou.usra.edu/meetings/lpsc2019/pdf/3062.pdf

  • Gary Wilson August 22, 2019, 17:47

    I don’t know if this is completely fair but I consider it lazy science to just go after the low hanging fruit when designing landers for targets that are thought to possibly harbor life. By that I mean why aren’t we attempting to find microbes on Mars with dedicated probes? We (mainly NASA) have been putting rovers etc. on the surface for many years now. We know the surface geology quite. At least quite well compared to what we know about the subsurface and what we know about possible life. It’s the obvious target for searching for microbial life. The methane presence is intriguing. Let’s start looking properly. I realize it is a hard thing to do as detection of microbes is actually quite difficult. But I thought we were going into space, not because it’s easy but because it’s hard to paraphrase a famous President.

    • VIY August 23, 2019, 12:05

      It is just my opinion, but I think that the scientists who are directly involved in designing these missions do not seriously believe that there are microbes on Mars. Life is very aggressive, and if it exists it would have occupied the whole planet and terraform it to its liking. Either that or it should extinct. If life exists, it should be the easiest thing to detect as anomalous readings in any instrument we send there.

      • Alex Tolley August 23, 2019, 13:36

        A very Gaian idea that I would largely agree with. However, detecting life on the relatively clement (compared to Mars) Atacama desert is very hard. Similarly looking for life on the Arctic or Antarctic ice.

        As with these environments, any Martian life may have “migrated” below the surface.

        Also, bear in mind that eventually, the Earth will become so hot that all surface life will become extinct. However, subsurface bacterial life will be extant until the sun becomes a red giant. In those circumstances, the Gaian hypothesis will have led you astray.

        • VIY August 23, 2019, 16:34

          I fully respect arguments of finding life at difficult places on Earth, but there can be the argument that such life exist there only because it is flourishing everywhere else on the planet and migrated and adapted to even most remote places. And it may go extinct very shortly if the life on the whole planet disappears. Of course, it is difficult to prove or disprove this until we understand better the evolutionary pathways of life. But finding life in Antarctica is not a strong argument of possible life on Mars.

          • Alex Tolley August 23, 2019, 21:39

            But finding life in Antarctica is not a strong argument of possible life on Mars.

            Absolutely correct. However, that was not my point. Let me clarify. The Gaia Hypothesis is that life will try to change the global environment to maximize its habitability. The classic “Daisy World” was a thought experiment showing how this might work for keeping Earth’s temperature more constant than physics and chemistry would allow. From this, we might expect life to be abundant in unexpected places. To some extent this is true.

            However, there are limits. Extremophiles seem to have an upper limit of 122C. Liquid water availability is another limiting factor, which is why life is extremely scarce in deserts, both hot like the Sahara, and frozen like the Antarctic, or the tops of high mountains. If we landed a 1970’s technology Viking probe in the Atacama desert, it would find nothing (although there is life there). But we also now know there is life in the Earth’s crust, and environment that is much more stable than the surface, and would remain stable even if the surface was made sterile by heat or nearby supernova explosion.

            The surface of Mars is far less friendly to terrestrial life. Lik4e places on Earth, it may be too unfriendly for any sort of life to survive. But just like teh Sahara, dig down into the crust and you will find microbes where there is free water between the grains of rock. Sparse, to be sure, but present.

            Therefore we should be careful about assuming the capabilities of life to adapt and mold a planet so that there is almost a binary: “abundant life vs no life” dichotomy.
            Mars may be sterile, but it is definitely worth looking for subsurface life in the crust, where the temperatures imply water would be liquid, rather than frozen, before we pronounce Mars is dead.

            • Ron S. August 25, 2019, 12:06

              “The classic “Daisy World” was a thought experiment showing how this might work for keeping Earth’s temperature more constant than physics and chemistry would allow.”

              Life is not a fundamentally different category: it’s just physics and chemistry, though of a more complex variety. It may widen the environmental parameters within which some sort of planetary equilibrium can be maintained but it has its limits, just as Alex is saying.

              Abiogenesis needs clement conditions (details still not well understood) but once evolved beyond a moderately primitive threshold can adapt to environments in which it could have never arisen. Even then it will require an energy or chemical gradient to survive long term, in the crust or elsewhere.

  • Gary Wilson August 23, 2019, 15:58

    I don’t think the Gaia hypothesis as described for Earth will hold true in every planetary environment. At present Mars is a much more difficult place to survive than Earth and therefore life would have retreated underground to avoid dessication, low temperatures, and many forms of ionizing radiation to mention only a few difficulties. That doesn’t mean there is no life. But we definitely won’t find it if we don’t look for it. Does the Viking difficulty mean give up on attempting to detect life? It’s ridiculous. We have advanced a great deal since the Viking probes. Let’s get back to doing the difficult science and making huge discoveries.

  • ljk August 29, 2019, 9:45

    NASA’s mandate to put humans back on the Moon by 2024 may mess with Europa Clipper’s ride to the Jupiter system:


    And now Space Force is official:


    Maybe the Alien franchise and The Expanse series are going to be humanity’s future in space, rather than Star Trek. Relying solely on government funding and expecting only scientific expeditions have so far proven to be less than reliable in terms of a permanent presence in space.

  • Robert Clark August 29, 2019, 13:14

    It can be done at 1/10th the cost of a SLS-launched mission using the Falcon Heavy and can even be made a lander mission at a *shorter* flight time by using a high efficiency stage such as the Centaur atop the FH:


    Bob Clark

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