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Europa: Building the Clipper

Seeing spacecraft coming together is always exciting, and when it comes to Europa Clipper, what grabs my attention first is the radiation containment hardware. This is a hostile environment even for a craft that will attempt no landing, for flybys take sensitive electronics into the powerful radiation environment of Jupiter’s magnetosphere. 20,000 times stronger than Earth’s, Jupiter’s magnetic field creates a magnetosphere that affects the solar wind fully three million kilometers before it even reaches the planet, trapping charged particles from the Sun as well as Io.

We have to protect Europa Clipper from the intense radiation emerging out of all this, and in the image below you can see what the craft’s engineers have come up with. Now nearing completion at the Jet Propulsion Laboratory, the aluminum radiation vault will ultimately be attached to the top of the spacecraft’s propulsion module, connecting via kilometers of cabling that will allow its power box and computer to communicate with systems throughout the spacecraft. The duplicate vault shown below is used for stress testing before final assembly of the flight hardware.

Image: Engineers and technicians in a clean room at NASA’s Jet Propulsion Laboratory display the thick-walled aluminum vault they helped build for the Europa Clipper spacecraft. The vault will protect the spacecraft’s electronics from Jupiter’s intense radiation. In the background is a duplicate vault. Credit: NASA/JPL-Caltech.

The ATLO phase (Assembly, Test, and Launch Operations) begins in the spring of 2022 at JPL, with the radiation vault being one of the first components in place as Europa Clipper enters its final stage of fabrication. The 3-meter tall propulsion module was recently moved from Goddard Space Flight Center in Greenbelt, Maryland to the Johns Hopkins Applied Physics Laboratory (APL) in preparation for the installation of electronics, radios, antennae and cabling. Science instruments, meanwhile, are being tested at the universities and other institutions contributing to the mission.

Jan Chodas (JPL) is Europa Clipper Project Manager:

“It’s really exciting to see the progression of flight hardware moving forward this year as the various elements are put together bit by bit and tested. The project team is energized and more focused than ever on delivering a spacecraft with an exquisite instrument suite that promises to revolutionize our knowledge of Europa.”

Before the ATLO phase begins, Europa Clipper will also be subject to a System Integration Review later this year, a process in which all instruments are inspected and plans for the assembly and testing of the spacecraft are finalized. The destination for all these components and instruments is the main clean room at JPL in Pasadena, where what NASA describes as the ‘choreography’ of building a flagship mission will draw together components from workshops and laboratories in the US and Europe.

Image: Contamination control engineers in a clean room at NASA’s Goddard Space Flight Center in Greenbelt, Maryland, evaluate a propellant tank before it is installed in NASA’s Europa Clipper spacecraft. The tank is one of two that will be used to hold the spacecraft’s propellant. It will be inserted into the cylinder seen at left in the background, one of two cylinders that make up the propulsion module. Credit: NASA/GSFC Denny Henry.

The travels of the propulsion module emphasize the collaborative nature of any complex spacecraft assembly. The two cylinders making up the module were built at the Applied Physics Laboratory and then shipped to JPL, where thermal tubing carrying coolant to regulate the spacecraft’s temperature in deep space was added. The cylinders then went to Goddard, where the propellant tanks were installed inside them and the craft’s sixteen rocket engines were attached to the outside. It then returned to APL for the installation of electronics and cabling mentioned above.

Image: Engineers and technicians in a clean room at NASA’s Goddard Space Flight Center in Greenbelt, Maryland, integrate the tanks that will contain helium pressurant onto the propulsion module of NASA’s Europa Clipper spacecraft. Credit: NASA/GSFC Barbara Lambert.

Connecting to the thermal tubing will be Europa Clipper’s radiator, which will radiate enough heat into space to keep the spacecraft in its operating temperature range. APL is now integrating the propulsion module and the radios, antennae and cabling for communications, while a company called Applied Aerospace Structures Corporation in Stockton, California is building the 3-meter high-gain antenna. By the spring of next year, the antenna will be in place at JPL for insertion in the ATLO process.

Nine science instruments will fly aboard Europa Clipper, all being assembled and undergoing testing at NASA centers as well as partner institutions and private vendors. The spacecraft is to investigate the depth of the internal ocean as well as its salinity and the thickness of the ice crust. The latter is obviously a huge factor in any future plans to sample the ocean beneath the ice, but so is the question of whether Europa vents subsurface water into space through plumes that may one day be sampled.

Image: NASA’s Jet Propulsion Laboratory in Southern California is building the spectrometer for the agency’s Europa Clipper mission. Called the Mapping Imaging Spectrometer for Europa (MISE), it is seen in the midst of assembly in a clean room at JPL. Pronounced “mize,” the instrument will analyze infrared light reflected from Jupiter’s moon Europa and will map the distribution of organics and salts on the surface to help scientists understand if the moon’s global ocean – which lies beneath a thick layer of ice – is habitable. Credit: NASA/JPL-Caltech.

We’ll finally be able to update those Galileo images that have served scientists so well in the study of Europa’s surface with new, detailed looks at the surface geology. Launch is currently planned for October, 2024 aboard a Falcon Heavy rocket. Europa Clipper isn’t a life detection mission, but we’ll learn a good deal more about Europa’s potential for supporting life. What kind of mission grows out of that is something it would be foolhardy to predict. One step at a time as Europa reveals its mysteries.


Comments on this entry are closed.

  • Alex Tolley August 9, 2021, 11:18

    By coincidence, the BBC’s Sky at Night tv series examined Juno’s discoveries about Jupiter and ended with some explanation of the JUICE mission to be launched next year to eventually orbit Ganymede a decade later and what it might discover.

    5+ years out and there should be lots of exciting Jupiter space discoveries with JUICE, Europa Clipper, and Lucy missions.

  • Jeff Wright August 10, 2021, 3:42

    I am angry at the planetary science community for being ingrates myself.

    Culberson and other SLS supporters debunked the lie that there were no money/payloads by pushing Europa–and was stabbed in the back for his trouble.
    The Cassini crowd didn’t seem to mind Titan IV solids!
    Only Porco had any honor in this regard…because most of her co-horts always attacked LV development wanting yet more bomb-disposal robots on Mars atop Delta II sounding rocket JPL chain-smoked with no-vision Golden handed out like lollypops to spoiled children in the back seat so as to keep them quiet.
    Now they ditch the person who brought them to the dance for the cheap date to spin them around…where SLS would have them straight to Jupiter, while their new dallience will eat up more of the RTG coinage, no so cheap after all.
    Better hope all goes your way-otherwise..come time for replacement budgeting? You will find the feeding hand you bit has now become a fist.
    You should danced with them that brung ya’

    • Alex Tolley August 10, 2021, 11:20

      Are you saying that the SLS should have been used instead of the SpaceX FH?

      Firstly, the cost-saving alone would fund a decent mission. Is that worth nothing?
      Secondly, the SLS is still not ready. Hugely expensive, over budget, and delayed. For all its touted launch capabilities, it is a dinosaur of a launch vehicle that will suck up funding for little good effect.

      The “bomb disposal robots” on Mars seem to be doing a pretty good job to me. What is your preferred approach – boots on the ground with technology that may not be ready until the 2030s at the earliest? Or are you hoping that SpaceX’s Starship will put astronauts on Mars soon and ironically also obsolete the SLS at a stroke?

      Reducing the cost of missions, especially the launch costs is a very worthwhile goal, allowing for more missions on a fixed budget and focusing the costs on the science mission and not the transport. I don’t understand the animosity you appear to show.

      • Jeff Wright August 11, 2021, 2:18

        My point is that you might not even have Clipper it not for SLS, which gets the real hostility. MSFC deserves at least the same respect the toymakers at JPL get. SLS is not obsolete and it makes more sense to use it as a basis for wet workshops…no need to put a heat shield on it to do stupid tank tricks like the ‘Adama maneuver.’ SLS is what you need for NTRs because Musk uses super-greenhouse methane…Hank Hill trailer park tech :-) Look, I like Elon…but hydrolox is the way of the future. And last I heard, you need hydrogen to make methane on Mars. So howsabout we condemn the anti-SLS hostility? VULCAN and New Glenn aren’t as good as Musks rockets -were they even flying-and don’t launch enough LH2 for NTRs. They serve no purpose.

        • Alex Tolley August 11, 2021, 10:15

          For any project that is given the go=ahead, if the enabling technology costs $X, but during the project, a newer enabling technology at $X/5 becomes available and is a good substitute, it makes good sense to use the newer technology and abandon the original one. It saves money, it might mean more profits, earlier payback, more projects enabled, etc.

          This calculation is done all the time, and it has more general benefits. It ensures that innovation continues and that there is an existing “market” for the innovation, and reduces wasted effort and costs (especially important when using taxpayer’s money). In the case of Europa Clipper, the enabling technology, i.e. the SLS, isn’t even ready to fly, which could potentially delay the flight until it is ready.

          One of the major issues in space exploration is the cost. The SLS is regarded by many as a boondoggle and jobs program, protected at the time by Senator Shelby, against all opposition. Reducing costs and delivering more science and exploration should be a quintessential American goal, not protecting incumbents. Cheaper access to space is a key to unlocking more space activity, and any company or agency that can deliver on this will benefit everyone as opportunities increase.

          As for the future, we don’t know what is going to be best. Reusable launchers certainly seem to make economic sense and I see no data to suggest otherwise. As for propellants, yes LH2/LOX gives higher Isp than Methalox engines, but there are other considerations like size and mass of fuel tanks, the difficulties of handling LH2, all of which change the economic profile of the launcher. I laud the renewed emphasis on cost competition between launcher companies, and I see every sign that reusability to drive down costs is being taken seriously by the incumbents now that it has been demonstrated to work. I would still prefer a spaceplane for versatility, but there is no arguing that the NewSpace companies are making headway in this market. ULA has already admitted that it cannot compete against reusable launch vehicles and needs to adapt. SLS may be the last gasp of the old way of making launchers, and not a few people doubt it will ever fly more than once. It could be the Spruce Goose of launchers.

        • charlie August 11, 2021, 18:22

          NTRs ?????????

          • Alex Tolley August 11, 2021, 20:32

            This Planetary Society podcast may interest you on nuclear rocket choices:

            Space Policy Edition: Mars via the Nuclear Option

          • Jeff Wright August 12, 2021, 5:35

            Nuclear Thermal Rockets btw. That needs hydrogen that SLS has, unlike any of Musks rockets. SL S is worth its cost. Shelby and my state actually would have made more money with EELV assembly. Hydrogen can boil off easy, so it is best to launch as much as you can. The Rube Goldberg assembly and VentureStar? That’s your ‘boondoggle’ as if JPL wasn’t Pasadena’s pork. SLS is worth its money. Kill F-35 to save real money. Again, you only have Clipper due to SLS advocates like Culberson.

  • Edwin August 13, 2021, 6:22

    While were on the subject of Europa this is a good read

    Uplifts and Small Chaos Features on Europa

  • ljk October 5, 2021, 11:37

    Frigid Europa Holds a Huge and Maybe Habitable Ocean Beneath Its Thick Ice Covering. How is That Possible?

    SEPTEMBER 29, 2021



  • ljk October 15, 2021, 11:29

    Oct 14, 2021

    Hubble Finds Evidence of Persistent Water Vapor in One Hemisphere of Europa

    NASA’s Hubble Space Telescope observations of Jupiter’s icy moon Europa have revealed the presence of persistent water vapor – but, mysteriously, only in one hemisphere.

    Europa harbors a vast ocean underneath its icy surface, which might offer conditions hospitable for life. This result advances astronomers’ understanding of the atmospheric structure of icy moons, and helps lay the groundwork for planned science missions to the Jovian system to, in part, explore whether an environment half-a-billion miles from the Sun could support life.

    Full article here:


  • ljk October 15, 2021, 11:35

    OCTOBER 14, 2021

    Exploring Earth’s oceans to reach Europa

    by Kate Blackwood, Cornell University