A huge, multi-national mission to investigate Jupiter and four of its moons is now in its planning stages, and is tentatively planned for a launch in 2020. The project, which is called the Europa Jupiter System Mission (EJSM) in the U.S. and the LaPlace Mission in Europe, will involve two separate spacecraft launched at different times, and will give us our best view yet of Jupiter, its atmosphere and magnetosphere, as well as in-depth study of the moons Ganymede, Europa, Callisto and Io. If EJSM comes off as planned, it will also include a magnetospheric orbiter contributed by Japan’s JAXA, which will allow three-point observation of Jupiter and its moon system. While details are a bit hazy yet, there has also been talk of possible contributions by Russia and the U.K. Even if the mission gets scaled back in planning, as often happens, this promises to be quite an extravaganza.
The two main spacecraft in the mission are NASA’s Jupiter Europa Orbiter (JEO) and the European Space Agency’s Jupiter-Ganymede Orbiter (JGO). While the exact timeline has yet to be released, tentative plans would have the two crafts being launched about a month apart. They will travel for about six years, and for a while after reaching Jupiter, they will work together. The first part of the mission is an elaborate dance through the Jupiter system, collaborating on an overview of the giant planet and its system of satellites, which has been called a mini-solar system because of its size and complexity. After that, the probes will go into their separate orbits around Europa and Ganymede for in-depth study. During the course of the mission, there will also be flybys of Io and Callisto.
Because this mission is so big, and since it involves two spacecraft, we will divide it into two segments. In this part, we will look at NASA’s Jupiter Europa Orbiter. As the plan stands now, this probe will launch in February 2020 aboard an Atlas V 551 rocket. The course that it will follow will be called the VEEGA course, since it involves one gravity assist maneuver at Venus and two at Earth. On this trajectory, it will arrive at the Jupiter system in December 2025. (Dates may change slightly as plans become firmer.) After entering orbit around Jupiter, it will undertake a 30-month tour of the Jovian system, which will be followed by Europa Orbital Insertion (EOI) for a nine-month science mapping phase. There will be several highlights in this tour:
1. Four encounters with the moon Io, with a possible volcanic plume flythrough.
2. Six Europa encounters before the actual insertion into orbit around that moon.
3. Six encounters with Ganymede, to study that moon’s magnetosphere.
4. Nine encounters with Callisto.
5. Continuous monitoring of Jupiter and Io’s atmospheres.
After this, the probe will enter a 200 km. orbit around Europa, conduct a one-month mapping survey, then move to a 100 km. orbit for further observations.
The data collected by the JEO will add to the basic information we already know about this body. Europa is a little smaller than Earth’s moon. Like Earth, it is thought to have an iron core, a rocky mantle and an ocean of salt water. However, this ocean is deep enough to cover the entire surface, and the top layer is frozen solid. Europa is an ice world, its surface riddled with countless cracks.
When we look at Europa, we see evidence of the dominant theme of the Jupiter system: Jupiter. The enormous planet influences everything here with its gravity. It is tidal heating which causes Europa’s inner ocean to be liquid instead of solid, and it is Jupiter’s constant tugging on this water that causes the ice above it to be covered with an elaborate pattern of cracks.
Within that inner ocean, there may be life. Nature has created a perfect environment for it here, containing both water and heat. Of course, we won’t really know what’s in there until we can put landers down and take some samples, but the JEO will be doing the basic groundwork that will lead to that. Using the information that comes from this mission, future missions will know where to go on Europa, and what to look for. Someday a lander will reach this little world, put a periscope down through the ice, and have a look around. When that happens, will something be looking back? We won’t know until we try.
The investigation of Europa will follow the overall purpose of the entire EJSM mission: to assess habitability. Specifically, does Europa support life, or could it in the future? To simply ask this question is exciting. We’re talking about exploration, future colonies and the possibility of extraterrestrial life. The future is here.
But for now, we’re just trying to get a better idea of all the parts involved, and their relationship to each other. How big is this layer of liquid water, and how big is the solid core beneath it? How thick is the ice layer above it, and what are the variations in thickness and composition of this ice over the entire moon? What is the nature of the surface-ice-ocean exchange? What are the surface features? How quickly are they changing? What are the possible sites for future landings? These are some of the questions that will be addressed by the JEO.
In addition to its ongoing survey of Europa, the JEO will also perform observations of Io, one of Jupiter’s other moons. In contrast to Europa, Io is a fire world. It is the most volcanically active body in the solar system, its surface constantly erupting in an ever-changing array of volcanoes, some of which hurl plumes of matter far into space. Just as Europa’s inner ocean is the result of Jupiter’s gravity, so is Io’s volcanic activity. The same tidal heating which melts Europa’s ice is more extreme here, generating enough heat to melt magma. If there is a volcano conveniently erupting in the right direction when JEO flies by, the probe may be able to fly through the plume and take samples. Even failing that, we should be able to get some spectrographic data from starlight shining through some of the plumes, and we can expect some wonderful pictures of a world that is about as close to Hell as we’ll ever find.
The lifespan of the JEO is uncertain. It will eventually impact on Europa when it finally succumbs to radiation damage, or when it runs out of fuel for maneuvers. By that time, it will have added volumes to our knowledge of the solar system’s biggest planet and its moons.
In our next article, we’ll take a look at the other half of the EJSM/LaPlace mission, the European Space Agency’s Jupiter Ganymede Orbiter. As we said earlier, this probe will be performing some observations in coordination with the JEO, and will also do some “stand alone” science of its own, orbiting Jupiter’s largest moon while the JEO is orbiting Europa. Watch for part two!
Sources:
Solar System Exploration: Moons and Planets of the Solar System at NASA website: solarsystem.jpl.nasa.gov/planets/
Mission News: NASA and ESA Prioritize Outer Planets Missions at NASA website: nasa.gov/topics/solarsystem/features/20090218.html
OPFM: Outer Planet Flagship Mission at website of Jet Propulsion Laboratory, California Institute of Technology: opfm.jpl.nasa.gov/europajupitersystemmissionejsm/
OPFM: Outer Planet Flagship Mission- Jupiter/Europa Orbiter (JEO) Concept at website of Jet Propulsion Laboratory, California Institute of Technology: http://opfm.jpl.nasa.gov/europajupitersystemmissionejsm/jupitereuropaorbiterconcept/
News: LaPlace, Studying the Jovian System at website of the European Space Agency: esa.int/esaSC/SEMPHEWX3RF_index_0.html
Jupiter: Moons: Europa at website of Jet Propulsion Laboratory, California Institute of Technology: solarsystem.jpl.nasa.gov/planets/profile.cfm?Object=Jup_Europa