JUICE mission to launch study of oceans beneath Jupiter's icy moons

Update: risk of lightning at the launch site Thursday morning has postponed the launch to Friday.

The European Space Agency (ESA) is preparing the launch of the JUpiter ICy moons Explorer (JUICE) mission to study the icy crusts and oceans beneath Jupiter’s three large moons Callisto, Europa and especially Ganymede. Liftoff was originally scheduled for Thursday April 13, from pad ELA-3 at ESA's spaceport in Kourou, French Guiana but was rescheduled for Friday at 8:14 a.m. EDT.  

The launch team has just a single second long launch window each day available to them which means there is no opportunity to hold for weather or any technical problems.  Instantaneous launch windows like this one are used to reserve fuel for any mid course corrections on the way to Jupiter or to extend the mission years in the future rather than use it to steer the rocket back into the correct plane after a launch delay.

Additional launch windows available each day through the end of April.

A livestream of the launch begins at 7:45 a.m. with a post-launch press conference planned for 10:20 a.m. EDT.The most detailed observations will be of Ganymede when JUICE begins orbiting the moon

JUICE wont reach the Jovian system until July 2031 after four gravity assists from the Earth, Moon and Venus over the next six years. The mission will then make 67 orbits of Jupiter,21 flybys of Callisto, and 2 of Europa within about 120 miles of the surface before settling into orbit 125 miles above Ganymede in 2035, becoming the first probe to orbit a moon other than Earth's.

Three years later, JUICE will be flown into the surface of Ganymede to ensure that it does not collide with Europa and potentially contaminate it with any microbes from the Earth.

JUICE's instruments

The spacecraft is a just a platform that provides power, communications back to Earth, and a ride to Jupiter. Science aboard JUICE is provided by a suite of ten instruments provided by partner space agencies across Europe along with NASA, the Japanese Aerospace Exploration Agency, and Israel Space Agency.

• 3GM: Gravity & Geophysics of Jupiter and Galilean Moons, a radio package designed by the Italian Space Agency to study the oceans beneath nearly 100 miles of ice along with the structure of the atmospheres of Jupiter and its moons by measuring the surrounding gravity fields.
• GALA GAnymede Laser Altimeter, provided by the German Aerospace Center, will study topography of the surfaces of the icy moons and the tides Ganymede in particular
• JANUS, a camera provided by the Italian Space Agency to observe the surfaces of the Moons and map the clouds of Jupiter
• J-MAG, a UK Space Agency provided magnetometer to measure the Jovian magnetic field and its interaction the icy moons.
• MAJIS, the Moons and Jupiter Imaging Spectrometer, provided by the French National Centre for Space Studies, will observe clouds of Jupiter, and identify ices and minerals on the icy moon surfaces.
• PEP, the Particle Environment Package, provided by the Swedish National Space Agency to characterize the plasma environment of the Jupiter system.
• RIME, Radar for Icy Moons Exploration, provided by the Italian Space Agency to study the subsurface structure of the icy moons down to a depth of around nine kilometers.
• RPWI, Radio and Plasma Wave Investigation, provided by the Swedish National Space Agency to study the radio emissions and plasma waves around Jupiter
• SWI, Sub-millimeter Wave Instrument, provided by the German Aerospace Center, will investigate the temperature structure, composition and dynamics of the atmospheres of Jupiter and its icy moons
• PRIDE, Planetary Radio Interferometer & Doppler Experiment, provided by the Netherlands Space Office to precisely measure the spacecraft's position and velocity while providing information about gravity fields around Jupiter and its moons.
• UVS a NASA UV camera which will image the outer atmospheres of Jupiter and its icy moons, including the Jovian aurorae.

Why study Jupiter’s moons?

The mantra for planetary scientists is "go where the water is", because where there is water, there could be life.

Jupiter's Galilean moons; named for Galileo Galilei who, along with Simon Marius, first observed them in 1610; have long been a focus of planetary scientists. Pioneer 10 and 11 returned grainy images of the surfaces in the early 70s which fueled theories of an icy surface. Voyager 1 and 2 flybys later that decade provided more hints that pointed to a warm rocky interior, icy surface and perhaps liquid water in between.

JUICE will focus on Ganymede because, as the largest moon in the solar system, it has enough gravity a spacecraft to maintain an orbit that will support deeper study that will reveal much about about all icy moons. Ganymede's is less than half the size of Earth but its ocean is believed to be 10 times deeper than Earths and contain more water than all of Earth's oceans combined, all under nearly 100 miles of ice.

‘Europa is one of the best candidates for habitability because the liquid water is in direct contact with the silicate mantle. So there’s a possibility of the leaching out of minerals from the crust into the ocean. And the richer it is in chemical compounds, the better it is for the evolution of life.' explained Professor Joachim Saur, a planetary scientist from the University of Cologne, Germany in Horizon, the European Union's magazine on science research.

NASA's Europa Clipper set for launch next year. Europa Clipper will reach its target in April 2030 for 50 flybys as low as 16 miles (25 kilometers) above the surface, soaring over a different location during each flyby to scan nearly the entire moon.

You can watch assembly of the Europa Clipper spacecraft with a live cam in High Bay 1 in the Spacecraft Assembly Facility at NASA's Jet Propulsion Laboratory (JPL) in Pasadena, California.