Nfter the picture-perfect launch of the JUICE mission on April 14, it came as quite a shock when the European Space Agency ESA reported on April 28 that not everything went according to plan when the probe was commissioned. The reason for concern was not the 85 square meter photovoltaic system, the deployment of which had been an extremely demanding step, but the 16 meter long antenna of the RIME (“Radar for Icy Moons Exploration”) radar system. After arriving at Jupiter in 2031, the probe will use it to examine the icy surfaces and interior of Jupiter’s moons Europa, Ganymede and Callisto at a depth of up to nine kilometers. RIME had been folded for launch – a stuck mounting bolt now appeared to be preventing deployment.
Fortunately, ESA now reports, the ESA flight control team in Darmstadt had no shortage of ideas on how to fix the problem. First, they tried a brief thruster burn to shake the probe and turn it into the warming sun. “Each day, the RIME antenna showed signs of movement but not yet full clearance,” ESA said.
Yesterday, May 12th, the breakthrough finally came. The flight control team activated a mechanical component, a so-called “non-explosive trigger” (NEA) in the blocked bracket. This created a shock wave that moved the pin a few millimeters and allowed the antenna to unfold – but still not fully. A final piece remained folded. Only when a second trigger was fired did the hoped-for success message come out: RIME is unfolded, nothing stands in the way of exploring the interior of the ice moons.
NASA completes Lunar Flashlight mission
RIME is one of ten instruments on board the JUICE probe – albeit one of the more important ones. Because the nature of the oceans hidden under the ice crusts of the moon and their possible suitability for the emergence of life are the main questions that JUICE should help to answer. The oceans are warmed by the tidal forces between Jupiter and the moons. Previous observations of the moon Europa indicate that the chemistry in the oceans there could also be suitable for the emergence of life.
While the ESA engineers can now look forward to the further course of the mission, there was bad news from NASA – albeit not entirely unexpected. Yesterday, Friday, she announced the official end of the Lunar Flashlight mission. The CubeSat satellite was launched on December 11, 2022 to map ice occurrences in the permanently shadowed craters at the moon’s south pole. This information would also have benefited later astronautical moon missions, which speculate on the use of ice for the production of oxygen and fuel. However, the propulsion of the small satellite did not work as planned, and the intended lunar orbit was not achieved – despite months of efforts by the team.
NASA still considers the mission a success
The reason could have been possible deposits such as metal dust or shavings in the fuel lines. Initially, the team tried to steer the probe with just one drive, but failed – despite calculating an alternative orbit around the Earth instead of around the moon, which would have allowed a view of the South Pole every month. When time was running out to reach that orbit, the team tried again to clear the deposits by increasing fuel pressure well beyond design values, with only limited success.
The satellite’s engines were used for the first time on the mission, as were the on-board computer, the navigation system and a four-laser reflectometer that should have collected the scientific data. Despite everything, NASA therefore speaks of the success of the mission, the aim of which was also to test the new technology components. “Technology demonstrations inherently have both high risk and high reward. They’re essential for NASA to test and learn from,” commented Christopher Baker, NASA’s Small Spacecraft Technology steward. Nevertheless, the scientific team behind the mission will probably find little comfort in the fact that the evaluation of the mission will now be limited to the performance of the system during flight.
On May 17, Lunar Flashlight will once again come as close as 65,000 kilometers to Earth and then swing into a solar orbit in the lower solar system.
