European search for water on Jupiter’s moons jeopardised by key equipment fault

Scientists are trying to fix a £3.5m spring remotely after it became jammed a month into an eight-year journey

A landmark mission to study Jupiter and learn if alien life could live on its moons is at risk of being thwarted by a faulty spring, The Telegraph understands.

Astronomers are currently battling to save the Juice mission after one of the key pieces of equipment got jammed by what is thought to be a faulty spring mechanism.

Juice launched a month ago and is now more than 3.7million miles away from Earth.

It is due to spend eight years making its way to Jupiter, requiring flybys of both Earth and Venus to slingshot towards the Solar System's largest planet. If it successfully reaches Jupiter, it will spend at least three years making detailed studies of the giant gas planet and three of its moons; Ganymede, Europa and Callisto.

Juice will eventually orbit Ganymede, the first time a spacecraft has orbited another planet's moon. Ganymede is not only the solar system's largest moon - bigger even than Mercury - but has its own magnetic field and vast liquid oceans, scientists believe.

But one of the ten scientific apparatus aboard Juice, called RIME (Radar for Icy Moons Exploration), has a 16-metre long antenna that has failed to deploy.

There is now a remote rescue mission underway to free the instrument, which cost around €4 million (£3.48m), to build.

Giuseppe Sarri, Project Manager of JUICE at the European Space Agency, told The Telegraph he is 60 per cent confident RIME will be freed in time to be fully operational before Juice starts its scientific investigations of the Jovian system in 2031.

But despite Juice being one of the most complex scientific endeavours ever launched, the ESA scientists are having to resort to relatively rudimentary approaches to pry RIME free.

"The antenna is jammed and we have a plan in action to unjam it," Mr Sarri said.

"Of course the first question is why it is jammed. The most likely cause is that in one of the release mechanisms there is a spring which should have retracted and probably did not so is blocking the antenna.

"The reason why it did not retract is subject to speculation because, of course, we are not there. One reason could be elastic deformation because that side of the antenna where the spring is is very cold, it is at minus 80C (minus 112F)."

The plan to free RIME from this faulty spring is to spin Juice and let the Sun's rays warm up the area, before giving it a shake by blasting the engines and then letting the craft cool down rapidly.

It is hoped the contraction and expansion of the machinery in the changing temperature, as well as a gentle nudge from the engine's vibrations, may help knock the antenna loose.

The first attempts saw Juice spend about half an hour facing the Sun last weekend, but was unsuccessful. Repeated attempts with longer heating periods of around an hour also failed.

Mr Sarri said the "thermal cycling" and engine shaking method is its first plan to free RIME.

Other tricks the team from the European Space Agency are hoping will free RIME are making the antenna spin around in situ to break free of its bracket; and using the eight 22-newton thrusters to shake Juice in several directions, instead of the linear shunt from the main engine; and firing something called the boom expending actuator to force the spring loose.

The 22-newton thruster approach is more complex than the heat-cool engine-burst method but is being used this week, he told The Telegraph.

The team is also set to open the second boom which makes up the antennae in the hope that the shock, combined with the warmed up antenna, will free the antenna.

"There are several things that we can still do and we keep our fingers crossed," Mr Sarri said.

RIME is designed to define the thickness of the ice on Jupiter's moons using radar. It is, he said, "fundamental to understanding the depth of the oceans".

He said that should it be unable to work properly, then the other instruments on Juice will be able to cover for most of the lost capabilities.

"Losing this antenna does not mean we are missing the scientific objective of the mission, but of course we miss an important element," he told The Telegraph.

"If you talk with the scientists responsible for RIME they will say that it is the most important instrument on Juice. But if you talk to the other nine, they will say that it is one out of 10.

"The scientific objective of JUICE, which is characterising the environment around the icy moons, will be achieved with the working together of ten instruments.

"If we are missing this antenna, we will have one instrument less which is not good. I'm not saying that is good, it is not good at all. But we still have a good mission. I'm reasonably confident still, I think we still have a chance."

If the team are unsuccessful in this week's attempts to shake RIME free, all hope is not yet lost. The eight-year duration of the trip to Jupiter means there is ample opportunity to come up with new plans for RIME to work its way loose on its own, or for workarounds to be devised.

"We don't need the antenna tomorrow, we need the antenna in eight years time," Mr Sarri said. "Juice is now moving away from the Earth now and will come back for the first flyby next year.

"Then we'll do a Venus flyby in two years where it will be very hot and then we'll come back another two times so there are opportunities and plenty of time to think."