JUpiter ICy moons Explorer (JUICE) on it's way to Jupiter

[Astronuc]

JUICE launched on 14 April 2023, and one week later on the 21 April, the 10.6-metre boom was unfolded and the magnetometer instrument – J-MAG – was switched on. Data collected by J-MAG captured the moment of deployment.

The J-MAG instrument will be crucial for JUICE’s mission to characterise the oceans expected to be found beneath the outer icy crusts of three of Jupiter’s moons – Ganymede, Callisto and Europa – and determine whether they might be able to support life.

Although JUICE will take around eight years to get to the Jupiter system, the early deployment of the instrument is an important milestone for the feasibility of the mission.

https://www.imperial.ac.uk/news/244571/imperial-led-jupiter-bound-instrument-successfully-deployed/

https://www.esa.int/Science_Exploration/Space_Science/Juice

https://www.esa.int/Science_Exploration/Space_Science/Juice/How_to_follow_the_Juice_launch_live

https://en.wikipedia.org/wiki/Jupiter_Icy_Moons_Explorer

Launch mass	6,070 kg (13,380 lb)
Dry mass	2,420 kg (5,340 lb)

Power	850 watts from a solar panel ~85 m2

 

[mfb]

The antenna for its ice-penetrating radar (RIME) didn't extend as planned. ESA is working on it.

 

[mfb]

RIME has been deployed!

 

[Drakkith]

What's up with antennas and failing to deploy? Seems like it is a quite common issue.

 

[Astronuc]

Seems like it is a quite common issue.

Indeed

Flight controllers in Germany freed the 52-foot (16-meter) antenna Friday after nearly a month of effort.

The European Space Agency's Jupiter Icy Moons Explorer, nicknamed Juice, blasted off in April on a decade-long voyage. Soon after launch, a tiny pin refused to budge and prevented the antenna from fully opening.

Controllers tried shaking and warming the spacecraft to get the pin to move by just millimeters. Back-to-back jolts finally did the trick.

The radar antenna will peer deep beneath the icy crust of three Jupiter moons suspected of harboring underground oceans and possibly life. Those moons are Callisto, Europa and Ganymede, the largest moon in the solar system.

https://phys.org/news/2023-05-stuck-antenna-freed-jupiter-bound-spacecraft.html

 

[mfb]

All moving components in spacecraft are difficult. If they are well-contained, like gyroscopes, they tend to be somewhat reliable (but still often the first components to fail) - but large antennas, tethers and similar stuff need to be deployed after launch so they are always risky.

 

[Ibix]

All moving components in spacecraft are difficult. If they are well-contained, like gyroscopes, they tend to be somewhat reliable (but still often the first components to fail) - but large antennas, tethers and similar stuff need to be deployed after launch so they are always risky.

I presume this is because they have to survive fairly brutal g-forces during launch, and then operate in a vacuum where your WD40 evaporates instantly, and that there are a lot of moving parts so even a fairly low failure rate is likely to bite somewhere (c.f. the Birthday problem)?

 

[Dullard]

Also (most importantly, IMHO):
It's extremely difficult to ground-test the designs. Why doesn't someone build a zero-g test chamber?

 

[Drakkith]

Why doesn't someone build a zero-g test chamber?

That would require an aircraft and you'd get about 40 seconds of zero-g at a time.

 

[Tom.G]

That would require an aircraft and you'd get about 40 seconds of zero-g at a time.

And the parachute rigging would have to account for both a deployment success and a failure.