Annealing In Space: How NASA Saved JunoCam In Orbit Around Jupiter

The Juno spacecraft was launched towards Jupiter in August of 2011 as part of the New Frontiers series of spacecraft, on what would originally have been a 7-year mission, including a nearly 5 year cruise to the planet. After a mission extension, it’s currently orbiting Jupiter, allowing for many more years of scientific data to be gathered using its instruments. One of these instruments is the JunoCam (JCM), a visible light camera and telescope. Unfortunately the harsh radiation environment around Jupiter had led many to believe that this camera would fail before long. Now it seems that NASA engineers have successfully tested a fix.

Location of the Juno spacecraft's science instruments. (Credit: NASA)
Location of the Juno spacecraft’s science instruments.

Although the radiation damage to JCM was obvious a few dozen orbits in – and well past its original mission’s 34 orbits – the big question was exactly what was being damaged by the radiation, and whether something could be done to circumvent or fix it. The good news was that the image sensor itself was fine, but one of the voltage regulators in JCM’s power supply was having a bad time. This led the engineers to try annealing the affected part by cranking up one of the JCM’s heaters to a balmy 25°C, well above what it normally is kept at.

This desperate step seemed to work, with massively improved image quality on the following orbits, but soon the images began to degrade again. Before an approach to Jupiter’s moon Io, the engineers thus tried it again but this time cranked the JCM’s heater up to eleven and crossed their fingers. Surprisingly this fixed the issue over the course of a week, until the JCM seems as good as new. Now the engineers are trying their luck with Juno‘s other instruments as well, with it potentially providing a blueprint for extending the life of spacecraft in general.

Thanks to [Mark Stevens] for the tip.

A red, cuboid electrochemical cell is in the center of the picture, with a few wires protruding from the front. Tubes run from each side of the cell to a peristaltic pump and tank on each side. The frame holding the pumps and tanks is white 3D printed plastic.

An Open Source Flow Battery

The flow battery is one of the more interesting ideas for grid energy storage – after all, how many batteries combine electron current with fluid current? If you’re interested in trying your hand at building one of these, the scientists behind the Flow Battery Research Collective just released the design and build instructions for a small zinc-iodide flow battery.

The battery consists of a central electrochemical cell, divided into two separated halves, with a reservoir and peristaltic pump on each side to push electrolyte through the cell. The cell uses brass-backed grafoil (compressed graphite sheets) as the current collectors, graphite felt as porous electrodes, and matte photo paper as the separator membrane between the electrolyte chambers. The cell frame itself and the reservoir tanks are 3D printed out of polypropylene for increased chemical resistance, while the supporting frame for the rest of the cell can be printed from any rigid filament.

The cell uses an open source potentiostat to control charge and discharge cycles, and an Arduino to control the peristaltic pumps. The electrolyte itself uses zinc chloride and potassium iodide as the main ingredients. During charge, zinc deposits on the cathode, while iodine and polyhalogen ions form in the anode compartment. During discharge, zinc redissolves in what is now the anode compartment, while the iodine and polyhalogen ions are reduced back to iodides and chlorides. Considering the stains that iodide ions can leave, the researchers do advise testing the cell for leaks with distilled water before filling it with electrolyte.

If you decide to try one of these builds, there’s a forum available to document your progress or ask for advice. This may have the clearest instructions, but it isn’t the only homemade flow cell out there. It’s also possible to make these with very high energy densities.