RIME (Radar for Icy Moons Exploration) is the first instrument ever deployed to the outer Solar System that can make direct measurements of conditions below the surface of an object. That makes it precisely tailored for Europa as well as Ganymede and Callisto, two other Galilean moons that also seem to have an internal ocean. Consider it a radar ‘sounder’ that can penetrate up to 9 kilometers below surface ice. RIME is a major part of why JUICE is going to the moons of Jupiter.
Consider it problematic as well, at least for the moment, while controllers working the JUICE mission try to solve an unexpected deployment issue. The 16-meter long antenna shows movement, but continues to have trouble in becoming released from its mounting bracket. The antenna is currently about a third of its full intended length, according to ESA, partially extended but still stowed away.
Image: Shortly after launch on 14 April, ESA’s Jupiter Icy Moons Explorer, JUICE, captured this image with its JUICE monitoring camera 2 (JMC2). JMC2 is located on the top of the spacecraft and is placed to monitor the multi-stage deployment of the 16 m-long Radar for Icy Moons Exploration (RIME) antenna. RIME is an ice-penetrating radar that will be used to remotely probe the subsurface structure of the large moons of Jupiter. In this image, RIME is seen in stowed configuration. The image was taken at 14:19 CEST. JMC images provide 1024 x 1024 pixel snapshots. Credit: ESA.
Given that two months of commissioning remain for the spacecraft, the agency is saying that there is abundant time to work the problem out, which may involve something as simple as a stuck pin, potentially sprung by warming the radar mount by rotating the spacecraft and turning the assembly into direct sunlight.
The memory of the Galileo probe to Jupiter hovers over the mission at least momentarily. Controllers never did free up Galileo’s high-gain antenna, though they were able to return outstanding data through ingenious use of its low-gain counterpart. Needless to say, the hope here is that RIME follows a different path and soon springs free.
In-flight adjustment and occasional repair are no strangers to deep space missions. We’re reminded of this also by the plan to save precious energy and keep Voyager 2 (and potentially Voyager 1) operational for a few years longer than previously thought possible. Both craft rely on RTGs (radioisotope thermoelectric generators) converting heat from plutonium into electricity, so that plutonium decay produces less power each year. Hence the need to turn off unneeded heaters and other systems to reserve power.
The new method: Use power heretofore reserved for a voltage regulator that triggers a backup circuit in the event of a serious fluctuation in voltage. Power is set aside in the spacecraft’s RTG for that purpose, but can be redirected to keeping the craft’s five science instruments operating until 2026. That gives up a certain safety measure, but even after 45 years in flight, the electrical systems on Voyagers 1 and 2 remain stable, so it seems a good gamble to produce further interstellar science. If the approach works for Voyager 2, it may be tried on Voyager 1 in the near future.
Suzanne Dodd is Voyager project manager at the Jet Propulsion Laboratory:
“Variable voltages pose a risk to the instruments, but we’ve determined that it’s a small risk, and the alternative offers a big reward of being able to keep the science instruments turned on longer. We’ve been monitoring the spacecraft for a few weeks, and it seems like this new approach is working.”
Image: Each of NASA’s Voyager probes are equipped with three radioisotope thermoelectric generators (RTGs), including the one shown here. The RTGs provide power for the spacecraft by converting the heat generated by the decay of plutonium-238 into electricity. Credit: NASA/JPL-Caltech.
Anything we can do to keep these priceless assets functioning is to the good. They are our only operational craft outside the heliosphere, a striking thought given their projected mission duration of a scant four years. Operating without one of its science instruments, which failed much earlier in the mission, Voyager 1’s power issues are slightly less pressing than its twin, but decisions about shutting down another instrument still loom, so the new RTG power draw may again come into play.
“Fixing” deployment issues seems less like repair and more like banging the old valve tv sets to fix picture problems.
The RTG issue is more of a workaround for diminishing power output.
Sometime in the future, a real repair might be possible with self-repairing systems, either built-in or with robotic helpers to fix broken or damaged components. For example, the JWST had some micrometeoroid damage to one of its mirrors. The solution was a workaround. A repair would be replacing the damaged mirror.
SciFi stories abound with crews repairing damaged spacecraft systems. Star Trek’s Montgomery Scott is an archetypal Scottish engineer who is forever repairing the damage inflicted on the USS Enterprise.
Once we have sufficiently intelligent, robots, preferably with low mass, then we might be able to equip probes with true repair capabilities – removing damaged components and replacing them, or fixing damage in situ.
Yes, standardized robotic multi-tools for each mission
Some kind of a miniature ‘house keeper robot’ that could be launched with every spacecraft and give some better odds of fixing the problem should something arise. We do see a few ‘dum’ things happening somethimes, like antennaes that don’t deploy or solar panels that don’t quite work according to the recipe. A ‘basic deployment’ help, and ‘stuck valve jolter’ :)
Remember to send a repair system for the self-repair system. Of course you’ll also need a repair system for its human adjuncts and their malfunctioning biological self-repair systems.
“For example, the JWST had some micrometeoroid damage to one of its mirrors. The solution was a workaround. A repair would be replacing the damaged mirror.”
Repairing systems is far more difficult in the hostile environment of space than in the lab. It is more difficult than just replacing a mirror. Mounting the mirror requires exquisite precision, and working in zero-G is a perfect setup for unintended damage of the structure which, big as it is, is fragile in important ways. Once mounted, the mirror has to be minutely adjusted in all dimensions so that its contribution is in focus to within a small fraction of a wavelength. The adjustment room is also minute. JWST had to do this with all of its mirrors in the months after deployment before it was ready to do science. Launch and deployment stress is responsible for positioning errors that cannot be eliminated during on-ground commissioning.
Recall the large amount of work done on HST replacement parts when the initial focus system was defective. Not only did they have to make an unrepairable system repairable, they had to make the substitution nearly “idiot proof” because of the hostile environment the astronauts were in, to reduce potential for errors and enough post-repair adjustability to account for the uncertainties in replacement part positioning.
You rightly say that repair in situ is non-trivial, even before the issue of mass penalty is assessed. Biology solved that problem in 2 ways. Firstly, damage to the DNA could be handled via redundancy, creating a large number of offspring so that the damaged could be ignored in the population. Secondly, biological self-repair with “nanotechnology” obviated the need for external repair help unless the damage was very severe. Life heals, however imperfectly. Our technology isn’t even close to the sophistication that life offers. However, there are options. We build our machines with almost zero capability of self-repair unless the problem is software. There are microchips that can route around damage, a crude fix for localized damage, perhaps mimicking the plasticity of our brains to localized neural damage. An appendage[s] could be added to provide some self-repair help – think of a specialized, but small, Canadarm that reduces the “amputee” status of current space probes. Think how hard it is to self-treat wounds without functional limbs. Some things will be too hard to fix, and that constitutes severe damage. In the case of the JWST, the handling of the mirror damage was more like the routing around the damage mentioned above.
In principle, self-repair could be as good as crews repairing damage to a space ship, or even a sea-going ship. Unlike terrestrial ships, space probes cannot return to a port for repairs, and therefore I accept the limitations of self-repair without “magic technology”.
The JWST may be an example of extreme technology that eventually will be obsoleted by cheaper “good enough” technology that in swarms could offer as good, or better performance, yet not require the manufacturing and construction precision of the JWST, a strategy that terrestrial life has used over billions of years of Darwinian evolution.
I have no idea what cutting-edge technology and engineering will look like a century from now, but I would bet that it will be as different from current technology and engineering as our technology is from the days of steam engines and what Victorian engineers envisioned future technology would look like. In the meantime, I favor approaches to reduce the cost of access to space and the mass manufacture of space probe designs, facilitating a high redundancy strategy for space probe deployment where self-repair has its limits. As Ripley says about nuking the terraforming base from orbit: “It is the only way to be sure.”
Certainly technology will get better over time and as we spend more time in space learning more about what does and doesn’t work. Pretty well everything you said I agree with.
However, redundancy and repair systems (tech or human) has a price. It can seem so simple at first glance, yet it is anything but. When has a thing failed, or is simply not performing as well as it once did? This must be judged and weighed. What is risk of substitution and how can it be done so that the spacecraft work at least as well after the substitution? Are the repair systems fixed in their approaches or do they learn and adapt? Both approaches have significant risks.
When you add redundancy and self-repair you always increase the complexity of the total system. That’s adds more points of potential failure. Engineering the total system, including whatever self-repair mechanisms (software and hardware) so that the overall mission risk is lower can be exceptionally difficult; it is very easy to end up with a higher risk profile.
This is not an easy project, with or without humans on board.
So now they are saying NASA may not have enough plutonium to power deep space mission vessels..
https://spacenews.com/plutonium-availability-constrains-plans-for-future-planetary-missions/
The way I read that piece was that NASA both increased its demand and failed to develop the increased efficiency of RTGs (SLS costs got in the way?) IIRC, the Pu238 issue has been going on for a while, with the DoE having to restart production to support projected demand. It seems NASA is pushing the problem onto the DoE to increase production, while the DoE is saying that NASA needs to reduce demand by funding better generators. Congress should just fund NASA, or insist that funds be diverted from programs to pay for generator development.
*rant* NASA is already underfunded for the Artemis Moon program, not to mention the ISS. Science programs have suffered. A Republican HoR may even find ways to gut certain NASA programs it disagrees with, such as Earth Observation satellites to monitor GHGs. It is a perennial pity that the DoD gets more money than it asks for, yet NASA struggles to get the resources needed for some programs, especially the sciences. */rant*
The Ice Worlds may break the Earth Centered cult to intelligent life in the universe…
Habitability and sub glacial liquid water on planets of M-dwarf stars.
“A long-standing issue in astrobiology is whether planets orbiting the most abundant type of stars, M-dwarfs, can support liquid water and eventually life. A new study shows that subglacial melting may provide an answer, significantly extending the habitability region, in particular around M-dwarf stars, which are also the most promising for biosignature detection with the present and near-future technology.”
“As demonstrated below, considering tidally locked planets of M-dwarfs and an extended HZ due to subglacial liquid water may increase the abundance of potentially habitable worlds by a factor of up to approximately 100.”
“Estimating the abundance of habitable worlds, especially around M-dwarf stars is important to identifying eventual targets for biosignature research by JWST and future telescopes. In addition, it affects the likelihood and abundance of potential active extraterrestrial civilizations that should be expected according to the Drake equation and the Fermi Paradox”
https://www.nature.com/articles/s41467-023-37487-9
https://centauri-dreams.org/2023/03/24/ring-of-life-terminator-habitability-around-m-dwarfs/