Limiting probes to only those that can get through 10s of kms of ice is short-sighted.
Just saying, there are people in these comments observing that "you can buy a 25km fiber cable online" lol... I love the exuberance but people may not be fully grokking the scope of the engineering problem here :) every mission comes at the expense of other possible missions, and drilling 25km down into Europa could easily be a feat that we would fail to accomplish even with 5 or 10 missions. There are challenges we will not surmount in our lifetimes, and this might be one of them. Deep drilling is dramatically harder than your average HN user probably realizes... exuberance alone cannot conquer physics.
On a more serious note, it's a travesty that lawyers get all the hate and PEs get none.
Code & techbros are not the solution to everything.
Where is all of this energy coming from?
All 300 watts of it? It's not going to even make an indentation, let alone through 10s of km of ice.
Even a fully fleged nuclear reactor isn't gonna do much damage to Europa and potential life. Swimming in a nuclear reactor's fuel pool is quite safe; water's some of the best shielding we have. https://what-if.xkcd.com/29/
A nuclear reactor, probably.
(Google image search suggests that a similar approach has been taken by the TOW, it's not a spool that could be reversed by adding a motor to an axis, more like a tightly packed coil that gets straightened as wire is pulled out)
As for the energy, I assumed GP was thinking of solar panels on the surface. I also assume that we share scepticism based on the low sun intensity out in the orbit of Jupiter... (and that's before you even start wondering how much further away from the melting point that ice will be than all ice of conventional human experience)
Wouldn't this be limited to the tensile strength of the material and the weight of the cable? Granted, Europa has much less gravity, but 25km is a lot of cable weight.
Consider something as small as fishing line; one online estimate gives it .245g/m. At 25km, that's over 3 tons of line weight hanging down a hole on Earth or nearly 800 lbs on Europa.
What you have to worry about is the ice shifting and severing the cable.
>The probe bears on the ice below it
This implies it is bearing the weight of the entire cable above it. So instead of the tensile stress being the limiting factor, it's not the compressive stress. If you're intent is to retract the spool, it would still be in tensile stress as it comes up. (And you'd need enough torque to do so. But maybe you the plan would be to abandon in place).
>What you have to worry about is the ice shifting and severing the cable.
I agree, that's a pretty big concern.
Rest assured that incredibly smart people at a propulsion laboratory are working on solving these sorts of problems. If you are a citizen of the USA, you can help by asking your elected representatives to adequately fund these efforts so these personnel won’t be laid off in the next few months.
If that's not your claim then I don't understand your valuation and the rest of the comment doesn't track.
And not to engage at a base level but my use of immeasurable is correct in being interpreted as "large" unambiguously, at least by Merriam webster.
A "viable billion dollar mission" includes all sorts of other things that are of value, including developing capabilities to do things that are strategically important, which I would claim is where a large majority of that billion dollars comes from. Similarly, I would expect that JPL would very much inflate the value of their own work. Everyone does.
Also, I see "incapable of being measured" with "broadly : indefinitely extensive" tacked on in the MW definition. There is no requirement there that "immeasurable" mean "large", just "incapable of being measured" with the expectation that it is used when describing things that are extreme. My most recent use of "immeasurable" was "immeasurably small" which I'm sure you would agree is a proper use.
Hosting the photos costs money too, which I don't think GP is considering.
If NASA had to personally crowdfund these $5b missions, they'd probably still happen. That sum is also in the ballpark of Apple's marketing budget - I would not at all be surprised if they spent that much just to get their logo on the mission. Not to be outdone, Samsung pays next one.
But maybe you wanted to talk about the value-add to the society instead - which is easily going to dwarf $1m by many orders of magnitude just through advances in sciences, industry, and international cooperation that happen in the course of planning, building, executing, and pouring over results of such a mission. All of these things have a tendency to accrue interest, so the sooner, the better.
You could also take a state-centric view, and there also I guarantee you that the value of the image-lift and international cooperation is going to be worth more than a measly $1m to the US. A US president making a single international state visit costs multitudes of that.
I mean, that's why we go. Clipper is going to figure out, in part, whether we actually need to go down 20km or if we can just scoop up stuff kicked by cryovulcanism into low orbit. https://www.nasa.gov/missions/are-water-plumes-spraying-from...
https://en.wikipedia.org/wiki/Kola_Superdeep_Borehole
They did some drilling to the Ice at the Antarctica Vostok station, going donw to about 3 km:
https://en.wikipedia.org/wiki/Vostok_Station#Ice_core_drilli...
Still one of my favorite movies though.
Yeah, but if one of them had, he'd probably be too embarrassed to tell you!
Once the ice freezes again behind the probe it would protect the fibre... perhaps?
Fortunately something like that wouldn't be too difficult to test on Earth - probe recovery might be tricky though.
A nuclear reactor could produce basically no heat while offline, then be switched on and suddenly provide 100s of kW when it gets to wherever it's going. The hard part in space is radiating away the heat, but if you're on an ice world, that's orders of magnitude easier.
The hardest part I'd see would just be getting into the ice; there's not really any "melting" in vacuum. The constant boiling away of the water would keep insulating your heater from the ice. Meters 1 to 20,000 are probably pretty easy.
https://www.walmart.com/c/kp/water-wiggler-toy
So it can "slip down" by a continuous unrolling process!
In fact you could just boil the water to steam and vent it out the top via a surface valve assembly - the interior would act like a vacuum thermace flask.
You mean in the Arctic? https://en.wikipedia.org/wiki/Kola_Superdeep_Borehole
https://www.cambridge.org/core/journals/annals-of-glaciology...
I know this because I was always interested in the possibility of deep mining operations in other planets, and did some research on it. There are a few interesting things we can achieve with deep mines in other planets:
- Preserving resources and nature on earth. Mining is quite disruptive to the ecosystem and other planets are abundant with common minerals, like iron, cobalt, gold and silicates.
- Underground bases might be easiest and simpler way of building any settlements on other planets, removing material can be done in-situ without need send as much construction materials. It gives great protection against radiation, good insulation agains temperature changes, and can be pressurized to Earth's atmosphere.
- It gives access to materials only found deeper in the crust. And different planets might have different mineral deposits
- This is not practical, but also interesting, you could technically dig deep enough to have enough air pressure in a open cave to not need a pressurized suit. In Mars that would be around 20 km, a much more comfortable atmospheric pressure would be found around 40km though.
The mission is: > 50 ice-skimming flybys, remotely probing the ocean in hopes of finding a chemistry that could support life.