Layperson here, but isn't the ocean covered with several kilometers of ice? It seems daunting to get a vessel all the way to Europa, drill through that much ice, get the vessel into the water, and subsequently send signals back to Earth. I'm not saying we shouldn't do that--in fact--the thought of what might be in those oceans makes me giddy with excitement, but it seems like an extremely challenging exercise to make a mission like that happen given our current technology.

Ex-NASA guy here. Not directly involved in Europa mission planning, but heard a lot through the grapevine back in the day. Europa is very challenging to get to mainly because it's located in an extremely harsh radiation environment.

https://www.astrobio.net/news-exclusive/hiding-from-jupiters...

The limiting factor is building electronics that won't fry.

This is a mission where I’d like to see a continuous stream of missions instead of One Big Mission. Let’s bring the assembly line to space exploration.

Assembly lines work if you have economies of scale, i.e. if the incremental cost of production can eventually be brought below the value of the product on the open market and you can start turning a profit. The economics of planetary exploration are fundamentally different because the product is not the thing you're mass-producing. The product is data, not spacecraft. Furthermore, the hardware required to produce the most valuable data, i.e. the data you don't already have, generally needs to be different from the hardware you've already built. That's the fundamental reason planetary exploration is unlikely to benefit much from mass production any time soon.

I've just looked up, and the theory is that the ice is 15-25 km[1] thick.

The deepest hole on Earth is 12 km [2].

[1] - https://europa.nasa.gov/europa/faq/

[2] - https://en.wikipedia.org/wiki/Kola_Superdeep_Borehole

But to be fair, the limiting factor on earth was that it got much hotter much faster than scientists had expected. We aren't likely to have that issue on Europa.

Rather than having to keep the drill bit cool, to drill through ice you could use a heated drill bit. Perhaps using using radioactive material to heat the drill bit and cut through the ice like a hot knife.

(Of course, irradiating an alien ocean is perhaps not the greatest idea ever.)

It sounds to me like Elon Musk needs to combine efforts between SpaceX and The Boring Company.

Radium-knife: cooks the steak while you slice it!

It also means launching a large amount of radioactive material through the atmosphere which may end badly

The advantage on Earth is that you have dozens of machinists, operators, labourers, and tens of thousands of tonns of supplies necessary for digging these holes.

You can't do that with one robot, and a weight budget of a few tonns.

While I am radically milquetoast on engineering things, to me it doesn't seem nearly as impossible as mining the deep, deep oceans of Earth. Similar constraints, similar win/fail procedure. If we really wanted to drill into Europa, we'd have it up and running in a manner of years, imho.

Getting there, of course, is the other big challenge, but honestly .. a fleet of Starship's, maybe 100 or so .. sent to Europa with enough guts to build a base .. I could see it happening in 20 - 30 years, maybe .. if not sooner.

I don't think it isn't challenging. I think it's definitely possible; just expensive. And I think it's actually cheaper than a lot might think: the biggest expense until now has been getting there. But with SpaceX and reusable rockets that looks to be a helluva lot cheaper. It's still challenging on a technical level but tractable to the higher ends of science budgets, or even middle ends of, say, oil and mining budgets.

Once you are in an ocean covered with miles of ice, how do you send a signal?

Why would you dig deep into an ocean covered with miles of ice without a tether to a station?

Suppose it looks like this:

    ----- upper ice surface -----
     ice ice ice ice ice ice ice
    ~~~~~ lower ice surface ~~~~~

Then a tether station might look like this with a conduit/shaft between

         beep
         /|\
    ------|----------
          |
    ~~~~~~|~~~~~~~~~~
         \|/
        beep

Then you can have a swimmer-rover:

         hi!
         /|\
    ------|----------
          |
    ~~~~~~|~~~~~~~~~~
         \|/
        .
    <-> hi!

sorry I'm just a software dude :|

It would be my first instinct too, but I'm assuming miles of cable in frozen ice that probably move will not last for long.

But maybe setup a wireless relay? Not easy through that much ice.

This mission is starting to sound really expensive

Yup! It definitely would still be an expensive mission! But I think getting there is no longer the biggest expense :)

Ice carries radio waves a lot better than water. Once sunk through the ice, the entire probe, or a small buoy, could float up to the underside of the ice and transmit clearly to the surface.

leave sending station above ground. send down hot ice melting probe (no drilling) attached to long cable.

The meltwater would have to be removed, or the cable itself heated.

The Jupiter Icy Moons Explorer is scheduled to launch in 2022. It is scheduled to do 2 flybys of Europa, and several more of Callisto, before settling into orbit around Ganymede in 2032. [1]

The Europa Clipper is scheduled to launch in 2024. It will conduct many (wikipedia says 44) flybys of Europa before eventually being destroyed by radiation. The flybys should provide spectrometry and ground-penetrating radar images of the entire surface, and mass spectrometry of any dust it flies through at low altitudes. [2]

Finally, the Europa Lander is currently proposed to launch in 2025. Among other objectives, it would analyze the composition of the ice, looking for chemical signs of life. [3]

Unfortunately, neither of these Europa missions will provide spectacular, years-long presence like Spirit, Opportunity, Curiosity, or the various satellites in orbit around Mars. The radiation is too intense. Europa Clipper will do flybys to allow its instruments to capture brief deluges of data, then give the radios lots of time to transmit while the spacecraft isn't bathed in radiation. Europa Lander will not have solar panels or an RTG, instead being powered by non-rechargeable batteries. The battery duration roughly matches the estimated electronics lifespan in the high-rad environment: about 3 weeks.

[1] https://en.wikipedia.org/wiki/Jupiter_Icy_Moons_Explorer

[2] https://en.wikipedia.org/wiki/Europa_Clipper

[3] https://en.wikipedia.org/wiki/Europa_Lander_(NASA)