[jmyeet]

I'm not sure you truly appreciate just what a massive engineering challenge that would be. Try to do too many new things at once and you end up with the JWST being 2 decades late and costing 10x as much as originally projected.

The obstacles are numerous. Even Jupiter's magnetic field is a huge problem. There was recent talk that this missions electronics may not be sufficiently hardened. Typically, space probes to the gas giants will have a highly elliptical orbit to mitigate potential radiation damage.

So just surviving in Europa's orbit is a problem. Landing on Europa is another huge problem. There's no atmosphere to brake into. An icy surface may have crevasses and such and you could potentially immediately lose your probe. So how do you land safely on ice when you don't know how much weight that surface will support? A solution might be to do a burn to slow down and do a stationary land but that's also complex and adds a lot of weight. Also the engines and the fuel need to survive for 7 years until they're used.

Conquer all those obstacles and you're now on the surface. Now what? The ocea is under kilometers of ice so you can't really reach it. You really have to look for a volcano/geyser and you have to get to what that produces without being destroyed or damaged. Does the ice thin? Is there heat that means the ice thins and there's (heated) liquid water underneath? We really have no idea.

Finally you get a sample of subsurface ocean water and now what? What does life look like? How do you detect that? What signatures are you looking for? How do you avoid contamination from EArth-based life? That's not as easy as you might think.

The contingencies and redundancies required are jus tmind-bogglingly complex.

[yreg]

> An icy surface may have crevasses and such and you could potentially immediately lose your probe.

I wonder, would it be viable to send multiple probes? What cost effect would it have on the mission to build and launch an extra one?

I know that e.g. for the Curiosity mission they've built a second rover that they've kept on Earth for potential troubleshooting. How much more expensive would it be to build yet another one and launch two of them?

[cruffle_duffle]

Jesus the orbital injection alone wasn’t something I would have thought about. We rely a lot on the atmosphere to break our probes. Without that you need to burn just as much fuel slowing down as you did speeding up. Well, actually that isn’t true because your mass is way different so your fuel requirements are much, much less than that initial launch but still a non trivial amount.

I’m not a space probe engineer but I sometimes wonder if we go overboard on specialized compute hardware. I kinda wonder if that made more sense “back in the day”…. Ingenuity only rad hardened microchip is its flight controller. The rest is commercial off the shelf “normal hardware”.

I dunno… all I know is most people including myself ask the same questions as the parent. What the hell are we waiting for? Send some shit over there! Let’s do this.

[jmyeet]

> We rely a lot on the atmosphere to break our probes.

Yes and no. The atmosphere on Mars is a great example of the worst of both worlds. It's actually worse than having no atmosphere at all. It's not enough for aero braking. But it's enough to blow corrosive dust all over your solar panels and instruments and generally make your life miserable.

Of course, aero braking works exceptionally well on Venus but it has... other issues.

It did help on Titan though with the Cassini-Huygens probe.

> Without that you need to burn just as much fuel slowing down as you did speeding up

Not really. It's... complicated. If you were going between two points in the same inertial frame of reference then yes you need equal delta-V to slow down at the other end but, as you point out, that takes less fuel because your weight is lower (although part of your initial delta-V comes from the launch vehicle you disposed of).

But the EArth is going around the Sun at ~30km/s. Jupiter is going around ~15km/s. Europa is going around Jupiter at ~13km/s. So we have to speed up to escape EArth's orbit (around the Sun) and the EArth's gravityh well but also slow down to match Jupiter's velocity and also avoid speeding up too much as Jupiter's gravity well captures you.

But the lower orbital speeds of the outer planets is why we have never done an orbital insertion on Uranus or Neptune. This distance and delta-V requirements put flight times at like 10-30 years, depending. Heck, we haven't even done a flyby of each and that was back in the 1980s. Saturn is kinda of our practical limit for orbital insertion currently. And that's expensive and takes a long time.

But Europa having an icy surface is just a huge complication. Even if you do a burn to slow down, what's the heat on those thrusters going to do once you land? Is it going to melt ice and then you immediately drown? How thick is the ice? I don't mean overall thickness. I mean there may be crevasses and such. Just look at how dangerous it is to walk across glaciers.

How will you get traction on ice in relatively low gravity?

[zardo]

> immediately drown

You don't need to worry about puddles of water in a vacuum, you may need to worry about sublimated water vapor frosting up whatever you land though.

[digging]

> I’m not a space probe engineer but I sometimes wonder if we go overboard on specialized compute hardware. I kinda wonder if that made more sense “back in the day”

...Probably not.