[maitola]

"We’re not a life search mission. We’re a habitability mission,” says Robert Pappalardo, Clipper’s project scientist at the Jet Propulsion Laboratory (JPL), which manages the mission."

So we are going to wait 7 years, and spend $5B to actually not search for life on Europa? Why? Sometimes it feels like Nasa is doing everything possible for not searching for life outside earth, which would be a game changing discovery for humanity, several orders of magnitude more important than the habitability of Europa.

[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.

[Sharlin]

You seem to have a very naive understanding of the dynamics here. Making it a life finder mission would have taken two times longer and cost three times more, assuming it wouldn't have been cancelled long before that.

NASA is not in charge of its own budget. Neither it is, ultimately, in charge of what missions get greenlit. Sure, NASA is an inefficient organization in many ways, including planning and management practices that never seem to get better despite numerous reviews, but honestly it's incredibly difficult to be efficient when your bosses sit in the Congress. You don't want to know what NASA's Planetary Science division could have achieved in the last twenty years with all the billions that have gone to the boondoggle that's the Senate Launch System and its earlier incarnations.

[stetrain]

Because a close fly-by probe is something we know how to do, and is a much more affordable and achievable goal than a mission that would have the true goal of confirming life on Europa.

Such a mission would involve landing on an outer solar system body with no atmosphere, penetrating 10-15 miles of ice, and directly sampling liquid water for microbes. That's a huge undertaking that would cost a lot more than $5B. If any part of that failed, it would be a pretty bad look for NASA and those who voted to fund it, and a negative result still wouldn't mean there is no life.

I certainly think that's something we should be attempting to do in the future. But an initial close flyby mission is something we know we can do with a high probability of success, and data gathered from such a mission could build support for a more extensive follow-up in the future. The data gathered might even make that future mission less expensive and more likely to succeed by mapping likely places where the ice is thinner, or where tectonic activity pushes water to the surface.

And hey if a microbe in a plume of water happens to land in a collection receptacle on this mission, that's just an incredible bonus without setting the mission up for disappointment.

[DiogenesKynikos]

NASA is absolutely looking for life in the Solar System. Many of the Mars missions have looked for signs of life.

What NASA is not doing is looking for communications from intelligent aliens. Why? Because Congress decided in the 1990s that that would be a waste of money, and banned NASA from doing it.

[m3kw9]

Searching for life to confirm would only be useful if you have lots of pocket change. We all know life exists outside the solar system, only the biggest ego maniacs will truly believe humans are the only life in the universe

[cooper_ganglia]

I understand the view that life likely exists elsewhere in the universe, and I agree that, given the vast number of planets and galaxies, it's certainly a plausible idea. The sheer scale of the universe, coupled with our growing knowledge of exoplanets and extremophiles—organisms that thrive in conditions once thought inhospitable to life—makes it reasonable to think life could exist beyond Earth.

That being said, I have no logical reason to know life exists anywhere else except on this planet. I think it's important to differentiate between the likelihood of something and claiming certainty about it. While the possibility of extraterrestrial life is exciting and worth exploring, until we have direct evidence, we can't confidently say it’s out there.

In fact, we can't even answer the philosophical question, "Do other people aside from me even actually exist?" with 100% certainty. This brings us to the ironic part: sometimes, claiming we know life exists elsewhere can be a reflection of the same kind of ego that leads others to believe humanity is uniquely special in the universe. Both positions can, in a way, stem from an overestimation of our ability to know the unknowable.

I think it's great to remain curious and open to discovery, but also humble about the limits of our current knowledge. :)

[m3kw9]

in math they use a lot of approximations to do calculations like limits -> infinity. It's a good enough approximation that is almost unrefutable. Also, who has more ego, we are the winner of 1 in 10e30, or there is way more winners.

[generic92034]

The mass in the observable universe is considered to be 10^53 kg. So nothing is going to infinity when it comes to life made from matter (or energy).

I am not sure how to talk about things outside the observable universe. If light speed provides the ultimate limit for causality, this outside might as well not exist, from our perspective.

[crustaceansoup]

We have a lot of really useful things to learn about life away from Earth even if you assume that life exists elsewhere.

How common is it? In what environments does it occur?

Does it start the same way everywhere? Does it end up going the same directions the same way everywhere? Does it use the same metabolic pathways and the same genetic material?

Even just a confirmation without taking samples or deeper analysis is enough to start on these questions. Right now we can't even really start.

[sigzero]

> We all know life exists outside the solar system, only the biggest ego maniacs will truly believe humans are the only life in the universe

That statement isn't remotely true and it all depends entirely on what you define "life" as being.

[cruffle_duffle]

yes but do they have DNA or something like it? Are we their descendants? Are they ours? How much of that life is “intelligent” and how much of it is just microbes and stuff?

You are right in that it seems pretty “obvious” that we aren’t alone… the math is overwhelmingly in favor of it being everywhere. But there is a huge distance between the math saying it exists and actually looking at it with your own eyes.

[cmrdporcupine]

You almost wonder if there's budget-politics at work if you admit you're looking for alien life to lawmakers tinged by Christian fundamentalism.