42 votes
Accepted

Can a spaceship land on an icy body using retropropulsion? wouldn't the ice melt?

Sorry for the length of this, but it brings up some interesting facts and possibilities. The moons you mention, Titan, Europa, and Enceladus, are three very different places. Titan has a relatively ...
Tom Spilker's user avatar
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34 votes
Accepted

Why are we interested in visiting the giant planets' icy moons?

The icy moons are of interest for exploration as part of the overall "follow the water" strategy of exploration that NASA (and others) have been exploring for some time. The "where else can water be ...
astrosnapper's user avatar
  • 2,506
32 votes

Why aren't there any robotic missions on Europa or Enceladus?

There are probably many answers, but for guesstimating hypothetical missions a look at delta-V/subway maps like this are highly informative in terms of problem scale. Working from that getting into ...
GremlinWranger's user avatar
31 votes
Accepted

Why was Titan the first celestial body beyond Mars to be landed on?

Simple. It was the easiest to land on. Titan has an atmosphere, which makes landing there quite a bit easier than landing on Europa, which does not. In addition, Europa has only been known as an ...
PearsonArtPhoto's user avatar
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23 votes
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Why aren't there any robotic missions on Europa or Enceladus?

@GremlinWrangler's answer sums up several important points; Getting a low mass rover from Earth all the way to landing on the surface of one of those Moons requires much much more rocketry (delta-v) ...
uhoh's user avatar
  • 149k
19 votes

Can a spaceship land on an icy body using retropropulsion? wouldn't the ice melt?

It's probably going to be less of a concern than you'd guess. The icy worlds of our solar system have essentially no atmosphere, so the surface materials will sublimate directly to vapor and be ...
Russell Borogove's user avatar
19 votes
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What would ice-skating be like on Europa?

Why Is Ice Slippery? That's a surprisingly involved question. The main takeaways: The common explanations of "pressure melting" and "frictional heating" are indeed true to some degree, but they can't ...
SE - stop firing the good guys's user avatar
18 votes
Accepted

How unreachable are Jupiter's moons from Mars with the technology developed for going to Mars?

Let's go back our old friend the Pork chop plotter. Earth to Jupiter using minimum fuel takes around 2 years and you get one opportunity per year, more or less, to get there. You can shorten the ...
Steve Linton's user avatar
  • 19.6k
16 votes

Why are we interested in visiting the giant planets' icy moons?

The motivation is the growing understanding, from the Voyager, Galileo and Cassini probes, that these icy moons (I'd throw in Enceladus) are geologically active with sub-surface oceans of liquid water,...
antlersoft's user avatar
  • 1,213
12 votes

Would a Europa lander need radiation shielding similar to Juno?

A Europa lander would need much more shielding, and/or more radiation tolerant components. Juno's orbit avoids the main radiation belt, but Europa is right in the middle of it.
Mark Adler's user avatar
  • 58.2k
12 votes

How unreachable are Jupiter's moons from Mars with the technology developed for going to Mars?

I whomped up a spreadsheet to compare scenarios like this: Hohmann.xls. Typing Earth into departure planet cell and Mars into destination planet I get Launch windows open each 2.14 years (synodic ...
HopDavid's user avatar
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11 votes

Would it be possible to send a nuclear bomb to Europa and make a hole in the ice of more than 11 km?

You may not send a nuclear bomb into space if you're one of the 105 countries that have signed the Outer Space Treaty that, among other things, forbids deploying nuclear weapons or any other kinds ...
Camille Goudeseune's user avatar
10 votes

Is the far side of the tidally locked Europa moon safe from Jupiter's radiation?

The radiation that causes problems near Jupiter is not emitted by Jupiter. Jupiter has radiation belts, like Earth's Van Allen belts, but much more intense. This radiation doesn't consist of photons, ...
Mark Foskey's user avatar
9 votes
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Do you need a "wire" on a Europa submarine to phone home?

A wire would be needed to get any real amount of data out. Wikipedia has the state of the art communication with submarines. There are basically 2 ways to communicate with them. Using sound waves ...
PearsonArtPhoto's user avatar
  • 121k
8 votes
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Which side of Europa is which?

The standard for any tidally locked body, of which Europa is a member, is to have the 0 longitude be the point at the center of the planet-facing side. That being the case, the middle of the map ...
PearsonArtPhoto's user avatar
  • 121k
8 votes

Why aren't there any robotic missions on Europa or Enceladus?

The motive for the exploration of Enceladus and Europa is different from that of Mars. The primary motive for exploration of the two moons is the possibility of finding an independent instance of ...
Vince 49's user avatar
  • 2,611
7 votes

Would a Europa lander need radiation shielding similar to Juno?

That depends on where the spacecraft lands. The radiation belts rotate faster than the moon so the trailing side of Europa gets a lot of radiation while the leading side gets relatively little. It ...
ventsyv's user avatar
  • 1,496
7 votes
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Have there been any determinations of the water pressure in Europa's ocean just below the ice?

It is easy to calculate. The ice is reported to be 15 to 25 km deep. Simply take the weight of the ice in Europa's gravity over one square meter of the top of the ocean. Calculation in Wolfram Alpha ...
Mark Adler's user avatar
  • 58.2k
6 votes

Do you need a "wire" on a Europa submarine to phone home?

You would almost certainly need a wire. You have 2 things to contend with on Europa (besides the crippling radiation, extreme cold, vacuum, etc) and that is Ice and Water. Water absorbs radio waves, ...
GdD's user avatar
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6 votes
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How likely is that Europa actually has no ice layer?

The Hubble Space Telescope did an ultraviolet emission study of vapor plumes from Europa's southern hemisphere in 2012. It found that the emissions were consistent with $H_2O$. H2O freezes (19), ...
called2voyage's user avatar
  • 23.7k
6 votes

How to waterproof a rover?

Adapting an existing rover design to work underwater would be extremely cost prohibitive and it would be cheaper, more effective, and all around a better idea to design a whole new rover with ...
Dragongeek's user avatar
  • 18.7k
6 votes

What would ice-skating be like on Europa?

To complement: There is the highest resolution photo of Europa surface by Galileo probe. Resolution is 6 meter per pixel. We can see the surface is no so flat, more suited for alpine skiing than ice ...
Heopps's user avatar
  • 9,071
6 votes
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Have the Europa Clipper's flybys and gravity assists of Jupiter's moons been pre-planned in detail?

Yes, there are detailed plans. Maybe not the final version, details can change. On Preliminary Design Review (PDR) in 2019 the tour version 17F12 was chosen as reference. The details of this tour can ...
Heopps's user avatar
  • 9,071
5 votes
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How does not orbiting Europa maximize Clippers coverage of Europa for a given radiation dose?

It seems to be a duty cycle thing: Because Europa lies well within the harsh radiation fields surrounding Jupiter, even a radiation-hardened spacecraft in near orbit would be functional for ...
Bob Jacobsen's user avatar
  • 12.7k
5 votes

I'm going to invade Europa, any international interferences that could stop me?

TL;DR: We've all agreed to not do that, but there's no Intergalactic Police stopping you. But you would likely be stopped by earth police forces. Relevant Treaties and Organisations UN The UN's ...
SQB's user avatar
  • 169
4 votes

Why was Titan the first celestial body beyond Mars to be landed on?

They landed on Titan because Titan is the only natural satellite in the Solar System that has a dense atmosphere. And it is the only object other than Earth where surface liquid has been found. Source:...
Đorđe Milanović's user avatar
4 votes

A certain way to blow up Europa, what is wrong with this suggestion?

No. The water and ice are almost certainly under hydrostatic equilibrium. The ice is floating on the water. If you cut a hole in the ice, the water would fill the hole only part way, just like ice ...
uhoh's user avatar
  • 149k
4 votes

Would it be possible to send a nuclear bomb to Europa and make a hole in the ice of more than 11 km?

You'd have to bring a pretty large bomb to do this. We've detonated lots of bombs on Earth, and none of them came close to making a hole 11 km deep. We even did tests specifically aimed at making ...
Hobbes's user avatar
  • 128k
4 votes

What is the minimum pressure of a purely CO₂ atmosphere on Europa that can retain enough heat for surface liquid water?

A very rough starting point is how much this atmosphere would differ from a perfect blackbody. The melting point of water is roughly 270 kelvin for a wide range of pressures, so with that as a surface ...
SE - stop firing the good guys's user avatar
3 votes

How unreachable are Jupiter's moons from Mars with the technology developed for going to Mars?

Using @HopDavid's excellent spreadsheet, we get a delta-V of about 6.9 km/s for a 3 year mission from highly elliptical Mars orbit to Callisto, the only one of the large moons where the radiation ...
Steve Linton's user avatar
  • 19.6k

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