Jupiter's Moon Europa May Have Water Plumes That Rise Up About 125 Miles (npr.org)

NASA's Hubble Space Telescope released new images Monday, which will be published in The Astrophysicial Journal later this week, that show what appears to be plumes of water vapor erupting out of the icy surface of Jupiter's moon Europa. The discovery is especially intriguing as it means that the ocean below Europa's surface could be probed without having to drill through miles of ice. NPR reports: Europa is one of the most intriguing places in the solar system because it's thought to have a vast subterranean ocean with twice as much water as Earth's oceans. This saltwater ocean is a tempting target for astrobiologists who want to find places beyond Earth that could support life. The trouble with exploring this ocean is that the water is hidden beneath an icy crust that's miles thick. But if plumes are indeed erupting from Europa, a spacecraft could potentially fly through them and analyze their chemistry -- much like NASA's Cassini probe did recently when it sped close to Enceladus, a moon of Saturn that has small geysers. Scientists used Hubble to watch Europa's silhouette as the moon moved across Jupiter's bright background. They looked, in ultraviolet light, for signs of plumes coming from the moon's surface. They did this 10 separate times over a period of 15 months, and saw what could be plumes on three occasions. NASA says the plumes are estimated to rise up about 125 miles, and presumably material then rains back down onto Europa's surface. Using Hubble in a different way, scientists previously saw hints that salty water occasionally travels up to the moon's surface. In 2012, the telescope detected evidence of water vapor above Europa's south polar region, suggesting the existence of plumes that shoot out into space. The agency's Juno spacecraft is currently in orbit around Jupiter, but it isn't slated to take any observations of Europa.

Comments

Make Earth great again

[Hognoxious]

Big black rock be damned, let's just land there and make the aliens pay for it!

Re:Make Earth great again

[Zontar The Mindless]

And here I was only thinking it'd make a really spectacular view for a second honeymoon... but whenever I type "Europa" into booking.com, it just gives me offers on great deals for Barcelona and some little Greek island I never heard of before. Bummer.

Re:Presumably its ice particles , not water vapour

[wkwilley2]

I was going to say it could still be liquid if the salt concentration was high enough, but even at 30% concentration, the freezing point is between -20 and -30 C.

But in a vacuum, water tends to boil, not freeze.

Wat

[ThatsNotPudding]

In 2012, the telescope detected evidence of water vapor above Europa's south polar region, suggesting the existence of plumes that shoot out into space. The agency's Juno spacecraft is currently in orbit around Jupiter, but it isn't slated to take any observations of Europa.

WTH?

Re:Wat

[Anonymous Coward]

Juno was launched before this discovery, and it is in a highly elliptical polar orbit that keeps it far away from any of the Jovian moons. Even if they wanted to completely scrap the rest of the science scheduled for Juno they don't have the option to modify its orbit enough to actually make a fly-by.

Re:Wat

[Rei]

Right. Because brief observations from an already present spacecraft that could help make critical design decisions about an upcoming multibillion dollar mission are an absurdity.

Look, we know Juno wasn't designed for this sort of mission and is not well equipped or positioned for it. But if researchers determine that its observations could help pinpoint more details of the plumes, then yes, they damn well should regardless of whether "tomhath at slashdot" considers that to be "real science" (apparently some vague category that he doesn't even feel the need to expand upon -- apparently planetary scientists have been working on "fake science" all these years, who knew?).

Re:Wat

[Geoffrey.landis]

Look, we know Juno wasn't designed for this sort of mission and is not well equipped or positioned for it. But if researchers determine that its observations could help pinpoint more details of the plumes...

But they can't. Juno isn't a mission to look at Jupiter's moons, it's not in the right orbit to look at Jupiter's moons, it doesn't have instruments to look at Jupiter's moons. It's designed for looking at Jupiter and Jupiter's plasma and field environment.

https://www.nasa.gov/mission_p...

There's already a mission planned to investigate Europa: Europa clipper.

http://www.nasa.gov/press-rele...

Re:Wat

[Rei]

This is not correct. Juno is planned to do some limited observation/a> of the Galilean moons. It's a side mission, not central to it's focus (and Juno is anything but optimized for it), but it's one of those cases where, if you're there and you have the hardware...

Concerning Europa (remember that this was before the recent news):

The most significant opportunity for Juno to do Europa science would be to follow up on the plumes possibly detected by Hubble Space Telescope. Confirming Hubble's detection would be very scientifically valuable. Any information on the source location would be valuable. This science goal just may not be possible with the large distances from Juno to Europa, but we will look.

JunoCam or ASC can only detect plumes if they contain fine particles. The Hubble discovery (if real) only shows the presence of water vapor. We can predict by analogy to Enceladus that water vapor plumes will also contain particles. However, it is important to remember that the Hubble discovery was of gas, not particles. If the putative Europa plumes are Enceladus-like and do contain particles, they would not be as tall as Enceladus', because of Europa's higher gravity. Scaling for Europa’s gravity gives a maximum plume height of under 140 kilometers. To detect plumes, we need at least two pixels, so the image spatial scale would need to be better than 70 kilometers, at a relatively high phase angle where the particles would forward-scatter light to JunoCam and ASC.

To achieve resolutions better than 70 kilometers per pixel, UVS needs to be within 40,000 kilometers of Europa; JunoCam, 100,000 kilometers; and ASC, 170,000 kilometers. For the cameras, given the low expected height of the plumes, there is not much flexibility.

There are just four orbits that have Europa flybys that are closer than 300,000 km. Juno reaches the best available geometry in September 2017 as the rotation of the line of apsides brings Juno’s orbit close to Europa’s orbit:

2017-03-08 253,118 km
2017-09-19 264,043 km
2017-10-03 92,267 km
2017-10-17 204,654 km

Re:Presumably its ice particles , not water vapour

[Anonymous Coward]

Well, that is possible: https://en.wikipedia.org/wiki/Triple_point
Not saying that's what happening here, though.

Miles...

[wonkey_monkey]

Jupiter's Moon Europa May Have Water Plumes That Rise Up About 125 Miles

Ugh. I know the country that made the telescope that saw the plumes still insists on using miles, but can't we at least agree to outlaw imperial measurements for anything to do with space?

Especially spacecraft design and fuelling...

Re:Miles...

[stealth_finger]

Jupiter's Moon Europa May Have Water Plumes That Rise Up About 125 Miles

Ugh. I know the country that made the telescope that saw the plumes still insists on using miles, but can't we at least agree to outlaw imperial measurements for anything to do with space?

Especially spacecraft design and fuelling...

Jupiter's Moon Europa May Have Water Plumes That Rise Up About 1.34473e-6 AU.

Better?

Re:Too late to modify JUICE or The Europa Clipper?

[Rei]

They're already ahead of you :) Clipper will likely include the SUDA instrument for doing just that - roughly equivalent to Cassini's CDA
 

Re:So how is it supposed to communicate?

[Rei]

I think you're confused. Plumes means "in space". The whole benefit of plumes is that you don't need to go under the ice at all, you can do flybies to collect ice particles, or have a lander observe and sample the plumes at the surface. The key is that it means a recent connection between the depths and the surface, and that would be huge for simplifying exploration.

We're nowhere near to being able to launching an ice boring / swimming probe. If I recall correctly the last thing I read on the subject, however, the most promising means for communicating with such a probe on an affordable mass budget was.... not communicating with it. Aka, having it fully autonomous - melting its way down, sampling/observing the ocean, then re-melting its way back to the surface - then and only then transmitting. The waiting period with no data would be stressful (as if it failed you'd never know why), but it could potentially be used on almost any icy solid body regardless of the ice thickness.

It's also possible that there's liquid water much closer to the surface than the global ocean. There are some inferred lakes at a depth of only a few kilometers, which is potentially short enough for a probe to maintain a fiber connection with the surface. And after JUICE and Clipper, we may well have found locations that are even shallower.

Re:Presumably its ice particles , not water vapour

[Chrisq]

They has something about this on the radio. Evidently all that has been detected is oxygen and hydrogen, which they assume is from the decomposition of water

Don't

[Anonymous Coward]

We have already been warned!

All these worlds
Are yours except
Europa
Attempt no
Landing there

2 big aspects to this, if true

[Maritz]

1. It would mean that the subsurface ocean at Europa is connected to the surface - this makes the possibility of life below more likely, as chemicals/nutrients could be ionized at the surface and cycled through to the ocean below

2. It would mean that we could look for signs of life at Europa just by sending a probe into its orbit and collecting material from the geysers

An interesting discovery if true - Europa has a larger volume of water than Earth's oceans, and has been stable for billions of years. If there's nothing particular special about conditions on Earth, it's reasonable to expect life of some kind on Europa.

The JUICE mission is probably going to spend its time on the wrong objects in the Jovian system.

ice particles AND water vapour

[Geoffrey.landis]

Isn't vacuum always cold? I fail to see how it could have a temperature above 0K.

Vacuum in itself has no temperature at all. "No temperature" is not the same as 0 Kelvin.

The temperature of something IN a vacuum is determined by the sources heating it and the infrared radiation outward from it. Initially, water exposed to vacuum will start to boil; the boiling will reduce the temperature (losing the heat of vaporization), and the lower temperature will freeze the water. So, in fact, it will boil and freeze at the same time, resulting in ice particles AND an expanding cloud of water vapor.

I got cooled to absolute zero, but I'm 0K now.

Cute.

Re:So how is it supposed to communicate?

[MightyMartian]

At this point if a probe could just taste the plumes, it might be able to identify evidence of organic chemistry, heck maybe even be able to identify the vacuum-desiccated remnants of living organisms. We're decades away from building a probe that could actually bore through even a few kilometers of ice, but being able to build probes that could land on the surface and analyze the deposits left over from plumes should be well within current technical capabilities.

At the moment Europa really is one of our best shots at identifying life on another world. Even if Europa has never developed anything more complex than bacteria, being able to sample its DNA, or even cooler, finding some other system of protein encoding and heredity would literally be one of the most significant scientific discoveries in history. Just having life there, would go a long way to confirming the belief of many scientists that all life needs to get kickstarted is liquid water, organic compounds and energy.