Author Topic: NASA - Cassini updates  (Read 263353 times)

Offline notsorandom

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Re: NASA - Cassini updates
« Reply #520 on: 04/13/2017 07:17 PM »
Couldn't they use a stripped down version of Europa Clipper, as Saturn has a less fearsome radiation environment, as an Enceladus Clipper?

I can't help feeling maybe we should be going to Enceladus first not Europa?

Some reporting of what I assume is the Q & A session.

https://mobile.twitter.com/EBotkinKowacki/status/852585362362949633
I admit that personally I'd rather see an Enceladus mission. However, Cassini was able to study Enceladus better than Galileo did with Europa. That puts Europa at a disadvantage as it makes it seem less interesting. Clipper could discover a bunch of new things about Europa that make it potentially the better place for further study.

Offline Star One

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Re: NASA - Cassini updates
« Reply #521 on: 04/13/2017 07:21 PM »
Couldn't they use a stripped down version of Europa Clipper, as Saturn has a less fearsome radiation environment, as an Enceladus Clipper?

I can't help feeling maybe we should be going to Enceladus first not Europa?

Some reporting of what I assume is the Q & A session.

https://mobile.twitter.com/EBotkinKowacki/status/852585362362949633
I admit that personally I'd rather see an Enceladus mission. However, Cassini was able to study Enceladus better than Galileo did with Europa. That puts Europa at a disadvantage as it makes it seem less interesting. Clipper could discover a bunch of new things about Europa that make it potentially the better place for further study.

Would an Enceladus mission be automatically cheaper due to the less strenuous radiation environment?

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Re: NASA - Cassini updates
« Reply #522 on: 04/13/2017 07:54 PM »
Couldn't they use a stripped down version of Europa Clipper, as Saturn has a less fearsome radiation environment, as an Enceladus Clipper?

I can't help feeling maybe we should be going to Enceladus first not Europa?

Some reporting of what I assume is the Q & A session.

https://mobile.twitter.com/EBotkinKowacki/status/852585362362949633
I admit that personally I'd rather see an Enceladus mission. However, Cassini was able to study Enceladus better than Galileo did with Europa. That puts Europa at a disadvantage as it makes it seem less interesting. Clipper could discover a bunch of new things about Europa that make it potentially the better place for further study.

Would an Enceladus mission be automatically cheaper due to the less strenuous radiation environment?

It could last longer, but would not be cheaper due to the need for an RTG for power. Also depends if the probe is flying through the plumes to collect samples for return to Earth. Sample return will drive up mission costs.
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Offline sghill

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Re: NASA - Cassini updates
« Reply #523 on: 04/13/2017 07:56 PM »
I wonder how the heating occurs on a pole instead of at the equator, where tidal effects are the greatest on earth?

I believe it might be a case of the region with the thinnest ice reorienting itself to one of the poles due to a tidal gradient on a non-spherical body. IIRC, the active south polar region is actually topographically slightly depressed compared to the rest of the ice shell on account of liquid water underneath having higher density than bulk ice.

It doesn't mean there's necessarily a mechanism that somehow concentrates the heating to the pole, just that the largest liquid pocket ended up there on account of either ice shell (if the ocean is really global, but deepest at the pole) or entire moon rotational drift.

I like these theories. Let me proffer one more.  Because the heating is coming from inside rather than outside the moon, hot water will be concentrated where there is less mixing. In other words, the moon's ocean currents- like jet streams- are strongest away from the poles, so the water is warmest where it is relatively still.

For this to occur necessarily requires an obstructed global ocean underneath the ice crust.

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Offline Star One

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Re: NASA - Cassini updates
« Reply #524 on: 04/13/2017 08:00 PM »
Couldn't they use a stripped down version of Europa Clipper, as Saturn has a less fearsome radiation environment, as an Enceladus Clipper?

I can't help feeling maybe we should be going to Enceladus first not Europa?

Some reporting of what I assume is the Q & A session.

https://mobile.twitter.com/EBotkinKowacki/status/852585362362949633
I admit that personally I'd rather see an Enceladus mission. However, Cassini was able to study Enceladus better than Galileo did with Europa. That puts Europa at a disadvantage as it makes it seem less interesting. Clipper could discover a bunch of new things about Europa that make it potentially the better place for further study.

Would an Enceladus mission be automatically cheaper due to the less strenuous radiation environment?

It could last longer, but would not be cheaper due to the need for an RTG for power. Also depends if the probe is flying through the plumes to collect samples for return to Earth. Sample return will drive up mission costs.

Isn't sample return from the Saturn system technically beyond our current abilities?
« Last Edit: 04/13/2017 08:00 PM by Star One »

Offline vjkane

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Re: NASA - Cassini updates
« Reply #525 on: 04/13/2017 08:02 PM »
Couldn't they use a stripped down version of Europa Clipper, as Saturn has a less fearsome radiation environment, as an Enceladus Clipper?

I can't help feeling maybe we should be going to Enceladus first not Europa?

Some reporting of what I assume is the Q & A session.

https://mobile.twitter.com/EBotkinKowacki/status/852585362362949633
There is at least one New Frontiers proposal for a mission to return to Enceladus.  It is very narrowly focused on chemical analysis of the plumes; e.g., no study of the ice shell thickness or imaging to inform potential future landers.

See

http://www.lpi.usra.edu/opag/meetings/feb2017/presentations/Cable.pdf

Offline Star One

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Re: NASA - Cassini updates
« Reply #526 on: 04/13/2017 08:04 PM »
Couldn't they use a stripped down version of Europa Clipper, as Saturn has a less fearsome radiation environment, as an Enceladus Clipper?

I can't help feeling maybe we should be going to Enceladus first not Europa?

Some reporting of what I assume is the Q & A session.

https://mobile.twitter.com/EBotkinKowacki/status/852585362362949633
There is at least one New Frontiers proposal for a mission to return to Enceladus.  It is very narrowly focused on chemical analysis of the plumes; e.g., no study of the ice shell thickness or imaging to inform potential future landers.

See

http://www.lpi.usra.edu/opag/meetings/feb2017/presentations/Cable.pdf

Thank you for that. This announcement just did them a power of PR good.

Offline Bubbinski

Re: NASA - Cassini updates
« Reply #527 on: 04/13/2017 09:09 PM »
Bottom line: Enceladus has almost all the necessities for life in its ocean found in the plumes. (Sulfur & phosphorus not found yet). Stronger confidence of Europa plumes. JWST and Europa Clipper are follow on missions.

https://www.nasa.gov/press-release/nasa-missions-provide-new-insights-into-ocean-worlds-in-our-solar-system
« Last Edit: 04/13/2017 09:15 PM by Bubbinski »
I'll even excitedly look forward to "flags and footprints" and suborbital missions. Just fly...somewhere.

Offline redliox

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Re: NASA - Cassini updates
« Reply #528 on: 04/13/2017 09:15 PM »
So Enceladus has hydrogen and methane?  Certainly puts it on level with Europa for interest level at the least.
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Offline Star One

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Re: NASA - Cassini updates
« Reply #529 on: 04/13/2017 10:31 PM »
Alien life could exist in our solar system – here's what we do now

The findings could be the beginning of the most profound discovery in the history of space

http://www.independent.co.uk/news/science/aliens-enceladus-life-saturn-moon-cassini-mission-nasa-announcement-today-what-does-it-mean-a7681831.html

Offline Graham

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Re: NASA - Cassini updates
« Reply #530 on: 04/13/2017 10:58 PM »
So Enceladus has hydrogen and methane?  Certainly puts it on level with Europa for interest level at the least.
And regular plumes. Makes it far easier to sample than Europa. To me Enceladus is far more deserving of a mission for that reason.
« Last Edit: 04/13/2017 10:58 PM by Graham »
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Offline Star One

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Re: NASA - Cassini updates
« Reply #531 on: 04/13/2017 11:28 PM »
So Enceladus has hydrogen and methane?  Certainly puts it on level with Europa for interest level at the least.
And regular plumes. Makes it far easier to sample than Europa. To me Enceladus is far more deserving of a mission for that reason.

But I suppose the counter argument to that is because Europa is believed to be 4 billion years old compared to some estimates that Enceladus is only 100 million years old that life, if that's what you're looking for, is far more likely to have had the time to get started on Europa.

Offline Blackstar

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Re: NASA - Cassini updates
« Reply #532 on: 04/14/2017 03:02 AM »
So Enceladus has hydrogen and methane?  Certainly puts it on level with Europa for interest level at the least.
And regular plumes. Makes it far easier to sample than Europa. To me Enceladus is far more deserving of a mission for that reason.

Except that it's farther away, and any sampling mission has to go there and come back, and that takes a long time.

Science does not work like a bunch of fourth graders playing soccer, everybody running after the ball. There is a lot of benefit to building a consensus around the objective and then working steadily to accomplish it.

Offline yg1968

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Re: NASA - Cassini updates
« Reply #533 on: 04/14/2017 04:25 AM »
Archived video of the press conference:


Offline Star One

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Re: NASA - Cassini updates
« Reply #534 on: 04/14/2017 08:43 AM »
Lead story on BBC Radio 5 this morning on their discussion program. They are also talking about space science in general and that can only be a good thing.

Offline Torbjorn Larsson, OM

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Re: NASA - Cassini updates
« Reply #535 on: 04/14/2017 11:25 AM »
So Enceladus has hydrogen and methane?  Certainly puts it on level with Europa for interest level at the least.
And regular plumes. Makes it far easier to sample than Europa. To me Enceladus is far more deserving of a mission for that reason.

But I suppose the counter argument to that is because Europa is believed to be 4 billion years old compared to some estimates that Enceladus is only 100 million years old that life, if that's what you're looking for, is far more likely to have had the time to get started on Europa.

We can - finally - be fairly certain that life emerged in alkaline hydrothermal systems like those whose existence on Enceladus has now been tested yet again. The remaining evolutionary signal after 4 billion years is relatively weak [< 0.1 %! of gene clusters] but absolutely robust [> 95 % of clusters agree on the environment;  http://microbialcell.com/researcharticles/physiology-phylogeny-and-luca/ ].

The counter analysis to the possibly young date of Enceladus and/or its ocean is that it is geologically old (> 1 Myrs) and that it did not take 4 billion years of geological and biological evolution to produce life. Or even half life which is the moniker invented for the universal common ancestor that ingested H2, CO2, N2, amino acids, nucleobases, sugars, lipids and catalytic metals from the geological formation that hosted and nurtured it. We now know from zircon oxygen isotope ratios that there was a habitable ocean > 4.3 billion years ago, and both molecular clocks and an increasing series of putative fossils span the 4.3 - 4.1 billion year old era. It looks like Earth became habitable and within geological time - because it was a product of geology - life sprouted. If something emerged recently on Europa because the known route is blocked it would be completely different from life as we know it. [Que "2010: Odyssey Two".]

I would grade Enceladus higher, simply because we know it has the right geology. And perhaps it is the better target, if we must chose. (Seems like NASA got Culberson on board on the Ocean Worlds strategy to go for both worlds, as well as Titan.) Granted it takes more time to get there, but ELF promises to be an in situ test that could detect present life as opposed to the painstaking process of Mars or Europa sample return. It would risk the Viking dilemma of a naive, non-general experiment that tells us little compared to looking for both extant and extinct life over a large window of time and geology simultaneously. But as Gene Krantz lately said on NASA (and so astrobiology, an exploratory science) "an important part of this, [is] to step forward and accept risk."

Edit: Spelling.
« Last Edit: 04/14/2017 11:31 AM by Torbjorn Larsson, OM »

Offline sghill

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Re: NASA - Cassini updates
« Reply #536 on: 04/14/2017 12:33 PM »
Lead story on BBC Radio 5 this morning on their discussion program. They are also talking about space science in general and that can only be a good thing.

Not really if it's the BBC.

That network's religious insistence of ecumenical reporting requires them to give equal airtime to dumb statements like: "some people say we should solve all of Earth's pressing problems before devoting resources to space exploration" in every single article they write....

« Last Edit: 04/14/2017 12:34 PM by sghill »
Bring the thunder Elon!

Offline Star One

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Re: NASA - Cassini updates
« Reply #537 on: 04/14/2017 12:47 PM »
Lead story on BBC Radio 5 this morning on their discussion program. They are also talking about space science in general and that can only be a good thing.

Not really if it's the BBC.

That network's religious insistence of ecumenical reporting requires them to give equal airtime to dumb statements like: "some people say we should solve all of Earth's pressing problems before devoting resources to space exploration" in every single article they write....

Well you'd be wrong in this case as there was just general enthusiasm for the topic from commentators and callers.
« Last Edit: 04/14/2017 12:48 PM by Star One »

Offline Star One

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Re: NASA - Cassini updates
« Reply #538 on: 04/14/2017 07:06 PM »
“Ocean Worlds” discoveries build case for new missions

Quote
Congress, in its fiscal year 2016 appropriations bill, directed NASA to develop an “Ocean Worlds Exploration Program” to search for life on such worlds using a mix of small and large missions. That language was included by Rep. John Culberson (R-Texas), chairman of the appropriations subcommittee that funds NASA and a strong advocate for missions to Europa in particular.

A formal program is still being established within the agency, officials said at the briefing. Mary Voytek, astrobiology senior scientist at NASA Headquarters, said a “roadmap” document outlining studies of ocean worlds is in the final stages of development by an advisory group. “They’re about to deliver that to us any day now,” she said. That document, she said, will set science priorities and technology requirements for any future missions.

Some scientists have questioned whether Enceladus, with its constant plumes containing chemical energy that could support life, may be a better initial target than Europa. Voytek noted that the presence of hydrogen in the plume indicates that it is not being consumed by any life that might exist in the oceans in Enceladus. “It means that there might not be life there at all, and if there is life, it’s not very active,” she said.

She speculated that could be linked to the age of Enceladus, which may be much younger Saturn itself. Europa, by contrast, was formed at the same time as Jupiter, more than four billion years ago. “That’s a lot more time for life to have emerged and start taking advantage of these energy sources,” she said. “So my money, for the moment, is still on Europa.”

http://spacenews.com/ocean-worlds-discoveries-build-case-for-new-missions/#sthash.ORtZXZU1.dpuf
« Last Edit: 04/14/2017 07:07 PM by Star One »

Offline matthewkantar

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Re: NASA - Cassini updates
« Reply #539 on: 04/14/2017 07:22 PM »
Could we buy two mission for the price of maybe 1.3 missions? Could an Enceladus mission and EUropa mission use identical gear?

Matthew
« Last Edit: 04/14/2017 07:22 PM by matthewkantar »

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