Author Topic: NASA - Cassini updates  (Read 279920 times)

Offline Blackstar

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Re: NASA - Cassini updates
« Reply #540 on: 04/14/2017 08:43 pm »
Could we buy two mission for the price of maybe 1.3 missions? Could an Enceladus mission and EUropa mission use identical gear?

No.

Europa has nasty radiation. Requires very different hardware.

Online ThereIWas3

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Re: NASA - Cassini updates
« Reply #541 on: 04/14/2017 10:43 pm »
I doubt Saturn-space is exactly benign.  Turn it around.  Could a craft designed to Jupiter specs also work for Saturn?
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Offline Blackstar

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Re: NASA - Cassini updates
« Reply #542 on: 04/14/2017 10:49 pm »
I doubt Saturn-space is exactly benign.  Turn it around.  Could a craft designed to Jupiter specs also work for Saturn?

Europa is hell. It really is. It's hell. The radiation there is nasty. Designing for that environment is like nothing else.


Offline Nomadd

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Re: NASA - Cassini updates
« Reply #543 on: 04/14/2017 10:59 pm »
I doubt Saturn-space is exactly benign.  Turn it around.  Could a craft designed to Jupiter specs also work for Saturn?

Europa is hell. It really is. It's hell. The radiation there is nasty. Designing for that environment is like nothing else.


It's motto is "At least we're not Io"
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Offline Alpha_Centauri

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Re: NASA - Cassini updates
« Reply #544 on: 04/15/2017 01:20 am »
I doubt Saturn-space is exactly benign.  Turn it around.  Could a craft designed to Jupiter specs also work for Saturn?
Why would you want it to? It is not like there is a huge cost saving in making just two copies of a heavily custom system, this is not mass-production.

It would be cheaper to build a bespoke Saturn orbiter that didn't have excessive radiation shielding and rad-hardened components, which both increase cost significantly. Designing for high radiation environments also puts constraints on the spacecraft's capabilities that wouldn't exist otherwise.
« Last Edit: 04/15/2017 01:21 am by Alpha_Centauri »

Offline as58

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Re: NASA - Cassini updates
« Reply #545 on: 04/15/2017 06:42 am »
Would solar power (that Europa Clipper uses) even work at Saturn?

Offline Star One

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Re: NASA - Cassini updates
« Reply #546 on: 04/15/2017 09:10 am »
This kind of got lost in the Enceladus news.

Cassini Sees "Flying-Saucer" Moon Atlas Up Close

https://saturn.jpl.nasa.gov/news/3025/cassini-sees-flying-saucer-moon-atlas-up-close/

Offline Robotbeat

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Re: NASA - Cassini updates
« Reply #547 on: 04/15/2017 12:16 pm »
Would solar power (that Europa Clipper uses) even work at Saturn?
Sure. About a factor of 3.4x less sunlight, so your arrays need to be larger, but on the plus side, the much lower radiation environment means the solar panels can be much lighter per area, so it may not be much worse than Jupiter missions.
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Offline Archibald

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Re: NASA - Cassini updates
« Reply #548 on: 04/15/2017 03:30 pm »
Obviously the Europa ship is hardened against radiation. The electronic are housed into an armored box to protect them against radiation.  Maybe a carbon copy could be build with that armor removed to save some weight.
Cassini wasn't Galileo copy by any mean, but it could have been (there were at least a serious proposal made for a carbon copy of Galileo to be send to Saturn)
« Last Edit: 04/15/2017 03:33 pm by Archibald »
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Online zubenelgenubi

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Re: NASA - Cassini updates
« Reply #549 on: 04/15/2017 10:35 pm »
Here's an interesting counter to the general, popular-level assumption that the April 13 Enceladus confirmation/news = alien life...

From the Sky & Telescope on-line article, dated April 13: Enceladus: Hydrothermal Heating Confirmed

Quote
Among those speculating, astrobiologist Mary Voytek (NASA) says that the abundant hydrogen and carbon dioxide seen actually disfavors life in her mind. "If there is life, itís not very active," she said in an April 13th press conference. Think of hydrogen like pizza. "When you have stacks of pizza, much like in a graduate school department, it disappears. So we have this buildup of food thatís not being used."

Dr. Voytek has a point.  However, we don't have a way to determine currently if the detected hydrogen and carbon dioxide are a surplus escaping to space AFTER microbes have chowed-down on a larger initial source supply.

Or, is this speculation based on an assumption that life will grow to consume all available resources, and that little or no hydrogen or CO2 should be detected?

Hmmm...
« Last Edit: 04/15/2017 10:36 pm by zubenelgenubi »
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Offline Torbjorn Larsson, OM

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Re: NASA - Cassini updates
« Reply #550 on: 04/15/2017 11:12 pm »
Here's an interesting counter to the general, popular-level assumption that the April 13 Enceladus confirmation/news = alien life...

From the Sky & Telescope on-line article, dated April 13: Enceladus: Hydrothermal Heating Confirmed

Quote
Among those speculating, astrobiologist Mary Voytek (NASA) says that the abundant hydrogen and carbon dioxide seen actually disfavors life in her mind. "If there is life, itís not very active," she said in an April 13th press conference. Think of hydrogen like pizza. "When you have stacks of pizza, much like in a graduate school department, it disappears. So we have this buildup of food thatís not being used."

Dr. Voytek has a point.  However, we don't have a way to determine currently if the detected hydrogen and carbon dioxide are a surplus escaping to space AFTER microbes have chowed-down on a larger initial source supply.

Or, is this speculation based on an assumption that life will grow to consume all available resources, and that little or no hydrogen or CO2 should be detected?

It is hard to make an analogy to Earth conditions, since hydrogen release is scarce and tends to burn or be lost to space. But methane concentrations has increased to a new equilibrium (if that) in response to human activities. So while we can have an ecological response it cannot be a perfect cancellation.

Maybe the released paper - I expect there should be one - has somehow modeled what Voytek is discussing. But I have a hard time correlating the idea with the seeming direct path from ocean vent to plume exhalations earlier models have described. Any vent life would presumably try to catch the useful efflux but why would we expect that it would catch substantial parts when it does not happen here?

EDIT: Added commentary on Voytek's hypothesis.
« Last Edit: 04/15/2017 11:23 pm by Torbjorn Larsson, OM »

Offline CuddlyRocket

Re: NASA - Cassini updates
« Reply #551 on: 04/16/2017 12:45 am »
Or, is this speculation based on an assumption that life will grow to consume all available resources, and that little or no hydrogen or CO2 should be detected?

If it is, it's a flawed assumption. Consider the Earth's oceans. The number of photoysnthetic organisms hasn't increased to consume all the available light resource. This is because numbers have been capped at a lower level due to limited supplies of nutrients necessary to build and maintain the photosynthetic and other machinery of these organisms. When humans, either accidentally or purposively, increase the supply of such nutrients, the population explodes.

So, there may be plenty of hydrogen etc on Enceladus for microbes to consume, but their numbers may be limited by the restricted availability of some other resource.

Online Chris Bergin

Re: NASA - Cassini updates
« Reply #552 on: 04/21/2017 04:55 pm »

Offline Stardust9906

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Re: NASA - Cassini updates
« Reply #553 on: 04/21/2017 09:37 pm »
Chris Gebhardt overviews the grand finale....

https://www.nasaspaceflight.com/2017/04/the-grand-finale-cassini-final-mission/

Great article.

Sad to see the mission ending but since it has to I can't think of a better way to do it.

Offline catdlr

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Re: NASA - Cassini updates
« Reply #554 on: 04/22/2017 02:22 am »
Real Time Simulation - Track Cassini as it makes its final TITAN Flyby

Space Videos

Started streaming April 21, 2017
During the flyby, Cassini will attempt to study the elevations of Titanís smaller methane lakes ó maybe even measure their depth and composition.

So Long, and Thanks for All the Science
Cassiniís 127th and final close flyby of Titan marks the end of Cassiniís Ring-Grazing Orbits and sets the stage for the missionís Grand Finale.
This final close flyby of Titan provides Cassini with its longest-duration RADAR observation to look for changes in Titanís methane lakes and seas, as well as its first attempt to study the depth and composition of Titanís smaller lakes. The RADAR instrument will also take its final look at Titanís ďmagic island.Ē

During the RADAR observation, Cassiniís Ion and Neutral Mass Spectrometer (INMS) will collect its final samples of ions and neutral particles around Titan. Combined with Cassiniís previous INMS observations, this one will help scientists understand how the densities of these diffuse gas particles in Titan's uppermost atmosphere change over time.

https://www.youtube.com/watch?v=n6fSQczOJoM?t=001

Tony De La Rosa

Offline Nomadd

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Re: NASA - Cassini updates
« Reply #555 on: 04/22/2017 03:01 am »
« Last Edit: 04/22/2017 03:03 am by Nomadd »
Those who danced were thought to be quite insane by those who couldn't hear the music.

Offline eeergo

Re: NASA - Cassini updates
« Reply #556 on: 04/26/2017 10:31 am »
First ring plane crossing between the atmosphere and the rings should have just happened.
-DaviD-

Offline bolun

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Re: NASA - Cassini updates
« Reply #557 on: 04/26/2017 11:53 am »
Titan flyby 22 April 2017

In the early hours of Saturday morning, the international Cassini-Huygens mission made its final close flyby of Saturn's largest moon, Titan, coming within 1000 km of the atmosphere-clad world.

The image presented here is a raw image sent back to Earth yesterday, taken on Saturday 22 April at 18:42 UTC. It is one of many that can be found in the Cassini raw image archive.

The latest flyby used Titan's gravity to slingshot Cassini into the final phase of its mission, setting it up for a series of 22 weekly 'Grand Finale' orbits that will see the spacecraft dive between Saturn's inner rings and the outer atmosphere of the planet. The first of these ring plane dives occurs on Wednesday.

Cassini will make many additional non-targeted flybys of Titan and other moons in the Saturnian system in the coming months, at much greater distances. Non-targeted flybys require no special manoeuvres, but rather the moon happens to be relatively close to the spacecraft's path.

A final, distant, flyby of Titan will occur on 11 September, in what has been nicknamed the 'goodbye kiss,' because it will direct Cassini on a collision course with Saturn on 15 September. This will conclude the mission in a manner that avoids the possibility of a future crash into the potentially habitable ocean-moon Enceladus, protecting that world for future exploration.

http://sci.esa.int/cassini-huygens/59044-titan-flyby-22-april-2017/

Image credit:  NASA/JPL-Caltech/Space Science Institute

Online Svetoslav

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Re: NASA - Cassini updates
« Reply #558 on: 04/26/2017 12:39 pm »
 NASA JPL‏Verified account @NASAJPL 5m5 minutes ago

NASA JPL Retweeted CassiniSaturn

Stay tuned! Earth's first opportunity to regain contact with @CassiniSaturn no earlier than ~midnight PT April 26 (3am ET, 7am UTC April 27)

Online Svetoslav

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Re: NASA - Cassini updates
« Reply #559 on: 04/27/2017 07:06 am »
NASA JPL‏Verified account @NASAJPL  9m9 minutes ago
More
 Copy that! Ground controllers detected @CassiniSaturn's carrier signal. Deep Space Network waiting to lock. Stand by for spacecraft health.

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