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_Augustus_

By _Augustus_
in Science & Spaceflight

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PB666

PB666

Posted
Posted
2 hours ago, Green Baron said:

Oh there is much more than bacteria in a desert, no question.

Well at least when a heavy wind storms breaks out in Africa we notice a spike a month later over here in microbial allergies (namely molds).

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Green Baron

Green Baron

Posted
Posted (edited)

Wow, where are you ? I always get the dry dust laiden air when the Calima blows. Many people here have respiratory problems then (Canary Islands).

What i wanted to say is that even on earth water alone is no guarantee for rich lifeforms. There is no equation water = possible life in astrobiology or so. It needs more than that, that is why these proposals of subglacial geysers/vents/smokers on Europa or Ganimede came up.

Edited by Green Baron
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DDE

DDE

Posted
Posted
1 hour ago, Green Baron said:

that is why these proposals of subglacial geysers/vents/smokers on Europa or Ganimede came up.

I think these proposals have been around since as long as we’ve known of smokers on Earth.

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Green Baron

Green Baron

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Posted (edited)
10 hours ago, DDE said:

I think these proposals have been around since as long as we’ve known of smokers on Earth.

So, that'll be the late 70s then ? But by then we didn't know about Europa's icy shield and plumes ... probably rather since we speculate about Europa's/Ganimede's/Enceladus' inner structure i would say ... there are no serious papers with a date about this, so my guess is as good as yours.

If you think about it: these vents are a byproduct of earth's tectonic processes. They'd need a lot of convincing published material to let me think more seriously about the presence of such things on the outer moons. Mere "tidal forces" are not enough :-)

Edited by Green Baron
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DDE

DDE

Posted
Posted
4 minutes ago, Green Baron said:

So, that'll be the late 70s then ? But by then we didn't know about Europa's icy shield and plumes ...

Quote

The two Voyager probes traveled through the Jovian system in 1979, providing more-detailed images of Europa's icy surface. The images caused many scientists to speculate about the possibility of a liquid ocean underneath.

Plumes and the oceans of other moons came much, much later. I remember thinking of Europa as utterly unique. The shift of attention to Ganymede only hapenned a few years ago.

6 minutes ago, Green Baron said:

Mere "tidal forces" are not enough :-)

Tell that to Io.

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Green Baron

Green Baron

Posted
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2 minutes ago, DDE said:

Plumes and the oceans of other moons came much, much later. I remember thinking of Europa as utterly unique. The shift of attention to Ganymede only hapenned a few years ago.

Tell that to Io.

My guess was wrong :-)

Volcanic surface activity is a different thing, also it is not sure if Io's volcanoes result from tidal heating i think ? Who would expect life on Io ?

What they want to rectify a mission is a nice little constant energy and nutrient source in a shielded environment with enough solvent around, and they have their examples from earth, these vents. Earths extremely steady inner dynamics produce these vents at middle ocean ridges, along transform cracks (plate tectonics needed), over hot spots ...

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DDE

DDE

Posted
Posted
1 hour ago, Green Baron said:

Volcanic surface activity is a different thing, also it is not sure if Io's volcanoes result from tidal heating i think ?

It was predicted a few months before flyby. Tidal heating of Io produces 200 times as much heat as ordinary radioactive decay.

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Green Baron

Green Baron

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1 hour ago, DDE said:

It was predicted a few months before flyby. Tidal heating of Io produces 200 times as much heat as ordinary radioactive decay.

Well, as always, where's that from ? Not that i want to attack you, just know who said that, where and based on what, and is it some kind of research or just a claim out of the blue ?

The first question i'd have: what's Io's composition and how much radioactive decay is there ?

http://iopscience.iop.org/article/10.1088/0067-0049/218/2/22

Model calculation, speculative, and depending on assumptions that can neither be negated no verified atm.

Edit: In a study i can't find now it was inferred that the distribution of Io's Volcanoes does not support the assumption that the volcanism is caused by tidal heating ... but this may be outdated meanwhile.

 

Edited by Green Baron
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DDE

DDE

Posted
Posted
45 minutes ago, Green Baron said:

Edit: In a study i can't find now it was inferred that the distribution of Io's Volcanoes does not support the assumption that the volcanism is caused by tidal heating ... but this may be outdated meanwhile.

Yes, but they are quite uniformly shifted by about 60° in one direction, which allowed people to handwave that with more funky thermal flows 

And yes, I’m still just quoting Wikipedia, the apex of scientific knowledge, at you.

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PB666

PB666

Posted
Posted
1 hour ago, DDE said:

It was predicted a few months before flyby. Tidal heating of Io produces 200 times as much heat as ordinary radioactive decay.

Peale, S. J.; et al. (1979). "Melting of Io by Tidal Dissipation". Science. 203 (4383): 892–894. Bibcode:1979Sci...203..892P. doi:10.1126/science.203.4383.892. PMID 17771724

The vertical differences in Io's tidal bulge, between the times Io is at periapsis and apoapsis in its orbit, could be as much as 100 m. Its Laplace resonance with Europa and Ganymede maintains Io's eccentricity and prevents tidal dissipation within Io from circularizing its orbit. The resonant orbit also helps to maintain Io's distance from Jupiter; otherwise tides raised on Jupiter would cause Io to slowly spiral outward from its parent planet.

"Io: The Volcanic Moon". In Lucy-Ann McFadden; Paul R. Weissman; Torrence V. Johnson. Encyclopedia of the Solar System. Academic Press. pp. 419–431. ISBN 978-0-12-088589-3.

Moore, W. B.; et al. (2007). "The Interior of Io.". In R. M. C. Lopes; J. R. Spencer. Io after Galileo. Springer-Praxis. pp. 89–108. ISBN 3-540-34681-3.

-Good ole wikipedia.

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Green Baron

Green Baron

Posted
Posted (edited)

Yeah, thanks for the efforts, that's the model calculation i posted above, suggesting that the shift can be explained with a thick liquid asthenosphere rather than a solid one.

My question was were the "200 times as much" is from, but i stop the nitpicking :-)

Edit: Wikipedia is not acceptable as a valid source, sorry :-) Iamgine, i could write an article :sticktongue: Imagine further that i had look before i asked ;-)

Edited by Green Baron
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PB666

PB666

Posted
Posted
45 minutes ago, Green Baron said:

Yeah, thanks for the efforts, that's the model calculation i posted above, suggesting that the shift can be explained with a thick liquid asthenosphere rather than a solid one.

My question was were the "200 times as much" is from, but i stop the nitpicking :-)

Edit: Wikipedia is not acceptable as a valid source, sorry :-) Iamgine, i could write an article :sticktongue: Imagine further that i had look before i asked ;-)

Yes and I am not reviewing papers anymore or assisting the manuscript production . . . .thank god. Wikipedia is knowledge enough for the masses.

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Canopus

Canopus

Posted
Posted (edited)
33 minutes ago, _Augustus_ said:

So thanks to the new administration's pivot towards the lunar surface it looks like DSG/DST is not going to happen. Rest in pieces....

I wouldn‘t be so quick. Have you actually read Space Policy Directive 1? The whole part about sustainable exploration sounds very much like DSG. I‘ll try to find the link.

Edit: i think i found it: https://www.whitehouse.gov/the-press-office/2017/12/11/presidential-memorandum-reinvigorating-americas-human-space-exploration

Edited by Canopus
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DAL59

DAL59

Posted
Posted

Presidential Memorandum on Reinvigorating America's Human Space Exploration Program

MEMORANDUM FOR THE VICE PRESIDENT

THE SECRETARY OF STATE

THE SECRETARY OF DEFENSE

THE SECRETARY OF COMMERCE

THE SECRETARY OF TRANSPORTATION

THE SECRETARY OF HOMELAND SECURITY

THE DIRECTOR OF NATIONAL INTELLIGENCE 

THE DIRECTOR OF THE OFFICE OF MANAGEMENT AND BUDGET

THE ASSISTANT TO THE PRESIDENT FOR NATIONAL SECURITY AFFAIRS

THE ADMINISTRATOR OF THE NATIONAL AERONAUTICS AND SPACE ADMINISTRATION

THE DIRECTOR OF THE OFFICE OF SCIENCE AND TECHNOLOGY POLICY

THE ASSISTANT TO THE PRESIDENT FOR HOMELAND SECURITY AND COUNTERTERRORISM

THE CHAIRMAN OF THE JOINT CHIEFS OF STAFF

SUBJECT:        Reinvigorating America's Human Space Exploration Program

Section 1.  Amendment to Presidential Policy Directive-4.

Presidential Policy Directive-4 of June 28, 2010 (National Space Policy), is amended as follows:

The paragraph beginning "Set far-reaching exploration milestones" is deleted and replaced with the following:

"Lead an innovative and sustainable program of exploration with commercial and international partners to enable human expansion across the solar system and to bring back to Earth new knowledge and opportunities.  Beginning with missions beyond low-Earth orbit, the United States will lead the return of humans to the Moon for long-term exploration and utilization, followed by human missions to Mars and other destinations;".

Sec. 2.  General Provisions.  (a)  Nothing in this memorandum shall be construed to impair or otherwise affect:

(i)   the authority granted by law to an executive department or agency, or the head thereof; or

(ii)  the functions of the Director of the Office of Management and Budget relating to budgetary, administrative, or legislative proposals.

(b)  This memorandum shall be implemented consistent with applicable law and subject to the availability of appropriations.

(c)  This memorandum is not intended to, and does not, create any right or benefit, substantive or procedural, enforceable at law or in equity by any party against the United States, its departments, agencies, or entities, its officers, employees, or agents, or any other person.

(d)  This memorandum shall be published in the Federal Register.

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