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PostPosted: Mon Jul 10, 2017 2:29 pm
 


raydan raydan:
After reading a lot of the posts on CKA... I beg to differ. :(

ROTFL


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PostPosted: Mon Jul 10, 2017 2:31 pm
 


DrCaleb DrCaleb:
Tricks Tricks:
DrCaleb DrCaleb:
As a result of this phase change, the density of the atmosphere at the surface is roughly 6.5 percent that of liquid water. It's so dense that it's thought to have brought Venus' rotation to a standstill and then started it moving backwards. The planet is now rotating very slowly in the opposite direction to Earth's rotation—so slowly that, if you were there to see a sunrise, you'd have to wait 243 Earth days to see the next.

My (dumb?) assumption is that it slowed/stopped the rotation because of friction against the denser atmosphere. But why would it reverse?


One of the things we don't understand about Venus yet. Measurements of the surface winds have shown that the winds have picked up in the opposite direction of rotation since we started measuring them. The wind is accelerating, and we don't know why.

https://phys.org/news/2013-06-super-hur ... onger.html

Image

https://www.universetoday.com/36816/winds-on-venus/

And, there are no dumb assumptions. ;) Just hypotheses that haven't been disproven yet. The planet's rotation is reversing for, presumably, the same reason the winds are accelerating. [huh] We just don't know what that reason is.

There would have to be huge pressure changes to have that kind of effect. I wonder if there is something happening on the surface that we can't really see.


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PostPosted: Tue Jul 11, 2017 6:21 am
 


Tricks Tricks:
DrCaleb DrCaleb:
The planet's rotation is reversing for, presumably, the same reason the winds are accelerating. [huh] We just don't know what that reason is.

There would have to be huge pressure changes to have that kind of effect. I wonder if there is something happening on the surface that we can't really see.


Don't forget in that article - the pressure and density of the atmosphere on Venus is so dense that it basically acts like a fluid. Imagine an ocean traveling at hundreds of km/h over the surface! That's pretty significant drag.

Why it's rotating that way, and what's accelerating it, those are going to be the interesting questions to answer.

I recall hearing about the Russian Venus probes during construction. They created the toughest probe they could, and put it in a chamber simulating Venus' atmosphere.

It vaporized. 8O Quickly. 8O Venus is a tough planet to explore!


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PostPosted: Tue Jul 11, 2017 7:23 am
 


DrCaleb DrCaleb:
Tricks Tricks:
DrCaleb DrCaleb:
The planet's rotation is reversing for, presumably, the same reason the winds are accelerating. [huh] We just don't know what that reason is.

There would have to be huge pressure changes to have that kind of effect. I wonder if there is something happening on the surface that we can't really see.


Don't forget in that article - the pressure and density of the atmosphere on Venus is so dense that it basically acts like a fluid. Imagine an ocean traveling at hundreds of km/h over the surface! That's pretty significant drag.

Why it's rotating that way, and what's accelerating it, those are going to be the interesting questions to answer.

I recall hearing about the Russian Venus probes during construction. They created the toughest probe they could, and put it in a chamber simulating Venus' atmosphere.

It vaporized. 8O Quickly. 8O Venus is a tough planet to explore!

Right, but to get that atmosphere moving there would have to be pressure changes right? That's what causes wind here so my assumption is that that stays constant, even with vastly different atmospheres. So to have such a dense atmosphere moving that quickly would require huge shifts in temperature/pressure around the planet constantly to maintain that kind of movement.

Unless proximity to the Sun does it, gravity causing these changes.


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PostPosted: Tue Jul 11, 2017 8:20 am
 


Tricks Tricks:
Right, but to get that atmosphere moving there would have to be pressure changes right? That's what causes wind here so my assumption is that that stays constant, even with vastly different atmospheres. So to have such a dense atmosphere moving that quickly would require huge shifts in temperature/pressure around the planet constantly to maintain that kind of movement.

Unless proximity to the Sun does it, gravity causing these changes.


Yes, I realize there has to be a pressure differential. I'm guessing since the winds are equatorial, the pressure is lower at the poles. Venus has some weird storms at the poles.




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PostPosted: Wed Jul 12, 2017 8:36 am
 


$1:
Smallest-ever star discovered by astronomers

The smallest star yet measured has been discovered by a team of astronomers led by the University of Cambridge. With a size just a sliver larger than that of Saturn, the gravitational pull at its stellar surface is about 300 times stronger than what humans feel on Earth.

The star is likely as small as stars can possibly become, as it has just enough mass to enable the fusion of hydrogen nuclei into helium. If it were any smaller, the pressure at the centre of the star would no longer be sufficient to enable this process to take place. Hydrogen fusion is also what powers the Sun, and scientists are attempting to replicate it as a powerful energy source here on Earth.

These very small and dim stars are also the best possible candidates for detecting Earth-sized planets which can have liquid water on their surfaces, such as TRAPPIST-1, an ultracool dwarf surrounded by seven temperate Earth-sized worlds.

The newly-measured star, called EBLM J0555-57Ab, is located about six hundred light years away. It is part of a binary system, and was identified as it passed in front of its much larger companion, a method which is usually used to detect planets, not stars. Details will be published in the journal Astronomy & Astrophysics.

"Our discovery reveals how small stars can be," said Alexander Boetticher, the lead author of the study, and a Master's student at Cambridge's Cavendish Laboratory and Institute of Astronomy. "Had this star formed with only a slightly lower mass, the fusion reaction of hydrogen in its core could not be sustained, and the star would instead have transformed into a brown dwarf."

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https://phys.org/news/2017-07-smallest- ... omers.html


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PostPosted: Wed Jul 12, 2017 8:37 am
 


$1:
NASA closes Chamber A door to commence Webb telescope testing

Though the Webb telescope will be enveloped in darkness, the engineers testing the telescope will be far from blind. "There are many thermal sensors that monitor temperatures of the telescope and the support equipment," said Gary Matthews, an integration and testing engineer at NASA's Goddard Space Flight Center in Greenbelt, Maryland, who is testing the Webb telescope while it is at Johnson. "Specialized camera systems track the physical position of the hardware inside the chamber, monitoring how Webb moves as it gets colder."

In space, the telescope must be kept extremely cold, in order to be able to detect the infrared light from very faint, distant objects. To protect the telescope from external sources of light and heat (like the sun, Earth and moon), as well as from heat emitted by the observatory, a five-layer, tennis court-sized sunshield acts like a parasol that provides shade. The sunshield separates the observatory into a warm, sun-facing side (reaching temperatures close to 185 degrees Fahrenheit) and a cold side (400 degrees below zero). The sunshield blocks sunlight from interfering with the sensitive telescope instruments.

The James Webb Space Telescope is the scientific successor to NASA's Hubble Space Telescope. It will be the most powerful space telescope ever built. Webb is an international project led by NASA with its partners, ESA (European Space Agency) and the Canadian Space Agency.

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https://phys.org/news/2017-07-nasa-cham ... -webb.html


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PostPosted: Thu Jul 13, 2017 6:28 am
 


$1:
NASA’s Juno Spacecraft Spots Jupiter’s Great Red Spot

Images of Jupiter’s Great Red Spot reveal a tangle of dark, veinous clouds weaving their way through a massive crimson oval. The JunoCam imager aboard NASA's Juno mission snapped pics of the most iconic feature of the solar system’s largest planetary inhabitant during its Monday (July 10) flyby. The images of the Great Red Spot were downlinked from the spacecraft’s memory on Tuesday and placed on the mission’s JunoCam website Wednesday morning.

“For hundreds of years scientists have been observing, wondering and theorizing about Jupiter’s Great Red Spot,” said Scott Bolton, Juno principal investigator from the Southwest Research Institute in San Antonio. “Now we have the best pictures ever of this iconic storm. It will take us some time to analyze all the data from not only JunoCam, but Juno’s eight science instruments, to shed some new light on the past, present and future of the Great Red Spot.”

As planned by the Juno team, citizen scientists took the raw images of the flyby from the JunoCam site and processed them, providing a higher level of detail than available in their raw form. The citizen-scientist images, as well as the raw images they used for image processing, can be found at:

https://www.missionjuno.swri.edu/junocam/processing

Image



https://www.nasa.gov/feature/jpl/nasa-s ... t-red-spot

From the Processing Page: (8O 8O ! These are big, so I'll just link to them)

https://d2xkkdgjnsfvb0.cloudfront.net/V ... 1498672205

https://d2xkkdgjnsfvb0.cloudfront.net/V ... 1498672205

When other cameras are added to the visible light shots, they will be absolutely stunning images! Look back in a few days for those. [drool]


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PostPosted: Mon Jul 17, 2017 9:00 am
 


$1:
NASA Video Soars over Pluto’s Majestic Mountains and Icy Plains

In July 2015, NASA’s New Horizons spacecraft sent home the first close-up pictures of Pluto and its moons – amazing imagery that inspired many to wonder what a flight over the distant worlds’ icy terrain might be like.

Wonder no more. Using actual New Horizons data and digital elevation models of Pluto and its largest moon Charon, mission scientists have created flyover movies that offer spectacular new perspectives of the many unusual features that were discovered and which have reshaped our views of the Pluto system – from a vantage point even closer than the spacecraft itself.

This dramatic Pluto flyover begins over the highlands to the southwest of the great expanse of nitrogen ice plain informally named Sputnik Planitia. The viewer first passes over the western margin of Sputnik, where it borders the dark, cratered terrain of Cthulhu Macula, with the blocky mountain ranges located within the plains seen on the right. The tour moves north past the rugged and fractured highlands of Voyager Terra and then turns southward over Pioneer Terra -- which exhibits deep and wide pits -- before concluding over the bladed terrain of Tartarus Dorsa in the far east of the encounter hemisphere.




https://www.nasa.gov/feature/nasa-video ... icy-plains


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PostPosted: Wed Jul 19, 2017 6:51 am
 


$1:
Elon Musk knows what’s ailing NASA—costly contracting

The seas were calm in early December 2010 when a spacecraft fell out of the sky, deployed its parachutes, and splashed into the Pacific Ocean. No American spacecraft had returned this way to Earth in 35 years, not since the splashdown of the final Apollo mission. The Dragon bobbing in the blue water didn’t carry any astronauts, just a whimsical payload of Le Brouère cheese. But it had made history all the same, as no private company had ever launched a spacecraft into orbit and safely returned it to Earth.

Just two years earlier, Elon Musk’s SpaceX had been left for dead. Like so many other new space ventures that had come before, it had made big promises but delivered few payoffs. Bankruptcy would certainly have swallowed SpaceX had NASA not thrown Musk a $1.6 billion lifeline two days before Christmas in 2008—a contract for a dozen cargo delivery flights to the International Space Station.

For some critics, SpaceX seemed just another company standing in line for a government handout. NASA didn’t see it this way. In the months after the Dragon’s historic flight, NASA studied the cost of developing the Falcon 9 rocket, SpaceX's booster with nine engines that had lifted the Dragon spacecraft into orbit. The analysis concluded that had NASA developed the rocket through its traditional means, it would have cost taxpayers about $4 billion.

Instead of doing that, however, NASA simply asked SpaceX for a service—cargo delivery to the space station—and left the details to the company. And so Musk and his small workforce, with a Silicon Valley mindset that pushed employees hard, set about delivering. The analysis found that SpaceX spent just $443 million to develop the Falcon 9 rocket—a little more than a tenth of what NASA would have expended for a comparable rocket.

Dragon’s flight in 2010, therefore, not only gave America its first splashdown in more than three decades, it offered a potent argument for a new way of doing business in space. The world of federal contracting practices may seem arcane, but today as NASA and the US Air Force confront the need to modernize their spaceflight capabilities, it is becoming increasingly important to understand how agencies award contracts and measure results.

At the heart of this issue lies a tussle between traditional aerospace companies and their penchant for cost-plus contracts and a desire by new space firms such as SpaceX for fixed-price awards. This debate seems likely to become a key flashpoint in the emergent space policy of the Trump administration as it decides over the coming months what it wants to do in space and which companies will help achieve those ambitions.

As is his wont, Elon Musk has chosen not to stand on the sidelines. This past weekend, in fact, he doused what had been a smoldering debate with gasoline.

Image



https://arstechnica.com/science/2017/07 ... ntracting/


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PostPosted: Wed Jul 19, 2017 7:56 am
 


$1:
New Satellite “Mayak” Might Light Up the Sky

Russia's first crowd-funded satellite, named Mayak (Russian for "beacon of light"), promises to be the “brightest object in the night sky next to the Moon.”
Mayak

Image

The hunt is on. A Soyuz-2.1a rocket roared to life at the historic Baikonur Cosmodrome in Kazakhstan on July 14th at 6:36 UT, lofting its main payload, the Kanopus-V-IK, Russia's newest Earth-observing satellite.

But Kanopus didn't launch alone. Hitching a ride to space were 72 smaller satellites (a record-breaking payload) headed for three separate orbits. Among them was Mayak (Russian for "beacon of light"), a CubeSat of particular interest to amateur astronomers and satellite spotters.

Mayak is Russia's first crowdfunded satellite. Built around a standard 3U cubesat body measuring 34 × 10 × 10 cm, Mayak was designed by engineering students at Moscow Polytechnic University. The satellite will test an aerodynamic braking system that could de-orbit satellites without using an engine, and it comes equipped with reflectors to provide data on the satellite's visibility and distance.

To that end, the satellite is set to deploy a large tetrahedron-shaped reflector. Each triangular face is 4 m² (43 ft²) in area and should be readily visible from the ground on a twilight pass. In fact, the team claims, Mayak will be the “brightest shooting star” once unfurled with an estimated magnitude of –10, so glints from it might be almost as bright as the full Moon. Mayak could be visible in bright twilight and perhaps even during daytime passes as well.

Finding Mayak

At this point, it isn't clear yet whether Mayak has successfully deployed its reflector. Your best bet is simply to go out and look for it.

The team has a tracking app named CosmoMayak, though it's only offered in Russian. Worldwide sat-spotters may do better using Heavens-Above, which put up a dedicated section for Mayak on their homepage last night. Orbiting Earth once every 97 minutes in a 587-by-605-km orbit, Mayak is in a retrograde Sun-synchronous, 97°-inclination orbit, typical for Earth-observing satellites. Current passes this week favor latitudes 40° to 50° north around midnight, optimal for observers in United Kingdom and northern Europe.

Image


http://www.skyandtelescope.com/astronom ... light-sky/


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PostPosted: Thu Jul 27, 2017 7:50 am
 


$1:
Gamma-ray burst captured in unprecedented detail

Gamma-ray bursts are among the most energetic and explosive events in the universe. They are also short-lived, lasting from a few milliseconds to about a minute. This has made it tough for astronomers to observe a gamma-ray burst in detail.

Using a wide array of ground- and space-based telescope observations, an international team led by University of Maryland astronomers constructed one of the most detailed descriptions of a gamma-ray burst to date. The event, named GRB 160625B, revealed key details about the initial “prompt” phase of gamma-ray bursts and the evolution of the large jets of matter and energy that form as a result of the burst. The group’s findings are published in the July 27, 2017, issue of the journal Nature.

“Gamma-ray bursts are catastrophic events, related to the explosion of massive stars 50 times the size of our Sun. If you ranked all the explosions in the universe based on their power, gamma-ray bursts would be right behind the Big Bang,” said Eleonora Troja, an assistant research scientist in the UMD Department of Astronomy and lead author of the research paper. “In a matter of seconds, the process can emit as much energy as a star the size of our Sun would in its entire lifetime. We are very interested to learn how this is possible.”

The group’s observations provide the first answers to some long-standing questions about how a gamma-ray burst evolves as the dying star collapses to become a black hole. First, the data suggest that the black hole produces a strong magnetic field that initially dominates the energy emission jets. Then, as the magnetic field breaks down, matter takes over and begins to dominate the jets. Most gamma-ray burst researchers thought that the jets were dominated by either matter or the magnetic field, but not both. The current results suggest that both factors play key roles.

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https://astronomynow.com/2017/07/27/gam ... ed-detail/


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PostPosted: Tue Aug 01, 2017 8:54 am
 


$1:
Europa’s future: A runaway greenhouse

Stars like the Sun brighten over the course of their history, a trend that has significant consequences for the habitability of Earth and other bodies both in our Solar System and beyond. An icy world on the far edge of the habitable zone may turn into a temperate paradise given enough time.

Or, it could go straight to being a Venus-style hell if a new study turns out to be right. The study's authors tuned a full-planet climate model loose on a planet covered in ice. The find that, under a level of incoming light that's sufficient to melt the ice, the planet reaches a greenhouse state that would cause it to lose all its water to space and possibly head straight into a runaway greenhouse.

The only thing that saved Earth from a runaway greenhouse is, ironically, the presence of greenhouse gasses in its atmosphere.

Modeling an icebox

While there's been lots of talk of habitable zone exoplanets, that doesn't tell us much about whether a planet is actually habitable. That's defined by having the right temperature for liquid water to exist on the planet's surface. But that temperature isn't just set by the planet's distance to its host star. Instead, it depends on things like how much light its surface reflects into space, details on its clouds, and how much of its atmosphere is comprised of greenhouse gasses.

We do have tools for trying to understand these things: they're called climate models. Unfortunately, most of those were set up to look at Earth, and they don't allow researchers to just plug in any arbitrary values for things like the Earth's gravity. But with the explosion of exoplanet discoveries, that's starting to change. Here, the team of researchers were able to use a model called CAM 3.0 (you can download the CAM 3.1 source code if you want to have a look). CAM allowed them to try out a variety of conditions, and researchers had used it successfully to model times in the Earth's past when its waters had all frozen over.

Image



https://arstechnica.com/science/2017/08 ... reenhouse/


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PostPosted: Tue Aug 01, 2017 9:11 am
 


$1:
The study's authors tuned a full-planet climate model loose on a planet covered in ice. The find that, under a level of incoming light that's sufficient to melt the ice, the planet reaches a greenhouse state that would cause it to lose all its water to space and possibly head straight into a runaway greenhouse.


The problem here is the assumption that the computer model is infallible.


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PostPosted: Tue Aug 01, 2017 9:36 am
 


BartSimpson BartSimpson:
$1:
The study's authors tuned a full-planet climate model loose on a planet covered in ice. The find that, under a level of incoming light that's sufficient to melt the ice, the planet reaches a greenhouse state that would cause it to lose all its water to space and possibly head straight into a runaway greenhouse.


The problem here is the assumption that the computer model is infallible.


Another assumption would be that computer models are always wrong. Since many models are developed and tested on using past data to predict current conditions, and they pass, then you can be confident they are usually right.

Applying them to another planet might be problematic, but then again I don't do that for a living.


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