- Dr. Michio Kaku Claims UFOs Are Real and Not Man Made
- 'Firefly' Starship to Blaze a Trail to Alpha Centauri?
- Cluster Filled with Dark Matter May House 'Failed Galaxies'
- NASA and ESA telescopes trace ultra-strong winds blowing from black holes
- Michio Kaku Discusses Possible Alien Civilizations & Future Contact with Other Worlds
- Cycles in the Sky: Crash Course Astronomy #3
- Guys Talk About Dating Deal Breakers
- 50 AMAZING Facts to Blow Your Mind! #12
- 8 Simple Ways To Be Healthier
Posted: 20 Feb 2015 10:06 PM PST
Posted: 20 Feb 2015 10:06 PM PST
Excerpt from news.discovery.com
As part of Icarus Interstellar's continuing series of guest articles on Discovery News, Michel Lamontagne, Project Icarus Core Designer, discusses a conceptual starship that could use novel fusion techniques to travel to the nearby star system Alpha Centauri.
The Icarus Interstellar Firefly
Robert Freeland wants to launch an interstellar probe -- not 100 years from now, but within his lifetime.
As Icarus Board Member and Deputy Project Leader, Freeland presented at the Tennessee Valley Interstellar Workshop (TVIW) in November, to propose a design for an starship that has all the things he likes: speed, elegance, and a short lead time.
"Firefly" (named so for its bright tail) is almost too pretty. It doesn't seem right, after decades of tin can projects by NASA, to envision elegance in a practical design.
But let the hard science fans be reassured: the entire morphology of the vessel follows directly from physical constraints. Even the pretty curve of the radiators was chosen to follow the actual heat load from the drive, while minimizing pumping distance and pipe/coolant mass. The design is backed by as much hard science as is available today.
Firefly's main drive is fueled by deuterium-deuterium (DD) fusion in a Z-pinch reactor. Z-pinch fusion was first explored in the late 1960s, but plasma instabilities relegated it to the dustbin. The idea languished for decades until recent research by Uri Shumlak at the University of Washington brought it back.
Shumlak's design resolves the plasma instabilities by introducing a strong shear flow of plasma through the pinch area. Simulations and laboratory experiments have shown that this strong shear flow "smooths out" the plasma instabilities that would otherwise occur, resulting in a stable pinch. Lab tests have thus far only been performed with non-fusing plasmas for safety reasons, but the theory and tests strongly indicate that a properly-designed Z-pinch could maintain a stable fusion core.
This is not fringe science -- Sandia National Laboratories is doing tests on Z-pinch fusion, and NASA's Huntsville-based "Charger One" facility is preparing to undertake its own lab tests this year.
Pure deuterium fusion was selected for Firefly because it is available in sea water at about 150 ppm as "heavy water", and is already commonly extracted in facilities all over the world for service in CANDU type fission reactors. If hydrogen becomes a common fuel source here on Earth, deuterium could readily be extracted even more cheaply as a byproduct of bulk hydrogen production plants.
This contrasts with more exotic fuel choices commonly proposed for fusion starships, particularly deuterium-helium3 (DHe3). The DHe3 reaction is fundamentally more desirable because its first-level reactions are all aneutronic; meaning that they produce only charged particles, with no damaging neutrons. The problem is that He3 is unavailable on Earth except in microscopic quantities, so it would have to be mined from the moon or the gas giant planets. This would require an extensive space program that then pushes an interstellar launch far into the future.
The unfortunate reality of DD fusion, though, is the tremendous flux of damaging high-energy neutron radiation. Even considering beneficial secondary reactions, neutrons account for almost half of the energy released by the reaction.
The Z-pinch drive compounds this problem with a very high flux of x-ray Bremsstrahlung radiation as well, produced as the super-heated electrons in the plasma bang into each other. Owing to its long, thin core, essentially all of the neutrons and x-ray radiation produced in the Z-pinch drive immediately escape the core.
Posted: 20 Feb 2015 10:01 PM PST
A strange set of 48 galaxies appears to be rich in dark matter and lacking in stars, suggesting that they may be so-called "failed" galaxies, a new study reports.
The galaxies in question are part of the Coma Cluster, which lies 300 million light-years from Earth and packs several thousand galaxies into a space just 20 million light-years across. To study them, Pieter van Dokkum of Yale University and his colleagues used the Dragonfly Telephoto Array in New Mexico.
The array's eight connected Canon telephoto lenses allow the researchers to search for extremely faint objects that traditional telescope surveys miss. Often, such as when the researchers used the array to search for the faint glow that dark matter might create, the hunt comes up empty.
"We noticed all these faint little smudges in the images from the Dragonfly telescope," van Dokkum told Space.com.
The mysterious blobs nagged at van Dokkum, compelling him to look into the objects further. Fortuitously, NASA's Hubble Space Telescope had recently captured one of these objects with its sharp eye.
"It turned out that they're these fuzzy blobs that look somewhat like dwarf spheroidal galaxies around our own Milky Way," van Dokkum said. "So they looked familiar in some sense … except that if they are at the distance of the Coma Cluster, they must be really huge."
And with very few stars to account for the mass in these galaxies, they must contain huge amounts of dark matter, the researchers said. In fact, to stay intact, the 48 galaxies must contain 98 percent dark matter and just 2 percent "normal" matter that we can see. The fraction of dark matter in the universe as a whole is thought to be around 83 percent.
But before making this claim, the team had to verify that these blobs really are as distant as the Coma Cluster. (In fact, the team initially thought the galaxies were much closer.). But even in the Hubble image the stars were not resolved. If Hubble — one of the most powerful telescopes in existence — can't resolve the stars, those pinpricks of light must be pretty far away, study team members reasoned.
Now, van Dokkum and his colleagues have definitive evidence: They've determined the exact distance to one of the galaxies. The team used the Keck Telescope in Hawaii to look at one of the objects for two hours. This gave them a hazy spectrum, from which they were able to tease out the galaxy's recessional velocity — that is, how fast it is moving away from Earth.
That measure traces back to the Hubble Telescope's namesake. In 1929, American astronomer Edwin Hubble discovered one of the simplest and most surprising relationships in astronomy: The more distant a galaxy, the faster it moves away from the Milky Way.
Today, astronomers use the relationship to measure a galaxy's recessional velocity and thus calculate the galaxy's distance. In this case, the small fuzzy blob observed with Keck was moving away from Earth at 15.7 million mph (25.3 million km/h). That places it at 300 million light-years away from Earth, the distance of the Coma Cluster.
So the verdict is officially in: These galaxies must be associated with the Coma Cluster and therefore must be extremely massive.
"It looks like the universe is able to make unexpected galaxies," van Dokkum said, adding that there is an amazing diversity of massive galaxies.
But the clusters still present a mystery: The team doesn't know why they have so much dark matter and so few stars.
Though they look serene and silent from our vantage on Earth, stars are actually roiling balls of violent plasma. Test your stellar smarts with this quiz.One possibility is that these are "failed" galaxies. A galaxy's first supernova explosions will drive away huge amounts of gas.
Normally, the galaxy has such a strong gravitational pull that most of the expelled gas falls back onto the galaxy and forms the next generations of stars. But maybe the strong gravitational pull of the other galaxies in the Coma Cluster interfered with this process, pulling the gas away.
"If that happened, they had no more fuel for star formation and they were sort of stillborn galaxies where they started to get going but then failed to really build up a lot of stars," said van Dokkum, adding that this is the most likely scenario.
Another possibility is that these galaxies are in the process of being ripped apart. But astronomers expect that if this were the case, the galaxies would be distorted and streams of stars would be flowing away from them. Because these effects don't appear, this scenario is very unlikely.
The next step is to try to measure the individual motions of stars within the galaxies. If the team knew those stars' speeds, it could calculate the galaxies' exact mass, and therefore the amount of dark matter they contain. If the stars move faster, the galaxy is more massive. And if they move slower, the galaxy is less massive.
However, this would require a better spectrum than the one the team has right now.
"But it's not outside the realm of what's possible," van Dokkum assured. "It's just very hard."
The original study has been published in Astrophysical Journal Letters. You can read it for free on the preprint site arXiv.org.
Posted: 20 Feb 2015 09:40 PM PST
Excerpt from thespacereporter.com
According to a NASA statement, telescopes have revealed for the first time that powerful winds emanate from black holes in all directions. These winds are so tremendous that they can actually work to hamper the formation of new stars in the host galaxy.
The two telescopes that were employed by the agency, NASA’s Nuclear Spectroscopic Telescope Array (NuSTAR) and ESA’s XMM-Newton, focused on PDS 456, a quasar, an extremely bright type of black hole, over 2 billion light-years away. The results were then analyzed by a team led by Emanuele Nardini of Keele University in the UK.
The two telescopes studied the quasar PDS 456 at five different times throughout 2013 and 2014. By combining low-energy X-ray observations from XMM-Newton with high-energy X-ray observations from NuSTAR, Nardini and team were able to trace iron dispersed by the quasar’s winds. These data demonstrated that the winds blow outwards from the black hole in a spherical front.
Having ascertained the structure of the quasar winds, the team was then able to calculate the strength of the winds. So strong are the quasar winds that they push huge quantities of matter before them, dispersing it outwards through the host galaxy and preventing it from eventually coalescing to generate new stars. In an earlier period of the universe’s history, about 10 billion years ago, supermassive black holes were more abundant and their terrible winds probably had a hand in shaping the current shapes of galaxies.
“For an astronomer, studying PDS 456 is like a paleontologist being given a living dinosaur to study,” said co-author Daniel Stern of NASA’s Jet Propulsion Laboratory. “We are able to investigate the physics of these important systems with a level of detail not possible for those found at more typical distances, during the ‘Age of Quasars.’”
Posted: 20 Feb 2015 09:27 PM PST
Posted: 20 Feb 2015 09:15 PM PST
Click to zoom
Posted: 20 Feb 2015 09:12 PM PST
Click to zoom
Posted: 20 Feb 2015 09:07 PM PST
Click to zoom
Posted: 20 Feb 2015 08:47 PM PST
Click to zoom