NASA is about to test one of their first optical communication systems from the ISS in the hopes of improving the bit rates of communication systems that exist now. Radio transmission has long been a reliable way to beam information to and from spacecraft because it is not scattered by our atmosphere, but as the pressure to beam more information faster increases, radio transmission is just not capable of keeping up. Radio can transmit, as of now, at 200-400 kilobits per second with most spacecraft and the mars rovers.

Laser technology is very promising because scientists will be able to achieve much faster rates, because of the coherence of the laser and the wavelengths involved. OPALS will be able of beaming information at 50 megabits a second, which is a significant increase. Scientists expect as this technology improves, we will see rates of gigabits per second.  At these rates, scientists will be able to beam high-definition videos and large amounts of data from experiments. In an age of science where precision, computer modeling, and large data are increasingly necessary to prove anything new, these rates are very necessary.

This technology poses less practical use for cell phones or personal devices, because the laser aspect requires that the information be aimed precisely at the receiver constantly during the upload. Most of NASA’s testing for OPALS in the upcoming test will not only be testing the operation of the device, but the aiming of the laser. A ground telescope will search for the ISS in the sky as it passes overhead, and beam its own laser to the ISS to begin the upload. At that point, OPALS responds the ground laser and starts beaming information down via its laser, and as it orbits pass, it tracks the receiver making sure it is aimed correctly the whole time. As you can imagine, the ISS eventually passes out of view and the transmission is done. Thus, the longest transmission time for the ISS from any receiver is about 100 seconds, but with the improved upload rates, more information is still transferred than by Radio. It will be exciting to see the results of the tests.

Sources:

http://www.sciencedaily.com/releases/2014/04/140414103012.htm

Two critical aspects of living in space is being able to have enough fresh water aboard your ship and to be able to dispose of urine. Early NASA missions didn’t require extensive bathrooms and any water the astronaut needed for the daily mission was carried up with them. On the apollo missions, astronauts got water as a by-product of a fuel cell, and were given a urine ‘bag’ system that used a tube, since all astronauts were male at the time, attached to a one-way valve with an attachable bag. They eventually revised this urine bag system so that the urine could be ejected out of the capsule, simply disposing the urine into space where it would appear as streams of water vapor coming off the ship. One fun fact about the water filter on apollo 11 is that its hydrogen filter was broken, thus all the water they drunk was ‘bubbly’ and appeared as club soda.

This system of making water with fuel cells and then simply ejecting the urine afterward right into space lasted for quite some time for two reasons. First, NASA was not running long-term missions, nor was much of its manned equipment staying in space forever like the ISS. Secondly, using a typical distiller, like most urine on earth is recycled, is not as easy or practical in zero gravity, thus until it wasn’t necessary nor worth the effort. The distilling process on earth relies on the fact that water evaporates and the vapor rises while the solutes that pollute the water are held in the bottom of the chamber by gravity, thus without gravity the water vapor never separates from other substances within.

NASA has been working on recycling urine for use as long as the ISS became a project. In 2009, a distiller and purifier for urine was installed on ISS that used a spinning chamber to generate a ‘gravity’ with centripetal acceleration. In addition, it used several charcoal filters that filtered additional pollutants out. Because the spinning distiller requires a fair amount of energy, many are looking into filters and membranes specific for urine that rely on a process called ‘forward osmosis’ that can be used to recycle the water and convert the waste products, urea and other compounds, into energy using fuel cells. Thus, as technology advances, astronauts, might not only be able to recycle their pee for hydration use later, but get energy in the process. These purifiers might even have practical uses on earth as well.

Sources:

http://www.sciencedaily.com/releases/2014/04/140409103409.htm

http://motherboard.vice.com/blog/when-you-gotta-go-you-gotta-go-even-in-space

http://www.popsci.com/military-aviation-amp-space/article/2009-06/40-years-later-ten-things-you-didnt-know-about-apollo-ii-moon-landing

Probably the oldest technique of an astronomer to measure the distance to the stars is trigonometric parallax. Parallax can be used to measure the distance to any object, and was first employed by travelers to measure the distance to mountain ranges, and estimate the heights of mountains. In the case of measuring the distance to a mountain, one measures the apparent angular position of the peak, walks some known distance perpendicular to the direction of the mountain forming the base of the triangle, then measures the angular position again. From the change in angular measurements and knowing how far they walked, simple trigonometry solves for the distance of the mountain.

Same is true for measuring distances to stars, except instead of walking a known distance, astronomers wait 6 months for the earth to move in position 2 AU, and then measure the second position of the star in the sky. The difference for measuring stellar distances however is that the triangles involved have extremely small angles. Beyond trigonometric parallax, astronomers can measure distances based off other techniques that involve analysis of the light from the star, but parallax by far is the most reliable. Thus, these other methods can be used in modern astrophysics to look further than parallax can measure precisely, but its crucial that these be calibrated with known distances measured by parallax.

Hubble uses a new technique called spatial scanning to improve its ability to measure arc seconds (1/3600th of a degree) so that it can now measure distances as far as 7,500 light years, rather than the 750 light years it was capable of before. They used this new capability to measure the distances to a class of stars called Cepheids that pulsate in brightness at a certain period. Because astronomers know the relationship between period and luminosity, the brightness can be calculated and the distance can be extrapolated from the flux of light reaching earth. Hubble’s new capability hopes to analyze our current accuracy with measuring distances with cepheids and type 1a supernova to get a more accurate map of the cosmos.

Sources:

http://www.sciencedaily.com/releases/2014/04/140411091943.htm

http://www.nasa.gov/press/2014/april/nasas-hubble-extends-stellar-tape-measure-10-times-farther-into-space/#.U0skruZdWr9

Modern Astrophysics 2nd edition by Caroll Ostlie

A visual color coded image of the plasma energy distribution inside a supernova (left) and a white dwarf at the moment of detonation shoots out a initial plume. (right)

Physicists recently created more sophisticated computer modeling for supernovas in order to understand the 3 dimensional complexities of such an event. Previous theory and modeling relied on slower computers that generated three dimensional models only by making assumptions of symmetry for one or two directions, thus giving them a less detailed full picture of supernovas. Original simplified theory believed that a massive star’s structure prior to supernova was composed concentric spherical shells made up of heavier elements as one goes deeper into the star. When gravitational collapse first starts, right as nuclear fuel is running out, the star starts to emit large amounts of energy in the form of neutrinos weakly interacting particles due to the compression of the core causing temperature increase. As the core heats up more, this generates more neutrinos and eventually leads to a complete explosion of the envelope of the star leaving behind only a remnant of gas filled with heavy elements and possibly a white dwarf, neutron star, or black hole.

What this new super computer modeling at Argonne National Laboratory shows is that although this theory is true of concentric layers, convection and mixing occurs between layers and increases at the onset of a supernova, leading the star to pulsate and ‘flop,’ creating ejections of heavier material creating instability before the actual supernova explosion. This new theory explains a lot of experimental data on real supernovas, such SN1987A, where we see exactly this phenomenon; Heavy metal material is being ejected before the supernova occurred and then new debris during the explosion is ejected at much faster speeds and catching up with the material. Computer Modeling of this caliber is what is needed to understand the minor details and complexities of stellar evolution, especially for events as dramatic and quick as a supernova.

Sources:

http://news.discovery.com/space/simulation-gives-new-gimpse-into-supernovas-chaotic-guts-140319.htm

Modern Astrophysics 2nd Edition by Carroll Ostlie

Astrophysicists believe as of now, that 25% of the matter and energy in our universe is ‘dark’ matter. Although this name sounds flashy, all it means is that this mass can’t be seen with light, like the ‘normal’ illuminated baryonic matter we are made of. Many experiments have been done that confirm dark matter’s indirect existence. The overwhelming evidence for dark matter comes from when one gravitationally analyzes the stars’ orbits and structure within our galaxy. After a complex analysis of several galaxies structure, one is forced to conclude that there is not enough baryonic matter to hold the galaxy together, and that its’ stars will just fly apart, destroying the structure we see. But, the data shows that although the matter we see is not enough to hold the stars together, the galaxies are still forming as if there is a ‘sphere’ of invisible matter dispersed throughout the galaxy and in between the stars. This is the dark matter, and so much of it is needed to hold the gravitational structure we see that there must be more of it than normal baryonic matter

Part of science, however, is finding theory that supports the existence of a new type of matter. Rather than consider this flaw a failure of our theory of gravity, which many physicists think it could be, scientists believe that there must be a theoretical particle that could explain this phenomenon. Its a very similar reasoning scientists took when they discovered the neutrino; rather than refute the laws of conservation of energy and momentum, Wolfgang Pauli proposed a weakly interacting particle that made up for this energy and momentum, and it turned out to actually exist. The best candidate for a dark matter particle as of now is called a WIMP, weakly interacting massive particle, which is similar to a neutrino in that it interacts vey weakly with normal matter, but it is much more massive that a neutrino, thus it is capable of creating the gravitational attraction we observe. Many projects have started that are trying to build WIMP detectors that could detect a WIMP very similar to how we detect neutrinos. Using underground mines and a large tank of xenon or other baryonic atoms that weakly interact with WIMPS, scientists predict how many WIMPS should interact on average with their detector based on how much dark matter passes through the earth all the time, and the signature of the interaction to prove if dark matter is really there. It will be very exciting to see how these experiments pan out.

Sources:

http://www.sciencedaily.com/releases/2014/03/140310212316.htm

http://en.wikipedia.org/wiki/Dark_matter

http://en.wikipedia.org/wiki/Neutrino

Scientists at the RHIC (Relativistic Heavy Ion Collider) in Long Island are preforming similar experiments to the LHC, trying the probe the one of most fundamental, unconfined form of matter, the quark gluon plasma. This type of plasma one can think of as the ‘melted’ form of nuclear matter, because it is essentially a plasma so hot and dense that all of the protons and neutrons (collectively known as Hadrons because they are each made up of 3 quarks) within the gas have melted into the constitute particles known as quarks, as well as the force carrying particles of the strong nuclear force, gluons, that originally bound these quarks together in their proton and neutron forms. It takes very high energies to recreate these conditions in the collider, but ironically enough, when scientists tried to find the ‘melting’ point of nuclear matter after underestimating the energy needed the first time, their second attempt they overestimated and created the QGP without being able observe the physics of the transition. Scientists at RHIC are essentially trying recreate the phase diagram of nuclear matter, just like water has a phase diagram, telling us whether it is a liquid, ice, or vapor at a given temperature and density. They have recently come close to finding what they think might be a critical point of the phase diagram. Signatures of latent heat, and erratic behavior the nuclear fluid suggest so. latent heat can be thought as heat being taken in by the matter and used to change it phase rather than heat it more. It is the same effect that makes water stay at its boiling point temperature until all the water is vapor; Heat must be put in to make the complete transition, before the temperature of the fluid is to be raise more.

Advanced particle research such as this is also crucial for astrophysics and astronomy advancement, because as astronomers probed farther distances, and farther back in time, they have discovered that the universe is expanding. But not only that, it has been expanding from a singularity, a point. When astronomers look back to the beginnings of the universe, they are actually seeing the light from the early universe, and the image shows that the universe was just a hot dense ball of energetic matter. Before 380,000 years after the big bang, it was too hot and dense for light to even exist unconfined for us to see now, but we are still able to probe back indirectly. When the universe was small, and all the energy and matter of it was packed in this tiny space, the conditions were so extremely hot and dense, that scientists know now the QGP must have been the entire form of the universe. Understanding how this phase of matter behaves is crucial for understanding how the early universe created the initial conditions that lead to the universe as we see it now. For the most part, we have a very clear story of how everything in the universe formed from a few microseconds after the big bang, but we don’t know what happened before those couple of microseconds to create the conditions of what we see microseconds after the big bang.

Sources/Further Reading:

http://www.sciencedaily.com/releases/2014/04/140404135856.htm http://en.wikipedia.org/wiki/Quark%E2%80%93gluon_plasma

image from wikipedia

Many supermassive black holes, hundreds of thousands to billion times the massive of our sun, have been found at the center of not only our galaxy, but in many others. It seems that this supermassive black hole is a characterizing feature of most galaxies, responsible for holding the group of stars the galaxy together. Although theories of dark matter are still needed to fully describe the gravitational stability of galaxies, this supermassive black hole is responsible for the large density of stars at the center of our galaxy and others.

There are two curious properties of black holes that makes the supermassive black holes unlike typically stellar-size black holes, which are on the order of one solar mass up to 33 solar masses. Any black hole’s size is determined by its Schwarzschild radius, the radius in the gravitational field in which if an object passed it not even light can escape it, and this radius is directly proportional to mass. Because of this property, density and tidal forces can be expressed directly in terms of mass and not mass and radius. The density is equal to the mass divided by the volume of the black hole, which is proportional to the radius cubed, thus the density is proportional to m^-2. Tidal forces, the difference in the strength gravity between successive radii, can be also expressed as proportional to m^-2. What this means for supermassive black holes is that they are not very dense and have very weak tidal forces. If you could stand right above the event horizon of a 10 million solar mass black hole, you would feel similar tidal forces we have on Earth. This means stars can exist close to the black holes without getting ripped apart.

Formation of these gigantic black holes is still a process being researched. Black holes are only made from massive stars collapsing in a supernova explosion that leaves behind a black hole. Because there is an upper limit on the size of these massive stars, there is also an upper limit on the size of the black hole left. Scientists can then predict based off how much gas and matter is left near the black hole, how big it will grow to be based off how much of this matter is accreted inside the black hole. But based on these size calculations alone, we would never expect to find supermassive black holes, unless black holes themselves collided together to form even bigger black holes. It is believed now that supermassive black holes are made from older black holes that over time have collided to form bigger and bigger black holes, which then our galaxy forms around. When two older dwarf galaxies collide, it is very often the case that none of the stars collide or touch, but since black holes are at the center and have a much bigger pull of gravity, it is often the case that they combine. But, when scientists have looked further stellar distances back in time to see primordial dwarf galaxies, they have found that these smaller, ancient galaxies have intermediate size black holes on the order of 1,000 to 10,000 solar masses, which was bigger than expected from theoretical calculations based on accretion rates.  The fact that the black holes are bigger than predicted suggests that black holes are somehow getting bigger faster than just based on the gas accreted into them. But from what we know about these dwarf galaxies, they originated from a very isolated existence, and we wouldn’t expect them to be moving near each other often enough to collide and form these bigger black holes. We know that these galaxies begin to move and collide in the future enough to form the supermassive black holes we see today, but it is unclear how these primordial black holes initially formed.

Sources:

http://www.sciencedaily.com/releases/2014/03/140326170320.htm

http://en.wikipedia.org/wiki/Supermassive_black_hole

Beyond the orbit of Neptune and the Keiper belt,  lies a vast region of our solar system known as the Oort Cloud filled with icy bodies weakly bound to the sun in very long orbits. The Oort cloud is defined as a region of space that is spherical shell around the sun starting at 2,000 AU away from the sun, the beginning of the inner Oort cloud, and ending at about 50,000 AU away, the outer Oort cloud. The absolute maximum distance the Oort cloud extends to is usually defined by the Sun’s tidal truncation radius, which is 100,000 to 200,000 AU.  This is the radius away from the sun at which the gravitational pull of the sun is about equal to the galactic ‘tide,’ which is essentially the gravitational pull of other stars and the galaxy as a whole.

image from wikipedia

The farther out in the Oort cloud an object is, the weaker the pull of sun is, and thus the pull of gravity by the galactic tide plays a much larger role in changing the motion of the object. Galactic tide is similar to ocean tides in that as we orbit the galaxy, gravity pulls more strongly on one side of the solar system than the other, causing the sun’s field of gravity to warp from a spherical shape to more of an ellipsoid periodically. The inner planets like Earth never notice this effect because we are so close to the sun, the galactic tide would never shake us from the strong pull of the sun, but objects very far out in the Oort cloud are.

The cloud was named after Jan Oort, who proposed that comets originated from this cloud of icy bodies due to a slight displacement from its orbit that pulled it into a long elliptical orbit close to the sun. At the time, it was speculative to what would cause the displacement creating the comet’s orbit, but with computer simulations, many think that as much as 90% of comet’s orbits are made from changes in the periodic galactic tide versus random events such as stars or giant molecular clouds just happening to get closer to the solar system.

It was first proposed by Newton and showed by Edmond Halley (of which the famous comet is named after) that comets must orbit the sun in long elliptical orbits lasting hundreds to thousands of years. The only reason we can see comets is because as they approach the perihelion or their orbit, at 3-4 AU, the flux (energy/area) of the sun’s energy hitting the comet increases enough to melt the ice on the comet, creating a gas cloud on the surface called a coma. A dust tail is then formed due to radiation pressure from the sun and solar winds pushing dust off the cloud. This tail of matter coming off the comet is then illuminated by the sun’s UV light exciting the gas causing emission of visible wavelengths. Thus, making comet’s very noticable in the night sky for this time. Once the comet passes the perihelion, it then begins to freeze again, going dark in the night sky. This effect is what enabled Halley and others to learn about these far objects without large, advanced telescopes.

image from wikipedia

As scientists improve telescopes, especially in the infrared range, we are finding more and more Oort objects. Since all these objects are invisible to us the visible range, infrared telescopes are useful for detecting the larger objects that could have core heat signature in the infared range.  Sedna and VP 2113 are two inner Oort cloud objects that have been discovered in the past 10 years. We also now believe that much of the outer Oort cloud formed with the rest of the solar system, while the very outer edges may act like an ‘eddy’ in the tides of galaxy collecting objects that exist in the interstellar medium between stars. What remains a challenge however is detecting the objects in the outer Oort cloud, as it takes precision equipment as well as luck. There remain many questions on the distribution and size of these objects, as well as how they formed, and their evolution over time.

Sources used:

http://solarsystem.nasa.gov/planets/profile.cfm?Object=KBOs&Display=OverviewLong

http://www.nasa.gov/content/nasa-supported-research-helps-redefine-solar-systems-edge/#.Uzwnlq1dWr8

http://en.wikipedia.org/wiki/Oort_cloud

http://en.wikipedia.org/wiki/Comet

http://www.space.com/53-comets-formation-discovery-and-exploration.html

It is hard for the human to comprehend how small the planets are in comparison with the sun. If you shrunk the sun from its radius of 6.96E8 m down to the size of a beach ball with a radius of 20 cm, and then shrunk all the planet’s radii by the same factor, our earth would have a radius of 1.8 mm, like a large grain of sand. The largest planet jupiter would have a radius of only 2 cm, the size of marble. This is simply calculated by using a ratio, if you wanted to calculate the rest of the planet’s relative size you could use the relation, r=(0.2m/6.96E8m)R where R is the actual radius of the planet and r is the relative size in our scheme. It puts into perspective why to the early astronomers, and the uninformed observer, the planet’s simply look like stars in the night sky. We see our sun to be an actual circle in the sky, because not only is it very large compared to the planet’s, but also very close compared to the next closest stars. The planet’s appear so small, because they are actually much smaller than the sun. In addition, they are relatively the same distance from earth as the sun, when we consider how much farther it is to any object outside our solar system; the closest visible object is the next closest star, Proxima Centauri, which is 4.2 light years away, 272,000 AU (the distance from earth to sun), or 4E16 m.

Actual stars then are all much farther away from the earth than the planets, and as any person knows, things look smaller as they get farther away. This effect is simply perspective. If one changes their line of sight looking at the object its distance from you can be calculated based of the change in apparent angle of the star. More simply, this change in apparent angle is how fast you perceive the object to move. A perfect example is if you are in a car looking out the side window, you will notice that the houses right next the road move faster than the houses farther away from the road. This is how astronomers first calculated the distance to the stars: They would measure the apparent location of a star and then wait 6 months for the earth to orbit half-way and move 2 AU (2x the distance between the sun and earth) from its initial position, and then measure again, and find out the angular difference. When you take into account this effect of distance, and try to calculate the radius of these far off objects, you realize all the stars on average are about the same size as our sun, or bigger. Thus, the human eye sees stars and planet’s to be about the same size in the night sky, but in reality, only the planets are actually ‘small’ when compared with the sun. Most stars are just so much farther away they appear to be so small.

Another great example of this effect of perspective on the perceived size of an object is the sun and moon. To the average observer of the sky, it is pretty easy to notice that the only actual ‘circular’ objects and not ‘point’ objects, (I’m considering anything that has a angular width of less than a minute of a degree to be a ‘point’) are the sun and the moon. What is even more amazing is that the sun has an angular width of about 31.6′ and the moon has about 29.3′ of width: almost exactly the same! The result of this coincidence is that we are able to have total solar eclipses. If either was smaller or bigger in angular width, our solar eclipses wouldn’t completely cover the sun, or would completely block out the sun. The lunar width depends on the size of the moon and its distance from earth, and the solar width depends on the size of the sun and its distance from earth. In the case of the lunar width, the moon is actually smaller in radius than the earth, about 27% the radius of earth, but its about .0025 AU from the earth, or about 0.25% the distance from the earth to the sun, thus it appears to be large in the sky because it is so much closer. Whereas the sun has a radius about 110 times the size of earth, but is 400 times farther away, thus giving comparably the same angular width by total coincidence. I find this coincidence very puzzling, but beautiful at the same time.  Before astronomers could reason the distances to the sun and moon and their sizes, our perspective made us believe the sun and the moon were the same size (not to mention many thought the moon was a perfect sphere!). In reality however, the sun is a massive ball of hot gas/plasma much farther away that humans will never be able to step foot on. Conversely, the moon is a small, cold rock, that is so close to us, it only took humans 300 years after learning the laws of gravity to build a spaceship to travel to it in just 3 days and have a few humans walk around on it.

sources cited

http://en.wikipedia.org/wiki/Solar_eclipse

Bradley W. Carroll and Dale A. Ostlie. An Introduction to Modern Astrophysics. 2nd Edition http://en.wikipedia.org/wiki/Angular_diameter