Space junk

Collisions between space debris have been rare so far, but this number is expected to rise. BBC News.

After 60 years of sending things into space, the number of satellites, rocket stages, and pieces of debris floating around the Earth is gigantic.  As that number continues to increase, the number of collisions between these objects is expected to increase too.

We don’t think much about space junk. I guess we just hear about what this or that satellite has discovered and then forget about it, assuming it will just go away once it’s done doing its job. This stuff is a serious problem though. Collisions between these man-made objects could disrupt telecommunications or even cause some of the debris to fall to Earth, which could cause physical harm.

Currently we’re tracking over 20,000 objects in orbit around the Earth, with most of these falling into the category of low-Earth orbit.  The number of these larger objects is expected to grow 30%. There are even more things we’re not tracking – scientists estimate there are tens of millions of particles less than 1cm across orbiting the Earth. And with all of this stuff traveling at several kilometers a second, even the smallest fragment can do a lot of damage.

Image what would happen if some of this junk hit the ISS or one of the satellites your GPS relies on? All this junk is a huge problem, and no one seems super motivated to do anything about it.  China even purposefully contributed to the problem, destructively doing anti-satellite testing on one of its old spacecrafts.

If countries do start caring about the space debris out there though, there are plenty of solutions researchers have come up with, including a harpoon that would pull junk down so that it burns up in the atmosphere. Hopefully some of these solutions will be implemented in the future.

Source.

3 Prime Locations for Life

Scientists recently announced that Kepler has found 3 exoplanets that are our best bet for finding life outside the solar system.

These three planets – Kepler62e, Kepler 62f, and Kepler 69c – are the smallest to be discovered within the habitable zone, meaning that liquid water could potentially exist on any or all of them. And if there’s liquid water, there could be a good chance of finding life.

And although we probably won’t confirm the presence of life on these planets for certain since the Kepler 62 system is over 1,000 light-years from us, the fact that we’ve found 3 planets that could host life means that surely, life on Earth can’t be that special.  We learned last unit that most of the exoplanets we discover tend to be large Jupiter-like planets, so the fact that we found 3 Earth-like planets even though our current level of technology makes it difficult to find them surely means that there are likely to be several Earth-like planets out there. We’ve only found 3200 exoplants so far, but then again, Kepler is only looking at one part of space. Who knows how many actual planets we’ll find out there.

And knowing that there are probably millions if not billions of planets out there, surely there will end up being hundreds of thousands if not millions like these 3 planets, capable of supporting liquid water and thus life. This discovery definitely confirms my belief that ne  is high. For every habitable zone planet we discover, the chances of our finding life somewhere in the universe increase, and hopefully someday we will discover it.

Source

Dark Matter Discovered?

Dark Matter infographic from Space.com

Scientists announced today that they may have finally found dark matter. Dark matter is the invisible matter making up most of the universe, but scientists can’t see it because it emits no light.  Scientists only know it exists because dark matter’s gravity bends light – gravitational lensing – and because stars are orbiting in galaxies faster than expected.

So how have they finally found this mysterious substance? It’s all thanks to the International Space Station (ISS).  2 years ago, Endeavor delivered a $2 billion present to the ISS – the Alpha Magnetic Spectrometer (AMS).  The AMS measures cosmic-ray particles,  among which the most important (in terms of dark matter) are positrons. Positrons are also called antielectrons because they are literally the antimatter version of electrons. This means that if you ram a positron and electron at each other, they will be annihilated. The AMS found 400,000 of these particles, and their energy leads scientists to believe that they were created when dark matter particles collided. These dark matter particles destroyed each other when they met, which physicists suggest happens because dark matter particles are their own antimatter.

This is some crazy intense particle physics, but it just makes dark matter seem that much cooler. I mean,  how insane is it that 80% of our universe is made up of stuff we can’t see or easily detect? Not only that, but dark matter particles destroy each other when they collide. That seems weird to me because it’s the majority of the stuff in the universe, but if it comes into contact with itself, it gets destroyed. It seems like it would no longer be 80% of the universe. Maybe there was once more dark matter in the universe and it just destroys itself over time? I have no idea how often dark matter particles collide though, so this could be a really stupid idea.

Even with this positron discovery, scientists may have not actually found dark matter. Pulsars, for example, could have created the positrons. Scientists won’t know for certain until a ground-based detector picks up on dark matter particles.

Source.

Close Encounters

We usually only think of impacts in terms of comets or asteroids hitting the Earth, but scientists are closely monitoring a close encounter between Mars and Comet C/2013 A1 (Siding Spring).

The comet was discovered earlier this year and is estimated to have traveled about 1 million miles on its journey from the Oort Cloud. It will get closest to the red planet in October of next year, and current models have the comet coming within about 70,000 miles of the Martian surface.

Fortunately for Mars, the comet is not expected to impact the planet. The odds of that happening are 1 in 8,000. This still seems pretty probable to me though, especially considering that the updated odds of an Apophis impact are 1 in 140,000,000.

Even if the comet doesn’t strike Mars, however, it could still pose a hazard. All our orbiters around the planet and our rovers on the surface could potentially be in danger.  This means scientists will get a first chance at trying to protect against an impact, even if it is an impact caused by the debris from the comet’s close passage.  This is an interesting problem because most of the time when we think about preventing impacts, we are worried about protecting lives here on Earth and don’t care about the satellites orbiting the planet.

NASA’s Near-Earth Object Office is continuing to study the comet and its orbit, and continued study will probably reduce the odds of an orbit further. This is, after all, what happened when scientists continued to study Apophis. The biggest opportunity for study will happen when the comet passes – assuming it doesn’t damage the planet or its orbiters. The three orbiters will be at a prime spot to study the comet and its structure, and the comet’s brightness means its passage will create a spectacular image streaking across the Martian sky.

As much as I enjoy the fact that Earth doesn’t face close encounters on a regular basis, it would be cool to have more comets come close to Earth.  I think it would be a spectacular phenomenon to be able to witness, except for the fact that each comet basically marks a time when we got dodged a bullet, so to speak.

Source

The Little Solar System that Could

Pluto and its 5 moons, as seen by the Hubble Space Telescope. Space.com

Pluto may no longer be a planet, but it sure is proving to be one of the most interesting objects in our solar system.  We’ve kicked it out of the planet club, but Pluto seems to have plenty of friends of its own, with scientists thinking the little dwarf planet could have 10 more moons to keep it company.

It’s not even the biggest dwarf planet – that would be Eris – but Pluto has a surprisingly large number of moons. It’s less massive than the Earth (with 1 moon) and Mars (with 2), but Pluto already has 5 discovered moons, 2 of which have yet to be named. The newest moon, called P5 for now, was only discovered last year, and it was this discovery that has NASA scientists worried. The NASA mission New Horizons is set to get up close and personal with Pluto in 2015, but scientists are worried they may need to modify its path to avoid these newly-discovered moons or any other tiny moons lurking in the area.

Scientists think that the tiny moons exist because of computer simulations involving the formation of Pluto. Evidently a dust cloud once surrounded the dwarf planet, potentially following a collision of Charon with Pluto. This dust and debris gradually clumped together in much the same way the planets formed, only on a smaller scale.  The collisions that would have built the moons are hard for researchers to implement, so the correct number of additional moons could be anywhere from 1 to 10. These moons would be too small to be seen from Earth due to Pluto’s relative brightness, and the Hubble Space Telescope would barely be able to see them. Either way, that’s a lot of moons for such a tiny planet.  I think it’s great that just because Pluto isn’t a planet anymore doesn’t mean it isn’t still full of things for astronomers to discover.

Mars Suitable for Life

This image from NASA’s Curiosity rover shows the first sample of powdered rock extracted by the rover’s drill. NASA

NASA scientists have just finished analyzing a sample of rock Curiosity drilled last month, and the results are certainly promising for the theory that Mars once was home to life.

In the sample, they found elements like carbon, oxygen, nitrogen, and sulfur, all of which are essential for life as we know it.  This sample was taken from a rock found at the end of a now barren stream or lake, which could have been the perfect birthplace for life on Mars.  After all, many people think life on Earth started out in the oceans, so the same thing could have happened on Mars.  The minerals and chemicals found in the sample seem to indicate that the location was a mild one, without harsh conditions like acidity or saltiness that would make life hard to support. Scientists also believe that the oxidized and non-oxidized chemicals found in the sample could have provided a potential energy source for ancient microbes, if they behaved anything like those found on Earth.

These similarities in geology and chemical composition between the Earth and the Mars of the past seem to indicate that Mars could have once been home to life. Of course, this proof is only meaningful if the life that existed on Mars is anything like life on Earth. But since life on Earth is the only kind of life we know, it’s all we’ve really got to go on.

Curiosity will be continuing to examine the area surrounding the location of this rock  sample for further samples, so scientists can further determine if Mars was once home to life.

Artificial Gravity

Artist’s rendering of a typical design for a space station that produces artificial gravity, by the BBC.

Given the importance of gravity to life here on Earth, it’s interesting to think about the lack of gravity used in space exploration.

Of course there’s gravity in space, but not anywhere near the amount of gravitational force we feel on Earth. So why doesn’t NASA design its space shuttles and space stations to create artificial gravity for the astronauts? After all, we don’t exactly see Han Solo or Captain Kirk floating around their respective ships, eating globs of grape juice and somersaulting in mid-air. And if being in space causes a slew of problems for the astronauts living there – including weak and brittle bones, kidney stones, atrophied muscles – why not just design the ISS to provide artificial gravity and prevent these conditions in the first place?

Actually, in the beginning of space exploration, people assumed our spaceships would have artificial gravity.  These early designs almost all have giant spinning wheels, which generate centripetal force as they spin and thus simulate gravity on Earth. So, why did the plans change? There are two main reasons our astronauts float around the ISS instead of walking through its hallways.

The first reason makes a lot of sense.  A lot of the tests NASA scientists do involves performing experiments in reduced gravity, also referred to as microgravity. If we wanted to test how plants grow under normal gravitational conditions, we could do that just as well on Earth.  We need an environment where we can see how things function in microgravity, hence our need for a space station where astronauts are experiencing microgravity.

The second reason? Money. Since every space station designed so far has not included artificial gravity, it would be expensive to develop and test a design for a new space station which provides artificial gravity, let alone build it. With NASA’s budget and the state of the economy, there is not likely to be the money for playing around with giant spinning wheels on spaceships anytime soon.

It’s a bummer, really, because some of these designs look really cool. I suppose it would be strange to watch a video of astronauts who were eating normal food or walking around on a space station after years of tuning in to watch floating crew members show you how they use the bathroom or wash their hands in microgravity.  But think of all the possibilities if we did create a way for artificial gravity to be produced in space.  The article mentions space hotels, but I think artificial gravity is a real prerequisite if we ever want to have a large number of people living in space, whether that’s on missions to Jupiter or a full-time colony on a space station in orbit around the Earth.

Asteroid Flyby

Asteroid 2012 DA14’s projected trajectory, by NASA

Next Friday, Earth will be almost visited by 2012 DA14, an asteroid about 150 feet across. It will come closest to us at 1:24pm Nashville time on the 15th, at which time it will be only 17,000 miles above the Earth. For reference, that’s about 7% of the distance between the Earth and the Moon.

So why no call for fallout shelters and apocalypse preparedness? NASA says there’s absolutely no chance of the asteroid smashing into the Earth. They’ve been tracking the asteroid since it was first discovered by Spaniards a year ago. Evidently 2012 DA14 comes this close to Earth two times during its orbit around our Sun.

There’s no imminent demise to prepare for, but this asteroid’s approach is special because we’ve never predicted the path of something this large coming this close to Earth before. NASA has good estimates for its size and weight, and the article reports its estimated speed and distance from Earth fairly precisely. This information is comforting in a way. We can now track asteroids that come crazy close to Earth – closer to Earth than some of our GPS satellites – and know exactly what kind of danger, if any, they pose. NASA says even its risk to satellites is minimal.

On the other hand, NASA estimates that there are about half a million near-Earth asteroids about the size of this one. Half a million. And of those, NASA claims not even 1% have been discovered. That’s over 450,000 asteroids floating around in space that will make close approaches to us here on Earth. If we haven’t even discovered them, we don’t have any idea if they pose a threat or not.  The NASA article states that asteroids this size collide with Earth about every 1,000 years but conveniently leaves out when the last such impact occurred. Now I’m not saying we all need to start freaking out about asteroid impacts, but with these odds, shouldn’t we be doing more to encourage and fund research into these asteroids? We should be worrying about the technology we would need to try and deflect an asteroid that looked like it was about to collide with Earth because eventually, our 1,000 years will be up.

Source: NASA’s “Earth Flyby Reality Check”

Historical Astronomers in Context

Tycho Brahe, from the Galileo Project

Tycho Brahe (December 14, 1546 – October 24, 1601) was a Danish astronomer who is an important astronomical figure because of his naked eye observations. Before the telescope, he amassed a great trove of extremely accurate data that would be used by Kepler to develop his Three Laws of Planetary Motion. This means he basically provided the data that would begin the move to the sun-centered model of the universe as the norm. He witnessed a supernova and observed that the stars must be further away than previously thought. He was essentially the last astronomer to user only what he could see instead of using telescopes to look at the sky.Craters on both the Moon and the planet Mars are named after him.

For additional information:

• Tycho Brahe Biography at the Galileo Project
• About Tycho Brahe at The Tycho Brahe Museum Website

Contemporary Figures:

• Andreas Vesalius (December 31, 1514 – October 15, 1564) was a professor and court physician regarded as the father of the study of human anatomy. He labeled the chambers of the heart and introduced the idea that the skeleton was the essential framework in the body. His detailed dissections disproved many antiquated beliefs about the human body and set the standard for highly accurate pictures and drawings of anatomical features.

Contemporary Events:

• 1558 – Queen Elizabeth I took the throne in England in 1558. Under her rule, the Church of England was established as a Protestant church and English culture fluorished, most notably Shakespeare’s plays. 
• 1587 – Settlers from England try to settle Roanoke Island in Virginia for the second time. The first settlement was abandoned because of lack of supplies, but the second one becomes known as “The Lost Colony” after all the colonists disappeared by 1590.

What I found interesting about this assignment was realizing just how many famous scientists and inventors lived in the same time period. The foundations of all our modern scientists really did come from this one century. I never realized that across Europe, all these great minds were at work in different places and in different fields. I always thought that the large amount of rapid scientific advancement that we are living with currently was unprecedented, but mankind’s understanding of the world basically changed completely in just a few short decades. This period of time really separates the Dark Ages from the start of modern science.

I guess the number of great scientists living at the same time and how many scientific advancements they produced in this era reinforces how important collaboration and cooperation is in science because if only one of these famous men had been around during this period, there would not be near as long a list of scientific accomplishments for us to look back on.

Sources:

• Bennett, Jeffrey O., et al. The Cosmic Perspective: The Solar System. 6th ed. Boston: Addison-Wesley, 2009. Print.
• Wikipedia: The Free Encyclopedia. Wikimedia Foundation, Inc. 22 July 2004. Web. 5 Feb. 2013.

Lunar Phases

Screenshot of the Lunar Phase app, available for Android.

While searching for a good astronomy application to blog about, I found a lot of interesting moon apps, but I think the most helpful app for this class would have to be Lunar Phase. It’s a free app available for Android that not only shows you the current phase of the moon and the moon phases for the rest of the month, but also gives you pictures exactly like those we saw in lecture on Wednesday that are going to be on the test.

In the screenshot above, you can see that the app shows you an estimation of what the moon currently looks like (this one is a Waxing Gibbous). It also shows you a picture of how the sun, earth, and moon are aligned, which is going to be super helpful to practice with and study for the test on Monday. It’s even got the moon shaded properly, which I know confused me in Wednesday’s lecture. The bottom picture looks exactly like the clicker question we were shown Wednesday, with a view of where the moon currently appears in the sky. This screenshot was taken at midnight, and the moon is almost at its highest point. This tells us that it’s almost a full moon, since the full moon is at its highest point in the sky at midnight.

But this app isn’t just helpful in preparing for the test. Lunar Phase tells you the times that both the moon and sun will rise and set for a given day and lets you know the Altitude and Azimuth of the sun (wouldn’t that have been helpful for the last homework). Although it does have a few too many buttons – many of which I haven’t quite figured out yet – this little app is impressive. I would highly recommend using it as you study for Monday’s test.