Space Technology

You may have heard quips about how primitive the electronics used in space technology are compared to what you can buy as a consumer. This can be a puzzling fact given that space exploration is a very technical (and expensive) enterprise.  If we're going to spend hundreds of millions or billions of dollars to send a spacecraft out into the solar system (most of which just goes to getting to your destination), why give it old brains?

In fact, the example of the computers in the lunar landers isn't a very good one to illustrate the point I am trying to make.  While the computing power available is very small compared to devices today, it was actually quite advanced for the time.  So why would I mention an example that doesn't fit with the norm?  There are a couple reasons why technology in the early days of space exploration was more up-to-date than it is today.  The first is easy:  We were engaged in the "space race" with the Soviet Union.  NASA had an enormous budget compared to today, and was given the directive to take whatever steps (and often, risks) were necessary to win the race.

Core rope memory

The second reason takes a bit more explanation. The picture to the left is of a massive 128 byte (wow!) memory module from the Apollo Guidance Computer.  This is what is known as core rope memory, which means that a person sitting in a factory literally wove the wire into a pattern encoding the data.  So...how does that explain why Apollo-era technology could be sent into space easier than today's electronics?  If a human being put the memory modules together, that means the wires must have been at least a minimum workable size.  But consider current generation CPUs.  The size of transistor gates is 22nm.  For comparison, a human hair is about 50,000nm across and a silicon atom (which microchips are made of) is 0.11nm.

A Solar Flare

Both core rope memory and new computer components work fine on Earth, so why not in space?  The difference is that outer space is constantly flooded with radiation from the solar wind and cosmic rays, but (luckily for us) Earth's magnetic field protects us from most of this.  When enough highly energetic particles are passing through your spacecraft, one is bound to hit something important and transfer that energy into whatever it hits.  In old electronics that wasn't a big deal - the components were big enough that the energy could spread out and cause few problems.

Newer components are a different story.  As you may have noticed above, the current generation of computer parts have die features on the scale of a few atoms.  This means that it doesn't take very much energy to flip a digital bit from 1 to 0 or back. That's good when you need to power a CPU with over a billion transistors but very bad when you're being bombarded by high-energy radiation.  Then again, I'm not sure that's ever a good situation to find yourself in...  When a bit flips in a memory chip (usually causing a crash or data corruption), that's called a soft error.

Clearly, electronics on spacecraft must be different than personal computers to function in their environment. Any component that leaves Earth's protective magnetic bubble must be radiation hardened.  There are many techniques for accomplishing this, but they fall into 2 general categories. First, the components are often manufactured using different materials and surrounded by radiation shielding to prevent errors.  Second, there can be error correcting codes for memory and redundant calculations to check for errors that have already occurred.  All of this adds complexity to the design, which then must undergo multiple rounds of testing before it has a chance of seeing spaceflight.  This testing process, which is essential to ensuring spacecraft systems continue functioning after we hit "launch," is why these systems are less powerful than what you can buy at any electronics store.  So rather than making fun of NASA's newest Mars rover, Curiosity, for having a camera with less resolution than your cell phone (it's 2 MP), just enjoy the images it takes and remember that it survives being bombarded by radiation every day.

Telescopes a window to the universe

A telescope is an instrument made up of lens or mirror to observe the far away objects. A telescope magnifies and brings object much closer. Thus making the study of far away object much easier. The first telescope was invented in Netherlands in 17th century. Soon after that Galileo made similar telescope and used it to study the sky.

Observation of moon by Galileo and the picture he made from the observation.

http://www.nasa.gov/audience/forstudents/9-12/features/telescope_feature_912.html
Above link gives us brief history of the telescopes.

http://science.howstuffworks.com/telescope1.htm

The above image illustrates a very simplistic view of how a telescope work. Initially telescopes were made using lenses, later the use of mirror was introduced. There are various types of telescopes in use now.
It can be divided based on what range of electromagnetic waves we are looking at. The light we see is also a collection of a range of electromagnetic (EM) wave.  EM waves can be divided into various categories based on their wavelength. There is very limited range of wavelengths that a human eye can perceive.

Electromagnetic wave spectrum

Brief classification of telescopes on the basis of wavelength
a) Optical telescope
b) Radio telescope
c) X-ray telescope
d) Gamma ray telescope
e) Infrared telescope etc.


These different types of telescopes are used for different proposes. For example
the image here shows the galactic centre but
they are observed by different types of telescopes (i.e. in different wavelengths).
So depending on what they are trying to understand, scientists use different types of telescopes. Even though the older telescopes were ground based (i.e. they were used from the earth for observations) there are many telescopes now which are space based. Some of them are Hubble, Sptizer, Chandra etc. There are lot of beautiful images taken by these telescopes which you can find very easily in the internet.

Also the sizes and weight of telescopes varies a lot. There are telescopes weighing few pounds to thousands of pounds.
I encourage everyone to look through the telescope whenever you can. Most schools with observatories have open house. You can see many wonderful celestial objects through these telescopes if you go to an open house. Here at University of Denver, there is one open house at old Chamberlin observatory every month for the public. If you are in Denver area you should definitely make use of it. Click here to get more informations regarding the open house. http://mysite.du.edu/~rstencel/Chamberlin/

Stargazing Time

Ask yourself this question: "When do the stars come out?"  A first answer to this question might be "when the sun goes down."  I'm not going to say this is wrong...clearly you can see that stars at night.  However, I would say this is a rather inexact statement.  Think about this - how long after sunset does it take for it to get dark outside?  This period of time between sunset (or sunrise) and night is called twilight, and it has nothing to do with sparkly vampires.

As shown in the figure to the left, there are three different categories of twilight:

1) Civil Twilight: This is the brightest of the 3 since it is the closest to sunset or sunrise.  It lasts from when the sun is just below the horizon until it is 6 degrees below.  The name civil twilight comes from the fact that many laws define night to start at the end of this period.  For example, motorists must begin to use their headlights and pilots need to licensed to fly at night.  During this period of time, earthbound objects are usually distinguishable without artificial light while only the brightest stars and planets are visible.

2) Nautical Twilight: This twilight lasts until the sun is 12 degrees below the horizon, so it gets darker than civil twilight.  Nautical twilight got its name from the days when sailors would have to use a sextant for navigation.  It is the time where the sky is dark enough so well-known stars are visible for sighting while it is still light enough to distinguish the horizon for measuring elevation.

3) Astronomical Twilight: This period last until the sun reaches 18 degrees below the horizon, at which point the sky is dark enough for any type of astronomical observation.  Up until this time, most stars can be observed while some galaxies and nebulae cannot.  The sky can appear to be completely dark near the end of astronomical twilight.  Due to the effects of light pollution in populated areas, many observers don't see a sky darker than this.

It's more enlightening to see how twilight works in terms of an actual day, so I got a table of the twilight times in relation to sunrise and sunset for today (in the Denver area).  Of course, these times will change everyday like sunrise and sunset do.  They also depend on the latitude of your city.  If you're interested, click here and then on "more" in the bottom table to see a table for the current date at your location.  See...isn't this twilight so much better?

Supernova

“The nitrogen in our DNA, the calcium in our teeth, the iron in our blood, the carbon in our apple pies were made in the interiors of collapsing stars. We are made of starstuff.”

― Carl Sagan, Cosmos

Simplistic view of different stages of stars

Crab Nebula

 Doesn't it feel wonderful to be made up off starstuff. Well today I want talk about a spectacular phenomenon called supernova where most of the massive metals are made. Above is a very simplistic diagram of life cycle of a star. As you can see depending on the mass of the star (roughly if mass is greater than 8 times the mass of sun, it is considered a massive star) it can have different paths. During their life span they burn hydrogen initially to produce the energy. As the time passes, massive elements are formed. In the end they end their life as a supernovae.

 Supernova is an explosion of massive star at the end of its life. It is a very energetic event where energy equivalent to billion times the energy of sun is produced. To get the sense of this amount of energy, the energy consumption of the world for 2008 was about 5*10^20 joules. The energy from one supernova is nearly 10^46 joules.  From this explosion the elements made in star core is distributed in space. These event on average occur only once per galaxy per 100 years. In the universe there are around 30 supernovae per second. This interesting fact gives you idea as to how huge our universe is.

Whew, that was close!

Did you know that an asteroid flew past Earth last night? On the left is the trajectory. The 270 meter asteroid (about the size of three football fields), known as 2000 EM26, streaked past Earth at a distance of about 2.1 million miles (3.4 million km). Just for comparison, the mean distance from the Earth to the Moon is 238,900 miles (384,400 km). So this asteroid was about 8.8 times the distance from the Earth to the Moon at its closest point, and it will be traveling about 17,000 mph.

This object is classified as potentially hazardous when it was discovered in 2000 because of its projected path and because of its size. There were 32 observations in 9 days and then something interesting happened; it disappeared! Based on the trajectory determined in the those 9 days, this asteroid made close approaches in 2002, 2003, 2006, 2009, 2011 and 2012 and yet it was still never rediscovered! This asteroid is very faint, aka very low albedo, and thus hard to track.

Slooh, a community observatory where you can view live through a telescope, generally shows interesting astronomical events; transits, asteroid flybys, etc. Slooh also tracks newly discovered

asteroids and submits the data to the Minor Planet Center. This is in hopes of never loosing an asteroid again. 

Slooh hosted a "live" event last night for the asteroid flyby, which you can re-watch here. 

Spoiler Alert: Still haven't rediscovered it!! The Dubai Astronomy Group was feeding in live images of the sky of where the asteroid should have been based on its trajectory, again determined 14 years ago, but nothing could be deduced.

This asteroid is now nicknamed Moby Dick for its elusiveness.

We need your help! Amateur astronomers, help us find this asteroid before it is too far away! Check out some more information here. 

The idea of LCROSS

My grandfather has been able to do many things during his astrophysics tenure. I attribute my love of physics and astronomy to him. I remember wanting to wear one of his rocket missions-into-the-aurora borealis t-shirts for a week straight (I don’t remember if my mother allowed her crazy son to actually do it!). He has had a lot of impact on what I’ve chosen to do, even with very sporadic communication. Regardless, my head still turns when I hear about things that he has contributed to.

One thing that he was very excited about was his involvement in pitching the idea of LCROSS. He said it took about 25 years for the idea to come to fruition, but it finally did in 2009 when—if you recall—a spacecraft was hurdled into the depths of a crater on the south pole of the moon. A large series of figures and pictures are included here. One of the purposes of smashing into the moon was to find water (in the form of ice) at the base of the craters, where the water hasn’t been sublimated by the sun. Well, it turns out, my grandfather and his co-workers were correct.

They did indeed find water at the base of the craters. However, LCROSS also found a number of volatiles, including methane, ammonia, and hydrogen gas. A debate has begun on where or how those volatiles got into that crater. One of the most common thoughts is that comets or asteroids composed of those materials crashed into the moon and delivered those materials; this is a very viable option considering the number of impacts the moon has absorbed. The other thought is that the lunar ice is able to react with high-energy cosmic rays (that are not shielded by an atmosphere or magnetic field) over millions of years.

This idea was published by Crites et al. (2013). They state that these cosmic rays (because of their constant, high-energy bombardment of simple ices) have the ability to “stimulate organic synthesis.” This means that the growth of more complex molecules can happen anywhere that has volatile ices and exposure to high-energy cosmic rays. This would include many of the smaller planets and moons in our solar system (Mercury, Pluto, Jupiter’s moons, etc.).

An example of their modeling and experimental results are found above, which is Table 3 from their published paper. The important things to note are the starting compounds (column 1), the product resulting from cosmic ray bombardment (column 2), and the resulting mass of the product from a mass of 1kg of the starting compounds (column 5). So, just by starting from different combinations and ratios of water, carbon dioxide, methane, and carbon monoxide, they were able to get molecules of methanol (CH3OH), ethanol (C2H5OH), and many others.

To me, this shows the impact (no pun intended) and progression of ideas: (1) a group of scientists had a thought to create a plume of material from the base of a lunar crater; (2) that turned into a mission at NASA; (3) the discovery of water AND volatiles present on the moon’s surface; (4) theories of the origination of these materials concludes this conversion process could be occurring all over the solar system.

In other words: keep the ideas/thoughts/questions/hypotheses coming!

The Universe on Your Phone (or Computer)

Have you ever looked up at the night sky and tried to remember the names of the stars and constellations you are seeing?  If you have a smartphone, Google has a very nice Android app for locating constellations, stars, planets, etc.  If you're an iPhone user, Apple doesn't play nice with Google, so you don't get their toys...sorry.  I included a screenshot of what Google Sky looks like running on my phone.

Your phone knows several pieces of information that allows it to generate this sky map.  First, and not at all surprisingly, it knows the time.  It also knows your location.  Even without GPS, a phone can tell where it is by what cell towers are in range.  The time and place on Earth's surface are both necessary to determine which stars are overhead.  Then, you need to know which direction in which your phone is pointing.  This is done using an accelerometer, which can measure which way gravity is pulling on the phone.  With all that, you can point your phone up and - voila - the stars and constellations on the screen follow the ones in the sky...except these ones are conveniently labeled.  Another neat feature of Google sky is that you don't have to pan around the entire map to find a particular object.  Being a Google product, this also includes a search function.  I showed a screenshot of locating Mars.  The circle is red to indicate that I'm almost pointing directly at it, and it would be blue far away.  Google Sky also has a website here, which also includes visible, infrared, and microwave observations stitched together into a full-sky map.

While it is not as accessible as Google's products (it's a program that only runs on Windows 7/8 computers), Microsoft Research's WorldWide Telescope offers access to a much larger amount of data.  This includes planetary data, and the ability to browse in 3D.  If you click here, you can see a sample dataset they put online allowing you to look around the MilkyWay in 3D (click your mouse and drag on the picture...it's not just an animation).

The great thing about both Google Sky and WorldWide Telescope is that they are both intended to be used by the general public.  They were designed by consumer companies (Google and Microsoft) with that use in mind.  This has two big advantages:  First, the webpages and documentation were written assuming a home user would be reading them.  Second, the user interfaces were designed professionally, eliminating a great deal of confusion in the first place.  Happy...observing?

Astronomers discover oldest star to date

It was announced this week that astronomers at The Australian National University, led by Dr. Stefan Keller, have discovered a 13.7 billion-year-old star, meaning it formed soon after the Big Bang.  This is helpful to our understanding of the early universe, because by determining the chemicals present in this star (which has been done), astronomers can have a better sense of what the early universe was like.

Previously, astronomers believed that this type of star would have died in a supernova and emitted large amounts of iron into the surrounding space.  However, the signature of this newly discovered star shows no iron at all, which indicates a much smaller supernova than previously thought.

The star was discovered as part of the SkyMapper program which has been searching for ancient stars for several years, while also creating a map of the southern sky.

A link to a user-friendly article about the discovery:  http://www.sciencedaily.com/releases/2014/02/140209200836.htm

A link to the publication in Nature:
http://www.nature.com/nature/journal/vaop/ncurrent/full/nature12990.html

Our home: Milky Way galaxy

 

 One of my favourite ways to pass time has always been looking up at the sky and wondering how huge the universe is. When I was kid I lived in a small town so there were not much light pollution. Thus I could see the milky way band during clear nights. The band consists of stars which our eyes cannot differentiate and seems fuzzy. These stars extend over the horizon giving the appearance of a band. Above is one of the many beautiful pictures you can find in internet of the milky way band. It is one part of the galaxy we reside in. Today I want to talk a little about our home galaxy. 

 

An artistic illustration for our galaxy. http://apod.nasa.gov/apod/ap050825.html

 

 

 

 

Milky way galaxy is a barred spiral galaxy. You can see  artistic illustration  in the above picture. It is composed of spiral arms and a central bulge.The central bulge has a massive black hole. Since this bulge is very dense we cannot even see the centre of our galaxy. Thus, we cannot see the other side of the galaxy. Our galaxy contains about 200 billion stars and, it also contains lots of gas and dust to create billions of more stars. It has a diameter of 31 to 37 kpc. 1kpc is nearly equal to 3*10^16km which is a huge number.

The scale of size in astronomy is very interesting as well as frustrating at times. It is very difficult to comprehend the size scale in case of astronomical objects. I have linked a video which try to give you the idea of how huge the stars are. Thus might help you to understand the size scale.

http://www.youtube.com/watch?v=HEheh1BH34Q 

Also I am liking the blog by Brandon Kuschel where he has talked about the size of the universe. http://astrorad14.blogspot.com/2014/01/scale-of-universe.html

Our solar system is out of the central bar. Here is an illustration of the location of our solar system in the galaxy. Our solar system is revolving around the centre of the galaxy at the speed of 220 km/s.  

 Our sun is an average mass star and around 4.6 billion years old. About half of the stars in our galaxy are older than our sun. Most common stars are red dwarf in our galaxy. These are cooler and less massive than  the sun. The oldest star known in our galaxy is older than 13.6 billion year.

Even though our galaxy is huge, we are part of even bigger structure, called the cluster of galaxies. And we belong to Virgo cluster. And there are many such clusters. It is amazing how huge the universe is. 

Let's not stop looking at the vast and amazing night sky.

Astrophotography

While many of the most famous images in astronomy (for example the Pillars of Creation) have been taken by very expensive telescopes like Hubble, that is not to say that amateurs can not take very beautiful images as well.  As Richard pointed out in his post on Sunday, not everything needs to be observed with a large telescope.  In fact, large, expensive telescopes can miss rare events simply because there are relatively few of them observing at one time.  In other words, you can't look everywhere at once.

That is where amateur astronomers come in.  Thanks to the magic of the Internet, you can find where in the sky to look to see events like meteor showers, conjunctions (eg. two planets appearing to come together in the sky), and transits (eg. a planet passing in front of the sun).  I am particularly fond of SpaceWeather.com, which also lets you know when to look out for aurorae and posts some amazing images.  One of those images that I remember in particular was of a transit of the International Space Station.  The picture I remember was of a transit across the sun rather than the moon (there are actually quite a few of those in Google images results), but the interesting part is that these were done by an amateur using a small (10") telescope and a video camera.  He even has a website dedicated to ISS transits with several more photos and videos.

Probably the best website for an introduction to astrophotography is called Catching the Light.  It includes guides on how to use a DSLR for astrophotography, processing images in Photoshop, and image galleries (which are definitely worth checking out even if you aren't interested in the rest).  I picked out my favorite picture from the DSLR showcase gallery to show just how good these look.  Yes...that is an amaeur image (of M31 Andromeda).  The description of the equipment used, exposure, processing, etc. is here if you are interested.

My own attempts at astrophotography have been rather less successful, to say the least.  This could mostly be attributed to the fact that I attempt to use the lenses I already own rather rather than buying a proper telescope mount.  Given that fact, the only truly successful shoot I've had was during a partial solar eclipse on May 20, 2012.  A word of caution:  Don't point your camera directly at the sun!  I was using an R72 filter, which blocks out light with a wavelength shorter than 720nm.  It looks nearly black because that is what is visible to the human eye.  Also, most cameras have a built-in filter to block out infrared, so almost no light was getting through, making it safe for me to take pictures of the sun.  Mostly to prove I can do better than a featureless photo of the sun, here is my 500px page, which is in desperate need of updating.

Our earth, from space

This image was just released from NASA’s Curiosity rover on Mars:

http://www.universetoday.com/109095/you-are-here-curiositys-1st-photo-of-home-planet-earth-from-mars/#ixzz2sb2glJ8U

Clicking on the image will bring you to the Unvierse Today article where you can continue to enlarge the image. Once you enlarge it, zoom in as far as you can and you will find the following image (or something very similar to it):

The bluish-white dot is Earth, is “us”. The slightly grey splotch beneath Earth is the Moon. Yes, our “large” satellite (in astronomy an object that is gravitationally bound to and orbiting another, larger object is referred to as a satellite). It really is just amazing if you think about it: there is a man-made machine ON ANOTHER PLANET (!) that just took a picture of us from space. For some reason that just blows my mind.

It reminded me of the image taken last summer by Cassini, the spacecraft orbiting Saturn:

This made me ponder about other images of Earth from space. I dug this up from www.planetary.org:

The picture caption on the site states the following:

“This picture of a crescent-shaped Earth and Moon – the first of its kind ever taken by a spacecraft – was recorded Sept. 18, 1977, by Voyager 1 when it was 11.66 million kilometers (7.25 million miles) from Earth. Image credit: NASA/JPL.”

We have come a long way since 1977, but it is still just as beautiful and incredible to see and ponder about. When I talk with non-astronomers about space, I always try to emphasize just how vast it is; space sure seems large (and empty) in these pictures.

Bill Nye the science guy vs creationism

I guess many of you heard about the debate between Bill Nye and Ken Ham.

I have linked the video below.
 http://www.youtube.com/watch?v=z6kgvhG3AkI
It is a debate of evolution vs creationism. Now it is sad that we still need to have this debate. When I heard this the first thing that came to my mind was, why  Bill Nye was doing it? I felt that this will give many people a viewpoint that evolution is a debatable topic. Still I decided to watch it.
Then I thought for some time and realized how important it is to have these debates. In CNN they talked about the same debate and showed a poll where 33% people in the US don't believe in evolution. While looking for information regarding this kind of debate, I found the gallup poll.
http://www.gallup.com/poll/21814/evolution-creationism-intelligent-design.aspx

In the  poll you can see still 46% of people believe that man was created in the current form. There are many such surprising results in the poll. So we can see still many people do not believe in evolution.
 I think most confusion arises due to the way words are used in scientific community and in general language. For example people think that scientific theory means something that is not a fact. Like hypothesis we propose in science. So it is important for a famous person like Bill Nye to convey these differences or at least try to do so. I thought Bill Nye did good job in this debate. If you listen to the debate, he never tried to attack a belief system, he just presented the facts regarding evolution to the general public. He gave good examples to prove evolution and age of earth. He tried to convince those 46% to at least think about scientifically proven theory of evolution and age of the earth.

The Eclipses of 2014

Even though it is February already, the year has only just begun. With that, comes the prime opportunity to mark our calendars for some pretty cool (predictable) events; eclipses.

Side note: There are some pretty cool unpredicted events that happen such as a Coronal Mass Ejection or solar flares that is directed toward Earth to cause the aurora in places like the northern states of the contiguous US. For those, you just have to watch and wait. Check out the Solar Dynamics Observatory webpage from time-to-time to check out how our sun is doing (and they have some cool images and videos too).

Eclipses: There will be 4 eclipses this year.

April 15th: Total Lunar Eclipse

This eclipse will be spectacular if you live within the dark shaded region of the image on the left (Europe, Asia and part of Africa) The level of shade indicates regions of visibility. The darkest areas are where you will see the total eclipse. The least shaded is where you will see no eclipse. Every where in between, you will see partial eclipses.

The times are given in Universal Time (UT). For example, Denver is in MDT which is -6 hours from UT during these eclipses. If we were able to see this eclipse, it would peak at 07:45:40 UT - 6 = 01:45:40 MST, which is at almost 2 in the morning.

April 29th: Annular Solar Eclipse

f you live in Australia or happen to be down in Antarctica during this event, you will see a rare one as this eclipse is classified as a non-central annular eclipse. According to Espenak and Messus (2006), out of the 3,956 annular eclipses occurring during the 5,000-year period (-2000 to +3000), only 68 of them or 1.7% are non-central.

This eclipse starts at 05:57:35 UT, peaks at 06:03:25 UT, and ends at 06:09:36 UT.




October 8th: Total Lunar Eclipse

Africa will take center stage for this beautiful eclipse. North America will be able to partially see this one, unlike the last one in April. In Denver, it will occur at 04:54:36. Better have some caffeine ready.





October 23rd: Partial Solar Eclipse

This eclipse will likely draw the most attention as it will be widely visible from the US (including Denver!). The eclipse begins at 19:37:33 UT, peaks at 21:44:21 UT, and ends at 23:51:40 UT. For the eastern half of the US, this will be a sunset eclipse. Get your cameras ready!

While this eclipse is only a partial solar eclipse, just remember always: NEVER STARE DIRECTLY AT THE SUN! No one needs to go blind. Make sure to wear "eclipse glasses" or use the pinhole projection technique.

Local observatories will likely have an open-to-the-public viewing events, so check your local news!


Information about these eclipses was gathered from the NASA Eclipse WebSite. Go check it out for further information about these eclipses and other cool space news!