Category: Science

Astronomy – The Next Generation

Astronomy is perhaps the most ubiquitous of human endeavors. Regardless of time or location, people have studied the night sky for an understanding of the universe. All five continents contain ancient sites used for astronomical purposes. From the ancient Egyptians noting the simultaneous rising of Sirius and the Sun to predict seasonal flooding, Chinese observation of the supernova that produced the Crab Nebula on July 4, 1054, Islamic astronomers high-precision measurements of celestial objects for time-keeping, astronomy has been a truly multi-cultural endeavor. The next generation of 30-meter telescopes promises to continue that heritage.

During the 20th century, large scale astronomy was dominated by the United States.  When the 200-inch Mt. Palomar telescope opened for business in 1948, the next largest telescope outside the U.S. was the 74-inch David Dunlap Observatory just north of Toronto.  The two World Wars created economic chaos across Europe and Asia.  At the same time, the vision of George Ellery Hale enabled the U.S. to surge ahead of the world in building large telescopes.  These two factors conspired to cause a listing of astronomy research towards the U.S. during this period.

From 1897 to 1993, the largest telescope in the world would be one designed by George Ellery Hale*. The first would be the 40-inch refracting telescope at Yerkes Observatory. This remains the largest refractor in the world. The final would be the 200-inch reflecting telescope at Mt. Palomar. In between was the 100-inch telescope at Mt. Wilson where galaxies outside the Milky Way and the expansion of the universe was discovered. These telescopes stretched the limits of the single mirror design.  A new type of mirror was required to construct larger telescopes, and the segmented mirror was the answer.

The 10-meter Keck Observatory in Hawaii ushered in the era of the segmented mirror design. The next generation of 30-meter telescopes, due to commence operations in the next decade, will radically expand Earth-based observatory capabilities.  In fact, these giant mirrors, combined with adaptive optics technology to remove atmospheric turbulence from their imaging, promise to have resolution capabilities several times that of the Hubble Space Telescope.

The first question one might ask is what is a segmented mirror? Lets take a look at the image below:

Credit: Palomar Observatory/California Institute of Technology

This is the 200-inch (5 meter) Palomar mirror as it is removed to be aluminized. Its total area is about 20 square meters. Single mirrors larger than this are problematic as the weight requires a massive support structure. Another factor is economics.  When the Keck Observatory was in the planning stage during the late 1970’s, a 10-meter mirror was estimated to cost $1 Billion ($2.9 Billion in 2015 dollars).  Funding prospects for that amount were rather bleak.

Now take a look at the mirror below:

Credit: This image was created by Prof. Andrea Ghez and her research team at UCLA and are from data sets obtained with the W. M. Keck Telescopes.

This is the 10-meter Keck mirror. As you can see, rather than a single mirror like Palomar, it consists of 36 hexagonal segments 1.8 meters wide. Each mirror segment is also very thin at 75 mm. The impact is two-fold as the total weight of the Keck mirror array is the same as the single Palomar mirror. As a result, the cost of the Keck Observatory was reduced to $270 million. The cost reduction enabled the Keck Observatory to obtain funding from the William M. Keck Foundation in 1985. When the Keck I opened in 1993, it was the first non-Hale telescope to become the world’s largest in 96 years.

The video below has an inside look at the Keck and its accomplishments:

Since the Keck, the Gran Telescopio Canarias 10.4-meter telescope was built in the Canary Islands as well as the 9.2-meter South African Large Telescope (SALT) in the Northern Cape region. The Gran Telescopio Canarias became the first world’s largest telescope outside the United States since the 1800’s. That telescope was funded mostly by the government of Spain, along with minor contributions from Mexico and the University of Florida. The SALT was funded by a partnership between South Africa, United States, Germany, Poland, India, United Kingdom and New Zealand. The next generation of telescopes will continue the trend of international partnerships for funding.

The success of the segmented mirror has prompted the design of 25-39 meter telescopes. This is an expansion of telescope size unprecedented is in modern times. Thirty years after the 100-inch Mt. Wilson telescope was built, the 200-inch Mt. Palomar telescope doubled aperture size for the world’s largest telescope. The planned 39-meter European Extremely Large Telescope (E-ELT) will nearly quadruple Keck’s mirror size in the same time frame.  Three telescopes of this class are set to commence operations in the next decade and they are:

The Giant Magellan Telescope (GMT)

The design of this telescope is quite interesting as it uses the upper end of monolithic mirror design as the basis for a segmented mirror.  The GMT will package seven 8.4 meter mirrors into an array 24.5 meters wide.  The telescope will be located at Las Campanas Peak in the Atacama Desert.  The total cost will be $1 billion and funding is provided by the Carnegie Institute for Science (who also funded both Mt. Wilson and Mt. Palomar), Smithsonian Institution, and several American, Australian, Korean, and Brazilian universities.  The GMT will begin observations in 2021 and will be fully operational in 2024.  The image below provides a good perspective on the size of the mirror array:

Credit: Giant Magellan Telescope – GMTO Corporation.
Credit: Giant Magellan Telescope – GMTO Corporation.

Thirty Meter Telescope (TMT)

This telescope will be located in Hawaii on the summit of Mauna Kae where the Keck Observatory is located.  Appropriate from an astronomy standpoint, as the TMT is the successor to Keck in that its mirrors will consist of 492 segments 1.44 meters wide.  The location has also become problematic as a result of protests by indigenous Hawaiians who consider the peak of Mauna Kae to be a scared site.   The protests have stopped construction for now.  While its more than likely the 18 story high TMT will eventually be built, its unknown what impact the current impasse will have on its planned timeline to be completed in 2024.  The TMT is expected to cost $1.4 billion to build and is funded by a consortium including Caltech and partners from China, India, Japan, Canada.

Credit: Courtesy TMT International Observatory

European Extremely Large Telescope (E-ELT)

The E-ELT will be the granddaddy of the next generation of telescopes.  Like the GMT, the E-ELT will be located in the Atacama Desert in Chile.  Its mirror will be 39 meters wide and consist of 798 hexagonal mirrors each 1.45 meters wide.  The cost of the E-ELT is expected to be 1.1 billion Euro.  The telescope will be funded by the European Southern Observatory with contributions from its 16 member nations.  Currently, the member nations are all from Europe with pending applications from Poland and Brazil.  First light is expected in 2026.  An artist conception of the E-ELT is below.  It is an ideal site to observe the Milky Way.

Credit: ESO

Why Chile?

The northern Chile desert provides the desired combination of dry air, high altitude, and lack of light pollution.  Currently, the ESO operates the Very Large Telescope (VLA) in the Atacama Desert.  The VLA has four telescopes each with 8.2 meter mirrors.  Also located there is the large 66 antennae ALMA radio telescope array which is run by a consortium consisting of the United States, Canada, Japan, ESO member states and Chile.  The  Astronomical Tourism website has a list of the remarkable number of observatories in Chile here.  Among some of the advantages of being in the Southern Hemisphere is that the Milky Way can arch overhead making it a very easy target to observe.  By 2025, it is expected that half of the world’s observing power will be located in Chile.  Below is a video that demonstrates the awesome clarity of the Chilean skies.

Expected Performance

All three observatories will utilize adaptive optics system.  This is a means to eliminate the twinkle in stars caused by atmospheric turbulence during observations.  While the twinkling of stars can have great aesthetic value, it hampers the performance of a telescope.  Adaptive optics works by shooting a laser into the sky near the observation target.  This laser excites sodium atoms located about 60 miles above the Earth’s surface.  The excited atoms then release the energy in the form of light causing an artificial star to be created in the sky.  The artificial star is used as a baseline to measure atmospheric turbulence.  This in turn is used to adjust a small deformable mirror in the instrument package of the telescope.  This deformable mirror removes most of the twinkling from the observed object prior to being imaged.  The picture below shows the galactic center before and after adaptive optics from the Keck Observatory is applied.

Credit: Keck Observatory and the UCLA Galactic Center Group

The large mirrors combined with adaptive optics is expected to give these telescopes resolution several times that of the Hubble Space Telescope.  In fact, the E-ELT is expected to provide 15 times the resolution ability of the Hubble.  To put the E-ELT in proper perspective, this telescope will collect more light than all the existing 8-10 meter telescopes combined.  Among the science objectives of these telescopes will be to peer into the farthest regions of the universe to study the first galaxies formed to the detection of Earth-sized planets and characterization of exoplanet atmospheres.  The latter could possible provide evidence of bio-signatures.

The cost of this science is not cheap.  However, it is not more expensive than other large scale infrastructure projects.  For example, the total cost of the three new observatories combined ($3.5 billion) is identical as the new Detroit-Windsor bridge to be built during the same period.  Nonetheless, the cost of large observatories are now on the scale that international partnerships must be used for funding. American society, competitive as it is, tends to fret when it comes to the possible loss of a dominant leadership position in any given field.  However, this recent development simply puts astronomy back at its natural state.  Rather than being an American endeavor, large scale astronomy research is now a global venture, just as it was during ancient times.  And that is exactly as it should be.

*There were other telescopes larger than Yerkes in 1897 such as the 72-inch Leviathan of Parsonstown, but those had fallen into disrepair and were no longer in use.

**Image on top of post is the E-ELT compared to the VLA and Statue of Liberty.  Credit:  ESO.

Pluto – Round Two

The images released today from New Horizons indicate the presence of carbon monoxide on the surface, possible wind erosion features, and the atmospheric loss of nitrogen.

In the heart shaped region of Pluto (dubbed Tombaugh Regio for now), New Horizons mapped a region of solid carbon monoxide ice.  Right now, it cannot be determined how extensive the carbon monoxide is.  It might be a sheen on the surface or it might be several meters deep.  We’ll find out more as the rest of New Horizons data comes in.  A map of the carbon monoxide ice is below:

Credit: NASA/JHUAPL/SWRI

Carbon monoxide (CO) differs from carbon dioxide as it only has one oxygen atom in its molecule instead of two.  Unlike carbon dioxide, CO is not a greenhouse gas.  That aside, carbon monoxide is pretty nasty stuff to be around.  If you live in a house that does not ventilate well, carbon monoxide poisoning is a serious threat.  On Earth, CO is emitted into the atmosphere by inefficient burning processes. This includes combustion engines and industrial emissions along with burning of forests.  Burning in the Amazon and in Africa releases large amounts of CO on a seasonal basis as can be seen on NASA’s Earth Observatory time lapse map of CO.

Unlike Pluto, we do not experience CO as an ice on Earth.  The freezing point of CO is -3370 F (-2050 C), so one has to go out into the furthest regions of the Solar System to see it in that form.  Comets originate from that region and have CO ice.  The gas in Halley’s Comet’s tail emanating from its solid nucleus during its last pass in 1986 was measured to be 10% CO.  Occasionally, Earth will pass through the tail of Halley’s Comet such as on the night of May 18, 1910.  However, the material in the comet’s tail is much too tenuous to have any effect on life.  The New York Times report on the events of that night can be found here.

CO gas does exist beyond the Solar System in the plane of the Milky Way.  Galactic CO was mapped by the ESA Planck mission and the results are below.  Where there is CO, there is hydrogen gas in far more abundance.  CO radiates more readily than hydrogen and serves as a useful guide for mapping galactic gas clouds where star formation occurs.

Credits: ESA/Planck Collaboration

Also within Tombaugh Regio, this interesting image was released:

Credits: NASA/JHUAPL/SWRI

Which might remind you of what you see in your backyard after a dry spell:

Image: Wiki Commons

As mud dries, it contracts and begins to crack.  A similar process on a much larger scale may have caused the segment formation on Pluto.  Another process that is theorized is the formations are caused by convection below the surface.  Subsurface heat would cause the ground to bubble up.  Right now, the data is too fresh to know for sure which geologic process caused these formations.  As more and more data comes in (only 1 gigabyte of 50 has been received from New Horizons), scientists will get a better handle on what exactly is going on here.

Credit: NASA/APL/SwRI

The final discovery announced today was the atmospheric loss experienced by Pluto.  Atmopsheric loss occurs when molecules attain escape velocity.  The lighter the molecule, the easier it is for heat to accelerate it enough to escape into space.  Mercury practically has no atmosphere as its closeness to the Sun imparts enough heat energy to any gas molecule on the surface to escape.  Both Venus and Mars lack the magnetic field Earth has which allows the solar wind to directly interact with the atmosphere and drag it away just like you see above with Pluto.  The video below describes the process on Venus:

Earth loses 50,000 tons of atmosphere a year.  Most of it is hydrogen and helium.  As these are the two lightest of the elements, they most easily reach escape velocity and leave our planet.  Worry not, at that rate, the Sun will turn into a red giant and swallow the Earth five billion years from now before our atmosphere is lost.

Pluto is losing atmosphere at a rate of 500 tons an hour or over 4,000,000 tons a year.  Projected over the course of Pluto’s lifetime, that equates to over a thousand feet of nitrogen ice lost.

As mentioned before, Pluto is pretty cold.  How does the nitrogen in its atmosphere acquire enough energy to escape.  At the mission update, it was explained that the greenhouse gas methane may trap just enough heat to give nitrogen atoms a boost into space.  The other part of the equation is Pluto’s small mass, only 0.002 of Earth’s.  This means Pluto’s escape velocity is 1.3 km/s compared to Earth’s 11.2 km/s.  Thus, it is much easier for nitrogen to escape Pluto than it is to escape Earth.  Pluto lacks a significant magnetic field and direct contact with the solar wind accelerates atmospheric loss.

One of the most important aspects of studying astronomy is to gain a greater perspective on Earth.  Looking at the atmospheric loss on Pluto and other planets in the Solar System, it can give a greater appreciation of the role the magnetic field here on Earth plays in protecting life.  The Pluto flyby is a great adventure, but it also goes to show, there is no place like home.

*Image on top of post is best Hubble image of Pluto vs New Horizons image. Credits: Hubble: NASA / ESA; New Horizons: NASA / JHU-APL / SWRI

Pluto and Earth

The first thought I had watching the press conference on the initial images from the New Horizons flyby of Pluto was how much accessible these events are to the public than in the days of Voyager.  During the 1980’s, unless you had a NASA press pass, you did not get to watch mission updates live.  No twitter feeds to tell you right away when telemetry is being received, no websites to go back and review the images at your leisure.  And you had to wait at least a year, maybe more, for astronomy textbooks to be updated.  What you got was short segments on the nightly news such as this:

One of my favorite teaching techniques is to compare the surface features of planets to things we are familiar with here on Earth to give it proper perspective.  And that seems to me to be a good place to start with the first images released today.

Lets begin with the mountains located near the now famous heart-shaped region of Pluto.

Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute

This image was taken while New Horizons was 77,000 km away from Pluto.  That’s 10 times farther away than the closest approach and gives a good idea what to look forward to as more images are released.

The tallest of these mountains are about 11,000 feet (3,500 m).  How does this compare to Earth?  These are less than half as tall as Mt. Everest which clocks in at 29,029 feet.  Still, pretty impressive mountains considering how small Pluto is.  The height of these mountains are similar to Mt. Hood in Oregon.

Image: Wiki Commons

The first age estimate of these mountains are about 100 million years.  That sounds pretty old.  In fact, dinosaurs were roaming around on Earth when these mountains formed.  In geological terms, this is pretty young, only 2% the age of the Solar System (4.5 billion years).  How do we know these mountains are young?  By the lack of craters in the region.  The less craters there are, the younger a surface is.  These mountains are younger than the Alps which are 300 million years old.  They are older than the Himalayan Mountains which formed as the Indian Sub-Continent plowed into Asia 25 million years ago.

Mountains on Earth are the result of plate tectonics.  At this very early juncture, planetary scientist have their work cut out for them as none of the current models can account for such mountain formation on an icy outer Solar System body in the absence of tidal flexing.  It is thought that the mountains are regions of water-ice bedrock poking through the methane ice surface.  Methane ice is too weak to build mountainous structures.

Below is Pluto’s largest moon Charon:

Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute

The outstanding feature here is the large canyon in the upper right corner.  This canyon is 4 to 6 miles (7 to 9 km) deep.  The Grand Canyon’s greatest depth is a little over a mile.  This channel is comparable to the deepest reaches of the Pacific Ocean, the Mariana Trench, that lies about 6.8 miles below sea level.  It’s interesting to consider than more humans have walked the surface of the Moon (12) than have reached the bottom of the Mariana Trench (3).  To be fair, no nation has ever decided to spend $150 billion (2015 dollars) and employ 400,000 people to reach the Mariana Trench, such as the United States did during the Apollo program.

This image maps methane on the surface of Pluto.

Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute

The New Horizons press release describes the greenish area of Pluto’s North Pole as methane ice diluted in nitrogen ice.  Does that sound odd?  Typically, we see neither of these substances in a solid state on Earth.  Methane and nitrogen are known as volatiles, which means they take gaseous form at room temperature.  As you may have surmised, Pluto is not at room temperature.  The freezing point of methane is -295.60 F (-1820 C) on Earth.  The freezing point of nitrogen is even lower at -3460 F (-2100 C).  These figures are lower on Pluto as the atmospheric pressure does not match that of Earth.  The temperature of Pluto ranges from -3870 to -3690 F (-2330 to -2230 C).  Yeah, the outer reaches of the Solar System are pretty chilly.

In our day to day lives, you may be familiar with methane as the main component of natural gas.  You may have learned about it first as a source of middle school humor.  While methane is a gas on Earth, the Saturn moon Titan is cold enough for it to be a liquid.  Below is an image of methane lakes on Titan.  Instead of raining water, you could dance in the methane rain on Titan.  Earth and Titan are the only bodies in the Solar System to have stable liquid lakes on the surface.

Credit: NASA/JPL-Caltech/ASI/USGS

Neptune has trace amounts of methane in its atmosphere.  Methane has the property of absorbing red light and scattering blue light.  The result is the rich blue hue of Neptune as first seen in the 1989 Voyager flyby:

Credit: NASA

Methane also absorbs infrared light at certain wavelengths.  The methane profile image of Pluto was produced by measuring infrared absorption from surface methane.   When methane absorbs infrared light at these wavelengths, the infrared energy is converted in vibrational motion in the molecular bonds.  Once the molecule settles down, the energy is released back out as infrared light.  We cannot see infrared light, but we feel it as heat.  In the atmosphere, some of this heat is directed back towards the Earth, warming the surface.  In other words, methane is a greenhouse gas like carbon dioxide and water vapor.

And for that, we should be grateful.  Without greenhouse gasses, the Earth would be 600 F colder (like the Moon), and human life would not be possible.  However, you can have too much of a good thing.  As temperatures rise in the Arctic warming up the permafrost, methane that has been locked up for thousands of years as frozen, undecomposed plant life, could be released into the atmosphere.  When you consider the Arctic region has been most affected by rising global temperatures, then you can understand why climate scientists are concerned about this scenario.

On Friday, New Horizons should be releasing the first color images from the flyby.  Should be quite an interesting week.

*Image on top shows part of Pluto’s heart region the mountain closeup was taken.  Credit:  NASA

Success!

As expected, New Horizons ended its blackout period at 8:53 PM EDT tonight and verified the flyby of Pluto was a success.  All systems are nominal, which is to say running as it should.

If you were watching the flyby confirmation on NASA TV, the acronym MOM refers to the Mission Operations Manager.

NASA will have a presser from 3-4 PM EDT on NASA TV.  It is expected some of the first images downloaded from the flyby event will be presented.  These will be black and white images from the LORRI camera.  Color images take a bit longer to process and should be available for release later this week.

Congratulations to the New Horizons team!  Very much looking forward to sharing the results with my students.

*Image on top of post is false color representation of Pluto and its largest moon Charon.  This image was taken just prior to the blackout period during the flyby.  If you were flying along with New Horizons, this is not how you would see these two bodies.  False color is put into the image to allow are eyes to more easily discern differing regions.  Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute

Showtime for New Horizons

New Horizons has now entered its planned quiet mode in preparation for its big day on July 14th as it makes its closest approach to Pluto at 7:49 AM EDT.  We will not hear back from the spacecraft until 22 hours later around 9 PM EDT tomorrow.  So what to expect tomorrow and the upcoming week?  Emily Lakdawalla from the Planetary Society has a very detailed rundown that you can read here.  Below is a general timeline of events.

Patience will be a virtue.  New Horizons was built before the age of social media and is not sending Instagram pics.  If all goes well, there will be a tremendous amount of data to download across the Solar System and that will take time.  Keep in mind, even traveling at the speed of light, it will still take 4 1/2 hours for transmissions to reach Earth from Pluto.

New Horizons must either collect data or send it back to Earth.  It cannot do both simultaneously.  Consequently, New Horizons will spend July 14th diligently gathering data as it makes its closest approach to Pluto.  And that is why New Horizons will be quiet for 22 hours until Tuesday night.  Images should start to come in on Wednesday, July 15th.  The mission timeline is as follows:

July 14th – 8:53 PM EDT, New Horizons scheduled to signal Earth the flyby was completed successfully.

July 15th – LORRI images (black & white) start to download along with data from ALEX, REX, and SWAP instruments (see below).

July 16th – first color images from Ralph instrument package to arrive.

July 20th – data will continue to download until this date.  The data package received from July 15-20 is high priority science & public interest data and will represent a small percentage of total New Horizons data.

September 14th to November 16th – After a quiet period of 8 weeks, New Horizons will download compressed data set.

November 2015 to November 2016 – New Horizons downloads uncompressed data set.

A few of the highlights:

NASA TV will begin flyby coverage at 7:30 AM EDT on July 14th.  You may watch online here.

New Horizons has an excellent Twitter feed.

New Horizons has two websites, one from NASA, and the other from the John Hopkins Applied Physics Laboratory where mission operations are based.

The seven instruments at work are the following:

Long Range Reconnaissance Imager (LORRI) – this basically takes wide angle black & white shots of Pluto.  NASA intends to release these images close to real time as they arrive.

Ralph – this is the instrument that takes color images of Pluto.  It will take longer for NASA to release these images due to processing time.  This instrument will map the surface of Pluto by taking stereo images and search for organic compounds among its many functions.

Alice – this is an ultraviolet spectrometer that will study the composition of Pluto’s atmosphere and attempt to detect an ionosphere (upper part of the atmosphere where particles are ionized by solar radiation).

Radio Science Experiment (REX) – will measure temperature and pressure in Pluto’s atmosphere.  This instrument will be used after the flyby as it must be pointed towards the direction of Earth while in use.

Solar Wind Around Pluto (SWAP) – will measure the loss of Pluto’s atmosphere as a result of its weak gravity field.  As the atmosphere escapes into space, it is ionized by solar radiation and carried away from Pluto by the solar wind.

Pluto Energetic Particle Spectrometer Science Investigation (PEPSSI) – this instrument basically performs the same function as SWAP, but measures higher energy atmospheric particles escaping Pluto into space.  The combination of PEPSSI and SWAP will provide a comprehensive profile of Pluto’s atmospheric interaction with the solar wind.

Venetia Burney Student Dust Counter (SDC) –  Venetia Burney was the eleven year old girl who named Pluto shortly after its discovery in 1930.  This instrument has been measuring dust grain properties throughout New Horizons’ voyage and will provide a dust profile of the Solar System.  This dust is a result of collisions of various Solar System bodies.

After the Pluto flyby, the mission team will select a Kuiper Belt object to head to.  This flyby will take place in 2019.  The voyage continues.

*Image at top of post is the mission operations center that will receive the data from New Horizons.  NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research

Why is Pluto Red?

The short answer to the question posed in the title of this post is the surface of Pluto is covered by tholin, not to be confused with Star Trek’s Tholians.  The word was first coined by Carl Sagan in 1979.  It is derived from the Greek word tholos for muddy, due to the texture of this substance that Sagan was able to produce in laboratory experiments.  Tholin is not produced naturally on Earth as oxygen would break it apart in the atmosphere soon after its formation.  However, it is possible for tholin to have been produced early in Earth’s history and may have played a key role in the formation of life.

Tholin is found on some bodies located in the outer Solar System, notably Saturn’s moon Titan, Neptune’s moon Triton, and Pluto.  As tholin no longer occurs naturally on Earth, the study of these objects may allow us to acquire key information on the chemical processes that occurred early in our planet’s history.

The chemical process that produces tholin is fairly complex.  Ultraviolet light and negative ions (electrons) combine to breakdown methane (CH4) and nitrogen (N2) molecules in the atmosphere.  Natural gas that we use to heat our homes during the winter is mostly methane.  Through a series a chemical processes, tholin is formed and falls onto the surface as a reddish, gooey type substance.  Below is how tholin appears when produced in a laboratory:

Credit: Chao He, Xinting Yu, Sydney Riemer, and Sarah Hörst, Johns Hopkins University

The reddish tinge in Titan’s atmosphere is thought to be a result of the presence of tholin.  Below is an image of Titan taken by the Huygens probe as it descended towards its surface in 2005.  Huygens was originally part of the Cassini spacecraft that has been exploring the Saturn system for the past 11 years now.  As a side note, this is still the most distant landing from Earth successfully attempted by any space mission.

Credit: NASA/JPL

So why is this important and why did Carl Sagan spend several years researching this stuff?  When tholin is on the surface of a body, and there is water present on the surface, it dissolves and forms amino acids that are the building blocks of life.

The atmosphere of the young Earth was not anything like we enjoy today.  A half billion years after Earth’s formation, the atmosphere was dominated by the outgassing of volcanic activity and the Earth was covered with a blanket of carbon dioxide and methane.  At the same time, water began to form on the surface.  These conditions would have been ripe for the formation of tholins on Earth and the eventual breakdown into amino acids in the oceans.  How exactly this could have led to life on Earth is not completely understood at this point.  And that is why astrobiologists are very keen to study places where tholins are naturally present.

To learn more about the search for life in space and how it was formed on Earth, NASA’s Astrobiology website is a good start.  At Cornell University, the recently formed Carl Sagan Institute’s purpose is to continue Sagan’s quest to find life beyond Earth.  Their website can be accessed here.

*Image of Pluto at top of post.  Credit:  Credits: NASA/JHUAPL/SWRI

Sigh…No, We are Not Headed for a Little Ice Age

A recent report by Professor Valentina Zharkova does not predict a mini-ice age as has been publicized by popular media.  In fact, nowhere in the RAS press release is that stated.  What Dr. Zharkova does predict is that the solar cycle will resemble the Maunder Minimum when there was little solar activity. During the same time, both Northern Europe and North America suffered cold weather referred to as the Little Ice Age from 1300 to 1850.

This prediction is the result of modelling solar activity with two solar dynamos rather than with one.  Both these dynamos have cycles of activity. When two cycles offset, they cancel each other out.  Zharkova’s model predicts the activity from the two solar dynamos will cancel each other out between 2030 and 2040.  This is referred to as destructive interference and an example can be seen below:

Credit: NASA

The Maunder Minimum was a period of little solar activity and as a result, very few sunspots were observed on the Sun’s surface:

Credit: NASA

Can the same Little Ice Age climate event be extrapolated if the Sun goes into a similar quite period?  The answer is no.  Atmospheric conditions on Earth today are much different than during the nascent Industrial Age.

Credit: NASA

Both carbon dioxide and methane are greenhouse gasses.  That is, they trap heat at the Earth’s surface in the same manner a blanket traps bodyheat on your bed at night.  Carbon dioxide levels have increased 60% and methane has increased by 300% in the atmosphere since 1750.  And the trend is to keep increasing.  For the sake of argument, if we were to cap carbon dioxide at today’s level of 400 parts per million, what would happen?  Global temperatures would still rise 0.80 C (or 1.40 F) over the next few decades as the oceans continue to release heat trapped during the prior warming phase.  How much would a return of the solar cycle to Maunder Minimum conditions reduce global temperatures?  The drop would be 0.10  C globally.  Not nearly enough to offset the effect of current greenhouse gas levels in the atmosphere, and not nearly enough to offset the most conservative expected increase of 1.00 C (or 1.80 F) over the next three decades.

This is very poor reporting of Valentina Zharkova’s work.  A return to Maunder Minimum conditions refers to sunspot levels.  There is no reason to expect a change to the Little Ice Age climate conditions.  It’s unfortunate, if  Zharkova’s predictions hold out, it represents a great discovery in solar physics and will allow more accurate modelling of solar activity and space weather.  No small feat, as space weather does have potential damaging effects on electrical systems both in space and on Earth.  And that is the true ramifications of this model.

*Image on top of post is a frost fair on the River Thames during the Little Ice Age.

New Horizons Updates

New Horizons is getting close enough to detect geological features on the surface of Pluto.  Below is an image released on July 10th.

Credit: NASA

Craters are an indication of the age of the surface of a planet (or in this case, dwarf-planet).  The more craters there are, the older the surface.  The less craters there are, the younger the surface and it is an indication of active geological processes on that surface.

Lets take a look at a celestial body we are familiar with, the Moon.

Credit: NASA/Sean Smith

The bright, highly cratered areas are referred to as the highlands.  The surface age here ranges from 4 to 4.5 billion years old.  The darker, less cratered areas are referred to as mare regions.  These surfaces are about 3.5 billion years old.  Why are the mare regions younger than the highlands?  The mare regions were formed by large impact events that caused lava to flood these areas and eventually solidify into basaltic rocks.  This process wiped out the original cratered surface that existed before the impact events.

The Earth’s surface has very few craters due to a variety of geological processes.  This would include plate tectonics along with both wind and water erosion.  One crater that has been preserved, so far, is the Meteor Crater in Arizona.

Credit: USGS/D. Roddy

The dry climate (and lack of water erosion) has preserved this crater since the impact that created it 50,000 years ago.  Keep in mind, that is very young geologically speaking.  The Arizona Meteor Crater is only 0.0014% the age of the lunar mare regions.  One can visit the Meteor Crater and details on that are here.

The expectation is that Pluto will resemble the Neptune satellite Triton as both are about the same size.  Pluto is a Kuiper Belt object while Triton is a Kuiper Belt object that was captured by Neptune’s large gravity well.  Voyager 2 visited Triton in 1989 and this is what it saw:

The surface of Triton is lightly cratered and is estimated to be about 10 million years old.  Still pretty young, as that is about 0.3% the age of the lunar mare regions.  Voyager detected geyser like formations that vented nitrogen gas onto the surface.  This type of cryovolcanic activity is suspected to be the responsible party for Triton’s young surface.

How will Pluto compare?  We’ll know next week and the following months as images continue to download from New Horizons.  Keep in mind, the less craters there are, the more active the surface is.

*Image on top of post is artist conception of New Horizons flyby.  Credit:  NASA.

Hubble’s Successor and the Man it’s Named After

In 2018, NASA is scheduled the launch the James Webb Space Telescope (JWST). The JWST is the successor to the Hubble Space Telescope. The Hubble, upgraded in 2009, is still producing high quality science. However, it has been in operation for 25 years, and like an old car, will begin to break down sooner or (hopefully) later. It is projected that Hubble will fall back to Earth sometime around 2024.

The JWST will be fundamentally different from the Hubble in three ways, its mirror type, location, and the part of the electromagnetic spectrum observed.

The Hubble’s primary mirror is a single piece 2.4 meters (8 feet) in diameter. The mirror is made of ultra low expansion glass that weights 2,400 lbs. This is pretty lightweight; a regular glass mirror the same size would weigh five times as much. The JWST primary mirror will consist of 18 segments with a total weight of 1375 pounds. The total mirror size will be 6.5 meters (21 feet) in diameter.

Why are the JWST mirrors so light?

The mirrors for the JWST, rather than composed of glass, are made of beryllium. This substance (mined in Utah) has a long history of use in the space program, as it is very durable and heat resistant. In fact, the original Mercury program heat shields were made of beryllium. In space, weight is money. Currently, it cost $10,000 to put a pound of payload into orbit. Since the JWST mirror has 7 times the area of the Hubble mirror, a lighter material had to be found.

Beryllium itself is a dull gray color. The mirrors will be coated with gold to reflect the incoming light back to the secondary mirror to be focused into the JWST instrument package.  The choice of gold was not for aesthetic purposes, but rather gold is a good reflector of infrared light and that is key to the JWST mission.  The total amount of gold used is a little over 1 1/2 ounces, worth roughly $2,000, which is a minute fraction of the JWST $8.5 billion budget (about the same price tag for an aircraft carrier).

The final assembly of the primary mirror will take place at the Goddard Space Flight Center in Maryland. The contractor for the assembly is ITT Exelis, which was formally a part of Kodak and is still based in Rochester, NY.

The JWST will launch in 2018 on an Ariane 5 rocket at the ESA launch facility in French Guiana. This is near Devil’s Island, the site of the former penal colony featured in the film Papillon. Its location near the equator provides a competitive advantage over the American launch site at Cape Canaveral. The closer to the equator, the greater the eastward push a rocket receives from the Earth’s rotation. In Florida, the Earth’s rotational speed is 915 mph. At French Guiana, it is 1,030 mph.  That extra 1,000 mph boost allows a launch vehicle to lift more payload into orbit.

Even if the shuttle program were still active, unlike the Hubble, it would not have been used to lift the JWST into space. The Hubble is situated in orbit 350 miles above the Earth. This was the upper end of the shuttle’s range. The JWST will be placed 1,000,000 miles away from Earth at a spot known as the L2 Lagrange point.  What is the L2 point?  Think of the launch of the JWST as a golfer’s drive shot.  The interplay between the Earth and Sun produce gravitational contours as seen below:

Credit: NASA / WMAP Science Team

The gravitational contours are like the greens on a golf course.  The arrows are the direction gravity will pull an object.  The blue areas will cause the satellite to “roll away” from a Lagrange point.  Red arrows will cause the satellite to “roll towards” the desired destination.  Kind of like this shot from the 2012 Masters:

The L2 spot is not entirely stable.  If the JWST moves towards or away from the Earth, its operators will need to make slight adjustments to move it back towards the L2 spot.  Due to this placement, the JWST will not have the servicing missions the Hubble enjoyed. The specifications of the JWST must be made correctly here on Earth before launch.

Why does the JWST need to be so far away from Earth?

The answer lies in the part of the electromagnetic (EM) spectrum the telescope will observe in. Don’t get turned off by the term electromagnetic, as we’ll see below, you will already be familiar with most parts of the EM spectrum.

Credit: NASA

The word radiation tends to be associated with something harmful, and in some cases, it is.  However, radio and light waves are also forms of EM radiation.  What differentiates one form of radiation from another is its wavelength.  Cool objects emit mostly long wavelength, low energy radiation.  Hot objects emit short wavelength, high energy radiation.  The JWST will observe in the infrared.  And this is a result of the objects the JWST is designed to detect.

The JWST will search the most distant regions of the universe.  Due to the expansion of the universe, these objects are receding from us at such a rapid rate, their light is red-shifted all the way into the infrared.  Planets also emit mostly in the infrared as a consequence of their cool (relative to stars) temperatures.    The infrared detectors on the JWST will enable it to study objects in a manner that the Hubble could not.

The L2 location allows the JWST to be shielded from the Earth, Moon, and Sun all at the same time.  This prevents those bright sources of EM radiation from blotting out the faint sources of infrared that the telescope is attempting to collect.

The video below from National Geographic provides a good synopsis of the JWST.

So, who was James Webb? And why did NASA name Hubble’s successor after him?

The short answer is that James Webb was NASA Administrator during the Apollo era. Given that Apollo may very well be NASA’s greatest accomplishment, that alone might be enough to warrant the honor. However, Webb’s guidance during NASA’s formative years was also instrumental in commencing the space agency’s planetary exploration program. To understand this, lets take a look at John Kennedy’s famous “we choose to go to the Moon” speech at Rice University on September 12, 1962.

During that speech, President Kennedy not only provided the rational for the Apollo program, but stated the following:

“Within these last 19 months at least 45 satellites have circled the earth. Some 40 of them were made in the United States of America and they were far more sophisticated and supplied far more knowledge to the people of the world than those of the Soviet Union.

The Mariner spacecraft now on its way to Venus is the most intricate instrument in the history of space science. The accuracy of that shot is comparable to firing a missile from Cape Canaveral and dropping it in this stadium between the 40-yard lines.

Transit satellites are helping our ships at sea to steer a safer course. Tiros satellites have given us unprecedented warnings of hurricanes and storms, and will do the same for forest fires and icebergs.”

It has to be noted here that soaring rhetoric notwithstanding, Kennedy was not exactly a fan of spending money on space exploration. At least not to the extent the Apollo program demanded. Kennedy felt the political goal of beating the Soviet Union to the Moon trumped space sciences.  Nonetheless, you can see the origins of NASA’s planetary & Earth sciences programs along with applications such as GPS in Kennedy’s speech. So how does James Webb fit into all this?

When tapped for the job as NASA administrator, Webb was reluctant to take the position. Part of it was his background as Webb was a lawyer. He was also Director for the Bureau of the Budget and Under Secretary of State during the Truman Administration. Webb initially felt the job of NASA Administrator should go to someone with a science background. However, Vice President Lyndon Johnson, who was also head of the National Space Council, impressed upon Webb during his interview that policy and budgetary expertise was a greater requirement for the job.

That background paid off well when dealing with both Presidents Kennedy and Johnson. As NASA funding increased rapidly during the early 1960’s, there was great pressure to cut space sciences in favor of the Apollo program. Webb’s philosophy on that topic was this; “It’s too important. And so far as I’m concerned, I’m not going to run a program that’s just a one-shot program. If you want me to be the administrator, it’s going to be a balanced program that does the job for the country that I think has got to be done under the policies of the 1958 Act.”

The 1958 Act refers to the law the founded NASA and stipulated a broad range of space activities to be pursued by NASA.  The law can be found here.

During the 1960’s, NASA’s percentage of total federal spending is below:

Credit: Center for Lunar Science and Exploration

NASA has never obtained that level of funding since. Most of it was earmarked to develop and test the expensive Saturn V launch vehicle. And pressure was often applied from the President to Webb to scale back or delay NASA’s science program to meet Apollo’s goal of landing on the Moon before 1970. The video below is a recording of one such meeting between Kennedy and Webb.

Webb’s law background served him well in making the case for a balanced NASA agenda.  Despite pressure of the highest order, Webb was able to guide both Apollo to a successful conclusion and build NASA’s science programs as well.  The latter would include the Mariner program that conducted flybys of Mercury, Venus, and Mars.  Mariner 9 mapped 70% of Mars’ surface and Mariners 11 & 12 eventually became Voyager’s 1 & 2, humanity’s first venture beyond the Solar System.

Quite a legacy for a non-science guy.

This also demonstrates you do not necessarily have to have a science/engineering background to work in the space program.  Take a gander at NASA’s or SpaceX’s career pages and you will find many jobs posted for backgrounds other than science.  As James Webb proved, it takes more than science to study the universe.

*Image at top of post is JWST mirror segment undergoing cryo testing.  Credit:  NASA.

Pluto & New Horizons

When I was in grade school, I designed a crewed mission to Pluto and dubbed it Hercules, obviously taking a cue from the then recent Apollo program. The ship itself was armed with laser banks. Not sure what exactly I was expecting to run into out there, perhaps just Cold War paranoia. The crew was also top heavy in security personnel. As anyone who watches Star Trek can tell you, just like pitchers in baseball, you can’t have enough redshirts on a space mission. The mission was planned to go in the year 2002.

It’s really funny to see the ideas one can conjure when you do not have to worry about budgets, research, and politics. The people at NASA who do have to worry about that stuff are unable to send humans that far, but have pulled off a most excellent mission in New Horizons that will flyby Pluto with its closest approach on July 14th.  An added bonus, with the advent of social media, we will get to see the images from this mission almost in real-time.

The mission was put together at a cost of $700 million.  That is the same amount spent in Colorado on marijuana during its first year of legalization.

This particular mission has a personal tie to me in that it was launched on January 19, 2006, the very same week I started my first class teaching astronomy. Next fall, in my 10th year of teaching, I will finally be able to discuss the New Horizon’s images of Pluto rather as something to look forward to. An animation of New Horizon’s voyage to Pluto is below. You’ll note that New Horizons performed a flyby of Jupiter to receive a gravity boost towards Pluto.

The gravity boost from Jupiter in 2007 shortened the journey to Pluto by three years. The flyby of Jupiter provided a test run for New Horizon’s imaging equipment and the results were impressive. The video below shows New Horizon’s look at the rotation of Jupiter.

New Horizons also took this shot of a volcanic plume on Io, which is the most volcanically active body in the Solar System. This activity is generated by gravitational flexing of Io as it is stretched back and forth by Jupiter, Europa, and Ganymede. This is similar to the heat caused by stretching a putty ball back and forth.

Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute
Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute

The image above of Io was taken from 1.5 million miles away.  While Pluto is only 60% the size of Io, New Horizons will approach much closer at 6,200 miles and should provide exceptional image quality.

A lot has happened to Pluto itself over the past decade. Not so much Pluto, but rather our perception of it. Of course, when New Horizons was first proposed in 2001, Pluto was still classified as a planet. It is now referred to as a dwarf planet. Over time, as memory of Pluto as a planet fades, I suspect this will eventually be changed to simply a Kuiper Belt object (KBO).

The reclassification was portrayed in the popular media as a demotion for Pluto. It really was not so much a demotion as it was an expansion of our understanding of the nature of Pluto and the Solar System.  For those of us who went to grade school before the reclassification, we were introduced to the planets with a diagram such as this:

Credit: Rice University

An updated version of this diagram looks like this:

Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute/Alex Parker

The yellow line is the path of the New Horizons probe.  The yellow dots?  Those are Kuiper Belt objects of which Pluto is one of.

Pluto’s classification as a planet was shaky from the start.  Pluto’s orbit is inclined much more than the other eight planets and its composition is unlike the four gas giants which occupy the outer Solar System.  Questions about Pluto’s planet classification were raised only a few months after its discovery by Clyde Tombaugh of the Lowell Observatory, as this New York Times article from April of 1930 indicates.

However, Pluto’s size was thought to be much larger at the time than it actually is and that caused the planetary classification to stick.  Gerard Kuiper himself, as late as 1950, calculated Pluto to be about the same size as Earth.  In fact, it was this overestimate of Pluto’s size that caused Kuiper to predict the following year there would not be what we now call the Kuiper Belt.  It’s a bit ironic that the Kuiper Belt is named after the astronomer who predicted its non-existence, as Kuiper felt Pluto would have cleared out that region of the Solar System during its formation.

Nonetheless, Kuiper had a distinguished career that included the discovery of Titan’s atmosphere, carbon dioxide in Mars’ atmosphere, and the Uranus satellite Miranda.  Kuiper played a key role as mentor to Carl Sagan during the 1950’s as well.  Unlike most astronomers at the time, Kuiper felt there was an abundance of planets outside the Solar System.  In turn, this inspired Sagan to explore that along with the possibility of life beyond Earth.  This was mentioned prominently during Ann Druyan’s remarks at the recent inauguration of the Carl Sagan Institute at Cornell University.

The Kuiper Belt is a region of the Solar System past the orbit of Neptune that is thought to contain thousands of small celestial bodies composed of water ice, methane, and ammonia.  Short period comets originate from this region.  An excellent overview on the Kuiper Belt can be found here.

The first Kuiper Belt object discovered besides Pluto came in 1992.  Since then, some 1,300 Kuiper Belt objects have been observed.  This, along with more precise measurements of Pluto’s mass, which have come in at 0.002% of Earth’s, have resulted in the reclassification of Pluto to its present dwarf-planet designation.  Pluto is simply too small to be considered a planet and its placement in the Solar System puts it among other Kuiper Belt objects.

Does this reclassification affect Clyde Tombaugh’s legacy as the discoverer of Pluto?  I think not.  Consider this, Tombaugh discovered a Kuiper Belt object 62 years ahead of the next observation of another such object.  Tombaugh also discovered Pluto six years before earning his bachelors degree at University of Kansas.  Keep in mind, the discovery of Pluto would have been a suitable topic for a Ph.D thesis.  Tombaugh’s legacy is quite safe.  In fact, a portion of Tombaugh’s ashes are aboard the New Horizons probe and will flyby  Pluto along with the spacecraft.

The flyby of Pluto next July may very well represent a once in a lifetime opportunity to observe Pluto this close.  No other missions are in the proposal stage at this time and given the travel time to Pluto, it will be at the very least, 15-20 years before another mission arrives in that part of the Solar System.  NASA has just released the first color image of Pluto and its moon Charon (below).  I consider myself very fortunate to be able to witness the culmination of this 15 year effort .

Pluto and Charon orbit shared center of gravity. Credit: NASA

*Image on top of post is the Pluto discovery plates.  Credit:  Lowell Observatory Archives.