Wednesday, December 24, 2008

Merry Christmas, Happy Holidays, and a happy new year

Apollo 8 Earthrise
Image Credit: NASA

Forty years ago today, humans circled the moon for the first time, when Apollo 8 astronauts Frank Borman, James Lovell, and William Anders safely slipped into lunar orbit. At the end of a three day journey to the moon, the astronauts must have been greatly relieved when their rockets fired, their module slowed (else it would have continued on into deep space), and the Earth appeared to rise over the moon for the first time. The above picture, "Earthrise," is one of those enduring and iconic moments of human history.

In the above picture, the Earth is only a quarter million miles away; the sun is still another 93 million miles away, the nearest known star is about 25 trillion miles away. And yet, from that relatively nearby vantage, look how small the Earth looks. For no matter how it seems, our planet is small; us denizens of its outermost layer inhabit but the tiniest shell of a tiny globe in an incomprehensibly vast Universe.

Apollo 8 was launched at the end of 1968, one of the most tumultuous years in recent American history. 1968 had seen the assassinations of Martin Luther King, Jr. and Robert Kennedy, riots at the Democratic National Convention in Chicago, and the end of the Prague Spring with the Warsaw Pact invasion of Czechoslovakia. The success of Apollo 8 gave a positive end to a dismal year.

This year hasn't exactly been a stellar one, either. As we head out of 2008 and into 2009, there's a lot of uncertainty regarding the economy, wars are still raging around the globe, and many of us just don't know what the future holds. There are some signs of hope; maybe 2009 will be better. We can only hope.

I am travelling for the holidays now, so this will probably be my last post for the year. Next time you hear from me, the Year of Astronomy will be underway; there are lots of exciting activities planned that I'll be blogging about soon.

I'll end with Frank Borman's message to all of us as he delivered it in 1968:

"And from the crew of Apollo 8, we close with good night, good luck, a Merry Christmas, and God bless all of you - all of you on the good Earth."

Saturday, December 20, 2008

The longest year since 1992

Dali and the Persistence of Memory
Image Credit: Salvador Dali /

Does it feel like this year has gone on a lot longer than normal? Granted, now that we are all realizing that we aren't ready for the holidays, it is positively rushing toward its end. And maybe the sense of a long year is just due to the exceptionally long presidential election combined with a total meltdown of the world economy. The bad news on the latter topic just refuses to end.

But if it seems like this year has been longer than normal, you are right! Don't forget, it was a leap year, so it had an extra day. But even this year is long for a leap year, because an additional leap second has been added. The poor, drunken souls in New York City's Times Square will have to hang on one extra second before ushering in 2009.

The need for leap seconds arises from the fact that, as diurnal creatures, our internal clocks are tied to the position of the sun in the sky. We therefore set up our clocks to try and mimic the 24-hour cycle of the sun in the sky. Astronomical observatories, such as the Royal Observatory in Greenwich, England, took careful observations of the sun and stars in order to keep time. They learned that the Earth's rotation was not constant, but tended to change from year to year, and was in fact slowing down, albeit very slowly, over time. But since time was based on the sun, this didn't really cause a big problem.

As machines became an integral part of society, time became important for machinery as well as for people. And for many things (like satellites and computers), the position of the sun on Earth is not relevant. It became more important to define time in a way that was not dependent on the vagaries of Earth's rotation. So the second was defined in terms of physical constants; specifically, a second is defined in terms of the radiation emitted by a specific process in cesium atoms at a temperature of absolute zero. Since a minute is 60 seconds, an hour is 60 minutes, and a day is 24 hours, the "day" according to computers and atomic clocks is now independent of how fast the Earth is spinning. And, a spaceship far from Earth could keep perfect time without staying in contact with Earth.

But since the "official" day is now independent of the actually spinning of the Earth, the two tend to drift apart, with the Earth spinning slower than the real second. So, a commission of geologists and astronomers gets together a few times a year to decide if a leap second needs to be added at the end of June or the end of December.

This year we get a leap second at the end of December. It's the first time a leap second has been added to a leap year since 1992. So, 2008 is indeed the longest year in 16 years. Since better things are hopefully ahead next year, we'll just have to be an extra day and one second patient for this year.

There is some talk about getting rid of leap seconds, and waiting until a full hour is needed (which would be about 3000 years from now) before adding in a leap hour. The arguments for abolishing leap seconds are that they are somewhat tricky to deal with when dealing with computer programs and operation. The arguments against abolishing a leap second include that it makes life a little harder for us astronomers (since finding objects in the sky requires precise knowledge of the time), and eventually it means that, in a few thousand years, the sun will appear to be behind by about an hour (and isn't it already dark enough when you wake up on these long winter nights?). And there are already time systems available (like GPS time and international atomic time. Frankly, none of the arguments for either side have been really compelling to me. I think we as humans are pretty able to either adapt our computers or our lives to whatever time system we choose.

So, try and enjoy your extra second this year!

Thursday, December 18, 2008

Why Intelligent Design Isn't Science

First, if you haven't my last post, please do so.

Second, let me state, in case it matters to you, that I am a religious person. I'm active in a mainstream Christian church, and have been my entire life. But I am not here to proselytize, nor am I here to knock anyone's religion (or lack thereof); I consider religion an intensely personal matter. I write this blog to share my knowledge and excitement about science, particularly astronomy. My comments in this post are not a discussion of religion, but a discussion of science. (And I contend that the two are different, but not mutually exclusive. But that is a discussion for a different forum).

And last, let me remind everyone that this is just a blog post, so I can't cover every single detail of every single argument that's ever been made. If you want more detailed information, or if you want links to articles espousing the other side, go ahead and use Google or your favorite search engine. I guarantee you'll get a surplus of reading material.

As I mentioned in my last post, Texas is revising its state science standards this year. And this should interest all Americans, because Texas state education standards influence text books across the nation.

I think it is for this latter reason, combined with the fact that Texas is a socially conservative state, that proponents of an idea called "Intelligent Design" are making a big push to get that idea into the Texas state science standards. Further, they are on the verge of succeeding. Nearly half of the state school board, and fully half of the special commission set up to review science standards, publicly support Intelligent Design.

Intelligent Design is an idea that evolved from Creationism, the idea the Earth was created exactly as described in the first few chapters of the book of Genesis. Creationism (or "creation science") was effectively barred from public school science classrooms in a series of court rulings (most in the 1980s). Shortly thereafter, the term "Intelligent Design" appeared to describe a less overt version of Creationism.

Intelligent Design has many forms (and adherents to some versions are vehemently opposed to other versions), ranging from the fairly weak (that the Universe is so complex, there must be a "designer" behind it all, but otherwise modern science explains the natural world properly), to moderate (the Universe is old, modern science is mostly right, except for evolution, because every form of life, or maybe just humankind, was created in its current form by a "designer"), to strong flavors that are equivalent to Creationism (the Earth is 6000 years old, and any science that doesn't espouse this view is just wrong). And Intelligent Design backers have written scientific-sounding books (like Of Pandas and People), have a scientific-sounding institute (the Discovery Institute), and even have a few PhD scientists behind the idea. But none of this makes Intelligent Design scientific, let alone a true scientific theory.

Intelligent Design, regardless of whether or not it is true, is not science. Recall, scientific hypotheses and theories make specific predictions that, if they don't come true, invalidate the theory. For example, let's look at some real astronomy-related theories:

  • Einstein's Theory of General Relativity -- Einstein proposed this theory in a series of talks and papers around 1915. The theory was proposed, among other reasons, to make gravity consistent with Einstein's earlier Special Relativity. Einstein noticed that this idea could also explain why the planet Mercury didn't exactly orbit the sun like Newton's Laws said it should. Quickly, it was realized that General Relativity made some testable predictions. It said gravity should bend light, so stars very close to the sun's position in the sky should appear in slightly different locations than when the sun is in another part of the sky. This prediction was quickly proven correct. Many other tests have also since been proposed, and all are consistent with General Relativity. If relativity had failed any of these tests, the theory would have been discredited. Instead, Einstein remains an icon of scientific genius.
  • The Big Bang Theory -- The Big Bang theory was first proposed in 1931 by a Belgian physicist (and Catholic priest!), Georges LemaĆ®tre. The idea naturally comes out of Einstein's General Relativity (though Einstein himself hated it at first), and it explained why most galaxies in the Universe appear to be moving away from us. The Big Bang implied that, at some point billions of years ago, the entire Universe was compressed into a tiny point in space and time, and something like an explosion propelled it outward. Many astronomers thought that this idea was quite silly (the name "Big Bang" was given to it by a famous, intelligent, and ultimately wrong astronomer named Fred Hoyle). But the theory made two very specific predictions. It predicted that the Universe should be bathed in microwave light, an "echo" of the Big Bang. It also predicted that roughly 75% of the atoms in the Universe should be hydrogen, and most of the rest helium (at the time, these numbers were unknown, and no other theory predicted this composition). When the Cosmic Microwave Background was discovered by Arno Penzias and Robert Wilson in 1964, and again when it was found that the Universe is made up mostly of hydrogen and helium in the predicted ratios, the theory passed its first two big tests.

When both of these now iconic theories were proposed, they were not instantly accepted by the scientific community. They were not taught in elementary or high schools. They were considered kinda wacky. But because they made specific predictions, and because those predictions held up to scrutiny, these two ideas were accepted as viable scientific theories. Many people received Nobel Prizes. High-school text books were re-written to discuss this. Disproven theories fell by the wayside. That's the way science is supposed to work.

Intelligent Design does not make specific predictions. There is no test I can run where the results would prove that there is no need for an intelligent designer. If a hypothesis cannot be falsified, it is not a scientific hypothesis. Until Intelligent Design makes a testable prediction, it cannot be considered scientific.

There is one other important point about the non-scientific nature of Intelligent Design. Many of the arguments voiced as supporting Intelligent Design are really just pointing out supposed problems in the primary competing theories. For example, the idea of "irreducible complexity" claims that there are complicated parts of living things (like the eyeballs or blood clotting) that serve no purpose if they are not found in their current, complete form. Let's ignore the fact that most biologists can prove this is not valid, and let's even assume for the moment that irreducible complexity exists in the world. This does not prove that there must be a creator. Perhaps there is some other means of "irreducibly complex" features appearing that hasn't been proposed. It's sort of like coming home from vacation, finding your house is gone and saying, "Well, it didn't rain, so there wasn't a flood. The IRS must have repossessed it and taken it," when in reality a tornado had carried your house away. In science, ruling out one idea doesn't prove any alternatives. So, just because existing theories may not be able to explain every aspect of the world around us does not mean that there must be a creator behind it all.

In short, Intelligent Design should not be taught in science classes because it is not science. And until Intelligent Design can make specific, testable predictions (where a failure of the prediction would mean that Intelligent Design is wrong), it is not science.

Lastly, it is important to know that science is not anti-religious. Science is a well-defined process for exploring the natural world. It is a very good tool, too. But science is not the only tool in the box. Science cannot tell us whether Charles Dickens wrote better stories than Victor Hugo. Science cannot tell us whether we should buy the black shoes or the brown shoes. Science cannot tell us whether or not Henry the Eighth was a good husband. Science cannot tell us whether or not there is a deity. Anyone who claims otherwise is mixing science with other subjects.

In my opinion, there is no doubt that Intelligent Design is not science, but rather theology. There are appropriate places for theological discussions, but the science classroom is not an appropriate place. In fact, if Texas were to adopt any portion of Intelligent Design into the classroom, the state should expect strong opposition, including lawsuits on constitutional grounds. And those lawsuits would succeed, but not until costing the state millions of dollars and throwing science education in the state into tremendous disarray.

Tuesday, December 16, 2008

What is science?

Dr Bunsen Honeydew and Beaker
Image Credit: Walt Disney Co. / Muppet Wiki

The state of Texas is in the early stages of revising its science education standards (the science portion of the Texas Essential Knowledge and Skills). This promises to be a very contentious process, as several competing groups are gearing up for a big fight.

If you are not a citizen of Texas, why should you care what happens here? First, Texas is one of the largest markets for textbooks in the country, so Texas state educational standards influence the content of textbooks (and not just science, but every subject!). Second, the issues that are being argued over in Texas are very likely to come up in discussions over your home state's educational standards (assuming you are a US citizen), if they haven't already. Last, science and technology have been a crucial part of America's continued influence in the modern world. If we do not continue to hold ourselves to the highest standards, we will lose initiative and influence in the world at large.

I'll be blogging about many of these issues in the next several posts. But let's start with what you think would be an easy question, though it's really the heart of the entire conflict: What Is Science?

Part of the problem is that the definition of the word "science" isn't, well, all that scientific. To some people, "science" is a collection of subjects: physics, chemistry, geology, astronomy, etc. But why is astronomy considered "science," while English, philosophy and history are not?

Science is more than a list of subjects. It is also a process, and a very specific process at that. The scientific process is a method for explaining natural occurrences as a set of testable theories. Every scientific theory must make predictions that, if they don't come true, prove the theory is wrong. If a theory cannot make a such a prediction, it is not a scientific theory, even if the theory is about a topic most of us would call "science."

For example, let's say that I go outside and drop a hammer and a feather. The hammer plummets to the ground, while the feather lazily wafts downward. Now, I board a plane to France, and I repeat the experiment. I drop a hammer and a feather, and the hammer drops quickly to the ground, while the feather slowly floats downward. I then get back on a plane and fly to Australia, and I repeat the experiment again. Once more, the hammer hits the ground first, followed by the feather. So, being a clever person, I come up with the idea that "heavier objects fall faster."

Now, suppose that a NASA astronaut doesn't agree with me, so on a trip to the moon, he takes a feather and a hammer with him. Once on the moon, he drops a feather and a hammer. They both hit the ground at the same time. My theory has been proven wrong. That's science at work.

Now, suppose that I claim that the results of the experiment can be explained due to an undetectable substance called plumatardium. In my hypothesis, plumatardium causes feathers to fall more slowly than other objects, but plumatardium has absolutely no other effect on anything. Further, I claim that the presence of plumatardium in the Universe is random; there's no way to know if it exists on a given planet unless you compare the rates at which hammers and feathers fall.

My hypothesis, while it may sound scientific, would not be considered a scientific idea. This is because it cannot be falsified; I claim the only way to detect it is to drop a feather and see if it falls slowly, and that its only effect is to cause feathers to fall slowly. There is no way to prove that plumatardium doesn't exist --if you were to run the feather test on a random planet, and the feather fell at the same rate as the hammer, I could just claim that the particular planet has no plumatardium. Notice that my hypothesis could well be correct -- there's just absolutely no way to test it, so it is not a scientific hypothesis! No scientist would even consider my Plumatardium Hypothesis unless I could develop a test to see if plumatardium exists. So, though it might sound scientific, my plumatardium idea isn't scientific, and it wouldn't belong in a science classroom.

I'm not saying that there is necessarily anything wrong with non-scientific pursuits. For example, consider music, a big hobby at mind. At its most fundamental, music is what we perceive due to vibrations travelling through the air (That is physics!) You can even take classes in music theory (that sounds sciency!). But no matter how many physicists work on the problem, Mozart's composing of the "Magic Flute" is not a fundamental law of nature. Neither could music theory (or any theory) predict the British Invasion. Just because Mozart and the Beatles aren't scientific, though, doesn't mean that studies of classical music or Sgt. Pepper are not valid pursuits. Those studies just don't belong in a science classroom; there are more appropriate venues (like a music studio or even a social studies classroom).

Where I would claim things go wrong is if I blatantly ignore or misuse the scientific process. Again, go back to my plumatardium hypothesis. Suppose someone asks me why I do not think that air resistance is the answer, that the flow of billions of trillions of air molecules over and through the many nooks and crannies of the porous design of the feather prevents the feather from accelerating as fast as the smooth and dense hammer. I reply, "No one can calculate the trajectory of every single molecule around the feather, therefore the air resistance theory is unscientific, too!"

While it may be true that no person, nor any existing supercomputer can follow the path of every single air molecule, nor even a tiny fraction of the air molecules, I would be ignoring centuries of scientific experiment and theoretical works on wind resistance. Simply because we do not know the exact details of how wind resistance works on an atomic level does not mean that wind resistance is an invalid theory. Incomplete, perhaps, but not invalid. Don;t throw out the baby with the bathwater!

Or, suppose I were to argue that because we cannot yet determine air flows on a molecular level for a system involving trillions upon trillions of particles, that plumatardium must exist, as there is no other explanation for the feather dropping more slowly than the hammer. Again, even if the molecular theory of wind resistance is wrong, this does not prove that plumatardium exists. My hypothesis would still lack a test that would show whether or not my proposed substance exists. My hypothesis is still no more scientific then it was.

So, in summary, science is not a list of topics; it is a rigorous process for exploring the Universe around us. Some topics can sound like science, but still be non-scientific. And non-scientific things aren't inherently bad or wrong; they just aren't science. What is bad and wrong is bring ignorant (or willfully ignoring) the scientific method while still claiming it is science.

Hopefully all of this up to now doesn't seem too controversial. In my next post, that'll change, but all of my future arguments are based on the points I've made here.

Monday, December 15, 2008

Stars running hot and cold

X-rays from an extremely hot white dwarf Twin cool brown dwarfs
Image Credit: Univ. of Leicester (left); NASA/JPL-Caltech (right)

Over the last week, two press releases from two different groups have revealed both the hottest and coolest known stars in the sky.

We'll start with the new hottest known star, discovered by astronomy Klaus Werner and collaborators with the FUSE ultraviolet telescope. At a whopping 360,000 degrees Fahrenheit (200,000 Kelvin), this star is dang hot. The star, with the exciting (NOT!) name of KPD 0005+5106, is a white dwarf, or the ashes of a dead star. Until very recently, this white dwarf was a fusion nuclear reactor at the center of a star. But the star used up all of its fuel, and its outer layers blew away in a planetary nebula, revealing the super-hot nuclear engine.

While there are lots of white dwarfs known, very few of them are super-hot like KPD 0005+5106. This is because white dwarfs, without any nuclear power left, cool off very quickly at first. In "only" 300,000 years (short by astronomy terms), the white dwarf will cool from hundreds of millions of degrees to under 100,000 degrees. Most white dwarfs we see are hundreds of millions of years old, and are a relatively modest 10,000-20,000 degrees in temperature. So, the fact that KPD 0005+5106 is so friggin' hot means that it is very young, just recently emerged from the center of its dying parent star.

More than likely, there are even hotter stars waiting to be found, if we look in the right direction. We white dwarf researchers are looking! If we can find enough really hot stars, we can learn a lot about how a star ends its life, and how the white dwarf emerges from the cocoon of a dying star. We can also learn a bit about exotic physics -- these stars are so hot, they are making copious numbers of subatomic particles called neutrinos. Neutrinos are pretty hard to study, because they could pass through one light-year of lead like nothing was there. But if we can measure how fast these hot stars are cooling off, we can estimate how many neutrinos are escaping into space, which tells us a lot about how these weird particles are made.

At the other end of the spectrum, (both literally and figuratively), astronomer Adam Burgasser and his collaborators announced the discovery of the two coolest known stars, a pair of identical twin brown dwarfs. These stars are a chilly 600 degrees Fahrenheit! Granted, we'd feel a bit warm if we got too close to these stars, but compared to our sun (a mild 10,000 degrees Fahrenheit), these are downright cold. Replace our sun with these brown dwarfs, and the Earth would quickly freeze over.

Brown dwarfs are sometimes called "failed stars." They are at least 15 times more massive then Jupiter, up to about 80 times the mass of Jupiter. When newly born, brown dwarfs can turn do a few nuclear reactions, but they quickly die out. The star just isn't big enough for gravity to keep its nuclear engine running. So, like the white dwarfs, brown dwarfs slowly cool off and fade away. Only, since brown dwarfs were never more than a few thousand degrees to start with, they get very cold, very quickly.

To study brown dwarfs, astronomers need to look at infrared light (what many of us would call "heat" radiation). Using the Spitzer Space Telescope, an infrared light counterpart to Hubble, Burgasser and his team were able to measure the temperature of a brown dwarf called 2MASS J09393548-2448279 (a worse name than KPD 0005+5106!). They then used a telescope in Australia to measure the distance to the star, and they got 17 light-years. That's pretty nearby, in space terms, and one of the five closest known brown dwarfs. But when Burgasser's team compared the amount of light coming from the star to the amount of light that a 600 degree star should be putting out, they found the star was putting out twice as much light. The reason? It wasn't one star, but two -- identical twin brown dwarfs.

Why are cool brown dwarfs so interesting? When the planet Jupiter formed, it was once much hotter than these stars. Over time, it has cooled down to a frigid -200 degrees Fahrenheit. By studying cool brown dwarfs, it is like we are looking at a young Jupiter, so we can learn what our Solar System was like many billions of years ago. Brown dwarfs also teach us about weather and chemistry, because the stars are cool enough that molecules like water and ammonia can form. Tools similar to those we use to study weather on Jupiter and the Earth predict what these brown dwarfs should look like as they cool; finding new cool brown dwarfs allow us to test these theories and models.

Just like there are almost certainly hotter stars than KPD 0005+5106, there are almost certainly cooler brown dwarfs than these twins. They are so faint, these cool brown dwarfs could be hiding as close as just a few light-years away!

Thursday, December 11, 2008

Trouble at NASA with the transition

According to this story from the Orlando Sentinel, NASA chief administrator Michael Griffin is not cooperating with President-Elect Obama's transition team. I have no personal information to confirm this story, so it may not be true. But it would not surprise me if it is.

NASA's Constellation program, the proposed replacement for the Space Shuttle as the USA's primary means of getting humans into space, is Griffin's baby. And, understandably, he wants to see it go forward and succeed. He also wants it to progress quickly, because once the space shuttle is retired in 2010, the US will have no means to get humans into space, unless we hitch a ride with the Russians on their rockets. The earliest possible launch of the first manned rocket from the Constellation program won't be until at least 2016, if everything goes according to schedule.

Like most every government program, the Constellation program is running behind schedule and over budget. Some engineers (but not all) have raised serious-sounding concerns about the Constellation project, and have even proposed an alternative called Jupiter. I am not a rocket scientist, so I cannot speak to the validity of these concerns. The fact that they have been expressed publicly, though, means that they need to be addressed in a public and transparent manner, and I don't think this has been done. A major, independent review of the program is probably in order, so that we can keep our confidence in the Ares rocket and the constellation program.

The fact is, NASA is having an ugly internal fight right in the public's eyes. Former NASA science associate administrator Alan Stern recently wrote a scathing editorial about the state of NASA. Was this an honest opinion about the state of NASA? A thinly-veiled application to be Obama's NASA administrator? An airing of a private grievance? Or all three?

NASA is not served by such public bickering. Frankly, Michael Griffin should simply cooperate fully with the Obama team. If his rocket program is as good as he says it is, then it will go forward, and he will get credit for having started the program and seeing it through the always turbulent early design phases. If the program needs some tweaking or a major overhaul, it's best to do it now, and not three years down the road, when problems will cause a much longer and costlier delay. In that case, Griffin will be vilified for not having spotted these problems. In short, Griffin and NASA would be best served by eating some humble pie, being fully welcoming of the transition team, and letting the Obama administrator kick the tires of the Constellation program. If it's a good buy, they'll take it.

Monday, December 08, 2008

23 days until the International Year of Astronomy

2009 International Year of Astronomy logo
Image Credit:
A few months ago, I mentioned that 2009 is the International Year of Astronomy, and that you should strongly consider getting involved. Amazing as it seems, 2009 is now just over three weeks away!

If you haven't yet, please get involved. There are many ways to do this; my old post talks about many, and the US's International Year of Astronomy website has numerous ideas. Whether you are a professional or amateur astronomer, a teacher, or just an average person interested in space, there are many ways for you to contribute!

Speaking of contributions, monetary donations (tax-deductible!) are also accepted. This money will go to pay for numerous exciting activities and programs, such as the Galileoscope, a small, inexpensive telescope that schoolchildren across the world can build and use, at a price of only about $10 each. So, if you don't know what to give the space-enthusiast who has everything for a holiday gift, why not contribute money in their name to the International Year of Astronomy?

But, more than money, the way to make sure the International Year of Astronomy succeeds is to get involved, and soon!

Telescope shopping

Click here to see a cartoon about cavemen and telescopes
Image Credit: Scott Hilburn / Universal Press Syndicate / GoComics

Looks like telescope shopping hasn't changed much in the past million years. Then again, neither has the Universe.

Thinking about buying a telescope as a gift? Please reconsider. It's not that I don't want you to encourage someone to study the heavens; I just want to make sure that, if you do make a purchase, it's an informed one.

Friday, December 05, 2008

Good Luck Anna!

Anna Frebel, Stellar Astronomer
Image Credit: A. Frebel /
McDonald Observatory

Today, another postdoc here at the University of Texas leaves us for warmer climes. Anna Frebel, a German astronomer educated in Australia and now working here in the States, is leaving Texas to be a prestigious postdoctoral fellow at the Harvard-Smithsonian Center for Astrophysics in Cambridge, Massachusetts.

Anna works on metal-poor stars. Every star has some amount of metal in it. Most stars have about the same amount of metal as the sun. But the stars that Anna studies have only between one thousandth and one millionth the amount of metal that the sun has. These stars are thought to be some of the oldest stars in the Universe, formed shortly after the Big Bang, and before a lot of supernovae could churn out metallic elements. (The Big Bang only made hydrogen, helium, and tiny amounts of lithium; everything else in the Universe has been made by stars since then.) Recently, Anna proved that these stars are as old as the Universe, which confirms this theory.

Let me also point out the obvious: Anna is a woman. And she's a darn good astronomer (better than me, in many ways). So, if any of you women out there ever hear that girls can't do math or science, Anna (among many other women, historical and present) that prove you can, and that you can run circles around many of us men. Click here to read more about the improving, but still unequal, status of women in astronomy.

Anna is a fun person who has brought a lot of life as well as science know-how to this department and to our little group of postdoctoral researchers here. Postdoc life is tough in that we're always saying goodbye to one of our friends; our stay at any one place is only a few short years. Good luck, Anna, we'll miss you!

Short news bites

I don't have much to add to the conversation on the following news items, but just wanted to throw them out there.

  • The Mars Science Laboratory mission has been delayed for two years. This lab has been a focal point for NASA budget criticism in the past few years. The delay is ostensibly because of some technical problems that will be hard to solve by this fall's planned launch date. And, due to the orbits of Mars and Earth, Mars launch opportunities only come every two years. So, we have to wait. Yes, this costs even more money. But I think that rushing to launch the lab this time likely increases the risk of a failure, and a $2.3 billion failure is unacceptable.
  • The next and final Hubble Space Telescope servicing mission has a new launch date: May 12. If you remember, this launch was scheduled for October, but was delayed when a hardware failure on the Hubble occurred right before the launch. The longer delay allows NASA to make sure that the replacement part is in good working order (it wasn't, and needed repairs) and for the astronauts to train on how to do this repair. Like with the Mars Lander, this delay costs money, but again, it is money I think is well-spent. In the meantime, Hubble is back and working as well as it was prior to the October glitch.
  • A team of astronomers announced that a comet orbiting the sun (Comet Machholz 1) may have been born around another star. This conclusion was drawn from the fact that the comet has different amounts of certain chemicals than any other comet. We would expect that all of the comets formed in our Solar System should have roughly the same composition, because the cloud from which the sun formed was well-mixed. This comet is different, and other possible explanations (like the comet got "baked" by going too close to the sun) don't hold up under detail. This isn't proof, though. In order to prove that this comet is from another solar system, we'd probably have to send a spacecraft to run detailed tests on its composition.

Thursday, December 04, 2008

Getting NASA out of its funk

A rusty rocket
Image Credit: Clay Bancett / Flickr

I think there's little doubt that NASA is in a funk. The picture above, of the scaled-down design of NASA's Constellation rocket shows just how bad things have gotten (just kidding).

In my opinion (and that's mainly what this post is), NASA's big problem isn't that they can't design and launch wildly successful missions (look at the Mars Exploration Rovers, or the Hubble Telescope repair missions, or even the oft-maligned International Space Station). I think the NASA administration has just failed to come to grasp with two emerging realities: (1) Budgets aren't going to be unlimited, and (2) space travel isn't as sexy as it used to be.

First, let's look at the budget. Last week, former NASA science director Dr. Alan Stern wrote a scathing editorial in the New York Times about the budget woes surrounding NASA's newest big-ticket item, the Mars Science Laboratory. This mission is far over budget, and is taking money from other programs just in order to get completed and launched. As science director, Stern wanted to give the mission an ultimatum: come in on budget, or get canceled. Stern was over-ruled, and resigned in protest. Around here, many of us astronomers view Stern quite favorably, but we felt his editorial missed the mark a bit. He outlines many problems at NASA of which we were already aware, but he offers no solutions.

NASA's budget is essentially flat; it's not going to grow by leaps and bounds. And the NASA administrators know this. So, they have designed several classes of missions, each with a maximum cost. When the call for new mission ideas goes out, there's a budgeted maximum cost. And all of the suggested missions proposals come in to NASA just slightly under this maximum cost. But this is a sham. We know, the aerospace teams know, NASA knows that virtually none of these missions can be completed at the proposed budget; all will take more money. But if you are realistic about costs, your mission proposal will not sell, because it won't do nearly as much science as the non-realistic proposals. And so, unrealistic proposals get funded, and then have to come back, hat in hand, time and time again until the budget has been exceeded by large amounts. And yet NASA continues to fund these projects, which forces other projects to either delay or cut corners because that extra money has to come from somewhere.

Somehow, NASA needs to completely overhaul its bidding process, and require projects to submit realistic budgets. And, if budgets go above some pre-determined ceiling, the projects need to get axed, without mercy. But people (companies, astronomers, NASA centers, etc.) currently play a game. If NASA threatens to cut their program, people go to their congressperson and complain, and then laws get passed requiring NASA to fund certain projects, but without increased funds. Again, other projects get undercut. This culture, also, needs to change, though I don't know the best way to do it.

A realistic budgeting process would seem painful, but in the end it would allow for better planning. We scientists would have to face up to tough choices ("Ladies and gentlemen, we can either send a dune buggy to Mars, a drilling platform to Europa, or build a third-generation Hubble telescope. The mission will be chosen by a cage-fighting match. Each side can choose their representative in the ring."), but at least we would all know that a tough choice or painful compromise would have to be made. ("We'll let you have your dune buggy, on the condition that you fly no missions from 2015-2020, so we can build that drilling platform and that telescope.")

So, budgets are a mess. But there's also what I think is the second reality, that space science isn't as sexy as it once was. Yes, we all think astronauts are still way cool, and it would be great to see a human striding around on Pluto. But even with all of that, I don't see the public getting as excited about space travel as they did for the moon landings. "Been there, done that," as some would say.

Think back to your history classes. Most of us could recognize the names of some of the earliest trans-oceanic explorers: Columbus, Magellan, de Gamma, etc. But now, try and name some of the rum tradesmen of the 1600s and 1700s. I can't do it. Now, try name some of the Mercury astronauts, or the first men on the moon. Not too hard (I got Alan Sheppard, Gus Grissom, John Glenn, and Deke Slayton from Mercury, and Buzz Aldrin and Neil Armstrong from Apollo without cheating --my apologies to the other Mercury astronauts of Scott Carpenter, Wally Schirra, and Scott Carpenter). But name just one astronaut who was on the just-landed shuttle flight. I bet most of you can't do it. I'm, ashamed, but I couldn't (let's see, there's the one who lost the tool belt, the one who lost the spider, probably some Russian dude... [Note added much later: there were no Russians on this flight]) Space travel is changing. The early astronauts were like the early sailors: famous, lionized. Current astronauts are no less brave, are putting their lives on the line every time they leave port, but they aren't as famous.

I think NASA has yet to come to grips with this. Spacewalks to grease the solar arrays are no less dangerous than Ed White's first spacewalk, they are absolutely crucial to the operation of the Space Station, but they aren't going to catch the public's imagination. In fact, for most people, NASA's hyping of the spacewalks looks silly. ("Heck, I grease the transmission on mah Mustang twice a week, and there ain't no news crew talkin' 'bout that.") Or the news about the temporarily missing spider on the recent shuttle flight did not inspire me to wonder about the biology of microgravity, but rather reminded me of the Simpson's episode Deep Space Homer. (And I, for one, welcome our new arachnid overlords.)

Look at the results to the poll I put up on NASA's greatest success since the moon landings. Most people chose space telescopes (like Hubble); the combined votes for the solar system exploration programs is a close second. My guess is that people think highly of these programs because they work on a myriad of science, and routinely come up with new and different (and pretty) results. The failures sting bad for a time (remember Hubble's screwed up mirror? The Mars mission that failed because people mixed up English and metric units?), but these have been overshadowed by subsequent accomplishments, with completely new and unexpected results coming in.

Now look at the space station. We are building this incredibly large structure in space. That is amazing (and expensive, but still amazing). People can live and work on it for months at a time. Super! But now what? We're studying spider webs? I mean, there is science that can be done, but it's hard to get excited about microbiology in space. And pictures of zero-gravity bacteria just aren't that thrilling ("Looks like mold on a petrie dish to me.") Should astronauts make an important medical breakthrough through space station research, all of this hand-wringing and discussion will be forgotten, the astronauts will be celebrated, and the space station justified. This hasn't happened yet, and we don't know when or if it will. In the meantime, the public sees little coming out of the space station, so it's hard to keep people enthused.

In my opinion, the manned space program is still highly successful. We routinely put people into space and bring them back safely. The entire mundane nature of manned space flight means that it has succeeded wildly. Repairs of Hubble by astronauts are what made the Hubble Space Telescope one of the most popular and successful NASA missions of the last few decades. Without the space shuttle and our astronauts, Hubble would have been a disaster.

I guess what I'm saying is that NASA's funk is, in many ways, all in our heads. NASA's science and manned space missions are by-and-large highly successful. We just need to accept that the extreme popularity that NASA enjoyed leading up to Apollo 11 is over. Rather than trying to recapture the glory days, I would argue that NASA needs to accept it's emerging position as a routine part of government. One that has to fight for (and stick to) its budget. One that produces achievements, sometimes highly visible, sometimes mostly hidden, sometimes thinking long-term, sometimes addressing short-term problems. And I think this is done not by blowing the entire budget on a few high-visibility, high-cost, high-risk missions (Though the occasional one may be okay).

I'll end this long, rambling post with my own, personal list of suggestions of where NASA should focus. Most of these may not be good ideas, but at least they are ideas.

  1. Be strict on budgets. This sounds easy, but it involves preventing other dysfunctional government units (like Congress) from micromanaging NASA, which is hard to do. Especially if large amounts of money are involved. This also involves getting the scientists to think about a larger landscape than their own research interests, and this is nigh on impossible.
  2. Get a cheap, reliable rocket to get humans into space. I fear that the Constellation program is trying to design a single rocket that can do anything and everything. That got us into trouble with the space shuttle. Think of this like designing a car. Rather than trying to design a luxury SUV that can tow 50,000 lbs, carry 60 children to school, drive to Alaska and back on half a tank of fuel, and fight and win a war halfway around the world, just give us a family sedan that can get us to and from work. We know the thing with all the bells and whistles will cost an arm and a leg and probably not be all that reliable. Start with something cheap, functional, and safe, and we can go from there.
  3. Keep a stream of science missions going. Do some on Mars, some on other planets, some space telescopes. Again, don't necessarily try and pack everything we'd like to do on a single mission. This also involves trying to keep us scientists from running off to Congress when our favorite project gets cancelled or delayed. Again, that's not easy, especially if there is a lot of money involved.
  4. Accept reality. The moon missions are over. We beat the Soviets to the moon. This all ended 40 years ago. Rather than trying to re-live or top the past, let's build a good foundation and go from there. Yeah, it would be cool to walk on Mars. Yes, if we put a lot of money into it, we could do it in a couple of decades. But is it worth the cost (money, political, human lives) of centering all of space science around this? I don't think so.
  5. Set goals and work toward them. What do we want NASA to do? Make space accessible to all? Find life on other planets? Send humans to every corner of the solar system? All of these goals are laudable, but they are each giant leaps for humans. Like any other goals in life, let's prioritize and set intermediate goals. Do we want to go back to the moon? If so, why, and what do we seek to accomplish? How will that help us go to Mars or find life on other planets? Let's make a long-range plan, flesh it out, and then set about implementing it.

Wednesday, December 03, 2008

Think before buying that telescope for a holiday present

Edmund Scientific Astroscan Telescope
Image Credit: Edmund Scientifics

Lots of people say they want a telescope for Christmas. But don't just plunk down $19+tax at your favorite discount store; you'll be throwing your money away. First, ask a few questions:

  • Why does the recipient want the telescope? Did the person just happen to see a pretty picture of Saturn on the side of the box and say, "I want that!", or are they really interested in space and astronomy? If you don't think they are willing to go outside for an hour on a cold winter's night to use the telescope, then it's most likely going to sit in a closet and gather dust.
  • Does the recipient know how to use the telescope? Telescopes come with few, if any, useful instructions. And it can be amazingly hard to just point the telescope in the right direction and find something cool to look at. Before investing money in a tool that you and your special someone don't know how to use, do some research. Read about amateur astronomy and telescopes online. Go visit a few star parties with a nearby amateur astronomy club. Talk to other amateur astronomers. Only once you have a good feel for what a telescope is and how to use it do you have a decent shot at buying the right telescope.

    Also, in order to find anything other than the moon and perhaps a planet or two, the recipient will need to be able to identify constellations (and more than just the Big Dipper!) If they can't point out Orion and Taurus to you in the night sky, then they won't be able to look at cool things like the Orion Nebula.

  • Is this more than a passing fad? If your loved one just read an interesting article about astronomy yesterday, and you buy them a telescope, and then next week they decide they are more interested in NASCAR, then you've wasted a fair amount of money. If, on the other hand, the person has been reading books and magazines, surfs the web for astronomy, goes to planetariums, and has gone to multiple star parties, then they are clearly quite serious about astronomy as a hobby. In this case, a telescope is likely to be used, and used regularly.
  • What about something else, like binoculars or a magazine subscription? If you still insist on buying something nice that can be used to look at the heavens, I'd strongly consider buying binoculars. I started out with a pair of binoculars -- in fact, I was a winner in a contest to be one of the first kids to spot Halley's Comet with a pair of binoculars back in the mid-1980s. Binoculars allow you to see the Moon, many nebula, star clusters, a few galaxies, even the moons of Jupiter. But they can also be used for other things, like bird watching, or hunting, or spying on the neighbors (just kidding about that one!). In other words, there's a much better chance that your binoculars will get used. If you also buy a nice sturdy tripod for the binoculars, that is all the better,

    Since a good pair of binoculars is still expensive, consider a magazine subscription. Astronomy and Sky and Telescope are both good magazines that talk about astronomy news and what is worth looking at in the sky. Neither of these are appropriate for young kids, though.

    Books are also great. There are lots of books with tons of pretty pictures from Hubble or other telescopes. If you want to encourage star gazing (maybe to see if they really want that telescope for next year), you want more than pretty pictures. As a budding astronomer, I learned a lot from "365 Starry Nights" by Chet Raymo. I've been told that "Turn Left at Orion" by Guy Consolmagno and Dan M. Davis is also very good at teaching where things are in the sky -- it would make a great companion to the binoculars.

  • Finally, remember that you get what you pay for. A good telescope isn't cheap. In order to have nice-quality images, the telescope needs to be made out of precision parts. We're not necessarily talking thousands of dollars, but anything cheaper than $100 or even $200 is probably just throwing money away.

If, after all of this, you still want to buy a telescope for a gift, but you aren't sure what to get, then I'll make a suggestion. I would suggest Edmund Scientific's Astroscan (pictured above). Yes, it looks a little funny. But it's a great little telescope. It's portable. It's easy to use. It gives some of the best views of star clusters and galaxies I've seen in a small telescope. And I've seen them sold online for the purchase price -- they keep their value. They're available for $200 online. For a beginner, I don't think there's a better buy. (BTW, I don't get paid to advertise for the Astroscans. I just like to use them. I bought one for my daughter several years ago. She never got that interested, so I use it myself all the time. I just got the basic package.)

Finally, please don't buy a star for a present. There's nothing "official" about that racket, it's expensive, and often the materials that come in the package are just plain wrong. Spend the money on a book instead, and take your loved one outside and let them choose their own star. There's no cost, and you'll always know where to find it.

Monday, December 01, 2008

Moon, Jupiter and Venus in conjunction

Right now, looking out of my office window, there is a gorgeous arrangement of the moon, Venus, and Jupiter in the twilight sky. If you have clear skies early tonight, go take a look to the west. The moon is a thin crescent, and Venus and Jupiter are the two brightest "stars" near the moon (Venus is the brighter one).

If you don't have clear skies tonight, Venus and Jupiter will still be close to each other for the next couple of days, but the moon is moving further eastward along her path.

Principled Astronomers

Image Credit: Larry Kolvoord / Austin American-Statesman

There are times when people like to vilify scientists. It seems that, half the time, James Bond is battling some crazed scientist for control of the world. Most science fiction movies have a mad scientist. Jurassic Park, has several unprincipled scientists. When the Large Hadron Collider started up, I got sick of people (most of whom probably thought they were being both clever and original, when they were neither) quoting Jeff Goldblum's character from that movie, "Your scientists were so preoccupied with whether or not they could, they didn't stop to think if they should."

Hey, I love a good fiction piece, and I love Jurassic Park (book and movie). But I get tired of people who think that scientists are unprincipled, power-hungry megalomaniacs. Many of the most principled people I know are scientists. And today I can present a good example of such an ethical scientists: Texas's own Professor John Lacy.

In a story that appeared in Sunday's Austin American-Statesman newspaper, it was revealed that Professor Lacy quit working on a major NASA project, the SOFIA telescope, because of his personal concerns about the environmental impact of the telescope. Professor Lacy is a very soft-spoken, intelligent scientist, not an environmental nut, nor an attention-seeking egomaniac. He quit the project out of genuine concern, and didn't make a big deal out of it; the news article was written by a student who caught wind of the story.

SOFIA is an infrared telescope. It is very hard to do infrared astronomy from the ground, because water in Earth's atmosphere blocks infrared light. So, you either need to launch a telescope into space (which costs billions of dollars) or put it on an airplane and fly above most of the atmosphere's water. SOFIA obviously chose this latter approach.

SOFIA is being assembled on a converted 747 jet. When it becomes operational, it will fly a few times a week, using an entire plane load of jet fuel each flight. If you work out how much fuel SOFIA will use, each flight is only about one ten-thousandth of the USA's daily jet fuel usage, a tiny percentage. But it still adds up to 3+ tons of CO2 emitted per flight.

The ethical question is, therefore, "Is that worth it?" If the benefit from the telescope were very high, and SOFIA contributes greatly to astronomy, then that cost may well be worth it. When Professor Lacy thought through the issue, he decided that the scientific payoffs of SOFIA were not worth the environmental costs. So, after much deliberation, he quit the project.

Obviously, not all astronomers agree with him. Personally, I don't know if I would come to the same conclusion. And, I doubt there is a "right" or "wrong" answer on this particular issue. All astronomy, in some way, has a significant carbon footprint. We travel to observatories, our computers use electricity, our journals use trees. But we do more than contribute to the problem; we contribute to the solution. It was astronomers trying to understand why Venus is so hot and why the Earth isn't frozen solid that lead to the discovery of the greenhouse effect. It is astronomers who have proven that the recent rise in global temperatures is not due to increasing energy output from the sun. And by keeping people interested in science, we astronomers can help people feel more a part of the fragile world in which we live, which leads people to be receptive to solutions to the greenhouse crisis.

So, I don't know that I would have made the same choice as Professor Lacy. But I do know that to walk away from a project that one has worked on for a significant fraction of one's career takes strong personal morals, courage and conviction, those very properties that movies and some elements of society often claim we scientists don't have. So, the next time you hear someone saying how scientists only have their own personal interests at heart, think about John Lacy and the SOFIA telescope. We do consider the impact and implications of what we do.

Saturday, November 29, 2008

Astrophysicist Edwin Salpeter Dies

Edwin Salpeter
Image Credit: Cornell University

This afternoon, I learned that renowned astronomer Edwin Salpeter died last Tuesday from leukemia at his home in Ithica, New York.

Salpeter was one of those astronomers that few in the public had heard about, but who had a tremendous impact on the science of astronomy. I never met Salpeter, but I am well aware of his impact on our field. Most of us younger astronomers first become aware of Salpeter's name through what we cann the "initial mass function," which is a simple mathematical equation giving the number of stars of each mass arising from stellar nurseries, like the Orion Nebula. Salpeter's equation describes how there are a lot more little stars than big stars. His equation is still in common use some 50 years later.

Salpeter's biggest contribution may have been in understanding how stars burn helium into carbon. To make carbon requires three helium atoms smashing together almost simultaneously; it took some tricky quantum physics work to figure this out. Along with Nobel-prize winning physicist Hans Bethe, Salpeter developed the mathematical framework for some types of two-particle systems (but don't ask me to explain it, because I personally have never studied this field of physics). Salpeter's list of achievements goes on; running through his obituary and his webpage, I found myself reading about an important bit of astronomy research and saying, "I didn't know he worked on that." It's quite impressive.

Wednesday, November 26, 2008

My foreign Thanksgiving

Tom Turkey wishes everyone a happy Thanksgiving
Image Source: National Geographic

Tomorrow is Thanksgiving day here in the United States, one of the biggest holidays of the year. I had never thought too highly of Thanksgiving as a kid: it meant traveling 14 hours through at least three states in heavy traffic, a huge meal in a house full of relatives stuffed to overflowing, and generally getting into trouble because I was in the way. But that changed in 1996, when I was living in Munich, Germany for the school year.

I was studying astronomy at the Max-Planck-Institut für extraterrestriche Physik in Garching, Germany as part of the Fulbright program. In Germany, the fourth Thursday of November is a normal work day, not a holiday. So, on that day, I found myself in front of a computer in my cubicle, trying to analyze X-ray pictures from the ROSAT satellite. And, surprisingly, I found myself quite dejected, since nobody knew (or cared) that it was a major holiday. In the early afternoon, I gave up and went home.

The next afternoon, I headed to a southern part of Munich. A German lady there was holding an American Thanksgiving dinner for all of the Munich Fulbright scholars and our host families. We were going to have turkey, mashed potatoes, pumpkin pie, and so on. We (the scholars) were supposed to arrive early to help with the cooking and preparations.

I showed up just a few minutes early. The Germans, and in particular our dinner host, are big on the idea of punctuality, or being exactly on time. (I often joked to my American friends in Munich that Pünktlickheit is fast göttlichkeit , or "punctuality is next to Godliness".) The other scholar didn't show up on time, and our host quickly started to mutter "Americans never come when they say they are going to." And as the time stretched on, our host grew more and more angry that my friend and fellow scholar was late.

In the meantime, I learned that our "American" Thanksgiving dinner was anything but. My host told me that she couldn't find Turkey, so we'd be having pork. And she didn't feel like making mashed potatoes, so we were having sauerkraut. And she didn't want to make a pumpkin pie, so we were having a strudel for dessert. As I helped set the table and tried to help cook these foods, I noticed that it was snowing heavily, and my friend still wasn't there.

Finally, almost two hours late, the doorbell rang. The other scholar had finally arrived. My host opened the door wide, and I saw what looked like a snowman on the front step. My friend had taken the wrong bus, ended up about 4 or 5 miles away, and then found that she had ridden the last bus of the day on that route, so she had to walk the entire distance through the snow. So, cold, wet, shivering, and with a good inch of snow perched on her hood, she was greeted with a stern, "Why don't you Americans ever come when you promise to?" I felt ill. So much for a jolly holiday celebration.

Things did improve about an hour later, when our German host families arrived right on time. Both of these families are very jovial and friendly, and they lightened the mood considerable. So, in spite of having a Thanksgiving meal consisting of pork, sauerkraut, and strudel, it wasn't horrible.

But the best part came that night. Back at my apartment building, there were five American students (counting myself). We decided to have a proper Thanksgiving meal. We only had a small kitchenette (with only a stove and a few pots and utensils), so we couldn't roast a turkey, but we found some canned turkey that we heated. We made some stuffing (that was a little runny) and some mashed potatoes (that were very lumpy).

But in spite of the failings of the food, we all discovered that it was the fellowship that mattered. Sitting around a small table in a strange country with only the barest remnants of a true Thanksgiving feast, we were all truly happy and thankful for the blessing that was our camaraderie. Although we all enjoyed our studies abroad, we'd found that we still needed to cling to each other and those unique cultural traditions that we shared.

So, these days, when Thanksgiving preparations start to get too frustrating, I always think back to that Thanksgiving in Germany. That's where I learned what I am truly most thankful for. Not a giant feast, not a day off of work, nor other ephemeral things. But I am thankful for friends and family, and the support we give each other, even in the roughest of times or the strangest of places.

A happy Thanksgiving to everyone!

Wednesday, November 19, 2008

The true reason for the demise of Mars Phoenix: its spare Illudium Pu-36 Explosive Space Modulator was stolen

Jawas haul away Mars Phoenix
Image Credit: John Fischetti

Last week, NASA announced the demise of the Mars Phoenix mission, ostensibly because the setting sun at Mars's north pole caused the lander to run out of power. To celebrate the Mars Phoenix mission, Gizmodo held a Photoshop contest -- what pictures did Mars Phoenix take that NASA will never show? Here are the winners.

Note: Except for this picture, I guarantee that all of these are fakes.

P.S. For those who want to continue to get updates on the Mars Phoenix findings, try Twitter.

P.P.S. Those of you who don't know what a Illudium Pu-36 Explosive Space Modulator is, who would want to steal it, or why, click here.

Monday, November 17, 2008

A new poll on NASA

Over on the right-hand side of the blog, there is a "new" poll (it's been up for a week, but I haven't mentioned it yet) asking your opinion on NASA's biggest success since the moon landings. Feel free to register your opinion. If you don't see a choice you like, feel free to add it in the comments to this post. I'll talk about the results and my opinion once the poll closes.

NASA had a good weekend -- the shuttle Endeavour safely launched on a mission to add more living space to the International Space Station, and the Spirit rover on Mars called home to say that it was a little low on energy, but otherwise is doing fine.

I, on the other hand, am having fun trying to define my "teaching philosophy" for job applications. It is a one-to-two page essay that everyone asks for, but nobody has ever bothered to tell us postdocs what it is supposed to convey. I've found tips online, and find that if I read enough helpful hints, they all contradict each other. Thanks a lot.

Thursday, November 13, 2008

Yet more planets imaged!

Planets around the star HR 8799
Image Credit: Gemini Observatory

In what was obviously a press release coordinated with the Hubble announcement of a picture of a planet around another star, astronomers at the Gemini Observatory in Hawaii announced today that they have pictures of two planets around a single star. This star, known just by its catalog number HR 8799, is 130 light-years away in the direction of the constellation Pegasus. Further follow-up with the Keck Observatory revealed a third planet closer to the star.

These are big planets, about 10, 10, and 7 times the size of Jupiter. Like the planet around Fomalhaut, these planets orbit pretty far from their parent star: 25, 40 and 70 times the Earth-sun distance. For comparison, Jupiter orbits the sun at 5 times the Earth-sun distance, Saturn at 10 times the Earth-sun distance, and Neptune at 30 times the Earth-sun distance.

We've entered a new era of planet discovery today. For the first time, we have a growing number of pictures of other planets. Sure, they are all bigger than Jupiter, and we can't yet see any features on those planets (they are just too far away).

Hubble sees a planet around another star

Hubble picture of the planet Fomalhaut b

Image Credit: NASA, ESA, and P. Kalas

In the fall, low in the southern sky hangs a lone bright star named Fomalhaut. Other than being one of the brighter stars in the sky and being relatively nearby (about 25 light-years away), Fomalhaut remained fairly obscure for most people until the 1980s. That's when a NASA infrared satellite called IRAS discovered that Fomalhaut had a lot of extra infrared light that could be explained by a lot of dust around the star, dust that could be explained by a forming planetary system. In 2005, the Hubble Space Telescope took a picture of this dust, and it looked like almost a perfect ring. Except that the ring was not exactly centered on the star, like you would expect -- it was offset a little bit. The team taking the Hubble picture suggested that a planet's gravity could be pulling the ring off-center, and astronomer Alice Quillen calculated that this planet could be as small as Neptune. But the planet remained hidden.

In a paper accepted to the prestigious journal Science, astronomer Paul Kalas, who had taken the first Hubble picture of Fomalhaut, announces that a second Hubble picture (above) has revealed a planet about twice the size of Jupiter orbiting Fomalhaut. In the picture above, the box shows a blow-up of the same portion of the old and the new images, and a tiny dot of light is seen to have moved a tiny bit in the same direction as the ring, just what one would expect for a planet orbiting the star!

Not shown is the more important bit of information for us astronomers, that the ring and the dot are both following Fomalhaut through the sky. All stars move in the sky as our Solar System and the stars move relative to one another. Fomalhaut moves at a fairly high rate, so that accurate pictures taken a few years apart can show its motion. A few other dots in the Hubble image didn't move with Fomalhaut, indicating that they aren't related -- they are just other stars in the distance. But since the ring and the planet, now called Fomalhaut b, moved with Fomalhaut, we know that they are all related. Past claims of pictures of planets around other stars proved to be premature, as later pictures showed them not to be moving with their purported parent across the sky; Fomalhaut b does not have this problem.

Based on the pictures and how far the planet moved in its orbit, and based on new models of the ring by team member Eugene Chiang, Paul Kalas's team estimates that the planet is about twice the mass of Jupiter, and located 115 times further from Fomalhaut than the Earth-sun distance, or about 10.7 billion miles away. It takes this planet almost 900 Earth-years to orbit Fomalhaut once.

There are many head-scratching things about this planet. First, how could such a big planet form so far away from the star? We didn't think that was possible, so maybe the planet moved out from closer to the star (this happened to Neptune and Uranus in our Solar System), or maybe it formed out there, showing we don't understand planets. Fomalhaut b is also about 100 times brighter in visible light than models predict for a planet of its size. Maybe Fomalhaut b has a ring around it, like Saturn, or maybe our models of its atmosphere are completely wrong. We have only a very few limits on planetary atmospheres outside our Solar System, so it wouldn't surprise me if these models are just plain wrong.. Also, Fomalhaut b's brightness changed by about 60% in between the two pictures, which could mean that any ring around the planet is changing fast, or perhaps that the weather on the planet is rapidly changing, or perhaps that there is a variable amount of dust and rock blocking some of the planet's light. There's obviously still a lot of work to be done here!

To me, the most amazing part of this discovery is the technical aspect. Fomalhaut b is one billion times fainter than Fomalhaut, and it is located just 15 arcseconds (or four thousandths of a degree) away from the star. This is roughly like trying to find a single lightning bug four feet away from a collection of 150 searchlights from ten miles away. That ain't easy. And that's the power of the Hubble Space Telescope.

Congratulations to Paul Kalas and his collaborators on their discovery!

Mars Spirit Rover now in trouble

Mars Spirit rover covered in dust Image Credit: NASA / JPL-Caltech / Cornell

Just ten days after the Mars Phoenix lander fell silent, the Spirit rover, one of the intrepid twin rovers exploring the surface of Mars for almost 5 years, is in serious trouble due to a dust storm.

The above picture, taken a year ago, shows the reason. That is a picture of Spirit's solar panels, which give it power. They're now covered in a thick layer of dust. To top it off, a small but powerful dust storm crossed Spirit's home in Gusev Crater last week, blocking so much sunlight that Spirit was in serious danger of using up its batteries and falling forever silent. To try and prevent this, NASA radioed Spirit some emergency energy-conserving measures on Tuesday and told Spirit not to try and call home again until today. (The radio takes a lot of energy, and NASA essentially wants Spirit to bask in what little sunlight there is and build up some power reserves.)

Yesterday, NASA didn't hear anything from Spirit. This means one of two things: either it received its energy conserving instructions and is following them, or the instructions came too late and Spirit is dead. The third option, that Spirit didn't get the instructions but is still alive, is ruled out, because Spirit would be radioing data or radioing for help.

So, this is a nail-biting time for the Mars rover team. It's like parents hearing their kid in the next room, jumping off on and off the furniture. So the parent yells, "stop that, or you'll get hurt!" And then silence falls. Did the kid stop the jumping, or did they actually get hurt? We'll know more later today. Update: NASA announced today that Spirit did communicate, as instructed, and so is still alive. The future is still uncertain, but she's still with us.

It's a bad time for Spirit to be having trouble. Mars is about to move behind the sun, as seen from the Earth. During this time of conjunction, any radio waves between Earth and Mars get messed up by the sun, so it's not possible to communicate detailed instructions clearly with the rover. (Some minor communications can get through, but not much more then beeps saying "Hi, we're here, we'll call back tomorrow!") In about another week or so, we'll have to let Spirit try and survive on its own for a few weeks.

Even if Spirit does not survive, it's important to remember that the rovers were designed to last for three months, and they've survived for four-and-a-half years. In a harsh place like Mars, that's not too shabby! And Spirit's twin, Opportunity, is still happily scurrying across the plains of Mars half a planet away.

Wednesday, November 12, 2008

Things that go boom in the night

The star cluster Messier 35
Image Credit: Kurtis Williams, NOAO

Today, on our astronomy preprint server (a website where we can put professional papers before they appear in our trade journals), a paper of mine appears. I've been working on the specific data presented in that paper for about 7 years now, so I am happy that this particular paper is almost completely finished (just some copy editing and exchange of bribes publishing fees remain).

The paper involves looking at white dwarfs, the glowing embers of dead stars, in the open star cluster Messier 35. Messier 35 is a group of related stars about 3000 light-years away in the constellation Gemini; the stars in the cluster are 150-200 million years old.

The reason I was looking at the white dwarfs in Messier 35 is because I want to know what the line is between stars that end their lives as supernova explosions and those that end their lives as white dwarfs. We astronomers are pretty confident that this difference is due almost entirely to the mass of a star -- very massive stars explode, and lower-mass stars make white dwarfs. But what is that line, exactly?

In Messier 35, the stars that are currently ending their lives are about 5 times the mass of the sun, and we see white dwarfs in the star cluster. That tells us that stars 5 times the mass of the sun aren't big enough to explode. But my collaborators and I went one step further.

White dwarfs have no nuclear energy source. They shine because they used to be at the middle of a star, which was hundreds of millions of degrees! Now that the star is dead, the white dwarf cools off, just like a hot poker taken from a fire will cool off and fade away. We can calculate how fast white dwarfs cool, so if we can measure how hot they are, we know how long they've been cooling off. That means we know how long ago the white dwarf's parent star died. So what?

Now comes the tricky part. We know how old all the stars in Messier 35 are, about 175 million years old. Say that I find a white dwarf that's been cooling off for 75 million years. That means that the white dwarf's parent star was 100 million years old when it died (175 million - 75 million = 100 million). We then look at tables that tell us how long a star's life is (that just depends on the star's mass), and, voila! We know how massive each white dwarf's parent star is.

If you don't understand, I can put this in human terms. Suppose you know that your friend John Q. Public is 50 years old. You see John's kid Emily running around the park, and you ask her how old she is. Emily cutely responds, "I'm four!" while holding up three fingers. So, you know that John was 46 years when Emily was born. We do the same, just with white dwarfs. (And white dwarfs aren't quite as cute as other people's four-year olds, but that can't be helped.)

When I did this in Messier 35, I found some white dwarfs came from stars as massive as 6 to 6.5 times the mass of the sun, but none had parent stars more massive than that. Perhaps this means that stars more massive than 6.5 times the mass of the sun explode?

Maybe, maybe not. Perhaps the star cluster didn't have any stars more massive than 6 times the mass of the sun. This seems doubtful, but it's hard to be sure. Or perhaps the white dwarfs that came from stars 7 or 8 times the mass of the sun escaped from the star cluster, so we don't see them. All we know for certain from Messier 35 is that stars that are 6.5 times more massive than the sun make white dwarfs. We are also pretty sure that all stars less massive than this make white dwarfs, too.

In order to determine which stars explode, we need to tackle this from the other end, too. Some colleagues of mine in Europe are looking at older Hubble Space Telescope pictures of nearby galaxies. If a supernova is seen in a galaxy, and if Hubble took a picture of that part of that galaxy, they can actually look and try to find the individual star that exploded. Along with some fancy statistics, they have determined that stars bigger than about 9 times the mass of the sun definitely explode.

So, now we know that stars smaller than about 6.5 times the mass of the sun make white dwarfs, and that stars bigger than about 9 times the mass of the sun explode. The trick now is for both of us to continue to work, and try and squeeze those two limits together until they meet. Only then will we know for certain how big a star has to be to explode.

Tuesday, November 11, 2008

Thank you to all veterans

A very personal and heartfelt thank you to all who have served the United States in the military. Whether you fought the battles of protecting us at home, fought abroad, secured the peace, or suffered at the cruelhands of our enemies, I deeply appreciate your service.

Monday, November 10, 2008

Mars Phoenix falls silent

Today it was announced that the Mars Phoenix polar lander sent her last transmission on November 2, over a week ago. At the North Pole of Mars, twilight is falling, and the lander can no longer recharge its batteries. So, after five good months of work, the mission is over.

Unlike the Mars rovers, which are soldiering on after four-and-a-half years, we knew that Mars Phoenix couldn't last. And while there is a tiny chance that Phoenix could rise from the dead next Martian summer (one Earth-year away, as Mars's seasons last twice as long as Earth's), this is extraordinarily unlikely.

Congratulations to the Phoenix team on a successful mission! Now the real work begins -- analyzing all of the data that Phoenix took over the past five months. That will keep scientists busy for years to come.

Obama and NASA

On several science-related websites, I've been seeing a lot of chatter about President-Elect Obama and the tough science-related decisions awaiting him. For example, this article from discusses the problems facing NASA, which is required to stop launching space shuttles in 2010, even though a replacement launch vehicle probably won't be available until at least 2015.

NASA has lots of problems, and this is a biggie. Many people want Obama to put his money where his mouth was, and work for extra funding for NASA, and state that this is a priority.

Frankly, while I think it is bad that America may soon be without a way to launch humans into space for 5+ years, I don't really want Obama spending a lot of time on NASA right now. We're embroiled in two wars, the economy is falling apart around us, and many people are losing their jobs by the hour. I'm sorry, but giving NASA an extra $2 billion to keep the shuttle flying isn't going to change any of that. That doesn't mean that NASA couldn't use the money, or that I think it shouldn't be done (it should!).

What that does mean, in my opinion, is that Obama shouldn't be spending much time at all worrying about NASA right now, and that we shouldn't be badgering him to do so. I'd rather Obama spends his transition period worrying about the economy and foreign policy.

Right now, arguments about competitiveness and technology don't carry much weight, and I think that the more we make a scene to try and get attention, the less attention we'll get. I think it is fine to write your Congresspeople and ask them to increase the NASA budget, perhaps as part of a stimulus plan -- after all, aerospace engineers are American workers, too! But I think it would be detrimental to harp on the issue. The overwhelming majority of Americans, myself included, are much more worried about retirement savings and banks then about NASA's woes. Let's let Obama get a good handle on those solutions before we try and divert his attention to other issues.

Some trails are happy trails, others are persistent trains

The smoking trail of asteroid 2008 TC3
Image Credit: Mohamed Elhassan Abdelatif Mahir (Noub NGO), Dr. Muawia H. Shaddad (Univ. Khartoum), Dr. Peter Jenniskens (SETI Institute/NASA Ames), APOD

In early October, astronomers in Arizona detected a small asteroid headed straight for Earth. The asteroid, a boulder only a few meters (yards) across, was predicted to streak through the skies over Africa. Some airline pilots reported seeing the bright meteor, and, over time, more reports are trickling in. The meteor exploded high in Earth's atmosphere; it's unclear if any meteorites survived to strike the ground.

The fireball from the explosion was detected by a European weather satellite over northern Sudan. Infrasound (low-frequency sound) detectors in Kenya recorded a boom from the explosion. And, in the picture above, the "persistent train" from the asteroid was detected in a video. (A persistent train is a trail of hot and ionized air left behind from a meteor's passage; because the air is so thin up there, it takes a long time for the air molecules to cool down and to disperse.)

Fireballs, high-altitude explosions, and persistent trains are fairly common meteor phenomena. It's rare for any one person to see these, but they are known to happen quite a bit. With the pre-encounter discovery of 2008 TC3, and with future such discoveries, perhaps we can tie meteor phenomena with properties of asteroids, and better understand how much tiny rubble there is in our solar system! Plus, the potential of discovering meteorites from this event could lead to a better understanding of the composition and structure of asteroids, which would be really good to know if we ever found a really big asteroid headed toward us.

For more on asteroid 2008 TC3 and its collision with Earth, try this page from NASA.