Tuesday, January 26, 2010

Spirit rover is stuck for good

Artist's conception of the Mars Exploration Rovers at work
Image Credit: NASA

Today NASA announced that the Spirit rover, one of the two robotic rovers exploring Mars, is stuck and cannot be freed from a sand trap in the Columbia Hills in Gusev Crater.  Spirit can still wiggle a little bit, and so the rover control team is trying to tilt the rover toward the sun in the hopes that it can survive the brutal, year-long Martian winter.  Spirit can still perform a lot of science, studying the rocks and soil within the reach of her arm, taking weather measurements, and even acting as a precise locator beacon, allowing scientists to look for wobbles in Mars' rotation that can help tell whether Mars has a solid or liquid inner core.

Again, Spirit is not dead, but it is stranded.  To date, Spirit has survived 2157 Martian days, and the mission goal was 90.  I think that counts as successful.  

Could the Mars rover team try and free Spirit again come the Martian spring?  Perhaps, though I doubt it.  The rover is dug in pretty deeply, and two of Spirit's wheels don't turn anymore.  Imagine trying to push a heavy shopping cart whose two front wheels don't work through a sandbox, and now imagine trying to do that with a remote control from 40 million miles away. At some point, the slight chance of freeing the rover is no longer worth the expense, and NASA believes that point has been reached.

After hearing the news that Spirit has been transformed from a rover to a stationary science platform, the song "And the Band Played Waltzing Matilda" started going through my head, though with slightly altered lyrics (my apologies to Eric Bogle; you can find the original lyrics from his page):
And she'll go no more waltzing Matilda, all around Gusev Crater on Mars
To climb through the hills, rovers need all six wheels
Now Spirit sits still 'neath the stars

Edit: As a side note, Mars is nearing opposition, when it is opposite the sun in the sky, and when Earth is closest to the Red Planet.  What does this mean?  If you have clear skies in the next few weeks, look toward the east in the early evening, or high overhead around midnight.  The bright yellowish-orange "star" you see is Mars.  The only other star nearly as bright as Mars in the evening sky right now is the star Sirius.  Mars has a distinct orangish hue, while in comparison, Sirius is a steely white.

Monday, January 25, 2010

Moving week!

I am busy moving my residence this week, so I may not blog much (or at all).  I do hope to have time to write about my move, as there are some instructive lessons about the arcana of academia and academic jobs, at least in astronomy. 

Thursday, January 21, 2010

Astro101: Solar Systems, Star Clusters, and Galaxies

Today I'm going to start an occasional series that I'll call Astro101.  In this series, I intend to try and talk about some basic astronomy concepts that come up a lot in astronomy news but that many people don't really understand.  My goal here is to give short and clear explanations, not exhaustive discussions covering every possible angle on a topic. 

All of these posts will be labeled with "Astro101", so if you come back and search the blog on that term, these posts should come up, and you can read them as often as you wish. 

Today's topic involves some definitions for three types of objects that are often confused: a solar system, a star cluster, and a galaxy.  I've even known some very intelligent and knowledgeable amateur astronomers to get these mixed up, so there's no shame in not knowing (at least until you've finished reading this post).

Wednesday, January 20, 2010

Choosing a graduate program

In the next several weeks, college seniors who've applied for graduate school in astronomy will be receiving acceptances and rejections.  So, here is some completely unsolicited advice for those who will be choosing which astronomy graduate program to attend.  One disclaimer: this is based on my own experience and observations, which leads right in to my first point:

  1. Selecting a graduate program is a personal choice.  Even before the offers start coming in, consider what is important to you in your graduate career.  Do you want the best possible education?  The best university name on your degree?  Do you care about where you will be living?  Do you have family or a significant other who factors in to the equation?  If you have to make a choice between some of these, which factors more highly?
    Don't be afraid to make decisions based on what you want, not how other people would choose.  I turned down an offer from what had been my dream school and what is arguably the absolute best astronomy program in the nation because I came to realize that I would be very unhappy there for several reasons.  As a graduate student, you will be spending up to six or seven years of your life working very hard for lower pay than you could get elsewhere, so you might as well be happy.

  2. Visit before making your decision.  Many graduate programs will offer to pay for you to visit their school; take advantage of that visit.  Visit multiple schools, if you are so lucky.  And, if the school(s) to which you've been offered admission can't afford to pay for your trip, try to scrounge up money for one or two visits.  I visited four schools, and it was those visits that helped me to realize where I'd have the best chance to succeed.  Some of the most unhappy grad students I've met are those who didn't visit.
    On a visit, remember that the school is courting you and will put on the best possible face.  Enjoy being recruited; it may not happen again for some time.  But also work hard to get some behind-the-scenes information.  Ask grad students about their courseload, workload, and what complaints they have.  Every grad student has complaints, and most will be honest with you.  You'll find some complaints are universal, such as grads working much harder than expected and some/many classes seeming useless and poorly taught.  Complaints that would raise flags in my mind would be things like faculty being unresponsive to student concerns, students not getting paid some semesters or summers, students thinking their fellow students are competitive, and so on.

  3. Think twice before entering a program without a Master's Degree.  Most new graduate students in astronomy enter with the intention of earning a PhD.   But, after a year or two, many students come to realize that astronomy research is not what they want to do with their lives.  If your program offers a master's degree, you can earn that in two or three years, feel proud of your accomplishment, and then take that degree into industry and earn much more money than your PhD friends ever will.  If, on the other hand, you don't have the option of a master's degree, you can either quit without a degree or slog through to the bitter end, at which point you will be disenchanted and several years older when you start your career outside astronomy.
    Earning a master's degree is not a failure.  Let me repeat that, since a lot of new grad students and many older academics do not believe it.  Earning a master's degree is not a failure.  It is a big achievement that requires successfully completing rigorous classes and research work.  It is a highly valued degree in the professional world.  In recognition of that, many astronomy graduate programs now require completion of a master's degree before a student can become a candidate for a PhD.  If one or more of the programs you are considering does not offer a master's degree, take that into consideration (but, as always, see point 1 above).

  4. Pay attention to the faculty's areas of interest.  If you really, really, really want to work on Solar System exploration, don't go to a school where the faculty work on galaxies.  If you like computational physics but the faculty are all observational astronomers who return a blank stare when you talk about blades, cores and clusters, it may not be a great fit.  On the other hand, keep an open mind.  If you think you really want to do quasar accretion disk reverberation mapping, you may find that you excel at other extragalactic projects, or maybe even that you have a knack for finding extrasolar planets.  But if even your most generic interests are not matched by one or more faculty members, you may not be happy.

  5. You always have a choice.  Many potential graduate students will only get an offer to one school, and many will get no offers of admission.   If you fall into this case, remember that you still have multiple choices available.  Let's say you visit your one school and you don't like it.  You can always decline admission, try to strengthen your credentials, and apply to grad schools the following year.  Likewise, if you do not get any offers of admission, you can either decide against grad school for the time being, or you can work to strengthen your application for the following year.
    If you are deciding not to take your one offer and applying again, or if you received no offers and still want to go, be sure to ask your professors why you didn't get more offers.  Were your physics GRE scores too low?  Were your grades low?  Was your application poorly written?  Were your letters of recommendation weak?  Examine every aspect of your application, and see if there is anything you can do to improve it the following year.  And, if professors you trust give you frank advice that they don't think you'd succeed in grad school, listen to them and consider their words carefully.

My one-sentence summary would be point number 1 - graduate school is your decision.  Like any decision, there are positives and negatives to any choice you make, and there may be no perfect or obvious decision.  Graduate school will be one of the most challenging (and rewarding) times in your career, so be sure to make a choice that is right for you.

Tuesday, January 19, 2010

Predictions for the new decade

In December, we were deluged by typical "Year-In-Review" articles summarizing big news stories of the previous year.  I also saw many (mostly dismal) reviews of the past decade.   I didn't feel like recapping other people's recaps, so I stayed out of that fray.

However, I have been thinking a lot about the future, and what may happen in the decade to come.  Therefore, I've decided to make a list of my predictions of astronomy-related happenings and discoveries that will be announced between now and December 31, 2019.  Unlike Nostradamus, I'm going to be relatively specific in my predictions, and I'm going to rank them by how likely I honestly think each event is.  Come back on January 1, 2020 and we'll see how I did. 

Thursday, January 14, 2010

Help for Haiti

We'll get back to astronomy tomorrow.  Today I want to add my voice to the chorus of those asking for donations to help the people of Haiti after the devastation of the major earthquake there.

The first few days after a disaster are the most crucial in terms of saving lives.  Medicine, water, personnel, and recovery equipment need to move in quickly.  However, many aid organizations are strapped for money due to the ongoing economic downturn and corresponding drop in monetary donations.  In short, money is needed, and it is needed now.

Please consider giving money to a reputable aid organization that has people on the ground in Haiti (while other aid agencies may want to help, it is currently very difficult for new people to get into the country).  Some of the groups in such a position are (U.S. affiliates are listed):

  • American Red Cross: Donate through their website: http://www.redcross.org or text "HAITI" to 90999 for a $10 instant donation that will appear on your next cell phone bill.
  • UNICEF USA: the United Nations Children's Fund, http://www.unicefusa.org
  • Doctors Without Borders: http://doctorswithoutborders.org

I purposefully did not include HTML links in the list above as a reminder to be cautious.  In times of disaster, many disreputable people will try and take advantage of human generosity.  Such scams can include providing links to websites that look legitimate, but are really scam sites.    When making donations, ALWAYS double-check URLs and make sure you are on the real site, even if you are entering a site from a blog or email you trust.  If you are not convinced you are on the right website, consider calling or mailing your donation.  Again, just be cautious.

Please help, both now and in the future.  The window for saving lives is short, and the rebuilding process will take years.

Wednesday, January 13, 2010

Congratulations Anna!

Yesterday, the American Astronomical Society sent an email announcing the 2010 winners of the society's prizes and awards.  Among the winners is Anna Frebel, a former office mate of mine and an absolutely outstanding astronomer. 

Anna won the 2010 Annie Jump Cannon Award, an award given annually to an outstanding young female astronomer.  Annie Jump Cannon was an astronomer at Harvard College Observatory, a member of a group of women hired in the late 1800s and early 1900s to work on data analysis and astronomical calculations.  Cannon's work was to try and classify the spectra of stars.  Cannon developed a system to classify stars that we still use today, a system of letters based on the types and strengths of lines in the spectrum.  Her system has since been shown to be indicative of the temperature of the star, one of the most important pieces of information we need to know to study an individual star.  Her work was published as the Henry Draper Catalog, named after an amateur astronomer whose memorial fund supported Cannon's work.  Today, whenever you see news of a planet discovered around a star, and the star's name is something like "HD 209458", that's one of Cannon's stars.

Annie Jump Cannon and her female colleagues at the Harvard College Observatory were a crucial part of starting to break down gender barriers in the science of astronomy.  Gender issues still plague astronomy.  Although the situation is slowly improving,  we astronomers are still struggling with identifying and correcting intentional and unintentional biases against women.

Anna Frebel's work is, in many ways, directly descended from Cannon's efforts.  Anna works on metal-poor stars.  Stars are nuclear reactors that shine due to the energy released by nuclear fusion.  Over the lifetime of the Universe, this fusion, along with nuclear reactions during energetic events such as supernovae and other forms of stellar death, has been slowly converting the main products of the Big Bang (hydrogen and helium) into heavier elements, like oxygen, carbon, iron, nickel, uranium, aluminum, calcium, ytterbium, and every other of the elements on the periodic table

Since the amount of these elements has been increasing over time, astronomers like Anna can identify old stars by looking at their spectra and finding stars with very little iron.  By studying how the amounts and ratios of elements change in ever-younger stars, astronomers hope to piece together where individual elements came from, and how the early Milky Way is different from the galaxy we see today.  Anna has even been able to detect the effects of radioactive decay of elements like uranium in her most metal-poor stars. This age-dating proves that the stars are as old as the galaxy itself, just like we expected!

Congratulations, Anna, on this prestigious, exciting, and well-deserved award!

Tuesday, January 12, 2010

On the road again

After being home for an entire 3 days, I hopped on a plane yesterday to travel to Tucson, Arizona.  After the hectic travel of the holiday season, with stuffed planes and weather problems galore, yesterday's travel was like a different world -- seemingly empty airports, planes with empty seats, and smooth flying.

I'm in Tucson to work with collaborators on a research project.  We've been working for quite some time over the telephone and internet, but sometimes not even the internet can replace face-to-face meetings.  My noticing someone grimacing at something I say communicates far more than a month of telcons and emails ever could.  We also have some computer and equipment issues to hash out.  We won't have a paper ready to publish by the end of the week, but hopefully we will have a good start.

Thursday, January 07, 2010

Day 3 of the American Astronomical Society

Yesterday was the third day of the 215th meeting of the American Astronomical Society, and the final day that I was there.  Today I am at the airport hoping to get home, though my original flight was canceled and my new flight is delayed.

Day 3 started with a talk by John Grunsfeld, retired space shuttle astronaut, Hubble Space Telescope repairman, and newly-appointed Deputy Director of the Space Telescope Science Institute, the governmental organization that oversees Hubble and the James Webb Space Telescope (Hubble's replacement).  Dr. Grunsfeld's talk was mostly about STS 125, the final space shuttle mission to repair Hubble.  He also spoke of a desire to use Hubble himself to study the Tycho crater on the moon, which formed about 100 million years ago in an impact that likely led to weeks or months of intense meteor activity on the Earth.  Grunsfeld mused about what the dinosaurs might have thought about the meteors ("BOOM. 'Well, there went Fred.'")

Wednesday, January 06, 2010

Wrapup of Day 2 of the American Astronomical Society Meeting

Yesterday, day 2 of the 215th meeting of the American Astronomical Society (AAS) was yet another exciting day, with new results from both Earth's backyard and the most distant known reaches of the Universe. Today promises to be another exciting day, starting with space shuttle astronaut, Hubble repairman, and newly-annointed Deputy Director of the Space Telescope Science Institute, John Grunsfeld. I'll be tweeting as time allows, and searching Twitter for #AAS and #AAS215 will get you more astronomy than you can shake a stick at.

Tuesday started with a talk by planetary scientist Maria Zuber. She gave a review of the search for water on Mars, starting with the earliest Mariner probe images that suggested the Red Planet was as dry as the moon to modern studies that suggest Mars has huge reservoirs of water ice just under the surface. None of these results were new announcements, but since few astronomers read a lot about the inner Solar System, many of us learned quite a bit.

Tuesday, January 05, 2010

AAS meeting Day 1: planets and people everywhere

Today begins day 2 of the 215th meeting of the American Astronomical Society in Washington, DC.  As I said yesterday, follow me on Twitter, or search Twitter for #aas and #aas215 hashtags for up-to-the-minute tweets with news and science results.

There are 3300 astronomers registered for this meeting, easily making it the largest meeting of astronomers in the United States ever.  The halls and restaurants are crowded.  I feel sorry for the hotel staff, as they try to keep us all in line.  Herding astronomers is worse than herding cats -- if you clap your hands and shout at a cat, there's a chance it will acknowledge your presence, or at least flinch.  Astronomers just ignore all other noise and keep arguing about the efficacy of  Bayesian analysis.

Yesterday, the biggest science results were from NASA's Kepler Mission, which is searching for planets around other stars.  You can read their press release here.  Kepler has been looking for planets for months.  Yesterday's announcement was of five new planets, all Neptune- to Jupiter-sized and all very close to their host stars.  You might expect more, because it was launched in March and these hot planets only take a few days to complete an orbit, but the Kepler team has to do several levels of follow-up research to make sure that they are seeing a planet and not some other type of variable star.  That's hard and slow, and even slower because the area of sky Kepler is looking at (in the constellations of Cygnus and Lyra) are not visible from the ground during the winter and early spring, so right now there is little work that can be done.  The current official tally is 5 confirmed planets, 52 suspected planets, 65 stars with uncertain signals, and 65 stars with planet-like signals that are really something else.

One of the planets is very low density, about as dense as Styrofoam.  We have no clue how you make such a fluffy planet.  According to theory, if you take hydrogen and helium, the lightest and most common elements in the Universe, and you make a Jupiter-mass ball of this gas, it should be many times more dense than this planet.  I think this is telling us that we don't understand the physics of dense hydrogen and helium very well.  This is good, because it means planets can tell us something about physics as well as about astronomy! 

I was joking with friends about how, in a 6th grade science fair project, I made models of comets out of Styrofoam.  Little did I know that I was 25 years ahead of my time in understanding the building blocks of planets!

Another hard-to-explain object that Kepler found is a star with a very hot star orbiting it.  The odd thing is that the very hot star is a couple times the radius of Jupiter.   My first thought was this might be a white dwarf, but white dwarfs are only the radius of Earth and much smaller in diameter than Jupiter.  My next (and current) thought is that this hot star must be what we call a "hot subdwarf".  These are stars that, due to an interaction with a close companion, are essentially the bared stellar nuclear reactor normally buried deep in the core of a normal star.  The Kepler team claims to have ruled this out, but I found their explanation of that unsatisfactory.  Really, though, there's no way to tell until we can get more ground-based information this summer.

There's much more to say, but I need to get to a talk about water on Mars.  Follow my tweets!

Monday, January 04, 2010

The 215th Meeting of the American Astronomical Society

Today, the 215th meeting of the American Astronomical Society (AAS) begins in Washington, DC.  I'll be on the scene through Wednesday, and will tweet anything I find interesting as I hear it; follow my Twitter feed, @professor_astro to see the latest.  I hope to blog daily, too.

This meeting of the AAS will likely be the largest AAS meeting ever.  Astronomers at all stages of their careers, from undergraduate students through Nobel Prize winners, will be listening to talks on
the latest astronomy research, networking, renewing friendships, and taking as much swag as possible.

Today's events feature new results from the Kepler planet-finding mission, a news announcement from ALMA (a massive international radio telescope array being built in Chile), three lectures by prize-winning astronomers, and hundreds of short talks and poster presentations. Stay tuned!