Blueshift - Episode Three

[music]

Sara:  Welcome to the June 2007 episode of Blueshift, produced by the
Astrophysics Division at NASA Goddard in Greenbelt, Maryland.  I'm Sara
Mitchell.

Mike:  And I'm Mike Arida.

Sara:  Okay, Mike, I have to ask... what are those ridiculous glasses?

Mike:  These are my X-ray specs!  I heard we were learning about X-rays
today, and I just had to get them to be prepared.

Sara:  Well, Mike, we use satellites to study X-rays around here, not
cheesy glasses.

Mike:  Oh, that's probably why I got them for such a low price.

Sara:  Well, the kind of X-rays we're talking about today aren't the kind
you get at the doctor or the dentist, where they're shooting X-rays from a
machine and looking at shadow of your bones or your teeth.  We're actually
talking about catching the X-rays coming from objects deep in space.

Mike:  That's right!  There are a lot of NASA scientists that study X-rays
coming from space.  They study black holes, supernovae, active galaxies -
in fact, there are several satellites up in space right now, looking at
these X-rays and trying learn more about these objects.

Sara:  That's right!  Well, since we study this right here at Goddard, we
actually sent a microphone out into the field - up and down the hallways,
bugging the scientists to hear about what they're studying.

Mike:  They love that.

Sara:  They do love that.  So, Koji Mukai and Maggie Masetti will report
back on what they had to say.

Mike:  And Louis Barbier spoke with Curtis Odell, and we'll hear about how
some of our X-ray satellites are designed and put together.

Sara:  And finally, we'll get a behind-the-scenes tour of the Astronomy
Picture of the Day website, which brings new images and information to
millions of viewers around the world each day.

Mike:  Let's start things off with a brain teaser - and here's Louis
Barbier.

Louis:  Since this episode is all about X-rays, this question is about one
of the satellites up in space that we use for studying X-rays.

In 2005, a new X-ray satellite was launched.  This satellite was built by
the United States and Japan, and we called it Astro-E2 for years.  But
after it was launched, it got a new name -- Suzaku.  So here's your
question:

Why was the Astro-E2 satellite given a new name?

The choices you have to choose from are:

A. The newly-elected Japanese government exercised its right to name all
spacecraft

B. The Hitachi Corporation was outbid by Suzaku, Inc. for naming rights

C. It's a Japanese tradition to rename spacecraft after they are launched

D. The name Astro-E2 was already being used by a British heavy metal band

Stay tuned, and I'll give you the answer.

[music]

Sara:  Now here's Koji Mukai and Maggie Masetti, with a bit more about
X-rays and what we can find out about them.

Koji:  Hi, I'm Koji.  Maggie and I are here to tell you a little bit about
X-ray astronomy today.  X-rays are emitted by some of the most extreme
objects in the universe, like black holes.

Maggie:  But what exactly are X-rays?

Koji:  X-rays are actually a form of light that is higher in energy than
visible light.  Our eyes can't see X-rays, but we can build detectors that
can!  Since our atmosphere absorbs X-rays...

Maggie:  ...and it's a very good thing for us that it does...

Koji:  ...to study objects that emit X-rays, we have to put our
instruments on board satellites.

Maggie:  And that's one thing we specialize in here at the ASD.

Koji:  We just celebrated the 11th anniversary of an X-ray satellite
called the Rossi X-ray Timing Explorer...

Maggie:  ...which is quite a long name, so we call it RXTE for short.

Koji:  11 years is quite a long time for a satellite, but RXTE is still
going strong.

Maggie:  RXTE's strength is actually its ability to detect very fast
changes in the intensity of X-rays coming from things like black holes,
and neutron stars, all of which, due to their natures, are variable
sources of X-rays.

Koji:  Meaning their X-ray brightness isn't constant.

Maggie:  That's right!  We might see pulses of X-rays from a rotating
neutron star!  Or some objects might give off bursts of X-rays.

Koji:  Exactly.  Like, when matter spirals into a black hole and heats up!

Maggie:  We can even actually translate X-ray data into audio signals, so
that we could listen to a black hole.

Koji:  That's what Ed Morgan of MIT did.  He took data from a black hole
called GRS 1915+105...

Maggie:  ...that is quite a name...

Koji:  ...and made this sound file that we'll play for you.  Maggie's
going to tell you what to listen for.

Maggie:  What you're going to hear is roaring noise, which is turbulence
in the disk of matter that circles the black hole (and we call this disk
the accretion disk).  The thumping noise is instabilities in the accretion
disk.  And te whistling noise is the accretion disk vibrating.

[the sounds of black hole GRS 1915+105 - roaring, thumping, and whistling]

Koji:  We spoke with Craig Markwardt to learn a little bit more about what
happens when matter spirals into a black hole.

Craig:  People often think of a black hole as a vacuum cleaner that sucks
up everything in its surroundings.  In reality, matter usually approaches
a black hole in a very ordered, disk-like structure.  Although we can't
see into a black hole, because it is black, we can use RXTE to listen to
the vibrations of that disk, like vibrations of a drum head.  RXTE hears
higher pitched vibrations than any other satellite, which means that it
can listen to the sounds of the matter right before it plunges into the
black hole.

Maggie:  11 years into its mission, RXTE is still discovering new X-ray
sources, like the black hole we just talked about.

Koji:  Some scientists use the instruments of another X-ray satellite,
called Suzaku, to look at the spectra of these sources.

Maggie:  Can't one satellite do it all?

Koji:  No, actually, it can't!  Different instruments are designed for
different purposes, and use different technologies.

Maggie:  Suzaku, a newer satellite, has been designed for spectroscopy,
and it can get much better resolution with its new technology.

Koji:  So what do we mean when we talk about the spectra of these X-ray
sources?

Maggie:  Well, spectroscopy is simply the science of measuring and
graphing the intensity of light at different energies.  X-ray light
contains a range of energies within it, just like visible light ranges
from reds to blues.

Koji:  And by studying the intensity and the energy of the X-rays, we can
learn a lot about the source that emitted them.  For example, iron atoms
emit X-rays of a particular wavelength.  But around a black hole, that
iron atom may be moving fast - close to the speed of light, in fact.  
That creates a huge Doppler shift.

Maggie:  And I know you all know what Doppler shifts are - that's like
when a police cars siren sounds higher or lower, depending on whether it's
coming towards you or away from you.

[siren sound]

Koji:  Preferably away!

Maggie:  Most definitely!  So, matter circling a black hole might be
moving towards us or away from us as well, and we can tell this from the
black hole's spectra.

Koji:  That's right!  Blobs of matter moving towards us will emit X-rays
that are blueshifted.  And, that's a nice tie-in to the name of our
podcast!

Maggie:  Which is entirely coincidental, I'm sure.

Koji:  Ahem.  Anyway, we spoke to Jean Cottam, who is a scientist in our
lab who has used data from Suzaku to study black holes and neutron stars.

Jean:  We study the light emitted from hot spots of matter that spiral
into a black hole.  These generate broad emission lines in the spectrum.  
The details of the line shape tell us a lot about the nature of the black
hole, and the conditions in the matter surrounding it.

Koji:  Thanks, Jean.  X-ray astronomy really is a great way to learn about
black holes.

Maggie:  That's very true, and hopefully now you know a little more about
them than you did before.

Koji:  Okay, that's it for now!  Thanks for listening!  I'm Koji...

Maggie:  And I'm Maggie.

[music]

Sara:  Thanks, guys.  I can't say I'd ever heard a black hole before.  
Mike, had you?

Mike:  Uh, nothing like that!

Sara:  It's probably not going to be a chart-topper this year.

Mike:  Well, we've heard about the ways that we're studying X-rays and
what we're looking at.  But now we wanted to talk a little bit about the
satellites themselves.

Sara:  Well, one of the things that happens here at Goddard is the
development of new satellites - many satellites have actually been built
right here!  And sometimes, we build parts of satellites that are put
together other places in the world.  So, Louis Barbier sat down with
Curtis Odell to talk about the X-ray satellites that have been worked on
here at Goddard.

Louis:  I'm here this afternoon to interview Mr. Curtis Odell, who's the
instrument manager for Astro-E2 X-Ray Telescope.  Astro-E2 is now known as
Suzaku, as you all know.  And Curtis has been here at Goddard for 18
years, and he's an expert in the art of making X-ray mirrors and X-ray
telescopes.  So Curtis, thanks for being here.

Curtis:  You're welcome.

Louis:  When I was in high school, I made my own telescope.  I got a piece
of glass, and ground it down by hand for many, many, many months, and got
a little lens from my father, and put it all together and made myself a
refracting telescope.  Why can't I do that for X-rays?

Curtis:  Well, Louis, the X-ray photons won't be bent by that lens that
you made.

Louis:  If I wanted to make an X-ray telescope, can you give us a big
picture of what we'd have to do to go about that?

Curtis:  Well, you'd have to do something that would cause a reflection of
the photon onto a detector.  And even a reflector telescope that you might
think of for optical telescopes would not work either, because the photon
would simply strike the surface and be absorbed.  It would not reflect.  
However, if you took that reflecting surface, a reflector telescope, and
turned it up on its edge, so that it was almost edge-on to the source of
the X-ray photons, then the photon would reflect at that shallow angle we
call a grazing incidence angle.

Louis:  Could you explain exactly what you mean by grazing incidence?

Curtis:  You're driving down the highway, and you're kind of drifting off
a little bit, and you go off the shoulder of the road and you bounce off
the guardrail and right back onto the highway.  That's a grazing incidence
angle.  You didn't hit it head-on, you just sort of touched it and came
off.

Louis:  So that's what you call a grazing incidence.  To come back to my
telescope I made in high school, the lens was about 3 or 4 inches across.  
How many inches, so to speak, are your X-ray mirrors?

Curtis:  The diameter of the ones that we produce for Astro-E are 16
inches - 40 centimeters.  But that doesn't tell us the same information
that your refractor told us.

Louis:  And why not?  Can you explain why?

Curtis:  Well, now, remember we turned our reflector up on its edge.  And
so now that we've got it up on edge, we have a lot of room in our 40
centimeter diameter telescope to nest a whole bunch of concentric
reflectors around from the outside inwards.

Louis:  Okay, so if I were to look at this thing from the top, looking
down, I would basically see a series of nested cylinders, is that a good
analogy?

Curtis:  Right.  Nested thin-walled cylinders.  That's correct.  
Actually, 175 to be exact.

Louis:  Okay, well that sounds great!  Well, Curtis, I want to thank you
very much for coming into the studio today.  This is Louis Barbier, for
Blueshift.

[music]

Mike:  Thank you, Louis!  To see video clips about the Suzaku telescope,
visit our website at universe.nasa.gov/blueshift.  We also have more about
X-rays and the missions you've heard about today.

Sara:  NASA has satellites out there studying all sorts of objects...
stars, galaxies, black holes, planets... and there are even some that look
back at Earth.  These satellites send back all different types of data.  
Some are really pretty pictures, and some are pictures that only
scientists find pretty.

Mike:  I'm sure you've seen some of these images - fields of stars,
swirling galaxies, up-close views of objects that look like tiny dots when
you look up at the night sky.

Sara:  Well, for the past decade, the Astronomy Picture of the Day website
has been showing off pictures from all sorts of telescopes.  Every day of
the year, they put up an image with lots of information about what you're
seeing.

Mike:  And one of those astronomers, Jerry Bonnell, works right here at
Goddard.  So Steve Fantasia paid him a visit to find out more about the
Astronomy Picture of the Day and all of those pretty pictures.

Steve:  For over a decade, the Astronomy Picture of the Day Website,
apod.nasa.gov, commonly known as APOD, has been delighting viewers with
pictures from all over the Universe.  It gets somewhere around a million
visitors every day, has over 20 mirror websites around the world, and has
been translated to more than 10 foreign languages.  I'm Steve Fantasia,
and it is my great pleasure to have with me today Dr. Jerry Bonnell, one
of the curators of the APOD website.  Hi Jerry, welcome to Blueshift.

Jerry:  Hi, Steve.

Steve:  So, just how did APOD get started?

Jerry:  The short answer to that question would just be over lunch.  My
good friend and colleague and former officemate, Bob Nemiroff, and I were
discussing over lunch one day what the World Wide Web might actually be
and how we could explore it.  And of the many projects that we came up
with, to sort of play around with the World Wide Web, Astronomy Picture of
the Day was one of them that the two of us thought we could have a good
time with.

Steve:  So, you're talking about the start of the web.  So how long has it
been going, then?

Jerry:  That would have been in 1995.  The first Astronomy Picture of the
Day was actually on June 16, 1995.

Steve:  So for two people, for twelve years, that's quite a commitment!  
Why do you guys do this?

Jerry:  Well, believe it or not, after twelve years, it's still fun.  I
guess that's the reason that I really still do it.  As an astronomer, in
my research, I tend to concentrate on just very tiny little specific
areas.  But doing the Astronomy Picture of the Day really forces you to
step back, at least occasionally, and, you know, look at the bigger
picture.  See what all is going on.  And I really like that.

Steve:  Do you have any idea what the favorite image of all time might be?

Jerry:  I know if you just judge by hits to the website, it was an image
of planet Earth at night.  It was a composite of satellite photographs,
which were mapped out into the whole Earth showing the distribution of
lights.  That was an extremely popular one a few years ago.

Steve:  Alright, thank you Jerry for your time, and for APOD.

Jerry:  Sure.

Steve:  For Blueshift, I'm Steve Fantasia.

Sara:  Thanks, Steve.  You can learn more about these stories at our
website.  Visit us online at: universe.nasa.gov/blueshift

Mike:  Well, you had questions... and we have answers.  Joining us now are
Jim and Beth, to answer a question for the mailbag.

Jim:  We recently received a great question: Do we know what's happening
this very second in the most distant parts of the Universe?

Beth:  Well, let's think about it.  How do we find out what's going on out
there?  To answer this, we just happen to have a good analogy, a
comparison - and we love these!

Jim:  Let's say you have a friend who lives far away.  She writes you a
letter and mails it on Monday, but you might not see it until Thursday or
Friday, or next week, or even next month... depending on how far away she
lives.

Beth:  So by the time you receive it, any number of things could have
changed.  She may have cut her hair, or sold her car, or even started a
new job.  But by reading the letter, you only have information about her
from the day she wrote it.

Jim:  Now here's the analogy part: Light is like the letter.  Light gives
us information about objects in the Universe.  In fact, it's almost the
only information that we have.

Beth:  And you probably know that there is a limit to the speed of light.

Jim:  Right.  In space, light travels at 300,000 kilometers per second.  
That's 186,000 miles per second.  You know, I once had a Chevy Nova that
went that far, but it took me 14 years to do it.

Beth:  That's pretty impressive, Jim!

Jim:  Which part?  The fact that the Chevy Nova that went that far?

Beth:  So anyway, this means that the light from an object 186,000 miles
away reaches you one second after it leaves the object.  So light from an
object 100 times as far away will reach you in 100 seconds.  And light
from the Sun takes 8 minutes to get here.

Jim:  I think I know where this is going! Light from the next nearest star
takes about 4 years, and light from the most distant object astronomers
have ever detected takes 13 billion years to reach us.

Beth:  So all we can learn about those particular galaxies and stars is
information from 13 billion years ago - from an object that may be 80
billion trillion miles away!  So, no, we don't know what's happening right
now in distant parts of the Universe, because the light takes so long to
get here.

Jim:  So the good news for astronomers is that this time lag allows us to
study the Universe as it was 13 billion years ago.  But how can we learn
anything about those most distant objects as they are now?

Beth:  Well, for some of them we have similar objects near us, and we can
learn a lot by comparing them.  But for objects like quasars and gamma-ray
bursts, we don't have obvious cousins anywhere near us.

Jim:  For these, we have to build computer models based on our knowledge
of physics to better understand their evolution and fate.  You could say
that we are creating physical movies of their lives, as we learn more
about them.

Beth:  You do like the movies, don't you, Jim?

Jim:  Oh, sure, I do!

Beth:  So have you seen any crazy movies about this topic?  "The Strange
Case of the Cosmic Rays" was quite a hit last month.

Jim:  No, no, nothing I can think of, oh but wait a minute! How about...

Beth:  I'm sorry, but we are gosh darned outta time, Jim.  We would love
to answer more questions from our listeners, so send us yours.

Jim:  This is Jim...

Beth:  ...and Beth...

Jim:  ...signing off.

Sara:  Now it's time to get the answer to that brain teaser.  Are you
ready, Louis?

Louis:  Why was the Astro-E2 satellite given a new name?

The answers you have to choose from were:

A. The newly-elected Japanese government exercised its right to name all
spacecraft

B. The Hitachi Corporation was outbid by Suzaku, Inc. for naming rights

C. It's a Japanese tradition to rename spacecraft after launch

D. The name Astro-E2 was already being used by a British heavy metal band

The correct answer is C, it's a Japanese tradition to rename spacecraft
after launch.  Now, why Suzaku?  Well, as you heard earlier in the
episode, Suzaku is an X-ray mission to help us learn more about extremely
energetic objects, like neutron stars, galaxies, black holes, and
supernovae.  All the hot stuff out there in the Universe!  Before launch,
we called it Astro-E2... the latest in a long line of satellites with very
clever names like Astro-C, Astro-D, Astro-E... you see how that works?

Anyhow, the answer is C, it is a Japanese tradition to keep a satellite's
final name a secret until after a successful launch.  So after years of
calling it Astro-E2 while it was being designed and built, it was launched
into space in 2005 and given its new name -- Suzaku.  Now for those of you
out there up-to-date on your Chinese and Japanese mythology, and I'm sure
that's most of you, will recognize Suzaku as the vermillion bird of the
south and a symbol of renewal.

Well, this is Louis Barbier, and we'll be back next time with another
brain teaser for you.

Sara:  For Blueshift, I'm Sara Mitchell.

Mike:  And I'm Mike Arida.  That's it for this episode.  Next month, we'll
be talking with our favorite Nobel Prize winner, Dr. John Mather.

Sara:  He actually works right here at Goddard!  Don't forget to send us
your comments and questions through our website at:
universe.nasa.gov/blueshift

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