Stars, Galaxies, and Fiber Optics

The first time I remember learning about fiber optics was in a behind-the-scenes article published in 1980 or so about the making of Star Trek: The Motion Picture. The article talked about how they got light to all the buttons on the bridge set and showed them illuminated with bundles of optical fiber. Nowadays, as I’ve mentioned in several earlier posts, I work with instruments that use optical fiber to carry light collected by each of the telescopes I work with to the instrumentation where its analyzed.

On the telescope side, those fibers are attached to an optical assembly that must be placed at just the right spot to catch focused light. If the star or galaxy is out of focus, not all the light goes down the optical fiber. We also have guider cameras that work to keep the object precisely aligned on the fiber so all the light gets to the spectrograph. It’s a lot of complex hardware to work right to precisely measure the the redshift of distant galaxies or look at a star and determine whether or not it has planets in orbit. This past week, we’ve been commissioning both the DESI spectrograph at the Mayall 4-meter and the NEID spectrograph at the WIYN 3.5-meter. One of the most important milestones is to get light from the object you want to measure to the spectrograph and see if you get the flux you expect. Here’s the NEID team at WIYN looking at early test results.

Yes, light leaves a star dozens of light years away, enters our telescope, goes down the optical fiber and is photographed with the spectroscope, then all that data can be viewed and analyzed on a laptop computer. When I filmed the trailer for The Astronomer’s Crypt a couple of years ago, I was asked why we didn’t use a room full of fancy computers and monitors. We just had a couple of computers, one of which was a laptop. The reason is that I’ve seen a lot of control rooms where simple computers are the only ones present!

As you can imagine, it’s quite a relief to see all the work pay off in a spectrum that shows the flux level you expect. All of this is pretty exciting stuff and, as it turns out, my birthday fell during this past week’s tests. Seeing NEID as it nears readiness for scientific use is pretty exciting in its own right, but we had another surprise on the day of my birthday. Ethan Peck, who plays Spock on Star Trek Discovery, was on a road trip and decided to visit the observatory. A tour was arranged and he spent the beginning of the night at the WIYN telescope. For me, it was quite a thrill to have Spock, of all people, wish me a happy birthday! He brought a Polaroid camera with him and we snapped a photo of us standing by my control station. Here we are at WIYN. Ethan Peck is in the center (in white) and I’m to the left.

Meanwhile, across the mountain at the Mayall 4-meter, commissioning has continued on the DESI instrument. The instrument had its official “first light” a couple of weeks ago and a wonderful image was released that, I think, really illustrates the power of DESI.

Image credit: DESI Collaboration, Legacy Surveys; NSF’s National Optical-Infrared Astronomy Research Laboratory/NSF/AURA

Here you see an image of all 5000 DESI fibers superimposed on the sky. At the bottom of the fiber array is M33, the Triangulum Galaxy. Below that is a view of the spectrum from just one of the 5000 fibers showing the light from that little piece of the galaxy. In it, you can see the lines labeled that denote the presence of hydrogen, oxygen, nitrogen, and even sulfur. Now remember that each fiber in that picture gives the same kind of data for the piece of sky its on. You can read the full press release about DESI’s first light at: https://nationalastro.org/news/desis-5000-eyes-open-as-kitt-peak-telescope-prepares-to-map-space-and-time/

All of the robotic positioners moving those fibers at the top of the Mayall telescope get hot and there’s a chiller system to keep them cool. This week, that chiller system will be automated, but last week, we had to monitor it by eye and it requires a person to turn the system on and off by hand. The person doing that remarked how spooky it is to be in the depths of the Mayall with all the lights out and remarked how she kept looking over her shoulder, wondering if someone was there. This is another aspect of my job that definitely helped to inspire The Astronomer’s Crypt. You can learn more about the novel and see the trailer I mentioned earlier at http://www.davidleesummers/Astronomers-Crypt.html.

Making Instruments Work

Today, I’m at the TusCon Science Fiction Convention in Tucson, Arizona. You can get all the details about the event at http://tusconscificon.com. One of the topics I’ll be speaking about is the work we’ve been doing for the last year, installing the DESI Spectrograph on the Mayall 4-meter telescope. At this point, installation is nearing completion and we’re beginning the process of commissioning the instrument. In short, we’re actually making it work with the telescope so we can get the data we hope to obtain.

DESI isn’t the only instrument that we’ve recently installed. We’ve also installed the NEID spectrograph on the WIYN telescope. While DESI has the goal of making a 3D map of about one-third of the sky, NEID has the goal of looking for planets around other stars. I’ve shared quite a bit about the DESI installation because that instrument is of a scale that it required a major refit of the telescope. The NEID spectrograph has involved a similar amount of time in development, but much of that development has happened off site at places such as Penn State University and the University of Wisconsin. NEID, which rhymes with fluid, takes its name from the Tohono O’Odham word meaning “to see.”

Two weeks ago, the port adapter, built by the University of Wisconsin, and the spectrograph, built at Penn State University, both arrived at WIYN and have been installed at the telescope. You can see the port adapter on the side of the telescope in the photo above. It’s job is to capture light coming through the telescope from a distant star and feed it into fiber optics that run downstairs to a high precision spectrograph.

The spectrograph itself lives in a clean room on the WIYN Observatory’s ground floor. To get the kind of precision needed to see planets around other stars, the temperature within the spectrograph must be carefully maintained and the spectrograph elements must be kept in the same relative position. Footsteps nearby could disturb this device. Because of that, the spectrograph itself is built inside a coffin-like housing. Once the Penn State team gets everything set up, they’ll seal up the coffin and, unless there’s a serious problem, no one will look inside again. I got to peak inside the spectrograph a few days ago and it may be my only view.

Now that the instrument is installed at the telescope, we have to make sure everything works as it should and programmers are working to make sure we have software to assure we can efficiently get the data we need. We’re starting with the port adapter itself. I point the telescope at stars and a team of scientists and engineers check the function of the various parts within the adapter to make sure they understand the alignments on the sky, which are necessary for tracking the stars. They check the tip-tilt electronics, which make sure we get as much of the star’s light as possible down the fiber, and make sure all the calibration functions work. After this, work will begin commissioning the spectrograph itself. This is a process which takes a few months to complete to assure we’re getting the performance out of this instrument that we want.

Commissioning nights are very different from normal observing nights at a telescope. On a normal observing night, it’s often me and an observer. Often the observer isn’t even at the telescope, but working from their home institution, controlling a camera on the telescope over the internet and talking to me through computer chat. On a commissioning night, I can have anywhere from five to fifteen people in the control room with me, all working on different elements of the instrument. This marks a busy and exciting time as we get these new instruments ready for service at Kitt Peak National Observatory.

Stars Wobbling at the Speed of a Desert Tortoise

In recent posts about new observing projects at Kitt Peak National Observatory, I’ve largely focused on the DESI spectrograph which aims to create a three-dimensional map of the northern sky. In fact, I’m in Denver, Colorado this weekend at MileHiCon and I’ll be giving a presentation on this very subject. However, this isn’t the only new instrument I’m helping to deploy and commission.

At the WIYN 3.5-meter we’re installing a spectrograph called NEID. Kitt Peak sits on the land of the Tohono O’Odham people in Southern Arizona. The acronym is derived from the Tohono O’Odham word meaning “to see.” The actual acronym is: NN-EXPLORE Exoplanet Investigations with Doppler Spectroscopy. In other words, it’s an instrument that will be used to look for planets around other stars. Like the DESI spectrograph, fiber optics are mounted to the telescope and feed a spectrograph two floors below the telescope. Just over a week ago, I helped to run the fibers from the point the instrument will be mounted down to the spectrograph room. In the photo, you can see the fiber optic cable laid out like undulating waves at the base of the telescope. The instrument itself will be mounted at the round port that currently has the white, rectangular sign.

The way a spectrograph like NEID finds planets around other stars is by measuring how much they move toward and away from the Earth when they’re pulled by orbiting planets. You likely see spectra all the time. A rainbow is a spectrum of the sun. In a spectrum are characteristic lines caused by elements in the star’s atmosphere. When a planet tugs the star toward Earth, those lines move toward the blue end of the spectrum. When a planet tugs the star away, the lines move toward the red end. Of course, one of the hopes of exoplanet science is to detect Earth-like planets around other stars, or more specifically, Earth-sized planets in the zone around a star where water can be liquid. If you imagine watching our sun from another star, we’d see the Earth pull the sun toward or away from us at about 30 centimeters per second, or about the speed of a desert tortoise!

To see this small motion, you need to be able to see the spectra—the rainbow—at very high resolution. This is more than magnification. You need to see it at great detail. A spectrograph that can do that is often fairly big and it’s very difficult to mount it to the side of a moving telescope. This is why we use a fiber to capture the light and send it to a spectrograph in a different room. This allows the engineers to build the spectrograph as big as they need, but only requires them to mount the fiber to capture the light to the telescope.

Fiber optic cable is meant to be tough, but it can break, so it’s gratifying after we make the run to be able to shine light through the cable and see it at the other end, as we see in this post’s second photo!

Besides looking very specifically for Earth-like planets, the NEID spectrograph will be providing support for NASA’s Transiting Exoplanet Survey Satellite, or TESS, mission, which is searching for exoplanets around the closest stars to Earth. Once TESS discovers a planet, we can observe it with NEID and get more precise mass and density information about the planet. Such measurements help us better understand the composition and formation of the planets around other stars. It’s a very exciting time at Kitt Peak as we deploy these spectrographs which will help us understand both planets in our galactic neighborhood and the overall structure of the universe.

The Pointing Dance

This week, I have been engaged in an important, albeit tedious activity at the WIYN 3.5-meter telescope. I have been building pointing maps. Telescopes are large, bulky machines that have to point with extreme precision and track the almost literal clockwork motion of the sky. They are engineered carefully, but like any machine they are subject to wear and tear. What’s more, to keep getting the best science, telescopes have to be upgraded from time to time. This changes the telescope’s behavior with time.

The WIYN Telescope ready for a night of collecting pointing data

Because the Earth turns constantly, the sky overhead appears to move at a constant rate. To keep objects in the telescope’s field of view, the earliest telescopes were literally mounted to clocks that moved at the sky’s rate. To make these work, you have to imagine a line in the sky that’s a projection of the Earth’s equator. Then you have to tilt your tracking axis to be at the same angle as that imaginary line in the sky. Another way to think about it is that here at Kitt Peak National Observatory, we’re at 32 degrees north latitude, so you have to tilt your telescope 32 degrees up from the southern horizon to track the sky.

Now, if you look at the photo of the WIYN Telescope above, you’ll notice that it’s mounted flat to the floor and it’s not tipped to match our latitude. That’s because it’s expensive to engineer big heavy telescopes so they can be tipped up at an angle. So, the WIYN telescope actually has to track the sky in two axes: azimuth and elevation, kind of like a radar mount. To track the sky, we have to use computers to adjust the tracking rates constantly. The computers only know how fast to track in each axis if they know where we’re pointing in the sky. If there’s an error in pointing, there’s also an error in tracking.

When I tell people I’m a writer and an astronomer who operates telescopes, it’s often assumed that I have lots of free time on quiet nights at the telescope to write. That doesn’t happen on nights of pointing maps. Instead, it’s a busy night of pointing to a star, noting how far off it was from where we expected it and then moving on again. We do this for anywhere from 75 to 100 stars with a telescope like WIYN and the exercise takes about half the night.

The way pointing and tracking are interconnected also make me think of how I use outlines as a writer. With the telescope, we can imagine that I point to a star and correct the pointing at one spot, then let the telescope track. If the computer thinks the star will be a different point in an hour than it really will be, it will track toward that different point and it won’t follow the star. You need to know where the star really will be in an hour.

For me, an outline is like a little like a pointing map. It tells me where the plot is at point A and it tells me where I want to be once I reach point B. With the telescope, it better be pointed at the star at both points A and B. An outline is more flexible. It’s more like a guideline. I try to listen to my characters when I write my outlines and make sure that points A and B make sense for them. However, sometimes as I write, I find characters do things I didn’t quite imagine the first time. The beauty of an outline is I can change point B. The challenge is that when I do, I realize I may also have to change points C, D, and E as the plot progresses!

I’ve been having a lot of fun rewriting my novel, The Pirates of Sufiro for its 25th anniversary release. I actually wrote some of the original draft when the WIYN telescope was first being built in the 1990s. Rewriting the book is the ultimate case of writing to an outline, especially since I don’t want to change it so much that people can’t pick up older editions of the sequels and follow them. I’m expanding the story and letting my characters breathe more. I’m letting them guide me and asking if what they did entirely made sense for those characters. I’m taking them from point A to point B. Those points can’t really deviate, but I do allow myself to add points A.1, A.2, and A.3 to better explain how they moved from point A to point B.

You can read chapters from the previous edition and see how I’m following my version of a “pointing map” by following me Patreon. My site is at: http://www.patreon.com/davidleesummers

Troubleshooting

My friend Darla Hallmark sells buttons that say, “The problem with troubleshooting is that trouble often shoots back.” In my job operating telescopes at Kitt Peak National Observatory, I often get to see the truth of that statement. Here I am in my natural habitat at the control station of the WIYN telescope.

My actual title at Kitt Peak is “Senior Observing Associate” and my job is more than being a telescope driver. I see myself as the person whose job it is to make sure the astronomers who use the telescopes actually get the data they hope to obtain. At night, especially at the WIYN telescope, I’m often the only person in the building. It’s quite common for observers using the telescope to control the cameras over the internet and talk to me all night on a Skype connection.

The observatory has a daytime staff of engineers, electricians, mechanics and more. Most of them are tucked snug in their beds when I’m working through the night. So, if something goes wrong, I’m the guy who has to fix it, or find a workaround until the next day when the daytime staff returns to work. I think its a real testament to the design and maintenance of the telescopes at Kitt Peak that serious problems don’t crop up all that often, but when they do, they can be a challenge.

We had one such problem this week at WIYN. We were using the Hydra spectrograph. Instead of an eyepiece or a camera looking directly at the sky, there is a metal plate. Fiber optics in magnetized housings sit on that metal plate and face the sky. A robot within Hydra can move those around so they’re in a position to capture light from distant objects. This week, each fiber was placed to catch light from galaxies approximately 11 billion light years away. As you can imagine, you need to place that fiber in just the right place to catch that tiny bit of light. This is what the inside of the Hydra spectrograph looks like. You can see the fibers on the left-hand side. The robot that moves the fibers is on the right.

The problem we had was that some of these fibers were missing the light. To confuse matters, not all the fibers were missing the light. We saw light from some galaxies. We saw light from all the stars that let us do fine corrections to our pointing on the sky. My first thought was that there was a calculation error and not all the fibers were being placed correctly. The astronomer looking at these galaxies checked and eliminated that possibility. Next, we used a camera on the robot to watch the fibers as they were being moved to see if they were being placed where we put them. The robot did just what it was supposed to do.

The final step in this procedure is that the metal plate on the left gets warped, because the telescope’s focal plane isn’t actually flat. We watched the fibers as the plate was warped. The fibers in the center “jumped.” That’s not supposed to happen. As of this writing, I’m not sure why warping the plate made some fibers jump but not others, but the obvious workaround is not to warp the plate. What this means is that some galaxies will be better focused than others, when we take data, but since we’re taking spectra, that’s not a showstopper. We just care that the light makes it down the fiber. Once that happens, the astronomer can see what elements exist in that galaxy and get information about how far away it is and how fast its moving. As the weeks goes on, that team of engineers and technicians will take the information I learned about the problem and work to find a solution.

If you enjoyed this behind-the-scenes look at my job operating telescopes, you might enjoy my novel, The Astronomer’s Crypt. It tells the story of ghosts, gangsters, astronomers, and a dangerous Apache spirit colliding at a New Mexico observatory on a dark and stormy night. You can learn more about the novel and watch a cool trailer at: http://www.davidleesummers.com/Astronomers-Crypt.html.

If spooky stories aren’t your thing, but you’ll be in Phoenix, Arizona on Thursday, May 9, you can join me at the next meeting of the Phoenix Astronomical Society, where I’ll be talking about the DESI project on the Mayall 4-meter telescope and sharing some behind the scenes photos of the installation. You can get more details about the meeting at: http://www.pasaz.org/index.php?pageid=meetings

Exploring Galaxies

This past week, I’ve been working at Kitt Peak National Observatory’s WIYN telescope using one of the workhorse instruments called HexPak to help astronomers better understand how galaxies work. At left is a photo I took of the galaxy M51 with the New Mexico State University 1-meter telescope. While we can learn a lot studying photos like this, wouldn’t it be nice if we could learn more, and understand what chemical elements make up the different parts of a galaxy? The instrument HexPak is designed to do just that.

One of the best tools we have for understanding the chemistry of objects in space is spectroscopy. Back in the nineteenth century, it was discovered that if you looked at heated elements through a spectroscope, you would see a characteristic set of lines in the rainbow-like spectrum. These lines are like a fingerprint for each element. It turns out that stars are really good at heating up elements! Below is a photo of the WIYN telescope with HexPak mounted.

HexPak is the white hose-like thing on the right plugged into side of the telescope. Inside that hose-like unit is a bundle of optical fibers arrayed in a hexagonal pattern. They look like this:

We can then align those fibers with a galaxy like M51 above, so different parts of the galaxy line up with different fibers. When that’s done, it looks something like this:

Now, I should note, this image was created just for illustration purposes. I haven’t tried to match the scale or alignment of my NMSU 1-meter image of M51 with the HexPak fiber array. However, you will see that different parts of the galaxy now line up with different fibers. That light is now sent downstairs to a bench spectrograph where it’s broken into its component parts. Here’s WIYN’s bench spectrograph. You can even see the rainbow like spectra on the grating at left we use to analyze the light from galaxies.

Light from each of the fibers in the array becomes a single spectrum and the image of that spectrum is recorded on a camera, shown at the right of the image above. Each one of those spectra will tell us about the elements present in each of the parts of the galaxy as lined up above. So, for example, you can figure out if the spiral arms have different amounts of a certain element than the bulge in the center. You can see what’s going on in the space between the galactic arms. If you look closely at my photo of M51, you’ll see it has bright regions that line up with parts of the spiral arm. An instrument like HexPak can help an astronomer learn if those parts of the spiral arm are different from other parts of the spiral arm, and maybe see what those regions are made of.

As I’ve mentioned in other blog posts, this work does inspire my writing. Sometimes I look at a galaxy like one we study with HexPak and think what it would be like travel between the different parts of a galaxy. M51 has a lot in common with our own galaxy. What’s it like in the arms? What’s it like between the arms? What’s it like the galaxy’s center? What’s more, working with astronomers in the control room sometimes does feel like being a crewmember on a spaceship exploring uncharted reaches. All of these elements have influenced science fiction stories like Firebrandt’s Legacy and The Pirates of Sufiro. I’m getting ready to release the former and I’m rewriting the latter with help from supporters at my Patreon site.

You can get involved in the fun by becoming a patron. My patrons are the first people who get to read new stories in my science fiction universe and they get to download complete books when they’re available. What’s more, one of my goals at my Patreon site is to make this blog ad free. If you like behind-the-scenes looks into astronomy like this one, but don’t like the ads at the blog, please consider supporting my Patreon site at: http://www.patreon.com/davidleesummers

NEID – A New Way of Seeing Exoplanets

Last week, I talked a little about the work we’re doing refitting the Mayall 4-meter Telescope for the Dark Energy Spectrographic Instrument. However, it’s not the only construction going on at Kitt Peak. The WIYN 3.5-meter telescope, which I also work with, is getting a new spectrograph installed called NEID. Deploying NEID doesn’t require a full telescope refit like deploying DESI, but there’s still quite a bit of work happening in the building.

Most of the work right now is going into building a new bench spectrograph room. NEID is an acronym for “NN-explore Exoplanet Investigations with Dopler spectroscopy”. The word “neid” is also the Tohono O’Odham word meaning “to see.” An appropriate choice, given Kitt Peak’s location on the Tohono O’Odham Nation in Southern Arizona. The goal of NEID is to provide the astronomical community with a state-of-the-art Doppler spectrograph to investigate exoplanets around nearby stars.

The way this will work is that an optical fiber assembly will be mounted to the telescope itself at the port in the photo to the right with the sign on it. That optical fiber will carry the light from the star to the new bench spectrograph downstairs where it will be spread out, like a rainbow. The reason for doing this is not to see a pretty rainbow, but to see dark lines interspersed through the rainbow. Those dark lines are like the star’s chemical fingerprint.

Now, here’s the fun part. When a planet moves around the star, it drags the star just a tiny amount toward the Earth which causes that spectral fingerprint to shift a little bit toward the blue end of the spectrum. When the planet passes behind the star, it drags it away from the Earth and moves the spectral fingerprint toward the red end of the spectrum. Looking for this shift is the “Doppler” approach to finding planets that NEID will employ.

In addition to discovering new planets, NEID will be used to follow up observations by NASA’s Transiting Exoplanet Survey Satellite (TESS) and will help to determine masses and densities for planets TESS discovers. By the way, the NN-Explore that’s part of NEID’s acronym stands for NASA-NSF-EXoPLanet Observational REsearch. The current plan is to begin commissioning the instrument this fall and for regular observations to commence in 2019.

Being part of on-going research into planets around other stars is what inspired Dr. Steve Howell of NASA’s Ames Spaceflight Center and I to invite science fiction writers to imagine what these planets around other stars might be like. The results were our two anthologies, A Kepler’s Dozen and Kepler’s Cowboys. You can learn more about the anthologies by clicking on their titles.

Once NEID goes online and starts making discoveries, Steve and I may have to “see” into the future and collect a third anthology. This time, including stories about planets discovered by a telescope on a mountaintop in Arizona’s Tohono O’Odham Nation.