Ramping up the Refit

This past week, I’ve continued my work supporting the refit of the Mayall 4-meter telescope for the upcoming DESI spectrograph. DESI is the Dark Energy Spectroscopic Instrument and it will be capable of measuring of the spectra of 5000 objects at a time. Its mission objective is to collect data to help us understand the nature of Dark Energy in the universe. We don’t yet know what Dark Energy is, all we really know is that appears to make the expansion of the universe accelerate with time. To be able to collect these 5000 spectra, the telescope needs a new top end. Indeed, the first thing I saw when I came to work on Monday morning was the old top end sitting on a flatbed trailer outside the telescope being ready to go into storage.

The Mayall 4-meter is a reflecting telescope and the primary optical component is a big 4-meter diameter mirror at the bottom. The light from that mirror is then focused at that top end and either collected by a camera sitting there at “prime focus” or a sent down to an instrument underneath the telescope using a secondary mirror. The top end held both the prime focus and the secondary mirror and could be flipped end-for-end to allow either to happen. DESI will have its 5000 fibers in a new top end and indeed, part of the reason for selecting the Mayall was to have a telescope sturdy enough to handle that large an instrument. At the moment, the telescope is missing its top end, but the new one will be installed soon. There are work platforms, which enabled people to loosen the old top end so it could be lifted out with a crane. The work platforms also keep the telescope structurally stable while there’s no top end in place.

The top end only holds part of the instrument. It will have 5000 optical fibers which may be precisely positioned onto target objects. The light from those fibers is sent along the fibers to spectrographs in an environmentally controlled room where the light will be spread out and photographed so it can be analyzed. In the dark energy survey itself, most people will be looking at the so-called redshift—how far the characteristic spectral “fingerprint” of certain chemicals shifts to the red as a result of its velocity away from us. However, those same chemical fingerprints may be used to understand properties of the objects being looked at and this data will be available to anyone who wants to use it.

Because dark energy is an exciting topic in its own right, but also because this project will be generating so much raw data that’s useful to so many astronomers, it’s a major worldwide undertaking. To break the light from the fibers into spectra will require ten spectrographs which will reside in a carefully climate-controlled room. An exciting milestone I got to watch this week, was unpacking the first of those spectrographs when it arrived from France. Below, you can see the engineers inspecting the optical elements. Note the rainbow visible on the corrector plate of the right-most optical element. That’s exactly what this device is built to do! Break the light into rainbows.

Today finds me in Phoenix, Arizona for Leprecon 44. If you’re in town, I hope you’ll drop by and check out some of the panels and workshops.

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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.

Refitting the Mayall: Teardown

I was in 8th grade when Star Trek: The Motion Picture came out. One of the things that fascinated me in that movie was the refit of the Starship Enterprise. I was captivated by how the ship looked at once much the same and yet completely different. It looked sleeker and more powerful and familiar space on the ship such as the bridge, sickbay, and the transporter room had all been updated. I’m getting to experience something much like the Enterprise refit in real life. In this case, I’m involved in refitting the Mayall 4-meter telescope at Kitt Peak National Observatory.

Like the Starship Enterprise, the Mayall has a forty-five year history of discovery. Originally built to use photographic plates, the telescope has played an important role in such discoveries as establishing the role of dark matter in the Universe from measurements of galaxy rotation, and determining the scale and structure of the Universe. Over the years, new instrumentation has been added to the telescope including advanced digital cameras and spectrographs.

The purpose of the refit is to install a new instrument called DESI, which stands for Dark Energy Spectroscopic Instrument. 5000 optical fibers will be installed at the telescope’s prime focus (the top end of the telescope) and run to cameras in another room. The goal is to observe tens of millions of galaxies and quasars, constructing a three-dimensional map spanning the nearby universe to 10 billion light years.

In order to achieve this goal, the entire top end of the telescope has to be replaced and much of the control software and electronics are being redone so that it’s truly state of the art. To achieve this goal, we literally have to gut the telescope and install new components from the inside out. During my most recent shifts at the telescope, I’ve been involved in just that. In the photo to the right, you can see that the bottom of the telescope is missing and replaced with scaffolding. That’s because the large 4-meter mirror is out for recoating. Also, all the optics are missing from the secondary mirror assembly at the top of the telescope. Ultimately, that will be removed completely and replaced with a new secondary ring. The men in the photo are removing a counterweight assembly used to precisely balance the telescope when instruments are added and removed. Electrical panels are open on the side of the telescope where control cabling going back to the photographic days will be removed and replaced with new control cabling. Modern electronics mean the telescope will have about 10% of the cables as it did when originally built!

The refit has also allowed me a rare opportunity to see parts of the telescope I’ve never been to before, even after operating it for some thirteen years. Earlier this week I got to help the electronics technicians work on some cabling in the “horseshoe.” That’s the big, blue horseshoe-shaped mount you see in the photos above. We actually ended up working down in the broad, blue, oval-shaped tube you see in the photo just above. I dubbed it the sinking submarine, because it’s a cramped space and we were standing at a 32-degree angle relative to the ground!

It’s going to be exciting to watch the telescope take shape again after the teardown process. New parts will be arriving in the coming months. A large crane will be deployed outside the 4-meter to lift out the old secondary ring and bring in the new one. The plan is to be back on sky to test components of the new instrument later this year. Once those tests are completed, other components will be finished, revised if needed and then installed. At that point, the Mayall’s new five-year mission to map the universe will begin.


Finder Scopes

One of the things I like about working at Kitt Peak National Observatory is that my job has a lot of variety. I contribute to important science projects and I help with engineering that helps to achieve the observatory’s science goals. Sometimes I act as something of a councilor, commiserating with observers during inclement weather. I even get to employ my writing skills when documenting tasks for our operations manuals.

This past week, one project I helped with was testing a new finder scope for the 4-meter telescope. Finder scopes don’t often get a lot of attention, but they serve an important function. Telescopes often give you such an enhanced view of the sky that it’s difficult to know exactly where you’re pointed. A finder scope is simply a smaller telescope mounted to the bigger telescope that lets you see a wide swath of the sky and confirm that you’re looking where you think you should be. Even my 90mm telescope has a finder scope on it. It’s the little tiny telescope piggybacked on the bigger telescope.

Here’s a view of the finder scope mounted to the top of the 4-meter telescope at Kitt Peak. Note that it’s basically just a camera lens directing light into a little digital camera.

This will prove vitally important when we start using the DESI spectrograph on the 4-meter. With that instrument, we’ll have fibers directing most of the light to spectrographs instead of a direct view of the sky. We will have a guide camera, but if, for some reason, the telescope pointing is off, it may be hard to find where we are. Because of that, it’s nice to have a widefield view of the sky. The images taken with the finder scope won’t be the ones you see in most magazines, but still, we played a little while testing and took a nice photo of the Andromeda Galaxy, M31 and it’s companion, M110.

We also took an image of the Pleiades, which is a nearby open cluster visible with the naked eye. These are young stars with nebulosity still around them. Even with our small telescope, it only took 30 seconds to see some of the nebular clouds.

Speaking of variety, another job I did this week was help an astronomer monitor a Jupiter-sized planet as it transited its star. This planet had a rotational period of only 1.6 days and we monitored it with the WIYN telescope at the same time the Kepler Space Telescope monitored it. Having two telescopes monitoring it at the same time allows for scientists to confirm and double check results. The system we were watching is very much like system I wrote about in the anthology A Kepler’s Dozen. You can learn more about the book and find places to order at http://www.davidleesummers.com/Keplers-Dozen.html. The book gives a unique look at the types of worlds discovered by the Kepler Space Telescope. My co-editor on the project was Dr. Steve B. Howell, head of the Astronomy and Astrobiology Division at NASA’s Ames Research Center.

Hunting Asteroids

I rang in the new year by helping Robert McMillan, Jim Scotti, and Melissa Brucker from the University of Arizona hunt for potentially hazardous asteroids in our solar system at the Kitt Peak 4-meter telescope. This is important work since asteroid impacts are one of the few completely predictable and preventable natural disasters. Here I am at the telescope console.

As it turns out, this observing run was something of a bittersweet milestone. Bob, Jim, and Melissa are the last scheduled visiting observers on the 4-meter. At this point, we have about five more weeks of observing with a scheduled imaging survey program and then the telescope shuts down so it can be refitted with an instrument called the Dark Energy Spectroscopic Instrument, or DESI. DESI will measure the effect of dark energy on the expansion of the universe. It will obtain optical spectra for tens of millions of galaxies and quasars, constructing a 3-dimensional map spanning the nearby universe to 10 billion light years.

So, what about the asteroids? Well, the good news is that there are smaller telescopes on Kitt Peak devoted to the search. The reason Bob, Jim, and Melissa use the 4-meter is that it allows them to look for more distant asteroids on nights when the small telescopes are not as effective. In this case, we were attempting our observations during the full moon. Because the moon is so bright, it’s hard to see faint, distant objects with small telescopes because you need to expose on the sky for a long time. The 4-meter can take shorter exposures and still detect these faint objects without having the skylight swamp the exposures. In the meantime, Bob, Jim, and Melissa have applied for time on other telescopes around the world to do the work they were doing on the Kitt Peak 4-meter.

Often times when I’m involved in these runs, I’m asked if I’ll let people know if something is going to fall on us. Well, if I know, I’ll tell. However, what we often do is identify small objects a long ways away. It’ll usually take more than the observations we get to determine the object’s orbit and find out whether or not it presents a serious hazard.

So what actually happens if we discover an asteroid that might hit the Earth? I found this NASA video that gives a nice explanation. I notice there is also an image credit from my friend Mike Weasner, a talented amateur astronomer who is also a science fiction fan.

If you want to get more of a sense of what life is like behind the scenes at an astronomical observatory, be sure to read my novel The Astronomer’s Crypt. You can learn more about the novel and get a sneak peak at http://www.davidleesummers.com/Astronomers-Crypt.html

Astronomy and Wildlife

I suspect one of the last things people consider when they think about working at an observatory is encountering wildlife. However, it can be a surprisingly common part of the job. During my last shift at Kitt Peak, I had two very close encounters with wild animals, both at the room where I stay. The first happened in the afternoon when I was heading out to do my laundry. I looked over to my left and saw a bobcat walking away from me. It stopped and looked at me, then continued on its way. Unfortunately, it vanished before I could get a photo. Two days later in the morning, I heard a rustling by the garbage can near my dorm room. I turned and looked out the window and a very disgruntled bear walked by, just outside my room. I was able to get a photo of the bear just before he disappeared into the woods.

Wildlife encounters aren’t limited to the wilder areas away from the telescopes. Sometimes wildlife visits us in the control rooms. I’ve seen ringtail cats on three separate occasions in observatory control rooms. For those not familiar with ringtails, they’re not actually cats, but a member of the raccoon family that lives in the desert southwest. One time, we saw a ringtail in the control room of the WIYN 3.5-meter telescope. He peered out at us through a hole in the ceiling tiles. Another time, I was working at the 2.1-meter telescope when a ringtail jumped out of the ceiling, landed by a computer, growled at us, and then disappeared into a conduit. Another time I looked over and saw a ringtail in the control room of the Mayall 4-meter telescope, peering out from behind a garbage can. This was especially remarkable, since the console room for the 4-meter is some twelve stories above the ground. As the observer and I were trying to figure out what to do about the animal, it disappeared down a conduit never to be seen again.

Famous astronomers are not immune from wildlife encounters. I once heard a story that Clyde Tombaugh, the astronomer who discovered Pluto, had finished observing one night at Lowell Observatory and was walking to his room in the dark. He saw what he thought was a dog and held out his hand to pet it. The animal backed away, growling. The next morning, a caretaker spoke to Tombaugh and said he’d seen some strange tracks in the snow. It appeared that someone had approached a mountain lion very closely!

Encounters like this helped to inspire a scene in The Astronomer’s Crypt where the telescope operator, Mike, encounters a raccoon at the telescope. I won’t give more details than that to avoid spoilers for the scene, but it’s the kind of reality from my day-to-day life at the observatory that I’ve tried to inject into the novel. You can learn more about the novel at http://www.davidleesummers.com/Astronomers-Crypt.html. And remember, you can learn about all of my books and short stories by visiting http://www.davidleesummers.com

The Biggest Explosions of All

I’ve spent a lot of time in my astronomy career pointing telescopes at some of the biggest explosions of all—type 1a supernovae. This kind of supernova starts with a white dwarf star and another star orbiting each other. White dwarfs are very dense stars at the end of their lives. The only objects more dense are neutron stars and black holes. The white dwarf’s gravity draws material off the companion star until it reaches critical mass and the whole thing explodes. One such star that I had the chance to observe in detail in was Supernova 2011fe in the galaxy M101. Here’s an image from the Mayall 4-meter at Kitt Peak, one of the telescopes I used to observe this object. The supernova is the bright blue star outshining everything else in the upper right-hand part of the image.

Image by T.A. Rector (University of Alaska Anchorage), H. Schweiker & S. Pakzad NOAO/AURA/NSF

These cosmic explosions are pretty interesting in their own right. Our own star is expected to end its life as a white dwarf and these explosions give us a glimpse at the hearts of these stellar corpses. These explosions are also one of the ways heavy elements formed in the cores of stars get distributed out into the universe. Supernova 2011fe was, in fact, one of the closest Type 1a supernovae we’ve ever observed. We caught the explosion soon after it happened, watched the supernova brighten to maximum, then start to fade away.

Type 1a supernovae also have another useful property. Because white dwarfs have a fairly uniform mass, the brightness of the explosion is also uniform. So, if every Type 1a supernova observed were placed at the same distance away from you, they would all, more or less, be the same brightness. This means that by measuring the apparent brightness of the supernova, you can figure out how far away it is. This is a bit of an oversimplification, but there are ways to calibrate that information based on the how fast the explosion brightens and fades.

Back in the 1990s, an astronomer named Saul Perlmutter was granted target-of-opportunity time on Kitt Peak telescopes. In this case, it meant if a type 1a supernova went off, he could ask the telescope to point to it and take an image and calibration data. He and his colleagues hoped to get distances to as many galaxies as possible. I helped acquire some of that data which was combined with a lot of other data from a lot of telescopes to provide evidence that the expansion of the universe is accelerating. Perlmutter would go on to share a Nobel prize with Adam Riess and Brian P. Schmidt for this work.

This is one of those discoveries that shows some of the true fun of science. We learned that the expansion of the universe is accelerating, but that raises an even bigger question. Why is it accelerating? Typically that’s attributed to something called “Dark Energy.” This attribution isn’t meant to be an answer in itself. It’s meant to be a placeholder. It’s “Dark” energy because we don’t know precisely what kind of energy it really is, or even if it’s energy at all! Later this year, a new instrument called DESI will be installed on the Mayall 4-meter which will endeavor to get answers to some of those questions. But like all good science, I expect a veritable explosion of new questions raised for every answer we’re able to get.