Assembling the Puzzle

This has been another week helping to install the Dark Energy Spectrographic Instrument or DESI at the Mayall 4-meter telescope at Kitt Peak. In short, the goal of DESI is to study the effect of dark energy on the expansion of the universe. We plan to collect spectra of tens of billions of galaxies and quasars with the goal of making a three-dimensional map of the universe out to about 11 billion light years. You can read more about the DESI project at https://www.desi.lbl.gov/

The DESI project is spearheaded by Lawrence Berkeley Lab in California and being installed at Kitt Peak in Arizona. However, it really represents a worldwide collaboration. There are scientists working on this project from England, France, Spain, Italy, South Korea, China, France, Canada, Colombia, Australia, and others plus numerous institutions within the United States. All of these agencies are not only contributing expertise, but actually building components that will go into the finished instrument.

In an earlier post, I spoke about how we worked to remove the Mayall telescope’s original top end. The top end originally housed both a secondary mirror and a prime focus camera. Both of these have been used to make groundbreaking discoveries over the last five decades. The Mayall was the telescope Vera Rubin used to study rotation curves of galaxies, which led to the discovery of dark matter. I’ve helped with observations that have led to the confirmation of numerous exoplanets. We’re now replacing the telescope’s original top end with a new one that will hold 5000 fibers at prime focus. Each of those fibers will run to spectrographs that will break up the light from objects in the sky so it may be analyzed and the position of the object can be measured. In the photo above, you can see the new top end being assembled to the left of the telescope.

To get light from the sky onto the fibers, the telescope will collect it with the primary mirror. That sits in the big white structure at the center of the big blue horseshoe-like structure in the photo above. The mirror will direct that light to the top end. Because the mirror is curved, allowing the light to be collected and redirected, it means the focus changes across the field of view. To deal with that, you need to put some lenses in front of the fibers, sort of like glasses. Another real world problem of telescopes is that as you point toward the horizon, light gets spread out. So you need optics to compensate for where you’re pointing in the sky. Sort of like glasses that automatically adjust themselves for where you’re looking.

Scientists from England assembled those specialized “glasses” for the telescope. Those arrived last week and I was on hand during their assembly at Kitt Peak. You see those assembled optics in the lower photo. Scientists from Italy built the “Hexapod” pointing system, which keeps those optics aligned. That arrived and was tested about a month ago. Scientists from Fermilab in Chicago are responsible for integrating those systems and putting them together in the top end ring. That process will start next week. It’s all quite a puzzle and it’s been remarkable to see it all come together. It’ll be even more amazing to see what science it yields.

Of course, work at Kitt Peak helps to inspire my science fiction. As a reminder, this is the last weekend of the Smashwords Summer/Winter sale. You can learn about my science fiction books that are on sale at:

We also have fantasy and steampunk titles on sale. You can learn about them at:

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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.

Astronomy on Independence Day

I spent my Independence Day this week in the operator’s chair at the Mayall 4-meter telescope at Kitt Peak. Astronomers typically work every single clear night, regardless of weekends or holidays. I’ve worked during many Thanksgivings, Memorial Days, Presidents’ Days and more. In particular, I was supporting a project looking at stars with planets or planet candidates identified by the Kepler Space Probe and getting spectra of them. Spectra tell us things like the chemical composition of the star and the temperature, which in turn helps us know whether any planets discovered are potentially habitable.

4meter Console

Basically, when operating the 4-meter, I spend the night at the console shown above. It’s not as colorful as watching a fireworks show, but it’s still pretty thrilling to point the telescope at faint stars, then take a glimmer of light, spread it out through a spectrograph, and understand an object that’s hundreds or even thousands of light years away.

Quiet nights at the telescope can be a good time for reflection and on this weekend after Independence Day I do find myself privileged to be an American. I’m fascinated by the history of this great land, and I’ve turned to expressing that fascination through my steampunk writing. That said, I recognize this country is far from perfect and its leaders have made more than their share of mistakes, but one of the things that makes America great is perhaps that it’s easier to correct those mistakes here than it is in other countries. We’re still generally free to form our own opinions and express them.

I express my thoughts and explore ideas through my writing. Recently I came across a review of one of my books, claiming I was clearly a member of a certain political party because of some remarks a character made. It left me scratching my head. Sure, if a character expresses an idea, it’s something I’ve thought about, but my character and I may have very different outlooks. What’s more, even if I do share an opinion about one subject with a political party, it doesn’t mean I agree with others.

If there’s one thing that concerns me about America today, it’s a tendency to view things along very polarized party lines. If a person believes A, they must by necessity believe B,C, and D also. The truth is that like starlight, there’s a whole spectrum of ideas.

As the fireworks fade and light shows end this weekend after Independence Day, I encourage you to form your own opinions and take constructive action when you see a need for a change. Don’t be afraid to disagree with a friend and remember you can still be friends even if you disagree. I think that’s a viewpoint most of the protagonists in my novels and stories would agree with and it summarizes why this country really is so great.