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.


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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

The Robots Are Taking Over

I spent this past weekend at Bubonicon in Albuquerque, New Mexico. Yesterday, I moderated a panel called “Are Robots Still Scary? Danger Will Robinson!” As it turns out, I suggested this panel to the event organizers because it occurred to me that I work with a robot quite a bit at Kitt Peak National Observatory and it’s a far cry from the anthropomorphic robots of pulp sci fi and probably more irritating at times than scary. The robot I’ve spent most of my time with is called the Hydra gripper. The reason it can be irritating, is that I’m one of the guys who has to go fix it when it breaks down!

hydra

The gripper is on the right-hand side of the photo above. Its job is to pick up the fibers on the left side and position them on the plate so that they line up with objects on the sky. When the telescope is pointed at the target, light from the objects will go downstairs to a spectrograph, where it will be broken into a spectrum and projected on a camera. Astronomers can take that light and analyze it to understand the chemical composition of the objects they’re studying. These objects can range from stars, to galaxies, to nebulae. Some objects are nearby, others are among the most distant in the universe.

The reason for this post’s title, is that we’re about to get another robotic spectrograph at Kitt Peak. This one is called DESI (which stands for Dark Energy Spectrographic Instrument). Hydra allows us to take spectra of upwards of 200 objects at a time. DESI will let us take spectra of 5000 objects. You can read more about DESI in this press release from the Department of Energy’s Berkeley Lab. The goal of the instrument is to get spectra of all the known galaxies obtainable by the 4-meter in order to understand the phenomenon that’s been dubbed “dark energy.” Along the way, we’ll build an incredible database of spectra available to the entire astronomical community.

This week, I’ll be helping to test a prototype of DESI on the Mayall 4-meter telescope. The fibers of DESI are so closely packed that they aren’t moved around by a system like a gripper. Instead, each fiber is a little robot that turns on its own to optimize its position on the sky. Because of this project and the number of people it takes to get a project like this off the ground, DOE has helped to fund a new, larger control room for the Mayall. You can see the original on the left below. The new control room is on the right.

New-Old Control rooms

As it turns out, ghosts and stories of haunted observatories feature prominently in my forthcoming novel, The Astronomer’s Crypt. Our new control room is one of the “haunted” spaces in the Mayall. It used to be an old lounge and there were two rocking chairs that would sometimes be seen to rock on their own even when no one is in there. It remains to be seen if there are any ghosts, or if this motion was just due to sway of the building. If there are ghosts in the building, I hope they like company, because there’s going to be a lot of it in the coming years!