The great balancing act: Stabilizing telescopes at the George Observatory

Editor’s note: This post is part two of our three-part series on how you helped us Save Our ‘Scope at the George Observatory. Read part one here.

Many have asked us how we are still using the large research dome at the George Observatory while the 36-inch mirror is in Iowa getting fixed. The simple answer is that we are continuing to use the 11-inch refractor, which is mounted on the side of the 36-inch telescope. The refractor has near-perfect lenses and is an incredibly high quality instrument in and of itself. The 36-inch mirror is best used for deep space objects, and the 11-inch refractor is best used for closer objects like we find in our solar system. Together, they work in tandem to make a remarkable team to view near and far.

The entire telescope grouping and mount weight approximately 10 tons. The 36-inch mirror weighed almost 500 lbs with the mirror and the center hub that holds it in place.  Because everything is so perfectly balanced, the motor to run the telescopes is approximately the size of a sewing machine motor. This delicate balance is also what keeps the telescope working properly. When we removed the more than 500 lbs. for the primary and secondary mirrors, the entire system was totally out of balance.

We were advised that glass is the same density as cement by our mirror expert.  With this piece of information and the help of Tracy Knauss, Paul Halford and Chris Randall, a plan was devised to make an exact replacement of the glass mirror out of cement. Paul located the materials and then Chris took over the project. He had scales and tools at his home and handily went about making the cement mirror.

First, Chris started with some rebar and a 36-inch sonotube.  

SOS Cement mirrorThen Brazos Bend State Park provided a fork lift to get it out of the truck.

SOS Cement mirror 2

SOS Cement mirror 4Then we had to get the 500-pound blank inside the building and placed underneath the dome so that it could be lifted three stories up into the dome and then installed.

SOS Cement mirror 6Here is the cement mirror blank installed in the real mirror cell.

SOS Cement mirror 9Finally, Tracy and Chris installed the cement blank into the back of the telescope casing where the real mirror will eventually be. By replacing the weight almost exactly, only a very few adjustments had to be made so that it was back in balance and able to support the 11-inch refractor again. 

With Jupiter, Mars and Saturn so prominent right now, this is the best ‘scope for viewing until the 36-inch returns to the George Observatory.

Save the Date: The George Observatory’s 25th Anniversary Celebrations
October 10, 2014: Members and donors event 
October 11 & 12, 2014:  Anniversary weekend. The Observatory will be open  from dusk until 11 p.m. Come look through the newly refurbished 36-inch Gueymard telescope that you helped save!

You saved our ‘scope at the George Observatory! And this is how it happened.

CliffsNotes: Thanks to all of you, we have done exactly what S.O.S. intended, and we saved our ‘scope!

HMNS is proud to own the largest telescope in the country that is open to the public on a regular basis, the Gueymard Research Telescope. Many of you have come and enjoyed the night skies and looked through this amazing telescope at the George Observatory. But it needed some well-deserved TLC this past winter.

SOSYou saved it!

The donations to repair the Gueymard telescope ranged from pennies to $10,000, and came from families, individuals, children, companies and foundations!

Special thanks go to Dr. Reggie DuFour, who launched the campaign with a generous $10,000 donation. We are also extremely grateful to major donations from The George Foundation and The Henderson-Wessendorff Foundation. We were also given a generous donation from elementary students at Shady Oak Christian School, who sent us over the top with their $1,800 donation, which was collected from their annual fun run.

Why is the Gueymard telescope so important to us — and to you?

On a clear night, it is incredible to be able to see with your own eyes the many wonders of the universe. There are other, larger telescopes, but they are far away and they are only available to scientists who apply for time and get their projects approved. These large ‘scopes use cameras which are then fed to an indoor area where scientists “look” with their computers. Here at the George Observatory, we think there is something very personal and magical about using your own eyes to look at Saturn or Jupiter or a galaxy far, far away.

The 36-inch Gueymard mirror and dome were purchased from LSU in advance of the 1989 opening of the George Observatory. LSU had owned and operated the ‘scope for 25 years in highly humid conditions, very similar to the ones in Brazos Bend State Park. Brazos Bend is a swamp and grassland, but it is also located conveniently about an hour away from light-polluted cities in and around Houston.

The unique relationship with Brazos Bend guarantees us a safe, dark place to view the skies. Most telescopes are put on top of mountains or out in dry deserts where the weather conditions allow for more nights of clear skies. When Halley’s Comet returned in 1986, thousands of visitors lined up at the park wanting to see the comet. We knew then, if not before (and certainly now), that there is a high interest level in everything astronomical in Houston.

We believed that because the mirror had already lived in a swamp for 25 years, it should continue to do well in similar conditions. This was true for a long time. However, several years ago we noticed that we really couldn’t see as well with the large scope. The mirror was becoming cloudy. In 2011, it was determined that the mirror surface had lost all reflectivity. After extensive research and phone consultations, the mirror was sent to Marian Schafer at Galco Electronics in Mesquite, TX. Galco, which is well-equipped to put coatings on mirrors, was selected based on its good reputation and, in part, its  Dallas-area location – which allowed our volunteers to transport the mirror, saving shipping costs.

Mirrors are supposed to be shiny. This one was not.

SOS 1Starting in December 2011, Marian stripped, cleaned, baked and held the mirror under a vacuum five times to try to remove contaminants from inside thousands of small microscopic fissures found on the surface and interior of the mirror. In addition, there are numerous other bubbles throughout the glass mirror that can be seen with the naked eye. Galco used a sub layer of chrome as a binder and then put a final coating of aluminum. When this coating failed, titanium was applied as the binder in order to block leeching contamination.

It was understood that if the titanium was put on, the only way to remove it would be to regrind the mirror. The titanium coating failed, and did not bond to the mirror surface. This first attempt helped us to determine exactly what needed to happen next with the mirror.

SOS 3Time to hit the grind.

The next step to fix the telescope was to bring in an independent expert on a Ritchey–Chrétien designed telescope like ours. James Mulhernin, from Optical Mechanics Inc. (OMI) was flown here from Iowa. Mulhernin determined the composition of the glass as excellent quality Pyrex, and also determined that the microscopic fissures were artifacts from when the mirror was originally made almost 50 years ago. Over time, pollution and microscopic “gunk” in the fissures prevented a coating from sticking to the mirror.

Mulhernin’s newer technology will allow us to re-grind the mirror and prevent any of these old issues from coming up again in the future. This is indeed great news for us here at the George Observatory.

SOS 4The mirror was shipped to OMI and is currently being serviced. Reports are all very positive.

While the mirror is gone, we can still use the amazing 11-inch refractor with near-perfect lenses mounted on the side of the big telescope. But that’s another story as to how we removed a 458-pound mirror and can still remain open on Saturday nights!

Stay tuned for more updates on the repair progress, and start looking forward to the 25th Anniversary celebrations in October here at the George Observatory.

NASA Fly-By at the George Observatory

At the end of November, the Space Shuttle Endeavor made its way back to Earth – and was rerouted to a base in California due to poor weather at Kennedy Space Center. To get the shuttle back to Florida and ready for its next trip to space, it was piggybacked on a modified 747 and flown cross-country on Dec. 11. When it passed over Houston, a science class taking place at the Museum’s George Observatory had a front row seat as it flew overhead. Here’s what Astronomer Barbara Wilson had to say about the experience:

IMG_3949crop
A photo of the shuttle – flown on the back of a modified 747 –
passing over the George Observatory in Brazos Bend State Park.

George Observatory/HMNS staff received this communication from NASA pilot Triple Nickel.

“For those who care the Shuttle landed in Ft Worth, if the weather is good Thursday the 747 will fly from Ft Worth down to JSC for a flyby and then back to Barksdale AFB.”

Then we received another notice from Flight Director Chuck Shaw of the actual flight path and times.  We watched the flight path on the Internet and figured out when the 747 with shuttle piggybacked on top would pass over the George Observatory,  all of the students and their Moms went up with us to the main observatory deck and we heard the plane first then saw it pass directly over the George Observatory at very low altitude.

Our home school students were here today taking a class on Origins of Flight and a Challenger Mission. 20 students were thrilled to get to see the Shuttle piggybacked on the 747!

The pictures are of the Space Shuttle being transported to NASA at 11:55 am today 12/11/08 and were taken by Laurie Knight, mother of two students attending classes. Thanks Laurie.

You can see more of Laurie’s photos (plus lots of other fabulous visitor-submitted photos of the Museum and its satellites) at the Houston Museum of Natural Science pool on Flickr or on Barbara’s Flickr photostream. You can also see another amazing closeup shot of how the 747 and the shuttle were piggybacked, taken by AlphaTangoBravo when the 747 came closer to the ground, here.