Thursday, November 26, 2009

Thanksgiving and a Bonus!

We received a Thanksgiving invitation from our friend Donna up in Gilbert (southeast suburb of Phoenix). The best thing is, she offered to do most of the work! We contributed a pumpkin chocolate marble cheesecake and green bean casserole, but the rest was her effort and it was great! The trip up to Phoenix was like being in rush hour for 2 hours - not quite bumper-to-bumper, but close. We got there about 11:30, a couple hours before eating, and helped with what we could, but Donna had most everything under control. The photo at left is our holiday table just after I hacked at the turkey and before chowing down. Donna is in the background holding the remnants of my beer for me...

An hour later, stuffed, with LOTS of leftovers, we adjourned while some of us (me) took a nap. Eventually we digested enough to have a piece of cheesecake - the girls thought it was the greatest!

Finally, I reminded them that the Space Shuttle and International Space Station (ISS) was making a pass just after 6pm. I had missed photographing an Iridium flare the night before, so we made it out in plenty of time to set up a tripod and camera to capture them. While the Shuttle Atlantis and the Space Station had been attached for the week-long mission, they had undocked in preparations for Atlantis' scheduled landing in Florida tomorrow morning.

In an open field only a block or two from Donna's house (near Power Line Road and Guadalupe)we easily spotted the bright ISS just off the northwestern horizon. The slightly fainter shuttle trailed by 15 or 20 seconds. It passed very close to Polaris and the Double Cluster before continuing to the east where it faded into the Earth's shadow. We waved and shouted a Thanksgiving greeting as they passed. The first exposure is 2.5 seconds, the other 2 are about 14 seconds, all with a Nikon 20mm F/2.8 and ISO 800 (click the images to load the full size version). To predict when the Space Station, shuttle or Iridium flares will be visible, THE Internet tool to use is the website - just enter your location from a map or database and you are on your way! Interestingly, it's appearance from Tucson, 120 miles to the Southeast, was very similar. But at 5 miles per second, it made the trip in less than 30 seconds - if only it were so easy for our return home!

Tuesday, November 24, 2009

Tooting Horns

A few months back (mid-August, actually), a reporter from the Los Angeles Times came through the lab to do an article about the Giant Magellan Telescope. After weeks and months, we sort of gave up for a story to appear, but then this morning, I got an unsolicited e-mail from a plaque company wanting to do a custom job for me "on my recent feature article". Switching over to the LA Times page, the article tells the tale of a former Iowa farm boy polishing "more square footage of optics than any human alive"! While bordering on hyperbole, it is downright false in parts, telling how I saved the LBT mirror from failure when the mold sprung a leak in casting. Sort of embarrassing, but haven't gotten too much ribbing from any of the Lab crew, though many have left early for the Thanksgiving holiday.

Unfortunately, the paper is not available in Tucson, though I hear the GMT project is forwarding some copies our way. Ray Bertram, who took the images to go with the story, provided the one shown here, which was on the front page of the Tuesday, 24 November LA Times (!). The image shows Buddy, the project scientist, and me inspecting the surface of the GMT segment. I've even heard from folks far and wide - my former boss e-mailed us this morning after spotting us (he moved to California), and my neighbor's sister called and made a fuss too. Check your watches - 15 minutes!

Monday, November 23, 2009

Spectacular Cassini Images of Enceladus

While Melinda and I take pride in providing nearly 100% of the images we show on our blog, the images released from the Cassini Saturn mission today are too amazing not to share. For a long time, I've also wanted to show some optical stereo images, and these are a spectacular place to start.

For a little background, Cassini has been circling Saturn for 5 years now and has been a spectacularly successful mission. It is currently on it's 121st trip through the Saturnian system, and 2 days ago had a close pass of the icy moon Enceladus, zipping only 1,000 miles (1,600 km) over it's south pole. Current models of the moon consist of a liquid water ocean covered by an ice layer. It has been known for some time that geysers form in cracks in the ice layer, spewing water vapor and ices into space, forming what is called Saturn's E ring.

Photo pairs from the satellite pass can be used to generate a stereo view. Taken a short time apart as the spacecraft moves past, if the slightly different perspectives are each viewed by our eyes, stereo depth is recreated. In these photos, the right image should be viewed with your left eye, the left image by your right. At a comfortable viewing distance, cross your eyes slightly, and 3 images should form, the center one showing stereo detail. Click for the full-size images, but the technique works for the small images as well.

Passing just 1,000 miles from the moon provides exquisite resolution with the telescopic lenses on the spacecraft. Scientists are just astounded with the backlit geyser images, and a full analysis of the images will no doubt revise current thinking about Enceladus, as well as Saturn and it's collection of other moons.

Saturday, November 21, 2009

Cottonwood Road Trip

We took the Highlander for a spin today. We had yet to take it out on the highway, and with a trip to the Midwest just over a week away, a performance check was needed. A perfect excuse - an astronomical garage sale in the center of Arizona - Cottonwood!

Bill Kelley hosted an astronomy garage sale 2.5 years ago - it happened to coincide with a visit by Melinda and she got her first 5" telescope there. Bill is an avid amateur astronomer and telescope maker and he had copious amounts of useful stuff last time as he downsized (made space in his garage). We got a late start today, not arriving until after 1pm, and I hear there were some gongas (bargains) early. Oh well, no worms for these birds! I got a couple small dodads, but the greatest joy was in seeing friends again - Steve Coe from Phoenix, Dennis Young of Sedona, space artist turned home renovation specialist Doug Ostroski, and of course, Bill and his lovely wife Lois. Also making the trip down from the Oak Creek area to see us was Margie - a friend I've had for a decade and a half from Grand Canyon Star Party connections.

Margie recently moved into a house in the area, and while she has been bugging us for a while to visit and stay, this was the first time we were in the area, so made the side trip to check it out. It turns out she only lives a few miles from former presidential candidate John McCain. Her house is beautiful, in a nice quiet neighborhood with gated entry. She has some spectacular furnishings and art work. One of the more interesting nooks in the house is near the kitchen where a beautiful hand carved and painted Mexican table holds a Hopi Indian kachina doll representing gluttony. Note the smear of watermelon juice down his front. We're both still nursing our colds and had cats waiting for us to feed in Tucson, so left just before sunset with a promise to return for a stay.

The Highlander performed great. No trouble with the little 4 cylinder going the speed limit (you would not believe the number of speed cameras between Tucson and the center of Arizona!). Even with the hills north of Phoenix we got 27+ miles per gallon on the 420 mile trip today - not bad!

Thursday, November 19, 2009

Moire Patterns Around Us

Across the street from work, they have been building a new addition to the Student Recreation Center. Construction has been ongoing for over a year or so, and soon to conclude. Almost every day, many staffers at the Mirror Lab cross the street to a convenience store, Circle K, to fill up on snacks, get a newspaper, or just get out of the lab for a few minutes to see the sun. About a month ago, I noticed something new - evidently they've incorporated a moire pattern as an architectural accent in the addition!

Now I've been a fan of "found" Moire patterns in everyday life for decades. Farms in Iowa have them all over if you look for them. In the simplest forms, if a repeating pattern meets another pattern, light and dark fringes are generated as the patterns work against each other to block or pass light. For instance, the two patterns of horizontal lines, slightly tilted, can generate vertical bands. This image is slightly modified from the Wikipedia entry on Moire patterns. On a farm like where I grew up, corncribs, fencelines, even power lines can form Moire Patterns.

In an urban area, they are harder to spot, but can still be seen - in protective screens over pedestrian highway overpasses, even in the reflection of a screen in a window. Here is a shot of a pattern formed by a window screen with it's reflection. The effect is often seen in some high-tech applications - sometimes when photographing a repeating pattern, say a brick wall, when examining the image on the camera's viewing screen, a Moire pattern can form with the limited sampling of the screen. Similarly, in the work we do measuring mirror surfaces, frequently the interference fringes we use to measure the mirror form patterns with the sensor's pixels.

But the Moire on the Rec Center was the first I've ever seen that were built on purpose. As soon as I had a chance, I took a short walk to see how it was formed. The pattern is caused by two separated screens - what looks like steel sheets with hundreds or thousands of regularly spaced holes a couple mm in diameter. The sheets are about 30cm (1 foot) apart, and when backlit with the morning sun falling on the east older wall of the Center, patterns form as the holes alternately let light through or block it. What is also interesting is that when driving along 6th Street westbound past the screens, the pattern has a dizzying motion that surly has a hypnotic effect on drivers. It would be interesting to come back and look at accident statistics in 10 years, comparing it to before it was installed!

While not exactly common, the use of Moire patterns in architecture is not unknown. I found an incredible blog while doing a Google search and found "Moire and Shadow Art". The blog hasn't posted anything new in over a year, but what he's posted is captivating. I recommend marching down all of his posts listed on the right hand side of the blog. Among my favorites besides the full building Moire at the above link is the photo of Jason Alexander shown at left. The pattern is caused by a repeating pattern in his suit interfering with the original printer's screen at some point in reproduction - another common place to find Moire patterns. He also has some videos and a link to a Moire-driven digital sundial - Neat stuff!

Tuesday, November 17, 2009

The newest 'baby'

We've been really pokey about posting this month, for some reason. We have had a lot going on, I'll admit to that, but we're almost embarrassed that we've only posted a few times and the month is half over!

One of the latest projects, a mission of Dean's, has been to find a vehicle that we could take to Illinois and leave there. We have found that when we fly to Chicago the greatest expense isn't the airfares, it's the car rental! We drove there, this summer, so we had one vehicle for the both of us for the 3 weeks. When we flew up in September we rented a car - to the tune of over $600. Last year, when we drove to Tucson, we towed my Jeep - which is not really convenient. The car dolly rental was over $400., plus the reduced gas mileage - $$$. Since we are planning to travel to Illinois frequently, we decided that maybe it would be a good idea to find a good, used, car to leave there. The added bonus is that we won't have to tow the Jeep again, either. If we drive the van to Illinois then we will still only have two cars there. All in all, a good move. So, with that in mind, Dean started doing some research. This is the first vehicle that Dean has bought since he purchased his '88 van, back in '94!

Dean's criteria for a vehicle was 1) used but in good condition, 2) reliable - we don't want to have to take it for repairs every time we're in St. Charles, 3) something big enough to haul a 4x8 sheet of drywall or plywood, 4) something that he wouldn't hit his head on every time he entered or exited the vehicle, 5) less than $7000. Numbers 3 and 4 on the list put him looking into SUV's right off the bat. After doing his homework he decided that a 2003 Toyota Highlander was exactly what was need for this "job". He found one at a dealership here, took a look at it (but didn't drive it) and decided that he liked it but would rather buy from a private seller. That took him to Craigslist, where he found exactly what he was looking for! The guy is good! He went to look at it, one evening, when I was at work - and immediately gave the seller a deposit. We picked it up from her a week later and have had no "buyer's remorse" yet! The car met all 5 of his criteria, and in fact I was amazed at home much room there really is! Dean has a full 4" of space above his head when he's driving (no knees against the dashboard, like in the Jeep), and yesterday I brought home a queen size headboard, and a chair, in the cargo area - with room to spare! It has slightly high mileage - 123,000; but that's not much compared to the van which has somewhere in the range of 325,000 miles on it! The car is clean, I mean really clean - and the seller had all of the repair invoices from the time she bought it. It does have a few dings, but nothing that is problematic. We've been driving it all over town with no complaints in how it handles. This weekend we'll give it a road test as we drive up to Cottonwood, AZ (near Prescott) to visit with friends and attend an "astronomy themed garage sale". Dean is absolutely loving driving this thing, though he has generously left it home for me to drive on my days off! It will be so nice to have our own car when we're in Illinois....good bye "Thrifty", "Hertz", "Avis", and "Budget"!!!

Thursday, November 12, 2009

Tile Time Update

Dean has reminded me that not only have I not authored an entry lately, but I haven't updated on the bathroom tile project. Time to remedy that!

My last entry on the tile project we were in the process of getting those first few courses of tile up. That is a critical step in the process. If you 'goof up' and those rows aren't level then the rest of the wall will also be off. Time is well spent in getting that first part right! Once things were hanging level on the wall then we were limited only by the time we had available - between work schedules, etc. If I hadn't mentioned it before, we had salvaged the soap dish from the original tile. Once it was cleaned up it was in great shape and ready to be put back up! Forgive me if I'm repeating some of what we had posted before.... The 'medallions' of Talavera were a challenge to apply. Talavera, being hand made, is irregular by nature. It's supposed to be that way. That means that no two tiles are the exact same, which translates into a headache when trying to match them up for a medallion, and fit them into the factory made tiles.

"A Bit of Whimsy" I had heard on one of the home makeover shows, many years ago, that you should always try to include "the unexpected" in decorating. There's some value to that, in my opinion. Keeping that in mind while we were shopping for tiles we found multiple variations of the shown crescent moon and stars tile, as well as some variations of the sun tile. The sun tile just didn't do it for us, so we decided to be a bit creative! Dean saw sun ornaments at the store where we bought the sink. Talavera, of course, but a bit three dimensional as well. I bought one and then had to figure out exactly how in incorporate it into our project. In the shopping around for tiles I have amassed a small cache of assorted tiles being given to me as samples by various sales persons. I picked up the creamy while Talavera tile that I had, set the sun on it and knew I had a winner! Some well applied "Omni-Set" and a bit of centering - viola`! Dean left it up to my discretion as to where the sun and moon would be placed, I chose the head wall for the sun - tail wall for the moon (no pun intended!).

Once all of the tile was on the walls we had to wait it out for a couple of days (accommodating work schedules and drying time) before we could get to the grouting process. In the picture you can see that we also installed a ceramic corner shelf. I really like that - no bottles of shampoo on the ledge around the tub -- no wire shower caddy! Since we don't plan on redoing this again anytime soon, this was the time to put in those little conveniences! This picture was taken before Dean cleaned the tiles in preparation for the grouting process. He did a great job cleaning the tile - which sounds easy, but it wasn't. Cleaning the tile is imperative in ending up with beautiful tile at the end of the project.

Finally, we did the grouting and after a day of "dry time" I caulked the nooks and crannies that had to be caulked and we were "ready for business" .... or so we thought..... We had a friend coming for the weekend, so she took the inaugural on Sunday morning. Before she showered she was given explicit instructions to make a mental note of what worked well, what didn't, etc. so that we could take care of those issues. We waited patiently for Donna's report....and then "the news". It seems that more water was coming out of the faucet handles, the tub spout, and the shower head extension arm joints than the shower head! Yikes!! The 'gravest' of those was the water coming out of the faucet handles. That was a clear indication that the faucet valves needed replacing. Have I mentioned? I hate plumbing. After doing some reading, and chatting with "Alice the plumbing lady" at the local Ace Hardware I was armed to tackle this situation. Alice sent me home with a loaner set of valve pullers, preferable to having to buy a set for this job. After many trials and errors the solution that I feared the most became more and more clear. Tile would have to be removed. Seriously! So, getting out the trusty chisel, I proceeded to try and remove just the two tiles where the valves are located. That dominoed into a total of 8 tiles - 4 blue tiles, 4 Talavera. Fortunately we had enough for replacement, but we did our best to not damage any more tiles! We had done such a great job of putting those tiles up, initially, that it was nearly impossible to get them down. In doing so, we destroyed the underlying cement board (just behind those tiles). After much deliberation we decided to get a piece of cement board or Hardibacker and fit a new piece in that area. That was our task on Veteran's Day. We affixed the Hardibacker in place with Omni-Grip, as well as Hardibacker screws. Today I was able to put the new tiles (newly cut holes...much bigger this time) in place. We'll let that adhesive dry throughout for a few days, with plans to grout the area on Sunday. Whew! Also, I caulked around the top and sides of the tile, where it touches the ceiling and the area of drywall outside of the tub. Yes, we did test the valves before reinstalling the tile - they seem to be working fine now. As for the leaky shower arm, just needed a bit more tightening - easy peasy!

Every job, whether it be here in Tucson or in St. Charles, carries an educational experience with it. This project should qualify us for some sort of "Home Improvement Degree"! Next up....the vanity and installing the new sink! Stay tuned for more excitement!!!

Wednesday, November 4, 2009

Ghosts of the Twilight

We had hopes for a pretty sunset tonight - clearing to the west, clouds overhead. It never developed into one of the postcard-gorgeous ones that the Southwest is known for. But one thing there were lots of - bats! I've mentioned their local abundance at twilight in previous blogs posts, but they seemed more abundant tonight. There seemed to be a couple dozen within 100 yards, so there were always a couple at any given moment against the sky. Since I had camera in hand waiting for the sunset, I tried taking shots of some of them. However the first thing you notice is that they do NOT fly like birds. They seem to change directions randomly over a time scale of a second or so. It was getting dark enough and they were moving fast and randomly enough that auto focus was worthless, so focused on a tree 30 yards away and shot a dozen or so shots with the telephoto, hoping to get one or two good ones. Well, these don't count as good ones, but are good enough to post as a blog topic. "Needs More Work", is how I would categorize these results!

I am not a bat expert, though I am a bat fan. These are likely Mexican Freetail bats - pretty common in these parts. I love observing them in the twilight during my walks. They are very beneficial for the environment - at least if you don't like flying insects, as they consume their weight in bugs nightly. There is, in fact, a "Bat Night" here in Tucson, complete with snacks and live music a couple miles from us here where Campbell Avenue crosses the Rillito Wash. A colony of upwards of 40,000 live in expansion cracks under the bridge. I've never attended, but saw it in the events section of the local paper. There is also a short, spectacular video on Youtube, of their exit from under the bridge. Be sure to check that out, and in the meantime, I'll work on getting better pictures!

Sunday, November 1, 2009

Steward Observatory Mirror Lab Update

It has been over a couple months since I've posted about work. Doesn't seem that long, but it was regarding the 6.5 meter mirror we are casting for a Mexican Observatory. That project is still in the oven, it's grand unveiling in a few weeks when it finally reaches room temperature. Progress is also being made on the Giant Magellan Telescope, but it is a complicated project, and I'm waiting to blog about it...

A couple months ago we finished polishing the rear surface of the Large Synoptic Survey Telescope primary, and a crew has been busy bonding loadspreaders to it. The loadspreaders are computer-modeled to best support the mirror while being polished in the lab, and while in the telescope on a Chilean mountaintop. The supports are passive, hydraulic supports while being polished, but will be under active computer control to fine tune the mirror shape as the telescope moves to different parts of the sky. Here Dan is installing a "double" against the brown blocks, previously placed with double-sided tape. On the right he is pressing out the 2-part RTV adhesive until pressed out to the correct thickness (the string spacers).

The loadspreaders need to be located to accuracies of better than a half millimeter (.020"). In years past we went to a great deal of work to survey and mark the rear of the mirror with tiny diamond marks to lay out the supports. These days we use a "lasertracker" to lay them out - using a beam of light to measure not only angles, but the distance to a cornercube to a thousandth of a mm (.00004"). They are getting to be a popular tool around the lab - in fact, we currently have 4 of them, at well over $100K each (several are dedicated to particular projects). At left here, Robert waits patiently for Dan to finish the loadspreader layout. At right, he monitors the computer display readout of the lasertracker (lasertracker is visible as the squat black cylinder left of his head) and fine tunes the position of the support.

Loadspreader gluing was finished early last week, and LSST was moved into the Casting lab for an overall survey (the entire backplate couldn't be seen on the generator machine where layout occurred). The image at right shows the variety of loadspreaders (singles, doubles, triples and quads) used with the entire mirror backplate seen. I heard that the loadspreader survey indicated that only one loadspreader was located slightly out of spec, so had to be cut off and re-adhered. The only work left to be done is the installation and wiring of thermocouples to measure the mirror backplate and faceplate temperatures during fabrication and in the telescope. This work has already started and needs to be finished before flipping the mirror and installing it in the polishing cell for start of work on the front surface.

When loadspreader bonding started, I moved over and filled in as needed on GMT, as well as working on procedures and preparations for LSST faceplate generation. However, for a week or so in the midst of the above, I got an interesting assignment. Roger Angel, the original "Idea Man" of the Mirror Lab, has a current interest is in solar collectors and high power photovoltaics. The Lab, in conjunction with the University of Arizona and Raytheon has been working on a prototype collector. As described in the Arizona Daily Star the collector and the new PV sensors, when produced in bulk, will make electricity from the sun at comparable costs to coal. I needed to make a little prism from stainless steel - the goal is to electroform a low-mass pyramidal concentrator, so needed to bring it to high polish. Never working with polishing metals before, I needed to try a couple combinations before hitting one that worked. As you can see, the left unit came out pretty well, compared to the right one which shows the machined, heat treated surface. The solar collector was finished last week, and gets shipped out this week. This is a shot with one of our students, Jason, for scale. Always something going on at the Mirror Lab!