Having Traded Wings of Wax for Cameras

Saw a great story about NASA's newly acquired images of the Sun. If you haven't run across this yet (it was a featured story on Yahoo's homepage earlier this week), I recommend at least checking out the video linked above.

If you're like me and have heard absolutely nothing about this project, never fear; I'll fill you in. The images of the Sun that the above story refers to were gathered by NASA's Solar Dynamics Observatory (SDO). The SDO is an orbiting observatory that was launched back in February. The goal of its 5-year mission is to provide data on the Sun that will allow us to better understand the glowing orb in the sky that is the source of all life on Earth, as well as to gain knowledge about Earth's precarious but fundamentally necessary relationship with it.

Over the past couple of months, while the craft was soaring over our heads outside the Earth's atmosphere, the SDO has been undergoing checks and testing to ensure that all of the on-board equipment is working properly. This equipment consists of three main instruments. The first is the Helioseismic and Magnetic Imager (HMI), which is primarily used for studying variability of the Sun's magnetic field and internal workings. The second instrument is the Extreme-Ultraviolet Variability Experiment (EVE), which examines what is known as extreme ultraviolet radiation produced by the Sun. EVE is capable of accurately measuring light with wavelengths lower than 30 nm, and it is this high-energy radiation that is responsible for heating the upper atmosphere of the Earth and thus giving rise to our ionosphere. The last piece of equipment is the Atmospheric Imaging Assembly (AIA), and it is capable of full-disc imaging of the Sun and will be taking constant video of the massive star throughout the SDO's mission lifetime.

The AIA, as one might expect, will be providing the coolest images and videos; at least for those of us not directly involved in solar research. It's these images that have been tossed around on the internet and shown in news stories. You can find the images at the SDO image gallery site, as well as videos at the briefing multimedia site, but I thought I would add a few of my favorites to this post. I hope you enjoy them. I sure have (the second one is my new desktop wallpaper).

Cooler Than UAVs? I Think So

This week, I'll be continuing upon last week's post, which focused on my experiences at the SPIE Defense Security & Sensing symposium in Orlando, FL. Hopefully, though, this post will be a bit more interesting to those who are not conducting research in sensor development. On the first day of the conference, after I had finished my presentation, an event called 'student lunch with the experts' was held. The event took place in one of the resort's ballrooms, and the dining tables were set up in such a way that every other seat at a table was occupied by an 'expert' - mostly high-level researchers at top laboratories, companies, and universities - and the seats in between were open, to be filled by the students attending the lunch.

At the 'student lunch with the experts,' I ended up sitting with two gentlemen from the Naval Research Laboratory. One of the NRL researchers discussed his research on analyzing and modeling light propagation in turbulent media, which was definitely pretty cool, but was more interested in having his colleague explain his work. Once coaxed into speaking about his work, the second NRL researcher explained that he was involved with 'gliders.'

"Are you familiar with gliders?" he asked us. We shook our heads no.

Gliders, it turns out, are unmanned vehicles. Similar in some ways to the UAVs - unmanned aerial vehicles - that the US armed forces have been implementing over the past few years, but these vehicles are quite different. The gliders are also known as AUVs - autonomous underwater vehicles. Unlike their airborne brethren, the underwater gliders are not piloted by a technician at a console in another location. Instead, the technician gives the glider a set of GPS coordinates. Once given its destination, off it goes, completely on its own at a nice leisurely pace of 1-2 knots. Upon reaching its destination, the AUV pops up to the surface of the water and establishes a satellite communication link with its home base. At this point, the glider can either stay put at its current location or can be given a new set of coordinates, in which case it will submerge and continue along to the new destination.

Another difference between the underwater gliders and the UAVs are that the glider has no visible means of propulsion; no jets, no propellers. Rather than relying on power-gobbling propellers, the glider makes use of ballasts, combined with fins and the ocean's thermal gradient, to transfer vertical motion into horizontal thrust. In practice, this would mean that the glider would receive its coordinates and then dive. As it dives, internal ballasts push the nose of the glider downward, pushing the glider forward. Once a certain depth is reached, thermal gradients buoy the glider back toward the surface. As it ascends, the nose points upwards, propelling the glider forward in a fashion similar to its descent. The resulting trajectory takes on a saw-tooth profile: up-and-down over and over again, but always moving forward. And because the AUV has no motor to speak of, its power consumption is minimal. So efficient are they that the duration of their submerged journeys can last for months, limited only by the life of the battery. That is unless they are attacked by sharks first, which has proven to be a bit of a problem.

Current research on these vehicles is focused on how to utilize them to solve practical problems. One area of interest, which we discussed during the lunch, is the ability to mount sensors onto the AUVs, allowing them to autonomously collect data and monitor ocean water for analytes, such as environmental pollutants. Given the fact that it would be totally awesome to see a glider in action, not to mention the fact that my research emphasis is on environmental sensors, I'm sensing a possible collaboration here.

A Little Taste of Mushy-Brain Syndrome

I've returned from SPIE Defense Security & Sensing both refreshed and also mentally exhausted. It was a multi-day bombardment of all things awesome in the world of remote environmental sensing and other similar fields. In fact, I left a day before the conference was scheduled to end because I knew my brain would turn to mush if I stayed for the entire duration. I know this because I stayed for the whole shebang last year and, although I learned much, could make little of the notes that I had taken once I returned. Those conference sessions seemed to boil together into a steamy stew of science in my brain. I kept getting confused between different sensing mechanisms and who, of the talks that I particularly enjoyed, gave talks about which subject...'Now, I think that was the Air Force Research Lab that's doing the aptamer-based sensors...or was it MIT? Oh no...'

This year at the conference, I tried to stick with sessions that were at least somewhat related to my research, which means that I strayed away from imaging and target detection and tracking and instead mostly attended sessions on environmental and chemical sensing and the like. It didn't take long for me to notice a very obvious trend. In fact, I noticed it on the very first morning when I gave my talk. I would've been a fool to not notice it because the topic every other speaker in my session presented was on a particular type of research. That research, you may be wondering, was SERS. SERS, not to be confused with SARS, stands for surface-enhanced Raman spectroscopy. To get a picture of how SERS works, let's start with the end in mind. And when I say 'end,' I mean the last two letters of the abbreviation: RS. Raman spectroscopy is a method of analyzing Raman scattering, the inelastic scattering of incident photons, from a species. The wavelength or wavelengths at which Raman scattering occurs are related to the vibrational energy of the molecular species, so that every molecule or compound has a particular Raman spectral fingerprint. By analyzing a particular sample, the Raman spectrum can be compared to known spectral fingerprints to identify the molecular makeup of the sample. The problem, however, is that Raman scattering is very weak, and this is where the first two letters, SE, come into play. Surfance enhancement of the Raman signal can be created when the sample being interrogated is applied to a nano-structured metallic surface. The gaps between nano-scale structures are tiny little amplifiers of the Raman scattering effect, most likely caused by local surface plasmon resonance effects.

This method of analyzing and identifying particular compounds with SERS is quite effective and also thoroughly documented, and so the primary research focus was on how to enhance the effect with various surface processing techniques and use of newfangled light sources, and also on how to apply this signal transduction method to a broader sensing platform. More specifically, how to grab the analyte of interest out of the environment so that SERS can be used to interrogate it. In fact, one group from the Army Research Lab was combining SERS signal transduction with molecularly imprinted polymers as a method for capturing the analyte. The reason this is of particular interest to me is because I also work with imprinted polymers and I found the entire scheme to be quite brilliant in its simplicity and effectiveness. However, I also realize from working with imprinted polymers that in practice there is absolutely nothing simple about it.

I have to admit that there were many other topics besides SERS that were discussed during the chemical and environmental sensing sessions at this year's Defense Security & Sensing. I noticed that laser-induced breakdown spectroscopy (LIBS) was a recurring theme, as was ion mobility spectroscopy (IMS), but SERS was overwhelmingly the most popular subject within the sessions that I attended. And now that I've got the topics that I was most interested in (and I'm probably the only one interested in them) out of the way, I will return shortly with another post that shares some of the more wicked-cool things that I learned about at this year's SPIE Defense Security & Sensing conference.