All posts by dpatter

Imaging Comet 46P/Wirtanen

Sunday night, December 16th, was the evening of the closest approach of Comet 46P/Wirtanen. The comet was close enough and bright enough with an apparent magnitude between 4.0 and 4.5 that you could see it with the naked eye if you had good, dark skies. Thankfully, that’s just what I have living out in rural Missouri, and we also had crystal clear skies. The comet can be seen between the Pleiades Cluster and Taurus through Wednesday, but as the Moon’s phase transitions from 1st Quarter to Waxing Gibbous, dim objects in the sky will be harder and harder to see. Throughout this coming week, the best time to view the comet will actually be in the very early morning after moonset. You can check out more about where to find and when to view the comet at Sky and Telescope,

Comet 46P/Wirtanen passing between the Pleiades Cluster and Taurus.

The image below of Comet 46P/Wirtanen is the result of stacking 63 exposures each with a shutter speed of 20-seconds, ISO 6400, aperture f/8, and a focal length of 200 mm on a Nikon D500 through a Tamron 70-200mm f2.8 riding atop a Celestron 8″ SCT. The telescope was there just to provide the clock drive so that the camera moved with the stars’ diurnal motion. Each raw image file was corrected for dark current, bias current, and the response across the frame was normalized using a flat field image. I’ll write up a tutorial on how to collect these images and why they’re necessary later. The images were then aligned and stacked on the comet, which is why the stars appear as streaks. Since the comet is moving quite rapidly past us, its motion relative to the distant background stars is very noticeable, even in the short timespan of this image set.

An long exposure image of Comet 46P/Wirtanen tracking the comet’s motion rather than the stars’ motion.

You may have noticed the very green color to many of the images of Comet 46P/Wirtanen, including this one. The green color is not a image processing artifact, but is indicative of the comet’s composition. Most comets contain a enough cyanogen (CN) and diatomic carbon (C2). As a comet approaches the Sun and its surface warms, volatile materials such as cyanogen, water, and others begin to vaporize forming the comet’s coma and tail. When cyanogen and diatomic carbon interact with the Sun’s ultraviolet light and fluoresce to create the characteristic greenish glow of many comets.

Voyager II Is Outta Here!

Well, perhaps more precisely, the Voyager II spacecraft is now making its way through the heliopause region.  Unlike planetary magnetospheric boundaries, the boundary between the heliosphere and the local interstellar medium (LISM) has substantial thickness compared to the length scales that Voyager II samples based on its data cadence and its velocity. It will take Voyager II time to make it completely through the region, but the data make it abundantly apparent that one of our oldest operating spacecraft is now set to join its twin as an interstellar traveler having entered the heliopause on November 5 at a distance of 119 AU, 35 AU past the termination shock.

Most of the data gathered by the spacecraft that indicate that Voyager II is now exploring a very different region of space are the sudden drop in the energetic ion intensity (E ~ 1 MeV/nuc) coupled with the simultaneous increase in the galactic cosmic ray intensity (E ~ 100 MeV/nuc). There are strong indicators in the magnetic field data as well. The field is significantly stronger than previously observed, there’s an absence of variation, and the field has a northward (+BN) component. All of this is consistent with what Voyager I saw when it entered the LISM.

Energetic ion and anomalous cosmic rays (ACR) rates as measured by the Voyager II Cosmic Ray Subsystem (CRS).

There are some significant differences between the Voyager I and II observations, though. The timescales of the transitions are very different with the Voyager II data showing a slower transition than as seen by Voyager I. The spectra for energetic hydrogen and helium ions (protons and alpha particles) also showed very little variation at Voyager II and compared to the change seen at Voyager I.

While many of the trends in the data are similar between the two spacecraft, these few and important differences will help the team to further refine our model for the shape of the heliosphere. Early models held that the heliopause was open and teardrop shaped, not unlike the shape of planetary magnetospheres. As the interstellar wind impacts the Sun’s magnetic field, it pushes on and distorts the field forming a tail structure downstream and a bow shock upstream. The data from Voyager I and the preliminary data from Voyager II coupled with remote sensing data from platforms in Earth orbit and on the now destroyed Cassini orbiter around Saturn are leading many to the conclusion that our heliosphere is a closed asymmetric bubble.

Fortunately, both Voyager spacecraft still enjoy good health for their age. The both still have plenty of fuel, but what they are both running low on is power. Solar panels simply won’t work when you’re 100 AU from the Sun. At the distance of the heliopause, you would need over 14,000 times more solar panels to provide the same amount of power that you could produce in Earth orbit. This is why the Voyager spacecraft are powered by radioisotope thermoelectric generators (RTGs). Small lumps of a highly radioactive isotope of plutonium provide a large amount of heat. That heat energy is then converted into electrical energy to provide power to the spacecraft. However, over the past 41 years of flight, the plutonium sources have decayed and cooled, therefore reducing the amount of electricity the RTGs can provide. Both spacecraft have the power they need for the instruments that are still on, but they’re losing power at a rate of 4 W/yr. Some hard decisions will need to be made very soon between turning on heaters, turning off some science instruments, or trying a time sharing scheme. The trouble is every on/off transition can result in an improper commanding sequence on Voyager II that could irreparably damage the spacecraft, and it’s not like we can send a repair crew to service them.

The two Voyagers are the most amazing missions of space exploration ever launched. The amount by which their data has advanced our understanding of the outer solar system and our Sun is beyond anything that any other single mission has provided, and they’re still going! Here’s hoping that we get a few more good years from our now TWO interstellar spacecraft.

The official press release can be found here:

Was the eclipse all you expected? No! It was way MORE!

Wow, wow, and triple wow! I expected the eclipse to be pretty cool, but it was absolutely mind blowing! Prof. Koch and I spoke with our Dean last spring and the three of us agreed that he and I needed to be on the path of totality in spite of that day being the first day of class. We were prepared from a gear perspective. We had an 8″ and a 12″ telescope, both fitted with white light solar filters, our new solar telescope with a built-in hydrogen-alpha filter to see prominances, and no less than six DSLRs between us with everything from a fisheye lens to a 400-mm f/4 prime lens. We hosted around 100 people including my fellow space physics researchers at Fundamental Technologies, science educator friends from Rockhurst University, racing buddies from the Sports Car Club of America (SCCA), and of course several other friends and professors and Dean Miller from JCCC.

Prof Koch and I started getting things set up pretty early, around 8am. As we looked to the southwest, though, we saw the rain coming and quickly grabbed some plastic sheeting and covered the telescopes. Thankfully, we didn’t get the torrential rains that the KC Metro received, but it did put a damper on our enthusiasm. The eclipse started a little after 11:30am, but our skies were still completely cloudy overhead. We held on to hope, though, as we could see a patch of blue sky approaching. A little bit past noon, after we had all stuffed ourselves on pulled pork, moon pies, sun chips, and enough potato salad to feed an army, the clouds broke and we had crystal clear skies. Just in time!!!

We watched the partial eclipse deepen using our various cameras, telescopes, eclipse glasses, and pinhole projectors. As the eclipse deepened, it became darker and darker. The dappled light under the trees started to appear more crescent shaped, and we all began to get excited. When totality finally came, I don’t think there was anyone who wasn’t blown away by the sight.

In the shadow of the Moon, we saw what looked like a sunset all around us on every horizon, the temperature dropped, and we saw a couple of planets and bright stars. Of course what was really spectacular was seeing the solar corona. My research focus for the past twenty years has been the solar corona and space weather, but Monday was the first time I have ever seen the object of my research with my own eyes. It was moving beyond anything I had expected.

Our location enjoyed a little over two minutes of totality, but it seemed like only two seconds. Just like that, the Sun began to peek out from around the Moon once again and back on went the filters and the glasses. We admired the partial eclipse a while longer and marveled at the rapidly brightening skies, but then we milled around, some of us packing up, some of us going back for more food. It was Leo, a friend and member of the Astronomical Society of Kansas City, that pointed out the crazy fact that there was a solar eclipse still happening right above us, but after totality, we had all gone back into our routine habits as humans.

As an avid photographer, of course I had gear set up to record the eclipse, but I didn’t let the photography of the event get in the way of my experiencing the event. I had my exposures all preplanned and the camera able to fire with a remote shutter release allowing me to image the sun while not needing to always be peering through the view finder.

The Van Allen Probes Turns 5 Today

Five years ago today, the Van Allen Probes were launched into orbit to begin their study of the trapped radiation belts first predicted by and then discovered by Dr. James Van Allen with the first US satellite, Explorer 1.  Fundamental Technologies in Lawrence, KS, where I do my space science research, is the Science Operations Center for the RBSPICE instruments on the two twin Van Allen Probes spacecraft.  Through my work at FunTech, my wife and I had the honor and privilege of being invited to the Kennedy Space Center to witness our spacecraft leave the planet.

We were at Cocoa Beach for three nights where during the day we interacted with visitors to the Kennedy Space Center where we had a large display assembled sharing information about the mission, its objectives, and its importance to improving our understanding of space weather.  As invited guests, we were given the opportunity to witness the launch from the same grandstands in which the families of the Apollo astronauts watched their husbands, brothers, and sons blast off on their epic voyage to the Moon.  It was an awe-inspiring, thrilling, and ultimately frustrating experience.

We had three nights and therefore three opportunities to get the Van Allen Probes off the planet, but on the first night, a launch was not even attempted.  Engineers had discovered a flaw in one of the RD-180 engines in Huntsville, AL, the same type of engine that powered the Atlas V rocket underneath our spacecraft.  The engines for our launch vehicle were inspected and found to be fine, so we were back on for night number two.

The launch window opened at 0430 which meant that we needed to arrive at Kennedy by 0030 to meet the shuttle busses that would take us to the viewing stands.  Once at the viewing location, we had a magnificent view of our launch vehicle standing on its pad and illuminated by the brightest lights you can imagine.  The atmosphere at the viewing site was thick with tension, anticipation, and mosquitoes.  Lots of mosquitoes! During the long countdown, several speakers gave talks about the mission, which we all knew about already, and details about the launch sequence and timeline, which many of us did not know.    What was truly special is that Maj. Gen. Charles Frank Bolden, Jr., Director of NASA, came out to address us and witness the launch with us.

At 0400, we reached the T-4 minute hold.  This was a preplanned hold during which final checks on the launch vehicle, the two Van Allen Probes spacecraft, and the launch conditions were made.  Talk about tense and exciting!  Movies always make the launch readiness poll sound over dramatic and you come away thinking, “Surely it’s not really that tense.”  Yes it is; it really is.  As each system was called out, the person responsible for that system would call out either “Go!” or “Go, Flight!”  I get goosebumps even now just thinking about that moment.

The Flight Director eventually got around to calling out, “Range.”  The response was a pause, and then an utterly disheartening, “No go, Flight. No go.”  That brought everything to an immediate halt.  When there’s a range fault, it could mean that there’s someone in the restricted space in the air or ocean that’s fouling the range, or it’s an instrumentation failure.  Many of our thoughts in the grandstands was that if it were a bunch of boaters out where they shouldn’t be, there might be violence done that day.  As it turned out, it was the fault of a transponder on the launch vehicle that couldn’t maintain a frequency lock on the downrange radar.

All launch vehicles are actively tracked.  A radar site doesn’t simply passively track them, they actively communicate with the launch vehicle to monitor the rocket’s attitude and trajectory with great precision.  The reason for this is that if a rocket begins to stray from its designated trajectory and begin headed inland where it may fall on a populated area, the vehicle will be destroyed instantly.  The last thing NASA wants is for a US missile to land and explode in a US city.

So with no launch on the second night, we all went back to our hotel rooms, caught what sleep we could before going back to the Visitor’s Center and our booth to do more public outreach in the afternoon.  That night, we all got up again and went back to Kennedy at 0030 to give the launch one more try.  Again with the speeches.  Again with the explanations.  Again with the waiting, the tension, the anticipation, and swarms of mosquitoes.  Once again, we reached the T-4 minute hold.  Once again, we listened nervously to the launch readiness poll.






And after a long pause, “Go, Flight!”

There was an uproar of cheers!  It was as our team had just won the World Series!  Everyone was jumping, clapping, and cheering, but the poll wasn’t over yet.


“…No go, Flight.  Weather is no go.”

It was a soul-crushing moment.  All the anticipation, all the excitement was dissipated in an instant. The weight of all of the work that had gone into making the Van Allen Probes, its array of instruments, and all of the software to control the spacecraft and their instruments crashed down upon us.  For many of us, myself included, this was our first time, perhaps the singular time in our lifetimes, of getting to witness a rocket launch, and certainly the singular time we would be able to watch from such a historically significant location.  There were tears.  I’m not ashamed to admit it.

My wife and I along with my fellow colleagues flew home.  There was still work that needed to be done on other missions, and the Fall semester had started, so I had to get back to the classroom.  It wasn’t a fun trip back, and I moped around campus that Monday.  The Van Allen Probes obviously did launch successfully, but not until the Thursday of the week after we were there.  My newborn daughter and I were up at 0300 to watch the launch on NASA TV, and again I wept. This time happy to see our spacecraft finally on their way during a flawless launch.

Five years later, the two spacecraft are still going strong and providing truly unique perspectives and data on the working of the Earth’s trapped radiation belts, the ring current, and space weather in general.  We’re still the Science Operations Center for RBSPICE, and we’re still finding out new things about our near-Earth space environment.  It’s been a great five years, and here’s hoping for at least a couple more.

You can learn more about the Van Allen Probes mission and the RBSPICE instrument by following the links below:

You can see my gallery of photos from our time down at the Kennedy Space Center and Cocoa Beach here:

GDC16 – Day 2

So yesterday was all math, and today was all education. …well sort of. Academic artists have a world view that is quite different from that of your typical scientist. I come from a very analytic background. Even my hobbies, playing poker and racing cars, and my artistic work in photography are a blend of the creative and the analytic. Once I wrapped my brain around the different way in which they were looking at the problem of pedagogy, there were some good take-away points from the morning and afternoon sessions.

One of the things that true of both artist and scientist is that we fail, and I mean we fail a lot. Most of our careers is spent creating one failure after another. This is NOT a bad thing, unless it’s the only thing you’re doing. The road to success is lined with a long sequence of failures, and those who do succeed accept this and even embrace it. When students finally arrive in a college classroom, they are absolutely terrified of failure. Personal note: This should not be a surprise given how frequently we subject our kids to high-stakes standardized testing, but that’s a topic for another article. Game development, much like the development of a new scientific model, is a process of constant iteration. You try, test, fail, tweak, test, fail, rinse and repeat. So many of our students are fearful of that initial failure that they don’t even attempt the work and fail in a far more destructive way. Mitigating, navigating, and learning from failure through iteration is paramount in game development just as it is in science, but it’s a tough thing to teach.

There were more ideas that I picked up throughout the day, but nothing really groundbreaking. I have some ideas related to the iteration process and managing failure I mentioned above that I will craft into some new exercises for the Astronomy courses. I’ll have more on that as I develop the idea into more than just thoughts in my head.

The last talk I attended was by Margaret Moser, “Teaching Designers to Code”. I thought that this would be useful not only because we occasionally get a more design-focused student in the Math and Physics for Games course, but also because even many of the programming-focused students are really just learning how to code efficiently. The two big take-away items here were not ones that were startling revelations, but rather stern reminder of what I already knew and should be deploying in my classroom. Something I could do better when describing algorithms in class is not to start writing line-items of pseudo code or equations, but instead to start with a block diagram of the process. This, of course, is the key to coding more complex solutions. Don’t think in terms of individual lines, but think in terms of functional blocks. That’s how I think of my scientific work. Think about the big blocks of the problem before you drill down into writing specific equations.

BeldonPlace_smThe evening ended brilliantly. Professor Hanna and I made our way down to a region where my good friend and fellow photographer, Bash Beard, took me when I was in town for the AGU Fall Meeting, Beldon Place. At first, it just looks like a sketchy back alley, but when you peek around the corner, it’s lined with one amazing restaurant after another with just about every type of food you can think to eat. We tried the last restaurant at the end of the alley, Brindisi Cucina Di Mare. Of course I was going to sniff out a seafood joint. What else did you expect?

Tomorrow is the first day of the main conference which means SWAG!!! The Expo Hall opens and it’s time to meander around the vendor booths and see what kind of cool loot I can drag back for my students, for Lillian, and for my officemate’s geocaches. It’s also the day of the Game Developers Choice Awards. Think the Oscars for video games, only with a bit more edge to it.