HiCal, Seals, Pegasus and a Herc

Finally got back to the blog, probably have a few more posts that I would like to get done.

Just a reminder, I have more photos at https://www.flickr.com/photos/114463775@N04/sets/72157646697801283

For this flight of ANITA, a balloon-borne calibration instrument called HiCal was developed and flown to get additional data. The idea behind it is that a pulsing antenna will send a signal in all directions when it is in the line of site of ANITA. Some of the signal will travel directly through the air to ANITA, while some of it will reflect off of the surface of the ice back up to ANITA. The differences between the two signals can be used to look at the effect the surface of the ice has on radio signals coming up through it as well as reflecting off of it. It turns out not we're not exactly sure what impact the surface of the ice has on the radio signal and it is very hard to model. An analogy would be ripples on the surface of a pool and the effect it has on the appearance of objects below the surface. The surface of the snow/ice has waves and ripples and varying degrees of roughness. This flight was largely a proof of concept. The pulser itself was a barbecue lighter hooked up to a motor that used a cam to press the button every 3 seconds. The lighter was hooked up to an antenna inside of a pressure housing. Another issue with flying balloons is the reduced air pressure makes it easier for electricity to arc and the antenna would arc to the computer that it flew with if it wasn't in the pressure housing.

Here you can see HiCal hanging from the hook. The electronics are contained in the rectangular box and the barbecue lighter and pulser are in the cylindrical pressure housing below it.

Here are some photos of one of the HiCal launches. We actually had three HiCal launches, two of which were successful. One of the launches went up a hundred feet or so and then came crashing down. 

The launch is a bit more involved than I expected. They call this a "hand launch", but it still involves bit of prep.

One of the successful launches. HiCal only has limited windows when it can launch.  We would like it to be close to ANITA, but not too close and of course there are the usual weather constraints with a launch.

Here is a photo of crack that formed near McMurdo and you can see a large number of seals near it in the middle of the photo. The sea ice cleared out in front of McMurdo a few weeks ago, but it has since frozen over again. It usually takes a good storm out of the south late in the summer season to blow the ice out into the open ocean. I have never been there for it, but the stories of orcas, minke whales, leopard seal, etc. immediately offshore are pretty amazing.

I had the opportunity to visit the "Pegasus" crash site, don't worry, nobody was killed in the crash.

As I understand it, a C-121J Constellation called "Pegasus" was making a run to McMurdo from Christchurch in 1970. They passed the point of safe return with the understanding that bad weather was headed towards McMurdo. They made it to McMurdo at the same time as the storm and had a hard time seeing the runway. After six or seven attempts, the crew realized they had only enough fuel for one last attempt. The plan was to make the final attempt and if they couldn't see the runway, retract the wheels and make a gradual decent into the snow a couple miles away. However, the pilot was able to see the ice runway on the last attempt and put the plane down. However, snow had started to form drifts on the runway because of the storm. One set of landing gear caught a snow drift and caused the aircraft to spin. The spin broke the landing gear and thus a wing.

Here is view of Ross Island looking at McMurdo from the crash site.

 And here is McMurdo zoomed in.

Lastly, a C-130 head to Pole taking off from Willy Field with one of my coworkers aboard.

Update, Emperor Penguin, calibration pulser

My apologies for not keeping this blog updated. ANITA was cut down a few weeks ago, and the Australian Antarctic Division was able to recover some of the crucial components. I recently made it back to Hawaii after doing some travel in New Zealand. I will try to update the blog over the next few days to document and share some of the highlights.

We buried some antennas in the snow outside of our hangar that we use to calibrate the instrument as it is flying. We can compare the strength and quality of the signal as well as the arrival timing of the signal from the calibration antennas with the known position of the antennas and the gondola as it is flying to get a pretty good idea about the performance of the instrument. I really only share this because during one of our launch attempts, an emperor penguin walked right through the area where the antennas were buried. From my understanding, it's not unheard of for penguins to go wandering or exploring on their own, but it's my impression that many don't survive. We were about six or seven miles from any place where the penguin could get back into the water, if it knew how to get there.

Here is the gondola hanging from the launch vehicle during one of the failed launch attempts. We would show up about eight hours before the scheduled attempt to get the gondola ready. All of the canceled attempts were due to weather conditions that weren't favorable for launch. Launching a balloon requires that the winds speed stay low up to about 2000 feet and they need to be convinced it will stay low and from the same direction for at least a couple of hours. If the winds are too light, the balloon doesn't move, or at least not in a predictable direction and they can't lay out the flight train. If the winds are too strong, the balloon will blow out of the launch pad before it's risen high enough to lift the gondola.

 Here you can see some of the procedure for prepping the flight train for flight. There are termination packages that are used to cut the parachute and gondola away from the balloon and another cut the gondola from the parachute when it lands.

One day there was a fuel truck out at LDB driving around with a rear tire showing some serious camber. It turns out all of the lug bolts had been broken off and the hub was just rolling along the inside of the rim. Thankfully they took the wheel off and it didn't come off while driving.

I was able to tour the SuperDARN facility while at McMurdo. SuperDARN, Super Dual Auroral Radar Network, consists of over thirty of these stations around the world that monitor the ionosphere by bouncing radio waves off of it. As the plasma moves, it causes a dopler shift in the returning radar signal which can be used to determine the movement and position of the ionosphere in different regions. Small changes in the ionosphere near the poles help predict larger changes of the ionosphere elsewhere. The ionosphere helps provide protection from space weather, so changes in it can have an impact on power grids,satellites, and astronauts. SuperDARN is also not nearly as photogenic as ANITA. 

Here you can see the display from the McMurdo site.

Here you can see one of the helicopters slinging an ATV out to some field camp. I liked the rudder on the ATV.