Antarctic Ballooning, 1996 Scott's other hut

In 1995, we had a proposal to NSF Polar Programs to launch small balloons to measure ClO and BrO in collaboration with Prof. Terry Deshler at the University of Wyoming, who regularly measures ozone and particles in the Antarctic ozone hole every year. To succeed, we needed to significantly reduce the size and weight of the instrument we flew in Kiruna in 1995. In the spring of 1996, Ralph Kolbush, Hiro Kosai, and I began to design and build and test new hardware and electronics in an effort to reduce the weight below 25 kg. A larger instrument, together with Terry's particle instruments, would exceed the limit for a safe launch without heavy machinery (loosely defined by the weight that one or two people can safely handle at -40 C on the ice and not get picked up accidently by the balloon). Although tight federal budgets in 1995/6 resulted in the proposal being rejected (remember, this was the year that the government shut down several times), the commitment to go to Antarctica had to be made well in advance, so in March of 1996 I agreed to accompany Terry's group (Bruno Nardi, Lyle Womack, and Jim Hereford) down to McMurdo for winfly. I spent two months on the ice, and assisted with launches of ozone and particle sondes nearly every-other day. Although we couldn't build five instruments as originally proposed, in our spare time we put together one new instrument from spares of our other instruments. When conditions were optimal (Sept. 21), we were able to launch our new combined payload as an engineering test flight. Photos of that launch can be found at Ethan Dick's Page.

C-141 on Ice Runway This is how we got to McMurdo on August 17 (need I say more?)

PC-104 This is the computer that we used to reduce the weight and power consumption of our data acquisition system. It isn't better than the one we used in Kiruna, but it sure is smaller! We had to build a special interface board (seen here on the top in the same size format as the PC-104 system (RTD) beneath). The system had 16 channels of 12-bit A/D, 8 digital output channels, and two high-resolution counters. We didn't have time or money to design a printed circuit board for the interface board, so what you see here was hand soldered by Darin at McMurdo only days before the launch (field work is so fun!). Fortunately, the circuit was simple enough that it worked without much debugging. It is so dry in Antarctica that one has to use anti-static mats (although bad practice, we often get away without them in the lab at Irvine), seen here as the red "background".

Electronics box We inserted the computer into a small box, together with the batteries (hard to see, but upright in the back left of box), the two gas regulators, and our DC/DC converters (on the left wall of the box). This arrangement was not only small and lightweight, but also reduced the need for additional heaters for the regulators because of all the heat generated by the computer, power supplies, and batteries. The heat was just about right for the flight, as the temperature of the box stayed well above freezing for the entire flight. However, the balloon floated higher than we planned, and at the low pressures, the box overheated, melting a small DC power supply on the RTD analog board. As a result, the system stopped working on descent at about 50 mbar. So we only have data from ascent to 20 mbar and part of the descent.

Side View of instrument This view shows the small box inserted into the instrument, which is about 13 inches tall. Also visible in this photo are the lightweight air bottle (Structural Composites Industries) and the nitric oxide pressure vessel, which was custom built by Ralph Kolbush. The penguin was purchased at Scott Base, and it did fly (it was needed to round off the final weight of the instrument to 18 kg). Air was pulled through the flow tube by an axial fan housed in a fibreglass duct, seen here behind the NO pressure vessel. This piece and the inlet (which isn't easily visible here) were constructed by Nancy Ciszkowski, who worked in my group for a month or so in the July of 1996 before I left for McMurdo.

Other side of instrument The other side of the instrument appears here. Visible are the lamp modules, photomultiplier tubes, and the fan duct.

Type I PSCs This is what we went down there for. This is a typical Type I PSC that we observed for the first couple of weeks at McMurdo. The Italian Lidar nearby told us all we needed to determine where these were, typically between 14 and 16 km, as the air above that was probably completely denitrified and significantly dehydrated. This photo was taken two or three hours after sunset. You can see the wavelike structure to the "cloud" and also the characteristic violet color.

Inflating the 160k Here is Ethan Dick's photo of the inflation of the 160,000 cubic foot balloon that was needed to launch this 50 kg (payload and load line) up to 30 km. The local time was about 12:00, and there was absolutely no wind (although we could have launched if it was windy).

Darin and Instrument This is another of Ethan's digital photos, in this case of Darin powering up the instrument a few minutes before the launch. It was obviously a warm day (it was about -15 C) because he isn't wearing his hood. The clothes are NSF standard issue.