The ATom mission has now flown from California to the equator and back, to Alaska, to Hawaii, to Fiji, to New Zealand on this second deployment. I met it in Christchurch, New Zealand to swap out with my colleague Aga, who flew this first half. We had a few days on the ground for maintenance and then were off to Punta Arenas, Chile.
At least we thought we were off to Chile, but we had something of a false-start. There was a heavy storm over Chile, meaning it might be too dangerous to fly. We had to wait for weather updates on the morning of the flight, so we all got up at 430am and started pre-flight, in-case we could fly.
As I started my pre-flight checks I noticed something odd with the flows in one of my instruments, they were fluctuating and not controlling well. On the ground in Christchurch we had changed out a filter to increase the pressure drop across it and allow a valve to cope better at high outside pressures. It had been tricky to get the pressure and flow control stable with this new system, but we thought we’d managed it and tested it thoroughly. As I scrambled to find the source of the fluctuations and eliminate it the message came through, the flight would be delayed by 24h because of the weather. Everyone was disappointed, except me, as I now had time to fix the problem with my instrument.
The crew kept power on in the plane for me for a few more hours. I fixed a bug in the software that had caused a pseudo-stability that tricked us into thinking the flows were stable before, then pulled the instrument part way out of the rack again, removed the new filter and replaced it with another one that was less radically different from the original, but hopefully still a high enough pressure drop for the valve. Without Aga here to work as a team it was harder, but one of our safety techs helped me out holding up the instrument while I worked underneath it and turning some valves while I monitored the response. The new filter, along with some software modifications got the fluctuations down to a manageable level and I tested all I could on the ground. It looked like it would work fine, but until I could see it in flight, I felt apprehensive.
This morning, we did a repeat of the 4.30am start, and luckily the weather was much better. Things looked good in my instrument during preflight and just before 9am we took off. I nervously watched my flows as we climbed to low pressure. Everything was steady, and I felt a wave of relief knowing everything was ok. This flight is an interesting one for us – very clean conditions, meaning the formation of small particles will be very visible if it’s happening.
The flight path for this flight was essentially an arc over the Southern-Ocean from the south island of New Zealand to the southern tip of Chile. At one point we started seeing icebergs way below. When it came time for a low dip we went down into the cloud, which was so low we couldn’t get below it for a long time. Finally it lifted a bit and we could see. A large iceberg appeared in the water close to the plane just before we had to head up again. It was maybe 200m across and really amazing to see.
Later in the flight we had really beautiful sunset colors. Because of the way the time zones and date line works this way, we had a very short ‘day’, and actually landed in Punta Arenas earlier than we set off from Christchurch, which felt very strange.