Nasa will launch its second super-sized scientific research balloon from Wanaka on Friday. Wanaka reporter Margot Taylor asked Nasa balloon programme project engineer Henry Cathey about preparations for the launch.
Q: What are the challenges of such a launch?
A: The big driver for a launch opportunity is the weather. We need to have a calm day with low and predicable winds for a long period of time (three to four hours). The balloon is quite big (532,000 cu m), and if the winds increase and blow on such a large surface area, it can result in very large forces which can be dangerous and unpredictable.
Q: What preparation still has to be done ahead of April 1?
A: There are a few items that are still being prepared, but the next major milestone is what is called a hang test.
The hang test involves suspending the payload from the launch crane and hooking the entire system up from top to bottom (balloon, parachute, flight train, and payload).
This will be the first time all the components that will be flown will be connected. A set of tests will be run through the system to ensure that everything works the way it is supposed to and that there are no mechanical issues or electrical issues like electrical interference problems.
The operational control centre in Texas will be up and running to make sure the data flows from the payload to the satellites and back down. Final weights of all of the systems need to be made and the amount of helium gas to be used will be calculated.
There will be a Flight Line Procedures meeting, a nominal launch walk-through (discussing as if everything works as planned), and off-nominal launch walk through (planning for the unexpected), Flight Safety meetings, the authority to proceed meeting, and more ... bottom line, we want to be ready for the expected, prepared for the unexpected, and know how to do everything safely.
Q: How has the balloon been modified to overcome the leak which caused last year's flight to be terminated?
A: It was found that the day/night temperature cycling on the balloon due to hot days in the sun during the day and cold nights in the dark helped slowly pull the balloon material out of the clamped fitting at the top of the balloon.
Pull the material out of the fitting and you have a leak. With the cause known, the interface of the balloon material to the fitting was changed to better clamp the balloon film and to make sure that the film could not pull out over time or with cyclic loading.
Recovery of the balloon allowed this issue to be identified and a fix made. Flight, recovery, flight improvements, and fly again - one of the great strengths of flying on balloons.
Q: Who is working on the launch?
A: There are PhD physicists, electrical engineers, computer programmers and more who work on the science payload.
The flight systems support personnel include electrical engineers, technicians, rigging personnel, heavy equipment operators, experts in handling compressed gases like helium, a launch crew chief and more.
The balloon support team is composed of mechanical, materials, and aerospace engineers. Campaign management, meteorology, safety, management, videographer, and others round out the team. There are local personnel at the Wanaka Airport, Queenstown Airport, and the like who are also supporting our efforts. All told, about 40 people have travelled to New Zealand to support this launch.
Q: After the launch, what does the focus for technicians become?
A: The science team starts operating their instrument, collecting data, and changing the way we as humans understand how the universe works (seriously, that is the point of the science!)...
The flight systems and balloon flight performance will be watched 24/7 for the entire mission.
This means people will be looking at the pressure in the balloon which varies based on time of day, temperature of key flight systems, power levels, data, communication, flight path and trajectory, and in-flight images of the balloon and surroundings.
The flight will be monitored locally for a couple of days and then flight control will be handed off to personnel in the United States for the duration of the flight.
Overarching every step of the process is Flight Safety, which monitors the mission to ensure that the system is healthy and that all phases of the flight are done safely.
-By Margot Taylor
