After several postponements due to atmospheric conditions following a week of unsettled upper-atmospheric and surface weather in the wake of Tropical Cyclone Pam, NASA launched its pressure balloon from Wanaka on the morning of 27 March. It has reached the designed float altitude and pressurised.”
So reads the official announcement relating to the launch of the very special NASA balloon that caught the imaginations of the people of Central Otago and indeed the whole of the South Island.
Once launched, the pumpkin-shaped balloon, made from 22 acres (8.9ha) of material and as large as a football stadium when fully inflated, ascended to a constant float altitude of 110,000ft (33.5km).
The balloon is now travelling eastward carrying a 5000lb (2267 kg) payload consisting of tracking and communications instruments. NASA expects the super pressure balloon (SPB) to circumnavigate the globe once every one to three weeks, depending on wind speeds in the stratosphere.
The science and engineering communities have previously identified ultra long-duration balloon flights at stable altitudes as playing an important role in providing low cost access to the near-space environment for science and technology.
Maintaining a constant float altitude in the stratosphere is a formidable challenge for airborne systems, including balloons. Most standard heavy-lift zero pressure balloons can vary in altitudes as much as 45,000ft due to the alternating warming and cooling of the day and night cycle.
In response, mission operators typically release excess weight in the form of ballast to maintain altitude. However, the SPB is designed to maintain a positive internal pressure and shape irrespective of its environment, keeping the balloon at a constant float altitude. Put another way, in much the same way a car tyre pressure changes based on the environment around it while maintaining its volume, so does the SPB.
This March test mission is set to validate the SPB technology, which has been under development by NASA for 15 years, according to Debbie Fairbrother, chief of NASA’s Balloon Programme Office and principal investigator for the SPB.
NASA’s scientific balloons offer low-cost, near-space access for scientific payloads weighing up to 8000lb for conducting scientific investigations in fields such as astrophysics, heliophysics and atmospheric research.
Ralph Fegan, long-time general manager of Wanaka Airport from where the launch was made, had an insider’s perspective of just how NASA went about preparing for and then activating the launch. He was there from the time the countdown started at midnight before launch and was the first outsider to be present at the launch pad when the balloon finally became airborne.
Ralph says there was a meteorology presentation at midnight and everyone gathered at the launching site and back in the United States was very aware that the decision on whether the launch went ahead or was aborted was in the hands of project meteorologist, Ross Hay.
According to Ralph it was not until after 5am on the morning of the launch that Ross was prepared to endorse the action. Until then he had been launching a series of trial balloons which he tracked using sophisticated technology.
One of the problems causing previous cancellations of the flight had been that while the weather at higher levels was suitable for the launch, the close proximity of mountain ranges to Wanaka Airport had produced turbulent winds.
While NASA had prepared a meticulous timeline with a launch scheduled for 8am, doubts about the weather meant about an hour was added to the launch time.
Ralph says there was an aspect of danger for people. However, “This only related to the balloon failing to gain altitude or alternatively something becoming detached from the gondola unit that could fall on somebody on the ground. There is no danger from the helium gas itself as it is inert, that is, non-explosive.”
Because of the danger to people if the balloon or its fuel were to explode, all non-essential personnel and other people working at the airport were moved under shelter. The road past the airport was closed and the fire service began to prepare for any possible danger to people or property.
Indeed, the balloon was finally prepared for launching just 20 minutes before liftoff. A clearance was requested and received by air traffic control and permission to launch was given. With all personnel in position was balloon was then launched.
Ralph says he is very proud that the gondola slung beneath the balloon, which was carrying technological equipment for NASA, was topped by a red Anzac Day poppy.
While the balloon did not look very impressive at first, it soon swelled to the size of two rugby fields, and Ralph says only a short time afterwards he received word that the balloon was clearly visible in Ashburton, close to where it crossed the New Zealand coast.
As the balloon travels around the Earth, it may be visible from the ground, particularly at sunrise and sunset, to those who live in the southern hemisphere’s mid-latitudes, such as New Zealand, Argentina, Australia and South Africa. NASA seeks to fly the balloon for an ultra-long-duration, potentially up to 100 days, at a stable float altitude. The current record for an SPB flight is 54 days.
The science and engineering communities have previously identified ultra-long-duration balloon flights at stable altitudes as playing an important role in providing low-cost access to the near-space environment for science and technology.
Ralph Fegan is proud to have been associated with NASA in this memorable project. He says that although NASA is commendably cautious in its predictions of the duration of the flight, he believes it will encircle the earth for “more than five times” before its descent.
- Report by Peter Owens, photograph by Ralph Fegan.