Seeing as how I just bade farewell to the majority of the Super Tiger team last night, I figured this would be a good time to finally devote a blog post to explaining the Long Duration Balloon facility….so back into the science we dive! (And apologies if this reads like a school essay on LDB but I really find it all so interesting I couldn’t help it!.)
First, some history:
Balloons have long been used to increase our knowledge of the world by widening the perspective from which we view it.
In 1961, however, the National Science Foundation (NSF) established a facility in Boulder, Colorado from which balloons could be launched specifically for the purpose of conducting scientific research. In 1963, the facility was moved to Palestine, Texas and in 1973, it was christened the National Scientific Balloon Facility (NSBF) and a second launch area was constructed for much larger balloons than they had been previously using. In 1982, sponsorship of the NSBF transferred to NASA’s hands which coincided with an increasing interest in balloon-based research from space agencies around the world. To keep pace with the others, NASA formed a team exclusively devoted to design, construction, and operational support of long duration balloons so that research missions could be undertaken on an annual basis. In the early 90s, NASA and the National Science Foundation collaborated on two remote campaigns in Antarctica to conduct test flights from Williams Field, about 7 miles from McMurdo Station, which would include science payloads. The success of these test flights led to the permanent installation of the Long Duration Balloon Facility.
Initially, the facility consisted of one 40 foot wide tent-like building made of fiberglass and Teflon and placed atop plywood platforms on Willy Field. The building housed the payloads as they were being prepared, as well as a 21 foot high rolling bridge crane to lift the payloads for launch. Unfortunately, this meant that at the end of each austral summer, the building had to be taken down, transported to McMurdo, and stored for winter, while the crane and platforms were left behind. Every spring, a work crew would have to reconstruct the building and try to unearth and re-level the platforms that had been buried in snow.
While undoubtedly a lot of work, it seemed to suit its purpose until a freak storm in 1995 rendered the structure unusable, only 3 weeks before the payloads were due to be assembled. Ever resourceful, McMurdo’s carp shop gathered some lumber already on station and built out an unused heavy machinery garage that was already at Willy Field.
This sturdier structure solved the problem of needing to set up and take down the facility at the end of every season but as another building was eventually added to accommodate the program’s growth, it was taking longer and longer to dig the buildings out of the winter snow. By 2000, it was taking three full weeks working 10-12 hour days for two large bulldozers (and their operators) to clear away enough snow to make the buildings functional. The cost of this was eating into the operating budget for the project, so NASA and the NSF invested in a new set of movable buildings on skis that could be placed on snow berms over the winter so the snow would not bury them. In the austral spring, electrical heating strips along the skis allow the buildings to slide free of their winter resting ground quite easily.
Since 2005, LDB has been housed in these six buildings out at Willy Field. Starting from the left, the first two buildings are the identical payload assembly buildings – they are the tallest buildings in Antarctica and the tallest in the world on skis. Then there’s the mechanical/rigging workshop, followed by the telemetry building (the one with the golf balls on top). The next two buildings are primarily devoted to all that is necessary for providing heat, hot water, and toilets for the facility. And the last little cylindrical building is the galley!
Yes, NASA not only provides a kitchen and dining room for the facility but their budget is something like $5/person per day more than the budget for the station’s galley. So the crew out there not only get better quality and more expensive ingredients but because there are so few people to cook for compared to the rest of the station, they eat really well. It also doesn’t hurt that Lisa, the LDB cook, is kind of awesome at her job.
So why was the facility established in Antarctica, you ask? Well, the program initially started with launch sites in Colorado and Texas and there have been other locations used for launches in Australia and the Arctic and Europe but there are several reasons why Antarctica trumps them all.
Firstly, Antarctica is a continent – this means that there is a permanent land mass on which the facilities for such a program can be operated and maintained. Secondly, Antarctica is politically neutral and sparsely populated. This greatly reduces the risk of disagreements over airspace usage and incidents where the payload crashes into somebody/thing during launch, flight, descent, or landing.
Thirdly, because of an atmospheric phenomenon called the “Polar Vortex”, it’s fairly easy to control the flight of the balloon without needing to fit it with a navigation system – the Vortex is a persistent, large, low-pressure system that constantly circumnavigates the continent, forcing the balloon in a roughly circular pattern. While the same phenomenon exists in the Arctic, it is less pronounced, less persistent and is elongated in shape with two centres – one in Canada and one in Siberia.
Fourthly, during the austral summer, there is constant sunlight. The benefit of this is two-fold: the reduction of day-to-night temperature fluctuations helps the balloon maintain a constant altitude; and, fitting the payloads with solar panels means there is no need to include an external power source for the electrical components.
Finally, and this is a very experiment-specific reason, the proximity to the magnetic pole means the experiment will have more exposure to cosmic rays…which, if you’re studying cosmic rays (like Super-Tiger was this year), is a very very good thing.
Okay, so now you may be asking why these researchers are using balloons since we’ve got all this great technology now, shouldn’t we be launching satellites? KC, I’m looking at you on this one – I’m remembering some desire of yours to launch a satellite in your backyard to detect populations of bioluminescent dinoflagellates. Maybe you should look into balloons…
Balloons can get above 99% of the atmosphere, they are much cheaper than satellites and can, in fact, carry much heavier payloads. The development time is only 3 to 4 years as opposed to 10-15 years and you can get your payload back, if you so desire.
The balloons used by LDB (as we colloquially refer to the facility) are basically giant plastic bags: polyethylene film – at a thickness of about 0.002 centimetres (or 0.0008 inches) – is cut into 180 giant banana-peel shaped sections, then heat-sealed together to form the balloons. At full float, they are basically the size of the Houston Astrodome.
To launch the balloons, they are partially inflated with helium gas. As they rise, the lower atmospheric pressure causes the gas to expand and fill out the balloon fully. The bottom is left open to the atmosphere to allow its internal pressure to equalize with its surroundings. These balloons can carry payloads weighing up to 3,600 kilos (7,936 lbs) and they can fly up to 42 kilometers (26 miles) high. AND, as we’ve learned from the Super Tiger project, they can stay afloat in excess of 50 days!
So how does this all come together? Well, all the projects intending to launch balloons must go through rigorous testing in Texas at the National Scientific Balloon Facility – which has now been renamed the Columbia Scientific Balloon Facility (or CSBF) in honor of the Columbia Shuttle Mission. If all goes well in Texas, all the equipment, instruments, and personnel are flown down here on the C-17s, and final assembly of payloads begins at the LDB facility on the Ice.
When a payload is ready for launch, and the polar vortex is confirmed to be in place, a pilot balloon is sent up to approximately 4,000 feet (1,220 meters) to calculate wind speed and direction so the actual long duration balloon can be laid out in the proper direction at launch time. Then the balloon is connected by very very long cables to a termination package, then a parachute, then a separation package, and finally to the payload, which is suspended from a crane fitted to a vehicle (nicknamed “The Boss” after Ernest Shackleton). This launch technique is called the dynamic technique – I assume because it allows the payload to be moved with the balloon as it inflates, avoiding undue stress on the cables and only releasing the payload once it is positioned directly under the balloon (thus avoiding any swinging 8000lb payloads).
Once the balloon is launched, the instruments on the payload begin recording data and transmitting it to the research team. A tracking system on the payload enables the scientists to track the progress of the balloon around the continent as it moves with the vortex. Once the measurements are completed and the balloon is positioned somewhere (relatively) convenient for retrieval, the termination package is activated, which separates the parachute from the balloon, while simultaneously tearing open the top of the balloon. The balloon quickly deflates and falls to earth to be recovered for disposal; our scientists try not to be litterbugs. The payload descends more gently, suspended by the parachute. Once on the ground, the separation package is deployed to separate the parachute from the payload so that an errant wind doesn’t accidentally drag the payload into the ocean…and yes, even with payloads of 8000 lbs, this is entirely possible – Antarctica is the windiest place on earth.
Then members of the research team are flown out to the landing site in a Twin Otter to recover any data recorders (if necessary) and assess how much of the rest of the payload can be retrieved safely. Once they’ve gotten as much as they can (or want), they get to go home.
And that’s the story of LDB.
*Special thanks to the Super-TIGER, EBEX, and BLAST-Pol teams for all the information (and drinks) as well as NASA, Stratocat, and Science Roadshow for pictures and history.