A very succesful Antarctic balloon campaign (1/23/2008)

Williams Field, McMurdo Base.- The stratospheric balloon launch campaign being carried out by NASA every austral summer since the early nineties in Antarctica had set this year a new record: for the first time three big payloads were launched and flew simultaneously around the white continent.

The campaign started last November with the arrival of the first technical staff from the Columbia Scientific Balloon facility (CSBF) to McMurdo base to put in shape the two big buildings to be used for the integration of the three payloads to be flown this year. A few days after them, arrived via Christchurch (New Zealand) the scientific teams in charge of each balloon-borne instrument which had came earlier that month by ship from the United States. As for December 5, the three payloads where declared "flight ready" only waiting the right weather to start they flight.

As occured last year, the climate was not much cooperative forcing to launch up to three pathfinder probes (small balloons attached with a GPS to trace the flight path of the stratospheric winds) before asset that the polar vortex acquired a minimum stability in his anti-clockwise flow, to allow the launch window to be opened.

The launches

Once opened the launch window the first balloon released carried an experiment called CREAM (Cosmic Ray Energetics And Mass) developed by the University of Maryland along with NASA's Wallops Flight Facility devoted to explore the supernova acceleration limit of cosmic rays, the relativistic gas of protons, electrons and heavy nuclei arriving at Earth from outside the solar system.

The flight started with a handbook launch at 3:29 utc on December 19. Two hours later the balloon (near 40 millon cubic feet of volume) reached float altitude of 120.000 feet and mounted on the polar vortex initiated a race around the continent.

At right we can see the exact moment of the balloon release. This was the third trip on ice for CREAM after other two succesfull missions in 2004 (which still holds the endurance record of nearly 42 days) and in 2005

Four days later, was carried out the second launch. This time the payload was an experiment called POLAR-BESS (Balloon-borne Experiment with a Superconducting Spectrometer - POLAR VERSION) devoted to search for antimatter in the cosmic radiation, as well as measure energy and intensity of less exotic components of the cosmic radiation. That instrument -a modified version specially suited to long-duration balloon missions of the standard BESS superconductor which had been flown near 15 times in the past since 1993- is a collaboration between NASA's Goddard Space Flight Center and the japanese High Energy Accelerator Research Organization.

The balloon was launched two days before Christmas and as well the one wich preceded it, started his way around the pole without troubles. This was the second flight of POLAR-BESS after a first succesfull mission in 2004.

The balloon constellation was completed on December 26, with the launch of ATIC (Advanced Thin Ionization Calorimeter) composed mainly by a ionization calorimeter with the objective of to measure the cosmic ray proton and helium spectra. The experiment, developed by the Louisiana State University was in Antarctica for his fourth flight after two succesful missions in 2000 and 2002 and a failed mission due to balloon problems in 2005. Thus, for the first time the Columbia Scientific Balloon Facility had in flight over the white snow of Antarctica three balloon/payloads simultaneously.

This achievement was possible due to the tight collaboration between the National Science Foundation which manages the U.S. Antarctic Program, and NASA. Both agencies signed three years ago an agreement in 2003 aimed at increasing the launch tempo to three balloons per season. With modest investments but considerable effort by both agencies, this goal was achieved. The feat is particularly significant, as it occurs during the height of the International Polar Year (IPY), a coordinated scientific campaign that is engaging scientists from more than 60 nations.

What goes up, must come down

At first, each scientific payload team had stablished a goal: to make if possible a minimum of two complete rounds to the pole, and even the CREAM people wished (the balloon wich showed the more stable "orbit") dreamed about equal or surpass their own record of more than 3 rounds and 42 days of flight. Nevertheless, soon these especulations where grounded because on January 14 the NSF informed to NASA that all balloons must be terminated as close as possible from McMurdo, because an airplane crash left reduced the flight cappability of the NSF and taking account that the recovery of payloads is not a high priority for the foundation, there were risk of the payloads never returned or returned with severe damage in case of a longer stay in the open ice.

Thus the first balloon terminated was ATIC. In the last days of the flight, after done a circle and a half around the pole the balloon path was somewhat erratic, so to avoid a risky recovery in a landing zone with hard accesibility, was decided to bring it down. The operation was carried out on january 14 when a Hercules C-130 which departed from McMurdo get close enough to the balloon and sent the balloon destruction and payload separation commands.

During that manouver, was tested for the first time in a scientific flight the new Ripstitch Shock Attenuator intended to reduce the parachute opening shock. This allowed during the critical phase of the descent also for the first time to maintain the telemetry link between the Operations Center at Palestine (both by Iridium and TDRSS) and the falling payload. Once landed the CSBF people in the other side of the world was able to follow the automatic procedures that separated the parachute from the payload, thus avoiding the risk of the former became a huge sail that would be dragged the payload across the Antarctic Plateau. This last part of the landing procedure was a vital one because until now, the separation commands were sent in a "blind" mode with no link or confirmation other than visual from the termination plane. ATIC's total flight time was 19 days, 10 hours and 43 minutes.

Two days later, was the turn for CREAM. Near completing his second full circle over the plateau (the first one was done on January 2 with an awesome appearance of the balloon directly over McMurdo base) the payload was succesfully separated from the balloon, landing a merely 177 nautic miles from the launch site. The gondola tipped over his side but landed in excelent condition thanks to the new Rip Stitch system which also worked flawlessly this time. The total flight time for CREAM was 28 days, 21 hours y 53 minutes.

Finally, BESS, the last balloon remaining in flight was grounded on January 22 landing in very good shape in a terrain of easy access between Patriots Hills station and AGO" research site, in the other site of the plateau. As occured with CREAM once landed, the parachute detached from the payload which remained upright, over his crush pads.

As a final word, let me say that during the following days surelly we will read about NASA surpassing their own records: three payloads in the air simultaneously, a total scientific weight near 13.000 lbs and that the three missions went more than succesfully. Probably what we will not read elsewhere, but still remains clear, is the fact that scientific ballooning even under hard environmental conditions as those present in Antarctica, is a superb tool serving the advance of the science. A tool that seems from another era, but, which with the help of technology and innovation is very competitive even today, in full space age.

More information availablle at:

Columbia Scientific Balloon Facility: http://www.csbf.nasa.gov/
CREAM web: http://cosmicray.umd.edu/cream/
ATIC web: http://atic.phys.lsu.edu/aticweb/
BESS web: http://bess.kek.jp/~masaya/bess/index.htm