McMurdo Station, Antarctica.- In less than 72 hours, the Columbia Scientific Balloon Facility (CSBF) entity in charge of the operations for NASA's balloon program, has landed the three large balloons that were orbiting the immense white Antarctic desert since last November. As every year since 1989, thanks to a very stable stratospheric anticyclonic vortex over the South Pole which sets at the beginning of December, the American space agency launched huge stratospheric balloons in circumpolar flight to carry out long-term missions around the continent with the most diverse scientific objectives: from particles physics and observation of the cosmic microwave background to astronomy and astrophysics studies throughout the visible and invisible spectrum.
In that context, the 2016/2017 campaign has had several singularities in its development that have turned it into one of the most fruitful -in operational terms- since the program's inception. Time will tell if those fruits are reflected in the scientific data obtained by each of the participating instruments. But that's another question.
After the completion of the BACCUS mission on December 28 which I've already commented in a previous post, the next instrument in finalizing its flight has been ANITA-IV. The payload was separated from the balloon around 5:30 utc on December 30, landing at a site near the Amundsen-Scott base, totaling two and a half turns to the continent in 27 days, 16 hours and 52 minutes..
This was the fourth Antarctic trip of the instrument, after other succesful flights performed in 2006 (ANITA-I), 2008 (ANITA-II), and more recently in 2014 (ANITA-III). As I've mentioned as I've started to chronicle from this pages the ongoings of the campaign, ANITA is an acronym for Antarctic Impulsive Transient Antenna and was developed to study from the stratosphere ultra-high-energy (UHE) cosmic neutrinos by detecting the radio pulses emitted by their interactions with the Antarctic ice sheet below. The instrument is the fruit of a collaboration between the University of Hawaii at Manoa, the University of California (LA), the Ohio State University, the University of Delaware, the University of Kansas, Washington University, the NASA Jet Propulsion Laboratory, University College London, University of Chicago and National Taiwan University.
This fourth flight of ANITA is the third in terms of duration, behind the ANITA-I mission that reached 35 days, 1 hour and 29 minutes of flight, and ANITA-II that completed its route around the pole in 30 days and 16 hours.
A few hours after ANITA's landing, would be the turn of the last balloon in flight to come down. That same day, December 30th. at 20:00 utc would arrive the end of its route for the mission 672N, launched the 8 of December and carrying the telescope STO-2 (acronym of Stratospheric Terahertz Observatory - II) a NASA-funded long-duration balloon experiment designed to address a key problem in modern astrophysics: understanding the life cycle of molecular clouds forming stars in our Milky Way Galaxy.
After separation from the balloon, the instrument landed some 340 nautical miles south of McMurdo, in a site located at the other end of the Ross Ice Shelf, at the opposite edge of which is located the American base. The total flight time for STO-2 was 21 days, 23 hours and 9 minutes.
This second incarnation of the telescope developed by the University of Arizona had to make its debut flight during the 2015/2016 campaign, but a very uncooperative climate forced to launch only one of the two participating instruments. As a result STO-2 had to wait its turn during the campaign that just finished, after spending a long winter in a warehouse in McMurdo. However, an earlier version of the instrument, already carried out an Antarctic mission in 2012.
This ends the operational flight phase of the campaign. What remains, is the recovery of the instruments and the valuable data they keep.
This second phase -which may be quite more complex than the first- will surely be the subject of a new post on this site, as it unfolds.
Stay tuned and, by the way, happy 2017 year for all!